AN cJU<^£jl

A^L

INTRODUCTION

ENTOMOLOGY

BY

JOHN HENRY COMSTOCK

PROFESSOR OF ENTOMOLOGY \M> GENERAL INVERTEBRATE ZOOLOGY
l\ CORNELL I NIVERSIT'S

AND FORMERLY

U N ! I ED S T A T E S E N T M O LOG I SI

WITH MANY ORIGINAL ILLUSTRATIONS

ft

I ik AWN AND ENGRAVED BY

ANNA BOTSFORD COMSTOCK

ITHACA, N. \.

PUBLISH ED BY T II E AC Til <> K

t888

AN

INTRODUCTION

TO

ENTOMOLOGY

BY

JOHN HENRY COMSTOCK

PROFESSOR OF ENTOMOLOGY AND GENERAL INVERTEBRATE ZOOLOGY
IN CORNELL UNIVERSITY

and formerly

United States Entomologist

WITH MANY ORIGINAL ILLUSTRATIONS

DRAWN AND ENGRAVED BY

ANNA BOTSFORD COMSTOCK

ITHACA, N. Y.
PUBLISHED BY THE AUTHOR

188S

Copyright, 1888,
By JOHN HENRY COMSTOCK.

>,1

PREFACE TO PART I.

This work has been prepared to meet the demand for a text-
book which shall enable students to acquire a thorough knowledge
of the elementary principles of Entomology, and to classify in-
sects by means of analytical keys similar to those used in Botany.
By means of the keys the student can readily determine to what
family any insect of which he has a specimen belongs. In many
cases tables of genera are also given ; and the more common or
conspicuous species in each family have been described.

Although much pains has been taken to render easy the classifi-
cation of specimens, an effort has been made to give the mere deter-
mination of the names of insects a very subordinate place. The
groups of insects have been fully characterized, so that their relative
affinities may be learned ; and much space has been given to
accounts of the habits and transformations of the forms described.
As the needs of Agricultural students have been kept constantly
in view, those species that are of economic importance have been
described as fully as practicable, and particular attention has been
given to descriptions of the methods of destroying those that arc
noxious, or of preventing their ravages.

The pronunciation of the technical terms has been indicated by
marking the accented vowel, and at the same time indicating its
length when the term is pronounced as an English word.

All the illustrations not credited to other sources arc original,
and have been drawn and engraved by Mrs. Comstock.

The specimens that have been studied in the preparation of this
work are nearly all in the collections of the Entomological Depart-

IV PREFACE TO PART I.

ment of Cornell University. That these collections are in a suffi-
ciently good condition for this purpose is due very largely to the
generous assistance of many Entomologists. Specific acknowledg-
ments will be made later.

As the completion of the work has been delayed by other duties,
it has seemed best to issue this part at this time. Other chapters
will be published as soon as practicable. In addition to the system-
atic part, the scope of which can be inferred from that given here,
there are to be chapters on the Means of Destroying Insects or of
Preventing their Ravages, the Collection and Preservation of Ento-
mological Specimens, Entomological Supplies, a Classified List of
Entomological Works, a Glossary, and an Introductory Chapter.

John Henry Comstock.

Entomological Laboratory, Cornell University,
September, iSSS.

AN INTRODUCTION TO ENTOMOLOGY.

CHAPTER I.

THE CHARACTERS AND METAMORPHOSES OF INSECTS
(HEXAPODA).

I. The Characters of the Hexapoda.

The term Insect is from two Latin words — in, in, and seco, to cut.
It refers to the fact that in the animals indicated by it the body is
divided by transverse incisions into a series of segments. As has
been shown in the Introductory Chapter, this insected form of the
body is characteristic of two of the larger divisions of the Animal
Kingdom, the Vermes, or Worms and the Arthropoda. But the term
Insect has become restricted to a portion of this great series of ani-
mals. There is, however, a lack of uniformity in the use of the term
among zoological writers. By some it is applied to all Arthropoda
that breathe by means of a system of air-tubes (tracked) extending
throughout the body. This includes Centipedes, Millepedes, Spiders
and allied forms, as well as the six-footed insects. Other writers in-
clude among Insects only those orders which are characterized by
the possession of but six legs. It is in this restricted sense that I
have used the term Insect. Whenever reference is made to all of the
Arthropoda that breathe by means of tracheae, they are designated
as the TracJiedta.

Insects, in the restricted sense indicated above, constitute the
class Hexapoda.* The insected or
segmented form of the body is shown
in Fig. i, and in nearly all of the
species figured in the following pages.
The peculiar structure of the respira-
tory system, which is characteristic of FlG , I# _ Nym;)h „ f the Re d-ie K ged Locust,
these animals, and which allies them (AflerE,nm ""-»

to other Tracheata, is described in the next chapter. In the Hexapoda

* Hexapoda : hex (e'|), six; pons (novi), a foot.

2 AN INTRODUCTION TO ENTOMOLOGY.

the typical adult is furnished with six legs ; the segments of the

body are grouped into three regions, head,
^-^r~ y< thorax, and abdomen, Fig. 2 ; and the

body is usually furnished with wings.
Exceptions to each of these characteristics
occur. The more important of these ex-
ceptions are discussed in the course of the
following chapters.

Fig. *.-Monobia. jj j HE METAMORPHOSES OF INSECTS.

Among the marvellous facts revealed by the study of insects,
none is more striking than the wonderful transformations which many
of these creatures undergo. A large part of this book is devoted to
indicating these changes. In this chapter I wish simply to make
a few generalizations regarding the metamorphoses of insects, and
to define a few terms which are used in describing these changes.

Complete Metamorphosis. — From the egg of a butterfly there
emerges a worm-like creature, known as a caterpillar, which has upon
superficial examination very little in common with its parents. This
caterpillar eats and grows, and when fully grown changes to an ob-
long, apparently lifeless object, the chrysalis. After a time there
bursts forth from this chrysalis a butterfly, like that which produced
the egg. In a similar way, from the egg laid by a fly upon a piece
of meat there hatches, not a fly, but a footless, worm-like maggot.
This when fully grown changes to a quiescent object corresponding
to the chrysalis of the butterfly. Later from this object there
escapes a winged fly like that which laid the egg. Those insects,
like the butterflies and flesh-flies, which when they emerge from
the egg bear almost no resemblance in form to the adult insect
are said to undergo a complete metamorphosis. In other words, the
change of form undergone by the insect is a complete one.

Incomplete Metamorphosis. — There are, however, many insects
which after leaving the egg do not undergo such a remarkable change
of form as that indicated above. A young grasshopper just out from
the egg can be easily recognized as a grasshopper. It is of course
much smaller than the adult, and is not furnished with wings. Still
the form of the body is essentially the same as that of an adult.
After a time rudimentary wings appear; and these increase in
size from time to time till the adult state is reached. During
this development there is no point at which the insect passes

THE CHARACTERS AND METAMORPHOSES OF INSECTS.

into a quiescent state corresponding to the chrysalis state of the

butterfly. Those insects which, like the grasshoppers, when they

emerge from the egg resemble in form the adult arc said to undergo

an incomplete metamorphosis. In other words, after leaving the egg

they do not undergo a complete change of form.

Moulting, Exiivice. — The body-wall of an insect is rendered more

or less hard by the deposition within its cuticular

layer of a horny substance known as chitine.

The result of this hardening of the skin is to

render it inelastic. Consequently as the body of

an insect increases in size its skin becomes too

small for it. When this occurs a second soft skin

is formed beneath the outer hard one. Then the

outer skin splits open, usually along the back, and

the insect works itself out from it. The new skin

being elastic accommodates itself to the increased

size of the body. In a short time this new skin

becomes hardened ; and as the insect grows, it in

turn is cast off. This shedding of the skin is

termed moulting or ccdysis. The cast skins are

sometimes referred to as the exuvice. The number

of moults varies greatly in the different groups of insects. In Fig.

3 is shown the cast skin of a dragon-fly clinging to a reed.

The Egg. — The egg is the first of the four principal stages through

which an insect passes in the course of its development. In a few

instances the egg is retained within the body of the female until

after it is hatched ; in this case the in-
sect is said to be viviparous. An ap-
parent exception to the rule that all
ps* insects are produced from eggs is pre-
sented by certain generations of the
Plant-lice {Aphididce). This is discussed
in the description of that family. The
eggs of insects vary greatly in their
external characters. While many of
them are furnished with smooth oval
shells, in others the shells are beautiful-
ly ribbed, or pitted (Fig. 4), or furnished

Fig 4 --Egg of Cotton-worm ^eatiy with spines or other appendages. There

enlarged, (F rom the Author s Report l ■-"*.« m^^in-ici^^o. ^"'-1'-

on cotton insects.) exists also in one end of the egz of an

insect one or more pores known as mieropyles ; through these the

Fig. 3. — Exuviae of a
Dragonfly.

4 AN INTRODUCTION TO ENTOMOLOGY.

spermatozoa pass into the egg, and thus fertilize it. Many of the
interesting exhibitions of instinctive powers which I have described
in the following pages are connected with the care of their eggs
by insects.

The Larva. — The larva is the second of the four principal stages
in the life of an insect. It is the stage in which
an insect emerges from the egg. Familiar ex-
amples of larvae are caterpillars, maggots, grubs,

. \ -r • i • i i i i Fig. 5. — Larva of Diatricea.

etC. (rig. *,). It IS during the larval State that (From the Author's Re-
, r , • i i port for 1879.)

the growth of the insect is made ; and conse-
quently in this stage nearly all the moults are undergone. The
moults subsequent to this period are simply those made when the
insect changes from one stage to another.

Nearly all of the creatures commonly known as worms are not
true worms, but are the larvae of insects. Away from the sea-shore
but few worms are known to other than zoologists ; these are
earth-worms, leeches, hair-worms, and the various species parasitic
in the bodies of higher animals. The many worm-like animals
found feeding upon the tissues of plants, as tomato-worms, apple
worms, etc., are the larvae of insects. Other larvae of insects are
predaceous or parasitic.

The Piipa. — The pupa is the third of the four stages in the life of
^^-s^ _ an insect. In this stage the insect is

£k usually quiescent. But a few pupae,
» as those of mosquitoes, are active.
■. : -*f The change from the larva to the
pupa state is made by moulting the
skin of the fully grown larva. In the

Fig. 6. — Pupa of Platysamia. ,11 1 • r ,1 1 ■,

pupa the legs and wings or the adult
are represented in a rudimentary state. In the pupae of butterflies and
moths these organs are closely soldered to the breast of the insect
(Fig. 6), while in the pupae of bees, wasps, and beetles they are
free.

Chrysalis. — The term chrysalis is applied to the pupa of a but-
terfly. This name was suggested by the bright, metallic spots
with which the pupae of certain butterflies are marked. Two forms
of this word are in use: chrysalis,//, chrysalides; and chrysalid,//.
chrysalids.

The Cocoon. — Many larvae, as those of moths, when fully grown,
and before they change to pupae, spin about the body a silken case,

THE CHARACTERS AXD METAMORPHOSES OF IX SECTS.

within which the transformations are undergone. This case is

termed a cocoon. Frequently these

cocoons are made within a rolled

leaf (Fig. f), or on the surface of

the ground, where they are covered

with dry grass or other rubbish.

Certain hairy caterpillars make

their cocoons largely of their hair.

which they fasten together by a

, . -. r ... Fig. 7. — Cocoon of Telia.

thin film ot silk.

Immature Forms of Insects with Incomplete Metamorphosis, The
Nymph. — The terms larva and pupa are applicable only to the early

Fig. 8.— Nymph of Melanoplus, first stage.
(After Emerton.)

Fig. 9. — Nymph of Melanoflus, second stage.
(After Emerton.)

stages of insects with a complete metamorphosis. In the case of
those in which the transformation is an incomplete one, the changes
through which the immature insect passes after leaving the egg are

*?=*»

Fig. 10. — Nymph of MelanofiZus, third stage.
(After Emerton.)

Fig. 11. — Nymph of Melanoplus, fourth stage.
(After Emerton.)

so gradual that one cannot indicate any point at which the insect
ceases to be a larva and becomes a pupa. Recent writers have used,
therefore, the term nymph (a term formerly used as a synonym of
pupa) to designate the immature forms of insects with an incomplete
metamorphosis. This term is applied to all the stages between the
egg and the fully winged or adult state.

A nymph when it leaves the egg has no indications of wings.
After undergoing a greater or less number of moults, differing in
different species, small prolongations appear projecting from the

AN INTRODUCTION TO ENTOMOIOGY.

dorsal aspect of the meso- and metathorax. These become larger
and larger with each successive moult, assuming the form of pad-

Fig. 12. — Nymph of Melatioplns, fifth stage.
(After Emerton )

Fig. i%.—Melanoplus, adult.

like wing-cases. But these wing-cases never approximate in length
the perfect wings of insects in which these organs become fully
developed. There is, therefore, usually a very marked change
between the last nymph stage and the mature insect. (See Figs.
12 and 13.)

With the nymphs of certain families, dragon-flies, crickets, grass-
hoppers, and locusts, the wing-cases are inverted ; i.e., the aspect cor-
responding to the upper side of the wing is next to the body, and
the first pair of wing-cases extend back beneath the second pair.
This characteristic is useful in distinguishing the adult forms from
the nymphs of those species in which the wings never become fully
developed.

THE ANATOMY OF IX SECTS.

CHAPTER II.

THE ANATOMY OF INSECTS.

The subject of insect anatomy is separated into two divisions :
one, treating of the structure of the body-wall or skeleton ; the other,
of the internal organs. The former is termed external anatomy ; the
latter, internal anatomy.

The External Anatomy of Insects *

The relative positions of the more important parts of the body of
insects can be easily comprehended by recalling what has been said,
in the Introductory Chapter, regarding the type of structure pre-
sented by the Arthropoda. In this branch of the Animal Kingdom,
which includes insects, the body is an elongated cylinder composed
of many rings (Fig. 14). A cross-section of the body shows it to be

Fig. 14. — Diagram of structure of Arthropoda.

a tube within which are the various viscera, — muscles, alimentary
canal, heart, nervous system, reproductive organs, etc. The tubular
body-wall, being hardened and furnishing support to the softer or-
gans, is the skeleton. This hardening of the body-wall is due to the
deposition in it of some hard substance. In insects the substance
thus deposited is horny, and is termed chitine.

Between certain rings or segments of the body the body-wall
remains soft and flexible. In this way provision is made for the
various motions of the body. The ring-like nature of the segments
is best seen in larvae, and in the caudal part of adult insects. In the
cephalic part of adult insects it is less obvious.

When a single segment of the body is examined, the hardened
portion is not found to be a continuous ring, but is seen to be made
up of several portions more or less movable upon each other. Such
a hardened portion of the body-wall is termed a scleritc.

* See Tabular Review at the end of this part of this chapter for an explanation of the
lettering of the illustrations.

8 AN INTRODUCTION TO ENTOMOLOGY,

The sclerites constitute the greater part of the body-wall, the soft
membranous portions separating them being in most cases narrow.

Usually these narrow portions are mere
lines ; they are then called sutures.

Frequently the sutures become en-
tirely effaced. We are therefore often
unable to distinguish certain sclerites
in one species of insect which we know
to exist in another. In such cases the
effaced sutures are said to be obsolete.
Fig. i 5 .— Poiistes beiikosa. The segments of the body in a fully

developed insect are grouped into three regions : head, thorax, and
abdomen (Fig. 15). In the larval state this grouping of the segments
is not well shown.

The Head.

The head is the first of the three regions of the body. It is sup-
posed to be formed of several body-segments grown together; but
entomologists differ in their views as to the number of segments
that have entered into its composition.

It does not fall within the scope of this work to enter into this discussion.
The main point, however, can be stated here. A careful study of the various
forms of Arthropods shows that the typical body-segment possesses a pair of
legs, and only one pair. It is known that certain mouth parts (mandibles,
maxillce, and labium) are modified legs. (This fact is easily seen in many
Crustacea.; The antennae and the eyes may also be modified legs.* It follows
that if we find represented in the appendages of the head the appendages of
several segments, the head itself must consist of several segments coalesced.

The principal portion of the chitinized parts of the head are firm-
ly joined together so as to constitute a box which contains the brain
of the insect and certain other important organs. To this are artic-
ulated a number of jointed appendages. The parts of the head
may be classed, therefore, under two divisions : first, the fixed parts ;
second, the movable parts.

The Fixed Parts of the Head.

In addition to the external portions of the organs of vision (the
compound eyes, and the simple eyes), the fixed parts of the head
consist of four sclerites. Three of these sclerites (occiput, epicra-

* The belief that the eyes are modified legs is based on the fact that in certain Crusta-
cea the eyes are situated on stalks which are jointed appendages of the head.

THE ANATOMY OF INSECTS. g

nium, and clypeus) pertain to the dorsal surface ; and the fourth
(gula) to the ventral surface.

Frequently the sutures between some of these sclerites arc obso-
lete ; but by studying a series of insects each of these parts can be
distinguished.

The Compound Eyes. — In many insects the most striking in appear-
ance of the fixed parts of the head are the eyes (3).* These are
situated one on each lateral aspect of the
head. They are usually nearly hemispherical
and of considerable size. When examined with
a microscope, they present the honey-comb-
like appearance shown in Fig. 16. Each of
the hexagonal divisions of the eye is a cornea
of a distinct eve. These lame eyes are there- Fi G .i6.-Part of compound eye,

J n J greatly enlarged.

fore compound. Each of the small eyes of

which they are composed is termed an ocellus. Compound eyes are

not found in larvae.

The Simple Eyes. — In addition to the compound eyes, many insects
possess simple eyes (4). These are situated in adult insects on the
dorsal aspect of the head between the compound eyes, and in larvae
on the sides of the head. They vary in number in the adult from
one to four. The most common number is three; see Fig. 15.
Each simple eye resembles an ocellus of a compound eye. The
simple eyes are usually termed ocelli ; sometimes, stemmata.

When the term ocelli is used in descriptive works, if there is noth-
ing in the context to indicate the contrary, it is almost invariably
applied to the simple eyes, and not to the elements of the compound
eyes. In the same way the term eye usually refers to the compound
eyes, unless otherwise indicated by the context.

The Epicranium. — The epicranium (21 is usually the largest of the three
sclerites which pertain to the dorsal aspect of the head. It is that sclerite in
which the simple eyes are situated, and which surrounds the compound eyes.
It occupies an intermediate position in the dorsal aspect of the head, being
bounded caudadt by the occiput, and cephalad by the clypeus.

From the fact that the epicranium occupies so large a part of the head, it
frequently becomes necessary to speak of particular regions of it in making
detailed descriptions of insects. Consequently names have been given to cer-
tain parts; although those parts are very rarely distinct. These names are
front, vertex, and gentz. It is difficult to define definitely the regions of the
epicranium to which these terms have been applied. Roughly speaking, the

* See Tabular Review at end of discussion of External Anatomy.

f For definitions of the terms denoting position and direction of parts, see Glossary.

IO AN INTRODUCTION TO ENTOMOLOGY.

front (2a) is the cephalic portion of the epicranium (Fig. 17). It is bounded

cephalad by the clypeus, and laterad by the eyes
and gense. The vertex (2b) is the remaining part
of the dorsal portion of the epicranium ; it ex-
tends from between the eyes to the occiput. By
many writers the term vertex is used in a vague
manner to indicate the summit of the head.
The gence (2c) or cheeks are the lateral portions
Tig. I7 .-Head of locust. of the epicran ; um> t h ose par ts which are usually

ventrad of the eyes and caudad of the mandibles. In many insects a distinct
suture extends cephalad from each compound eye, separating the front from
the gense.

The Occiput. — The occiput (1) is that part of the dorsal wall of the head
which is articulated with the cephalic margin of the thorax (Fig. 18). In many

Fig 18.— Dorsal aspect of head of Harfalus. Fig. 19.— Ventral aspect of head of Har/atus.

insects it is a distinct sclerite ; in others it is not distinguishable from the epi-
cranium.

The Clypeus. — The clypeus (5) is the cephalic part of the dorsal portion of
the fixed parts of the head. It is bounded caudad by the epicranium, and
gives attachment cephalad to one of the movable parts of the head, the labrum
or upper lip. The clypeus is typically composed of two sclerites. When these
are distinct they are designated as the ante-clypeus and post-clypeus respectively.

The Gula. — The gula (6) is the only one of the fixed parts of the head that
is confined to the ventral aspect (Fig. 19). It is bounded laterad by the lateral
parts of the epicranium and occiput ; and extends caudad to the caudal border
of the head. Cephalad it gives attachment to one of the movable parts of the
head, the labium or lower lip.

The Movable Parts of the Head.

Under this category are classed a pair of jointed appendages
termed the antennae, and the organs known collectively as the mouth-
parts.

The Antennce.

The antennce (7) are a pair of jointed appendages, inserted in the
head in front of the eyes or between them. They vary in form.
In some insects they are thread-like, consisting of a series of similar
segments ; in others certain segments are greatly modified in form.
In the beetles of the genus Collops the antennae bear a curious articu-
lated appendage arising from near the base of the third segment.*

* Horn, Trans. Am. Ent. Soc, III. p. 79, with figure.

THE AX ATOMY OF INSECTS.

II

In descriptive works names have been given to particular parts of the anten-
nae, as follows (Fig. 20) :

The Scape. — The first or proximal segment of an antenna is called the scape
(a). The proximal end of this segment is often
£ ..-'--., subglobose, appearing like a distinct segment ; in

such cases it is called the bulb.

The Pedicel. — The pedicel (b) is the second
segmentof an antenna. In some insects it differs
greatly in form from the other segments.

The Cldvola. — The term clavola (c) is applied

to that part of the antenna distad of the pedicel ;

in other words, to all of the antenna except the

In some insects certain parts of the clavola are

These are the ring-joints, the

Fig. 20. — Antenna of Chalcis-fly.

first and second segments.

specialized and have received particular names.

funicle, and the club.

The Ring-joints. — In certain insects {e.g., Chalcididae) the proximal segment
or segments of the clavola are much shorter than the succeeding segments ; in
such cases they have received the name of ring-joints (V 1 ).

The Club. — In many insects the distal segments of the antennae are more or
less enlarged. In such cases they are termed the club (c 3 ).

The Funicle. — The funicle (V") is that part of the clavola between the club
and the ring-joints ; or, when the latter are not
specialized, between the club and the pedicel.

The various forms of antennae are designated by
special terms. The more common of these forms
are represented in Fig. 21. They are as follows:

1. Setaceous or bristle-like, in which the seg-
ments are successively smaller and smaller, the
whole organ tapering to a point.

2. Filiform or thread-like, in which the seg-
ments are of nearly uniform thickness.

3. Moniliform or necklace-form, in which the
segments are more or less globose, suggesting a
string of beads.

4. Serrate or saw-like, in which the segments are
triangular and project like the teeth of a saw.

5. Pectinate or comb-like, in which the segments
have long processes on one side, like the teeth of a
comb.

6. Cldvate or club-shaped, in which the segments
become gradually broader, so that the whole organ
assumes the form of a club.

7. Capitate or with a head, in which the terminal segment or segments form
a large knob.

8. Lamellate, in which the segments that compose the knob are extended
on one side into broad plates.

Fig. ax. — Various forms of an-
tennae.

12

AN INTRODUCTION TO ENTOMOLOGY.

6'

Fig.

-Mouth-parts of the Red-
legged Locust.

The Mouth-parts.
The mouth-parts (Fig. 22) consist typically of an upper lip, labrum
(8), an under lip, labium (12), and two
pairs of jaws acting horizontally between
them. The upper pair of jaws are called
the mandibles (10); the lower pair, the
maxillce (n). The maxillae and labium
are each furnished with a pair of feelers,
called respectively the maxillary palpi
(lid), and the labial palpi (i2d). There
may be also within the mouth one or two
tongue-like organs, the cpipJiarynx (9) and
hypopharynx (13).

No set of organs in the body of an insect
vary in form to a greater degree than do the
mouth-parts. Thus with some the mouth is
formed for biting, while with others it is formed
for sucking. Among the biting insects some are predaceous, and have jaws
fitted for seizing and tearing their prey ; others feed upon vegetable matter,
and have jaws for chewing this kind of food. Among the sucking insects
the butterfly merely sips the nectar from flowers, while the mosquito needs a
powerful instrument for piercing its victim. In this chapter the typical form
of the mouth-parts as illustrated by the biting insects is described. The
various modifications of it presented by the sucking insects are described later,
in the discussions of the characters of those insects.*

The Labrum.— The. labrum or upper lip (8) is an appendage of the cephalic
margin of the dorsal part of the head. It is usually a narrow transverse sclerite.
In some insects it is large and projecting, and often notched ; in others it is
concealed beneath a largely developed clypeus.

The Mandibles. — The mandibles (10) are the dorsal pair of jaws. They vary
much in form, but are usually three-sided, with their lateral t surface more or

* The more important papers on the nomenclature of the parts of the mouth in biting
insects are the following:

Kirby and Spenxe. Introduction to Entomology, vol. III. (1818.)

MacLeav, W. S. Horae entomologicae (2 vols., 1819, 1821). This work I have not

Straus-Durckheim, H. E. Considerations generate sur l'anatomie des animaux
articules. (1828.)

Newman, Edward. A paper on the nomenclature of the parts of the head of insects.

(1834.)

Newport, G. The article " Insecta," Todd's Cycl. of Anat. and Physiol. (1839.)
Brulle, A. Recherches sur les transformations des appendices dans les Articules.

Annales des Sciences Naturelles, t. II. (1844.)

f I have not attempted to determine the normal position of the mouth-parts, but have

described each with its distal end directed cephalad. This seems to me the way least

likely to lead to confusion.

THE ANATOMY OF IX SECTS.

13

less convex, and their mesal surface concave. Usually each mandible consists
of a single segment; but in some insects these organs are much more com-
plicated.

In several genera of Rove-beetles [Staphylinidce) each mandible is furnished
with an appendage (Fig. 23). This was named the prosthcca by Kirby and
Spence.

Fig. 23. — Mandible of Staphylinus.

Fig. 24. — Mandible of Euphoria inda.

In many beetles of the family Scarabaeidae each mandible consists of several
more or less distinct sclerites. This is vvel. shown in the mandible of Euphoria
inda (Fig. 24). These compound mandibles have not yet been studied with
sufficient care to enable us to definitely name the parts.

The Maxilla. — The maxillae (11) are the more ventral of the two pairs of
jaws. They are much more complicated than the mandibles, each maxilla
consisting, when all of the parts are present, of five primary parts and three ap-
pendages. The primary parts are the cat-do or hinge, the stipes or footstalk,
the palpifer or palpus-bearer, the subgalea or helmet-bearer, and the lacinia or
blade. The appendages are the maxillary palpus or feeler, the galea or superior
lobe, and the digitus or finger. The maxilla may also bear claw-like or tooth-
like projections, spines, bristles, and hairs.

In the following description of the parts of the maxillae, only very general
statements can be made. Not only is there an infinite variation in the form of
these parts, but the same part may have a very different outline on the dorsal
aspect of the maxilla from what it has on the ventral. Compare Fig. 25 and
Fig. 26, which represent the two aspects of the maxilla of Hydrophilus. Except-
ing Fig. 26, the figures of maxillae represent the ventral aspect of this organ.

Fig. 25 —Ventral aspect of
maxilla of Hydrophilus.

Fig. 26. — Dorsal aspect of
maxilla of Hydrophilus.

Fig.

Maxilla of EUodes.

The Cdrdo or hinge (a) is the first or proximal part of the maxilla. It is
usually more or less triangular in outline, and is the part upon which nearly all
of the motions of this organ depend. In many cases, however, it is not the

14 AN INTRODUCTION TO ENTOMOLOGY.

only part directly joined to the body; for frequently muscles extend direct to
the subgalea, without passing through the cardo.

The Stipes or footstalk (b) is the part next in order proceeding distad. It is
usually triangular, and articulates with the cardo by its base, with the palpifer
by its lateral margin, and with the subgalea by its mesal side. In the Orthop-
tera, Pseudoneuroptera, and Neuroptera, the stipes is united with the subgalea,
and the two form the larger portion of the body of the maxilla (Fig. 22). The
stipes has no appendages ; but the palpifer on the one side, and the subgalea
on the other, may become united to the stipes without any trace of suture
remaining, and their appendages will then appear to be borne by the stipes.
Thus in Fig. 22 it appears to be the stipes that bears the galea, and that receives
muscles from the body.

The Palpifer or palpus-bearer (c) is situated upon the lateral (outer) side of
the stipes ; it does not, however, extend to the base of this organ, and frequently
projects distad beyond it. It is often much more developed on the dorsal side
of the maxilla than on the ventral (Figs. 25 and 26). It can be readily distin-
guished when it is distinct by the insertion upon it of the appendage which
gives to it its name.

The Maxillary Palpus or feeler {d) is the most conspicuous of the appendages
of the maxilla. It is an organ composed of from one to six freely movable seg-
ments, and is articulated to the palpifer on the latero-distal angle of the body
of the maxilla.

The Subgalea or helmet-bearer (e) when developed as a distinct sclerite is
most easily distinguished as the one that bears the galea. It bounds the stipes
more or less completely on its mesal (inner) side, and is often directly connected
with the body by muscles. In many Coleoptera it is closely united to the
lacinia; this gives the lacinia the appearance of bearing the galea, and of being
connected with the body (Fig. 28). In the Orthoptera, the Pseudoneuroptera,
and the Neuroptera, the subgalea is united to the stipes; consequently in these
orders the stipes appears to bear the galea, and to be joined directly to the
body if any part besides the cardo is so connected.

The Galea or helmet (f) is the second in prominence of the appendages of the
maxilla. It consists of one or two segments, and is joined to
the maxilla mesad of the palpus. The galea varies greatly in
form : it is often more or less flattened, with the distal seg-
ment concave, and overlapping the lacinia like a hood. It
was this form that suggested the name galea or helmet.
In other cases the galea resembles a palpus in form (Fig.
28). The galea is also known as the outer lobe, the upper
lobe, or the superior lobe.

The Lacinia or blade (g) is borne on the mesal (inner)
Fig. 28.— Maxilla of margin of the subgalea. It is the cutting or chewing part
Cicmdeia. Q f t { ie max jii a) an( j j s often furnished with teeth and spines.

The lacinia is also known as the inner lobe, or the inferior lobe.

The Digitus or finger (/i) is a small appendage sometimes borne by the lacinia
at its distal end. In the Cicindelidse it is in the form of an articulated claw
(Fig. 28) ; but in certain other beetles it is more obviously one of the segments
of the maxilla (Figs. 25 and 26). This part is sometimes termed the unguis, a

THE ANATOMY OF INSECTS. I 5

name applied by Kirby and Spence to it and to the other claw-like projections
of the maxilla. The French entomologists distinguish it as le firemaxillaire.
Neither of these names is desirable ; the former is not restricted to this part of
the maxilla, but is often applied to the terminal portion of the lacinia; the latter
name is objectionable both in form and signification ; it is hardly appropriate
to apply the prefix pra to the most distal part of an appendage. I propose,
therefore, the name digitus for this sclerite.

The Labium or Second Maxilla. — The labium or under lip (12) is attached to
the cephalic border of the gula, and is the most ventral of the mouth-parts. It
appears to be a single organ, although sometimes cleft at its distal extremity ;
it is, however, composed of a pair of appendages grown together on the middle
line of the body. In the Crustacea the parts corresponding to the labium of
insects consist of two distinct organs, very closely resembling the maxilla-. In
this case they are termed the second maxillae, a name which is sometimes
applied to the labium of insects. Hence in defining the Hexapoda it is stated
that they have two pairs of maxillae.

In naming the parts of the labium, entomologists
have usually taken someform of it in which the two fci .--^j . I"]

parts are completely grown together, that is, one yU^v^ f

which is not cleft on the middle line (Fig. 29).
I will first describe such a labium, and later one

in which the division into two parts is carried as I. *"*. ^ — CiC^fS

far as we find it in insects.

The labium is usually described as consisting of

, ... , . . „. Fig. 29. — Labium of Harpalus.

three principal parts and a pair of appendages. 1 he

principal parts are the submentum, the mentum, and the Hgula; the appendages

are the labial palpi.

The basal part of the labium consists of two transverse sclerites ; the prox-
imal one, which is attached to the cephalic border of the gula, is the submen-
tum (a). This is often the most prominent part of the body of the labium.

The Mentum (b) is the more distal of the two primary parts of the labium.
It is articulated to the cephalic border of the submentum, and is often so
slightly developed that it is concealed by the submentum.*

The Ltgula (c) includes the remaining parts of the labium except the labial
palpi. It is a compound organ ; but in the higher insects the sutures between
the different sclerites of which it is composed are usually obsolete. Three
parts, however, are commonly distinguished (Fig. 29), a central part, often
greatly prolonged, the glossa (c" 2 ), and two parts, usually small membranous
projections, one on each side of the base of the glossa, the paraglossce u s >.

* Unfortunately the term mentum is applied by some entomologists to the submen-
tum, and the true mentum entirely overlooked or distinguished by a different name.
This is the case in one of the most important works in the literature of American ento-
mology, "The Classification of the Coleoptera of North America," by Le Conte and
Horn. The student in the use of this indispensable work must bear this change of names
in mind. These authors have termed the true mentum the hypoglottis, and state that in
the Carabidre the homologous portion is often called the " basal membrane of the hgula"
(/. c. p. xviii).

1 6 AN INTRODUCTION TO ENTOMOLOGY.

Sometimes, however, the paraglossae are large, exceeding the glossa in size
From the base of the ligula arise a pair of appendages, the labial palpi (d).
Each labial palpus consists of from one to four freely movable segments.

In the form of the labium just described, the correspondence of its parts to
the parts of the maxillae is not easily seen ; but this is much more evident in
the labium of some of the lower insects, as for example a cockroach (Fig. 30).
Here the organ is very deeply cleft ; only the submentum
and mentum remain united on the median line ; while the
ligula consists of two distinct maxilla-like parts. It is
easy in this case to trace the correspondence referred
to above. Each lateral half of the submentum corre-
sponds to the cardo of a maxilla ; each half of the mentum,
to the stipes ; while the remaining parts of a maxilla are
represented by each half of the ligula, as follows : near
the base of the ligula there is a part (c 1 ) which bears the
Fig. 3o.—Labium of labial palpus ; this appears in the figure like a basal segment
of the palpus ; but in many insects it is easily seen that it
is undoubtedly one of the primary parts of the organ ; it has been named the
palpiger, and is the homologue of the palpifer of a maxilla. The trunk of each
half of the ligula is formed by a large sclerite (c k ) to which I believe attention
has not been called heretofore. This evidently corresponds to the subgalea.
At the distal extremity of this subgalea of the labium there are two append-
ages. The lateral one of these (c s ) is the paraglossa, and obviously corre-
sponds to the galea. The mesal one (c 2 ) corresponds to the lacinia or inner
lobe. This part is probably wanting in those insects in which the glossa con-
sists of an undivided part; and in this case the glossa probably represents the
united and more or less elongated subgaleae.

The Epipharynx and the Hypopharynx. — In addition to the mouth-parts
described above, either the labrum or the labium may bear on its ental surface,
within the cavity of the mouth, a more or less tongue-like organ. If borne by
the labrum, it is termed the epipharynx (9) ; if by the labium, the hypopharynx
(13). (See Fig. 22.) The epipharynx and the hypopharynx are rarely both
developed in the same insect, except in some Hymenoptera. The form and
position of the hypopharynx are analogous to those of the tongue of higher
animals. On this account it has been named the lingua or tongue. But as
both of these terms have been applied to the glossa, it is best to designate this
part as the hypopharynx, and to avoid the use of the terms lingua and tongue,
as liable to be ambiguous.

The Thorax.

The thorax is the second or intermediate region of the body. It
is readily distinguished by its appendages, which are three pairs of
legs and one or two pairs of wings. This region consists of three
segments. The cephalic or first segment is named the protJwrax
(14) ; the second, the mcsothorax (15) ; and the third, the mctatJwrax
(16). Each segment bears a pair of legs ; and in winged insects the
wings are borne by the second and third segments.

THE ANATOMY OF INSECTS.

V

Fig. 31. — Diagram of the
fixed parts of a thoracic
segment.

The Fixed Parts of the Thorax.*

Each segment of the thorax is composed of several sclerites. The shape
and relative position of these sclerites afford characters which are much used
in classification. Fig. 31 is a diagrammatic representation
of what is considered the typical arrangement of these
parts in eacli of the thoracic segments. Each segment
of the thorax is a ring, which is divided into four parts :
a dorsal, a ventral, and two lateral. The dorsal part
is named the notum or tergum ; each lateral part the
pleilrum. ; and the ventral part the sternum.

When the notum or sternum of a particular thoracic
segment is to be indicated, it is done by the use of one of the prefixes pro,
mesa, or meta. In this way are formed the terms pronotum, mesonotum, tneta-
notu/n, presternum, mesosternum and metasternum ; which are applied to the
notaand sterna of the prothorax, mesothorax and metathorax respectively.

By some writers the entire dorsal part of an insect is termed the tergum ;
the lateral part, the pleilrum ; and the ventral part, the sternum. These
writers apply the terms tcrgite, pleurite, and sternite respectively to the dorsal,
lateral and ventral regions of each segment.

The tergum of each thoracic segment is composed typically of four scle-
rites. These are arranged in a linear series. They are named, beginning with
the first or most cephalic, prasciitum (a), scut fan (d), scutellum (c), and postscu-
tellum (d). (Fig. 32.) In the prothorax the sutures between these four scle-

Fig. 32. — Dorsal aspect of the thorax of a beetle,
Dysticus, dissected. (After Audouin.)

Fig.

-Necrophorus, to show scutellum.

* The more important works on the nomenclature of the parts of the thorax are the
following :

Audouin, J. V. Recherches anatomiquessur le thorax des animaux articules et celui
des insectes hexapodes en particulier. Annales des Sciences Naturelles, T. I. (1824).

The works of Kirby and Sprue,-, MacLeay, Straus-Durckheim, Newman, and
port cited on p. 12. The description of the anatomy of the thorax by MacLeay was
republished in the Ann. des Sci. Nat. t. 25 (1S32).

AN INTRODUCTION TO ENTOMOLOGY.

rites are in many cases obsolete, the pronotum appearing to be composed of a
single sclerite. In beetles and bugs the scutellum of the mesothorax is usually
quite conspicuous, appearing as a more or less nearly triangular piece between
the first pair of wings at their base (Fig. 33). Most entomological writers refer
to this sclerite as the scutellum. Of the four sclerites which compose the ter-
gal portion of each thoracic segment, the scutum is usually the largest ; the
scutellum is the second in importance; while thepraescutum and the postscutel-
lum are frequently but little developed. We find in the Hymenoptera that the
scutum of the mesothorax is divided into three parts by two longitudinal
sutures. The lateral portions of the scutum thus separated from the mesal
part are termed the pardpsides (i5<£ 2 ).

Each pleurum is composed of two sclerites, arranged more or less obliquely.
The cephalo-ventral one is the episternum (e) ; and the caudo-dorsal one the

Fig. 34. — Ventral aspect of a beetle, Enchroma gigantea. (See Tabular Review, p. 23, for explana-
tion of lettering.;

epimeron {/). We find in many insects a third sclerite in each pleurum of the
mesothorax and metathorax. These sclerites when present are situated near
the base of the wing, and articulate with the dorsal margin of the episternum ;
they are the pardptera (g). In certain orders, especially Hymenoptera, the
paraptera of the mesothorax are small, corneous, concavo-convex scales, which
cover and protect the bases of the first pair of wings. By many writers these
paraptera are termed the tegulce, and by others the scapula. In the Lepidop-

THE AX ATOMY OF IX SECTS. 1 9

tera, the paraptera of the mesothorax are greatly developed. Here they appear
as leaf-like epaulets, which sometimes cover not only the bases of the wings, but
also the greater part of the mesonotum. In descriptive works on this order
they are usually termed the patdgia.

In the membrane connecting the head with the prothorax there is on each
side a pair of small sclerites. These are termed the jugular sclerites (i4g).

Each sternum is composed of a single sclerite. As indicated above, the
three sterna are designated as the prosternum (14O, mesosternuvt (152)1 and
inetastemum (16/) respectively.

In some beetles the metasternum is divided into two unequal portions by a
suture which extends transversely a short distance in front of the caudal mar-
gin ; the smaller sclerite which borders the posterior coxae in front and often
passes between them is called the ante-coxal piece of the metasternum.

The Appendages of the Thorax.

The appendages of the thorax are the organs of locomotion.
They consist of the legs and the wings. Of the former there are
three pairs ; of the latter, never more than two. The distribution of
these appendages has already been given (p. 16). The legs are
joined to the body near the lateral borders of the sterna ; the wings,
near the lateral margins of the terga.

The Legs. — Each leg (17) consists of the following-named parts
and their appendages : coxa, trochanter, femur, tibia, and tarsus
(Fig- 34).

The Coxa. — The coxa (a) is the proximal segment of the leg. It is the one
by means of which the leg is articulated to the body. It varies much in form,
but is usually a truncated cone or nearly globular. In some insects the coxae
of the third pair of legs are more or less flattened and immovably attached to
the metasternum (e.g. Carabidse). In such cases the coxae really form a part
of the body-wall, and are liable to be mistaken for primary parts of the meta-
thorax instead of the proximal segments of a pair of appendages.

In certain insects there is a small sclerite between the coxa and the epime-
ron. This is considered an appendage of the coxa, and is called the trochan-
tin (a 1 ). It is more often visible in the prothorax than in the other segments.

T/ie Trochanter. — The trochanter (b) is the second part of the leg. It con-
sists usually of a very short, triangular or quadrangular segment, between the
coxa and the femur. Sometimes the femur appears to articulate directlv with
the coxa; and the trochanter to be merely an appendage of the proximal end
of the femur (e.g. Carabidse). But the fact is that in these insects, although
the femur may touch the coxa, it does not articulate with it; and the organs
that pass from the cavity of the coxa to that of the femur must pass thn >ugh
the trochanter. In the sub-order Terebrantia of the order Hymenoptera the
trochanter consists of two segments.

The Femur.— The femur (c) is the third part of the leg; and is usuallv tin-
largest part. It consists of a single segment.

20 AN INTRODUCTION TO ENTOMOLOGY.

The Tibia. — The tibia id) is the fourth part of the leg. It consists of a sin-
gle segment; and is usually a little more slender than the femur, although it
often equals or exceeds it in length. In such species as burrow in the ground,
the distal extremity is greatly broadened and shaped more or less like a hand.
Near the distal end of the tibia there are in most insects one or more spines
which are much larger than the other hairs and spines which arm the leg ; these
are called the tibial spines or tibial spurs, and are much used in classification.

The Tarsus. — The tarsus (<?) is the fifth and most distal part of the leg, that
which is popularly called the foot. It consists of a series of segments, varying
in number from one to six. The most common number of segments in the
tarsus is five. The distal segment bears one or two claws (e 1 ). Sometimes
these claws are strongly bifid or toothed ; so that a tarsus may appear to bear
four or even six claws. The tarsi vary much in form, and thus present charac-
ters which are useful in classification. Sexual characters are also frequently
presented by this part.

On the ventral surface of the segments of the tarsus in many insects are
cushions of short hairs or of membrane, capable of inflation, or concave plates,
which act so as to produce a vacuum and thus enable the insect to walk on the
lower surface of objects. These cushions or plates are called pulvilli (e 2 ). In
many insects the pulvillus of the distal segment of the tarsus is a circular pad
projecting between the tarsal claws. In most descriptive works this is referred
to as the pulvillus, even though the other pul villi are well developed. The pul-
villi are also called the onychii by some writers.

With many insects {e.g. most Diptera) the distal segment of the tarsus bears
a pair of pulvilli, one beneath each claw. In such cases there is frequently
between these pulvilli a third single appendage of similar structure; this is
called the empodium. In other insects the empodium is bristle-like or alto-
gether wanting.

The proximal segment of the tarsus is designated in some descriptive works
as the metatarsus.

Tlic Wings. — The normal number of wings is two pairs ; but in
addition to the large order Diptera, there are many .insects which
have only a single pair ; and many other insects are wingless. As
already stated, the first pair of wings is articulated to the meso-
thorax ; and the second pair, to the metathorax. When but a single
pair of wings is present, it is almost invariably the first pair.

Each wing is a plate-like or membranous expansion which is first developed
as a sac-like projection of the body-wall.* In the course of the formation of
the wing, the dorsal and ventral walls of this sac become united throughout
the greater part of their extent. There are usually certain lines along which
the walls of this sac are thickened. The thickenings of the dorsal and ventral
walls are exactly opposed, and together constitute the framework of the wing.
These thickened lines are termed the veins or nerves of the wings ; and their

* The gradual formation of wings can be easily observed in insects with an incomplete
metamorphosis. See description of the transformations of the Acridiidae.

THE ANATOMY OF IX SECTS.

21

arrangement is described as the venation or neuration of the wing. The terms
veins and nerves are both in general use ; and when applied to the wings of
insects, have the same signification. Neither of them is good in this connec-
tion ; but thev are so firmly established that it would not be well to try to
change them. The former, however, is the better. For in very many insects a
groove extends along the ental surface of the thickenings of each wall ; and the
groove of the dorsal and ventral thickenings being exactly opposed, form a
tube in the centre of each so-called vein or nerve, within which the fluids of
the body circulate. In many insects these tubes, or veins as I shall call them,
are also traversed by the air-vessels or tracheae.

The thin spaces circumscribed by the veins are called cells.
An insect's wing is more or less triangular in outline; it therefore presents
three margins (Fig. 35). To these special names have been applied ; there is
however, a lack of uniformity among
entomologists in the terms which they
use. The cephalic margin, Fig. 35,
1-2, is termed the front margin, costal
margin, or simply the costa. The distal
margin, Fig. 35, 2-3, is known as the
outer margin, or apical margin. And
to the caudal margin, Fig. 35, 3-4, are
applied the terms inner margin and
anal margin.

The angle of the wing at the union
of the cephalic and distal margins,
Fig. 35, 2, is the apex of the wing; and
the angle between the distal and cau-
dal margins, Fig. 35, 3, is the inner
angle. The proximal end of the wing is referred to as the base.

With certain insects (Hymenoptera and some Homoptera) the cephalic mar-
gin of the hind wings bears a row of hooks, which fasten into a corresponding
fold on the caudal margin of the front wings. These hooks are named the
hamuli, and serve to hold the two wings of the same side together, thus insur-
ing their action as a unit.

In the moths the wings are united in a somewhat different way. On the
lower surface of the front wing near its base there is a hook formed of either a
portion of membrane or a tuft of hairs ; into this hook there fits a bristle, the
frenulum, which springs from the hind wing near its base. The frenulum is
simple in the males ; but it consists of several bristles in the other sex.

The wings present many characters which are much used in classification.
These are variations in texture, form, clothing and venation.

The most striking variations in texture are presented by the first pair of
wings. Special names have been applied to the wings exhibiting the more
important of these variations. These are elytra, kemelytrc, and tegmina.

The Elytra.— The, term elytra is applied to the first pair of wings of bi
and earwigs. These wings are thick, horny or leathery, without veins or with
merely traces of them, and when not in use they are horizontal, and meet

Fig.

-Wing of Hepialus.

22 AN INTRODUCTION TO ENTOMOLOGY.

in a straight line on the middle of the back. The elytra are also called wing-
covers.

The Hemelytra. — This term is applied to the first pair of wings when they
are horny or leathery at the base and membranous at the apex, as in the Hete-
roptera.

The Tegmina. — This name is given to the mesothoracic wings when they
are of an uniform leathery or parchment-like texture, and are furnished with
veins. Of this form are the mesothoracic wings of Orthoptera. Like the ely-
tra the tegmina are also called wing-covers ; but unlike elytra they overlap each
other when at rest.

The Hdlteres, Balancers, or Poisers. — With most insects that possess only the
first pair of wings (Diptera and the males of Coccidse) the metathorax is fur-
nished with a pair of appendages which are believed to be the homologues of
the second pair of wings. These are called hdlteres, balancers, or poisers. The
halteres are usually club-shaped or thread-like, terminating in a knob. In the
Coccidse each of the halteres is usually furnished with a bristle which is hooked
and fits into a pocket on the wing of the same side. In this case the halteres
appear to aid in flight.

The Pseudo-halteres. — The insects belonging to the family Stylopidae have
only the metathoracic wings developed. The mesothoracic wings are repre-
sented by a pair of slender club-shaped appendages, which are termed
pseudo-halteres.

Venation. — The number and situation of the veins of the wing afford charac-
ters which are much used in descriptive works. The variations presented by
these characters are very great. And unfortunately no one has published an
exhaustive work on the subject.* Much has been written upon it; but most of
the writers have confined themselves to a single order or even family of in-
sects. The result is that many systems exist ; and frequently homologous veins
bear different names in different groups of insects. It is necessary, therefore,
in the study of any order of insects to learn the system or systems that have
been established for that order. The more important of these are explained in
the discussions of the orders in the following chapters of this work.

The Abdomen.

The abdomen is the third or caudal region of the body. Its
segments are more simple, distinct, and ring-like than those
of the other regions. The number of segments of which it ap-
pears to be composed varies greatly. In the Cuckoo-flies (Chrysi-
didae) there are usually only three or four visible, while in many
other insects nine appear. Except in the lowest order of insects
(Thysanura) the abdomen of the adult bears no locomotive ap-
pendages. But many larvae have fleshy appendages which aid in

* The most important of the attempts to work out the homologies of the wing veins is
by Josef Redtenbacher. Ann. des K. K. Nat. Hofmuseums, I. (Wien, 1SS6). See Re-
view in Am. Nat. vol. xxi. p. 932.

THE ANATOMY OF IX SECTS. 23

locomotion ; these are termed prolegs, and are shed with the skin
when the larva changes to a pupa. In the adult the end of the
body in many families is furnished with jointed filaments, the cerci,
and caudal setce. Frequently also the body is furnished in the males
with organs for clasping, the claspcrs ; and in the females with saws,
piercers, or borers, the ovipositor. In the females of certain insects
there is a sting, which is used as an organ of defence ; and the ab-
domen of plant-lice and certain other insects bears a pair of tubes
or tubercles, through which honey-dew is excreted ; these are com-
monly called honey-tubes ; they are also termed cornicles, nectaries,
or siphuncles.

TABULAR REVIEW.

The numbers and letters preceding the names of parts are those
by which these parts are designated in the figures illustrating this
chapter. In some cases, where there is no danger of mistake, only
the letters are used in the illustrations. Thus, in the figures of
maxillae, the cardo is indicated by a, not na.

I Head \ F' xe( * Parts of the Head.

/ Movable Parts of the Head.
( Prothorax. ) -r.. , n
Body. •! II. Thorax. 1 Mesothorax. { Plxed Parts -
/Metathorax. ) Appendages.

III. Abdomen. \ Pixed Parts "

I. ( Appendages.

Fixed Parts of the Head.

I. Occiput. ( 2a. Front.

] 2b.

( 2c. Genae.

2. Epicranium. \ 2b. Vertex.

3. Eyes. (Compound Eyes).

4. Ocelli. (Simple Eves).

5. Clypeus. j 5f Antc-clypeus.

J J r ( y>. Post-clypeus.

6. Gula.

Movable Parts of the Head.
ha. Scape. | ?"'• Bulb "

7. Antenna. ^ ^dicel _
1 Jc\ Ring-joints.

I "jc. Clavola. < 7<r. Funicle.

. 7c*. Club.

8. Labium.

9. Epipharynx.

10. Mandible. \ loa ' Pro stheca.

2 4

AN INTRODUCTION TO ENTOMOLOGY.

ii. Maxilla.

i ia. Cardo.

\\b. Stipes.

\\c. Palpifer.

\\d. Maxillary Palpus.

v\e. Subgalea.

i if. Galea (Superior Lobe or Outer Lobe).

n^-. Lacinia (Inferior Lobe or Inner Lobe).

\\h. Digitus (Unguis).

12. Labium, or
Second Maxillae.

13. Hypopharynx.

\za. Submentum (= Cardo).
\2b. Mentum (= Stipes).

C \ic\ Palpiger (= Palpifer).

i2r 2 . Glossa (= Subgaleae).

\ic % . Paraglossa (= Galea).

i2<: 4 . (= Subgalea).

\2d. Labial palpi.

\ic. Ligula.

Fixed Parts of the Thorax.

Dorsal Surface.
(Pronotum.)

14. Prothorax.

Lateral Surface.
(Pleura.)

Ventral Surface.
'(_ (Sternum.)

\\a.
\\b.
1 4r.
14^.

Praescutum.
Scutum.
Scutellum.
Postscutellum.

I4<?. Episternum.

14/. Epimeron.
) \\g. Jugular Sclerites.
[ \\h. Peritreme.

14/. Prosternum.

15. Mesothorax.

Dorsal Surface.
(Mesonotum.)

Lateral Surface.
(Pleura.)

Ventral Surface.
(Sternum.)

Praescutum.

15^'. Scutum.

i5^ 2 . Parapsides.
Scutellum.
Postscutellum.

{iSa.
\$b. Scutum

I 56".

156/.

156'. Episternum.
15/. Epimeron.
i^g. Parapteron.
15//. Peritreme.

15/. Mesosternum.

16. Metathorax.

Dorsal Surface.
(Metanotum.)

Lateral Surface.
(Pleura.)

Ventral Surface
(Sternum.)

16a. Praescutum.
16/;. Scutum.
166-. Scutellum.
i6d. Postscutellum.

i66>. Episternum.
16/. Epimeron.
l6g. Parapteron.
16/1. Peritreme.

5 16/. Me

etasternum.

16/ 1 . Ante-coxal
piece.

17. Leg.

1 8. Wings.

19. Pro-legs.

20. Cerci.

THE ANATOMY OF INSECTS.

Appendages of the Thorax.

r* \ 17a 1 . Trochantin.
17a. Coxa.

ijb. Trochanter.

\jc. Femur.

\~jj. Tibia.

-, \ 17 e\ Claws.

ne. Tarsus, j ^ puWmi

f Membranous.

Elytra.
j Hemelytra.

Tegmina.

Halteres.
Pseudo-halteres.

( Cephalic.
Borders. ■] Distal.
( Caudal.

Angles. < Inner angle.
( Base.

A special nomencla-
ture for each order.

Veins. }

Cells. \

Hamuli.

Hook and frenulum

Appendages of the Abdomen.

21. Caudal setae.

22. Claspers.

23. Ovipositor.

24. Sting.

25. Honey-tubes.

The Internal Anatomy of Insects.

In order to obtain a clear idea of the relative positions of the
different systems of organs in the body of an insect, let us recall
the type of the Arthropoda described in the Introductory Chapter.
A diagrammatic representation of this type is given in Fig. 36.

j...,

Fig. 36. — Diagram of structure of Arthropoda.

The body-wall is a hollow cylinder ; within this the viscera are
arranged as follows : The alimentary canal is central ; the greater
part of the nervous system, ventral ; and the circulatory system,
dorsal. To this simple conception it will be necessary to add a
complicated respiratory system, not possessed by the lower Arthro-
pods, and the muscular system and organs of reproduction, the dis-
cussion of which was omitted from the Introductory Chapter.

The Internal Skeleton. — Although the skeleton of an insect is
chiefly an external one, there are prolongations of it into the body-
cavity. As these form support for various organs, and attachment
for many muscles, they are often described as the internal skeleton.

26 AN INTRODUCTION TO ENTOMOLOGY.

This internal skeleton becomes much more highly developed in
adult insects than it is in larvae. Special names have been applied to
the parts of it in the head and the three thoracic segments. Thus
the internal skeleton of the head is termed the endocrdnium or tento-
rium; and the principal parts of it in the thoracic segments, those
which project from the sternal wall, are distinguished as the ante-
furca, the mcdifnrca, and the postfurca. These are usually bifurcated ;
they support the nervous cord and give attachment to muscles.

The Minute Structure of the Body-wall. — Under the head of ex-
ternal anatomy the body-wall has been studied from one point of
view. Reference was there made to the hardening of it by chitine,
and a special study was made of the various sclerites. We have now
to study the more minute structure of the body-wall, as seen on
section with high powers of the microscope.

If a very thin section of the body-wall be taken and then dyed
with the proper reagents, so as to differentiate the various parts, it
will be seen under high powers of the microscope to consist of
three principal layers ; first, an outer chitinous layer, the cuticle,
which forms the parts already studied ; second, an intermediate
cellular layer, the hypodermis ; and third, a basal membrane.

The appearance of these layers is shown in Fig. 37. The chiti-

===r= »__ r nous layer is composed of many thin

i———— ^^ ^IsErr^ , c plates superimposed. It really con-

|lp -rzzz — - sists of an excretion of the inter-
(®\® fi @ \\ SP \®\®}®J, ®) "" 'f mediate cellular layer. It is not
"" **" composed of cells, but sometimes

Fig. 37.— Section of body-wall. ft i s marked by lines correspond-

ing to the outlines of the subjacent cells of the hypodermis. The
hypodermis is composed of distinct nucleated cells ; as it gives
origin to the other parts of the skin, it is often termed the matrix.
The basal membrane is a thin sheet of homogeneous tissue.

The Muscular System. — The relative positions of the muscles
and the skeleton in insects are very different from what they are
in Man. With the Vertebrates, the bones constitute a central axis,
outside of which the muscles are arranged. But in Insects, the skele-
ton of the body, and of any of its appendages as well, is a hollow
cylinder, to the ental surface of which the muscles are attached.
This is illustrated by Fig. 38, which represents the muscles in the
leg of a beetle.

If the body of an insect (preferably of a larva) be opened by a
longitudinal slit, and the alimentary canal removed from the centre,

PLATE I.

A Catekimllak (Cossus ligniperaa).

( After Lyonet.)

Fig. 4. Caterpillar opened on the ventral middle line. Fig. 5. Caterpillar opened on the dorsal
middle line. 1, principal longitudinal tracheae ; 2, central nervous system ; 3. aorta ; 4. longi-
tudinal dorsal muscles ; 5. longitudinal ventral muscles; 6. wings of the heart ; 7, tracheal trunks
arising near spiracles ; 8, reproductive organs; 9, vertical muscles; 10, last abdominal spiracle.

28 AN INTRODUCTION TO ENTOMOLOGY.

a large part of the muscular system will be exposed to view. Plate
I. represents the thorax and abdomen of a larva which has been pre-
pared in this way. In these figures the band-like structures repre-
sented as lining the body-wall are muscles. And the number is much
greater than shown here ; for between these muscles and the body-
wall there are in most places several layers of diagonal muscles.

The muscular system is composed of an immense number of dis-
tinct, isolated, straight fibres, which are always free (i.e., not inclosed
in tendinous sheaths as with Vertebrates). As a rule, the muscles
that move the segments of the body are not furnished with tendons
(Plate I.) ; while those that move the appendages are thus united at
the distal end (Fig. 38). In appearance the muscles are either

Fig. 38. — Leg of May-beetle. (After Straus-Durckheim.)

colorless and transparent, or yellowish-white ; and of a soft, almost
gelatinous consistence. When properly treated with histological
reagents, and examined with a microscope of moderately high
power, they present numerous transverse striations, like the volun-
tary muscles of Vertebrates.

The Alimentary Cana/. — In the ideal figure given on page 25, the
alimentary canal is represented as a straight tube extending from
one end of the body to the other. In the larva of some insects there
is an approach to this degree of simplicity. But usually the tube is
longer than the body, and is consequently more or less convoluted.
Moreover, it is not of uniform structure, but, as in the higher animals,
different parts are adapted to different functions. Names have
been applied to these special parts similar to those used to desig-
nate the analogous parts in higher animals. These are as follows :

There is within the head a portion of the alimentary canal that
is usually more or less enlarged ; this is the pharynx. It has been
shown recently * that in some sucking insects the pharynx is fur-
nished with powerful muscles, by which it can be distended, and
that it is doubtless the pumping organ, by which these insects

* Edward Burgess, Contributions to the Anatomy of the Milkweed Butterfly (Me-
moirs of the Boston Society of Natural History, 1880).

George Dimmock, The Anatomy of the Mouth-parts and Sucking Apparatus of some
Diptera (Boston, 1881).

PLATE II.

JtWIIT.SS

t^

A Cockroach {Periplaneta orientalis).
(From Rolleston.)

a, antennae ; b\, 62, £3, tibiae ; c, anal cerci ; d, ganglion on recurrent nerve upon the crop ■ e. salivary
duct; /, salivary bladder; g, gizzard; k, hepatic caeca ; i, chylific stomach; j, Malpighian
vessels: k, small intestine; /, large intestine ; m, rectum ; «, first abdominal ganglion; o, ovary ;
/, sebaceous glands.

30 AN INTRODUCTION TO ENTOMOLOGY.

obtain their food. We do not know yet how generally this is true

of sucking insects.

Following the pharynx and extending into or through the thorax

is a slender part, the oesophagus.

In many insects, both sucking and biting, there is a dilation of

the oesophagus near its caudal end, which serves as a reservoir of food,

and is termed the crop. The crop of sucking insects was formerly

thought to be the pumping organ, and is, therefore, described in the

older works on this subject as the sucking stomach.

Following the crop we find in some insects
a compact enlargement of the alimentary canal
with strong muscular walls, the proventricitlus
or gizzard. This is sometimes a very com-
plicated organ, furnished with teeth, spines,
and hairs, for the grinding of the food. (Fig.

Fig. 3q. — Cross-section of
the proventriculus of 39")

The stomach is next in order, and is easily
recognized by its central position, and usually by its large size.
It is also known as the ventriculus, or cliylific ventricle.

The remaining part of the alimentary canal is the intestine. This
is often composed of three specialized regions, named, as in the
higher animals, the ileum or small intestine, the colon or large intes-
tine, and the rectum.

There may be several sets of appendages to the alimentary
canal. The first of these are the salivary glands, which open near
the mouth. These glands vary greatly in form and number, and
are sometimes wanting. In Lepidopterous larvae they constitute
the silk glands, and, in this case, have a distinct opening through the
modified labium or " spinneret." At the beginning of the stomach,
there are in many insects several pouch-like appendages, the ccecal
tubes. These secrete a digestive fluid, which resembles the pancre-
atic juice of Vertebrates. Usually the most conspicuous of the
appendages of the alimentary canal are certain long, slender tubes
opening into the beginning of the small intestine, and floating free
in the body-cavity or lying upon the surface of the stomach. These
are named the MalpigJiian vessels, in honor of Malpighi, an anato-
mist who wrote more than two hundred years ago. Formerly they
were supposed to be biliary vessels ; but their function has been
determined to be urinary. There are other glandular appendages,
which, as they open into the alimentary canal near its caudal open-
ing, are termed anal glands. These probably do not constitute a

THE AX ATOMY OF IX SECTS.

part of the digestive system, but arc organs of offence, the secretion
being acrid or otherwise offensive.

Insects take the greater part of their food during the larva or
nymph state ; for it is in this period that they acquire their growth.
In some cases, as with the May-flies and the Bombycid moths, no
nourishment is taken during the adult state. With certain larvae
(larvae of the higher Hymenoptera, Pupipara, and Ant-lions), the
stomach ends blindly, and does not communicate with the intestine.
In the Ant-lions the rectum is transformed into a silk gland ; and
the silk of which the cocoon is made is spun from the anus.

The Adipose Tissue. — On opening the body of an insect, especially
of a larva, one of the most conspicuous things to be seen is fatty
tissue in large masses. These often completely surround the ali-
mentary canal, and are held in place by numerous branches of the
tracheae with which they are supplied. Other and smaller masses
of this tissue adhere to the inner face of the abdominal wall, in the
vicinity of the nervous system, and at the sides of the body. It also
abounds in the pericardial sinus. In a full-
grown larva of Corydalus cornutus I have
found the adipose tissue to be greater in bulk
than all of the other organs found inside of
the muscular walls of the bod}-. In adult in-
sects it usually exists in much less quantity
than in larvae.

The Circulatory System. — In insects the
circulatory system is not a closed one, the blood
flowing in vessels during only a part of its
course. The greater part of the circulation
of this fluid takes place in the cavities of the
body and its appendages, where the blood
fills the space not occupied by the internal
organs. The only blood-vessels that exist in
these animals lie just beneath the body-wall,
above the alimentary canal (Fig. $6. h). They
extend from near the caudal end of the ab-
domen through the thorax into the head.
That part of this system that lies in the ab-
domen is usually termed the heart, and con-
sists of a series of chambers corresponding to
the segments of the body (Fig. 40, d). The
number of these chambers varies, but it is rarely more than eight.

Fig. 40.— Heart of May-beetle
(after Straus- 1 lurckheim I. a,
lateral aspect of aorta; /.
interior of heart showing
valves; ,-, ventral asp< . | i i
heart and wing-muscles— the
muscles are represent'
cut away from the caudal
part of the heart; </, dorsal
aspect of heart.

32 AN INTRODUCTION TO ENTOMOLOGY.

Miall and Denny, however, describe the heart of a cockroach as
consisting of thirteen chambers, corresponding to ten abdominal and
three thoracic segments. The chambers of the heart are separated
by valves, which permit the blood to flow only towards the head.
There is in the walls of the heart a pair of lateral openings corre-
sponding to each chamber ; these also are furnished with valves,
which admit the blood to the heart, but prevent its exit. When,
therefore, the chambers contract, a stream of blood is forced towards
the head ; and when they expand, the blood rushes into them
through the lateral openings.

The circulatory system has been carefully studied in only a few
insects ; and these show a remarkable variation in the form and
arrangement of the openings and valves.* But the result
of their operation is the same in all. A diagram of a hori-
zontal section of the heart of a May-beetle, based on the
description by Straus- Durckheim (Graber represents
it as more complicated) will serve as an illustration.
\ Fig. 41, S, represents a chamber of the heart during
l/\J its systole or contraction ; the valves at the caudal
Fig. 41— Dia- end and at the lateral openings (1) have been
hear\ of closed by the pressure of the blood; while the

IVIsv-bcctlc

valves at the cephalic end have been forced
open, and the blood, represented by the arrow, is flowing
forwards. D represents a chamber regaining its natural
size, and the blood flowing into it through the lateral
openings.

I have observed a somewhat different arrangement of
openings and valves in the nymph of a dragon-fly. A
young individual was studied, one in which the skin was * \ > //
sufficiently transparent to allow the beating of the heart 2 / \-f 1
to be seen through it. In this insect the most active J I

part of the heart appeared to be the caudal chamber, F g G ra tolau'
which is represented in Fig. 42, a. This chamber was in of'hearTof
constant motion, expanding and contracting in rapid sue- Dra g° n - fl y-
cession. With each expansion the valves at 1 quickly closed and
the blood rushed in at 2 ; and when the chamber contracted, the
valves at 2 closed and the blood was forced forwards through 1.

* See Dr. V. Graber, Ueber den propulsatorischen Apparat der Insecten, Archiv fiir
mikroscopische Anatomie, Band IX. (1873).
Straus-Durckheim, Animaux Articules (1828).
Miall and Denny, The Cockroach (1886).

THE ANATOMY OF INSECTS. 33

In many insects, instead of a rapid alternation of contraction and
expansion of the chambers, the heart begins to contract at its caudal
end, and a wave of contraction passes towards the head along the
entire length of the organ ; frequently one wave will pass the entire
length of the heart before another begins.

The cephalic prolongation of the heart, which extends through
the thorax and into the head, is a simple tube, the aorta (Plate I.,
3 ; Fig. 40, c and a). The aorta ends in the head, near the brain,
where it is usually somewhat branched. The branches are very
short, and the blood passes from them directly into the body-cavity.
Here it bathes the viscera, receiving the products of digestion from
the alimentary canal, giving up to the various glands their secretions,
and carrying nourishment to all parts of the body. In its course
through the body the blood flows in regular channels, without walls,
like the currents of the ocean.

The blood is usually colorless, or slightly tinged with green ; but
its circulation is made conspicuous by the movements of the large
corpuscles with which it abounds. In transparent insects it can be
seen pouring forth from the cephalic end of the aorta, bathing first
the brain, and then passing to all parts of the body, even out into
the appendages. By tracing the course of any one of these currents
it will be found to flow sooner or later to the sinus in which the
heart rests, and from which it receives its blood.

The Pericardial Slims, to which reference has just been made, is
separated from the general cavity of the body by a membrane, the
pericardial diaphragm. This diaphragm is perforated by many open-
ings, through which the blood passes on its return to the heart.
Into the diaphragm there are inserted a double series of triangular
muscles (Plate I., 6 ; and Fig. 40, c). These meet on the mid-
dle line, and are attached by their smaller ends to the lateral walls
of the body. They were formerly supposed to be attached to the
sides of the heart, and to aid in the expansion of that organ ; they
were, therefore, named by Lyonet the wings of the heart.
The relation of these muscles to the heart is shown in /
Fig. 43, which is a diagram of a cross-section of the body. \^L I
In this w represents the position of the wings of the heart. FlG 43 ._Dj a -
I do not think that the use of these muscles has yet been f V j r n g S m f t h e f
fully determined. One function, though probably a
subordinate one, is doubtless to protect the heart from pressure.
One has only to watch the peristaltic movements of the alimentary
canal in a transparent larva to appreciate the importance of this.

34

AN INTRODUCTION TO ENTOMOLOGY.

The Nervous System. — The central part of the nervous system, as
already indicated, consists of a ganglion in the head above the oesoph-
agus, and of a series of ganglia (typically one for each segment of
the body) lying on the floor of the body-cavity, and connected by
two longitudinal cords. In the head, one of these cords passes on
each side of the oesophagus, from the brain to another ganglion in
the head below the oesophagus, thus forming a nervous collar about
the alimentary canal. From each ganglion nerves arise, which sup-
ply the adjacent parts ; and from the thoracic ganglia nerves extend
to the legs and wings. This series of ganglia is really a double one ;
but each pair of ganglia are more or less closely united on the mid-
dle line of the body, and often appear as a sin-
gle ganglion. Fig. 44 gives a general view of
the nervous system of Corydalus cornutus as
represented by Leidy. From the brain (a) two
large nerves extend to the compound eyes,
and a smaller pair to the antennae ; the sub-
cesophageal ganglion (b) supplies the mouth-
parts with nerves ; and each of the thoracic
and abdominal ganglia supplies its segment of
the body.

In Corydalus (Fig. 44) the eighth and ninth
pairs of abdominal ganglia are united, and
drawn cephalad into the seventh abdominal
segment. The same thing is presented by
the larva of Cossus (Plate I., 10). This is an
illustration of what has been termed ceph-
alization of the nervous system. In the adults
of insects of the higher orders this cephaliza-
tion of the nervous system is carried to a
great extent. In some cases the abdominal
ganglia are fused into a common mass and drawn cephalad into the
thorax. Between this and the form presented by Corydalus every
gradation exists. With the higher insects the nervous system un-
dergoes marked changes during the life of the individual. In a
caterpillar it is of the form shown in Plate I.; in the pupa state
it becomes somewhat shortened ; and in the adult the abdominal
ganglia are all or nearly all united with the thoracic ganglia into a
common nervous mass.*

Fig. 44.— Nervous system of
Corydalus.

* See figures by Newport, Cycl. Anat. and Phys. II. pp. 963-965.

THE ANATOMY OF INSECTS. 35

In addition to the central nervous system described above, there
is what has been termed the visceral nervous system. This consists
of two parts, — the oesophageal nerves, and the respiratory nerves.

There are two sets of oesophageal nerves, — the unpaired and the
paired. From each of the nerve-cords that connect the brain with
the subcesophageal ganglion there arises a nerve, which extends
cephalad upon the oesophagus; these unite to form the frontal
ganglion (Fig. 44, c).* From this ganglion a recurrent nerve passes
caudad through the oesophageal collar between the aorta and the
oesophagus. A short distance caudad of the brain, this nerve, in
some insects, enters a small ganglion, from which branches extend
to the sides of the alimentary canal ; in other insects it forms a
number of plexuses in the muscular layer of that organ without
apparent ganglia. These ganglia and nerves comprise the unpaired
system. The paired oesophageal nerves arise on either side from
the caudal aspect of the brain, and swell out at the sides of the
oesophagus to form ganglia (Fig. 44, d) which also supply nerves
to the walls of the alimentary canal.

The respiratory nerves are not represented in the figure of Cory-
dalus ; but they are well shown in that of the larva of Cossus (Plate
I.). They consist of the following parts: In each segment of the
thorax and abdomen there is a short longitudinal cord between the
two cords of the central nervous system. Each of these cords en-
larges into a ganglion, from which branches extend laterally to the
sides of the body, where they supply the tracheal trunks and the
muscles of the spiracles.

The Organs of Special Sense. — It is probable that insects possess
the five senses known to us ; and perhaps they have others the na-
ture of which we cannot conceive. Even in the case of the five
senses, the range of perception may be very different from ours.
Thus Lubbock has shown that ants perceive the ultra-violet rays,
which are invisible to us. There is, however, a great variation in
the degree of development of the different senses in different in-
sects ; for example, some are furnished with wonderful eyes, while
others are blind. It is probable that in many cases the great devel-
opment of one sense is correlated with a slight development of some
other. As an illustration, we find that in the Dragon-flies and Ci-
cadas, which are essentially directed by sight, the antennae are rudi-

* See William C. A'ruuss, On the Nervous System of the Head of the Larva of Co-
rydalus cornutus : an extract from a thesis in Entomology presented to the faculty of
Cornell University for the Baccalaureate in Science: Tivchr, vol. IV. pp. 170-184.

3 6

AN INTRODUCTION TO ENTOMOIOGY.

*f T ' ,H V-*' , *^>wiil"nTTi*ifc

mentary, and doubtless the sense of smell likewise. During the
night these insects are passive, while during the day they' trust to
their powers of sight, or possibly in some Cicadas also to hearing.

The study of the sensations of insects is at the same time one of
the most difficult and one of the most interesting of the departments
of entomology. But as yet comparatively little has
been done in this line. The great improvements that
have recently been made in the methods of histologic-
al research have resulted in the publication of several
very important papers on the structure of sense-organs ;
but there is a great lack of experimental basis for con-
clusions as to the functions of the various organs that
have been described.*

The best known of the organs of special sense are
the organs of sigJit. Of these there are two kinds,
the simple eyes and the compound eyes. Simple
eyes exist in both larvae and adult insects. In the
former there may be several of these, on each side of
the head ; in the latter there are usually not more
than three, situated between the compound eyes.
The compound eyes occur only in adult insects, where
they reach a marvellous degree of complexity. Each
compound eye consists of many ocelli united ; the
number varies from 50 in some ants to more than
30,000 in certain butterflies. The complexity of these
eyes does not, however, consist merely of the great
number of ocelli that enter into the composition of

;■:•

Ir-B.

Fig

4S. — Three
ocelli with retinu-
lse from the com-

M^y-beeT (After each ; but each ocellus is a highly developed organ

pigmenthaUeen consisting of many parts. The structure of these ocelli

fromt V wooft a hem y varies greatly in different insects. f Fig. 45 repre-

k, corn c e rystaUine sents three ocelli of a May-beetle as described by

cone; /, pigment- .

sheath; p, chief Grenadier.

pigment-cell; /", „_, , , , , . , ,,

pigment -cells of With regard to the organs of special sense other

the second order; . . .

.ff, retinuiae. than those of sight there is much doubt. It is prob-
able that many insects possess organs of hearing; for elaborate
sound-producing organs are common among them. But the only

* For a general discussion of this subject, and for many references to the literature,
see Experiences et Remarques critique stir les Sensations des Insectes, par Auguste Ford,
Recueil Zoologique Suisse, t. IV. (18S6).

f See B. T. Lowne, On the Modifications of the Simple and Compound Eyes of In-
sects (Philos. Trans. 1878); also the works cited by this author.

THE ANATOMY OF INSECTS.

37

organs of insects that are generally believed to be ears are the
so-called tympanal organs of Orthoptera, which are placed at the
sides of the first abdominal segment in the Acrididae, and near the
proximal end of the tibiae of the first pair of legs in the Locustidas
and Gryllidae ; and even in the case of these it is not proven that
they have the function of hearing.

As to the sense of smell many conflicting views are held ;* but
the weight of opinion now is that certain antennal structures are the
organs of smell. These structures are to be found in the antennae
of many insects. If, for example, the surface of the plates that com-
pose the club of the antennae of a May-beetle be examined it will
be found to be thickly studded with pits. These can be seen with a

XfJfe-

— hi

Fig. 46.— Organ of smell of Fig. 47.— Organ of smell of Fig. 48— Organ of Smell of

Caloptenus. (After Hau- May-beetle. (After Hau- Vespa. (After Hauser.)

ser.) ser.)

Lettering 0/ Figs. 46, 47, and 48.— aa, circular thickening of the skin surrounding the opening of the
olfactory pit; br, bristle; ch, chitinous integument of ihe antennae; /, invaginated pit; hyc, hypo-
dermic cells; i, entrance into the canal belonging to the pit; m, olfactory membrane; >nc, membrane-
forming cell; «, nerve of special sense; nc. nucleus of the sense- or ganglion-cell ; 0, opening into
the olfactory pit; /, olfactory pit; pw, wall of the pit; sc, sense- or ganglion-cell; st, olfactory or
sense-style, sometimes peg-shaped.

microscope of low power; but in order to determine the minute
structure of the organs thin sections of them must be made and ex-
amined with high powers. Fig. 47 represents a section of one of
these pits ; and Figs. 46 and 48 represent the corresponding organs
in a locust and in a wasp.f The form of these organs of smell varies

* See Packard's abstract of a paper upon this subject by Dr. K. Kraepelin, American
Naturalist, 1886, pp. 8S9 and 973.

f See Hauser, On the Organs of Smell in Insects, translated by Packard, American
Naturalist, 1887, p. 279.

38

AN INTRODUCTION TO ENTOMOLOGY.

greatly in different insects, as is shown by the accompanying
figures.*

What are supposed to be organs of taste in Hymenoptera and
Diptera have been carefully described by Will.:}: These consist of
pits on the labium and on the lower side of the maxillae through

-A

Fig. 49.— Organ of taste in the labium Fig. 50.— Similar organ in maxilla of the

of Vespa vulgaris. (After Will.) same insect. (After Will.)

Lettering of Figs. 49 and 50. — C, cuticle; P, pit in the same; Sc, sense-cell; Ne, neurilemma of sense-
cell; Ac, axis cylinder of sense-cell; E, end of the same; N, nerve connected with sense-cell; M,
matrix-cells; Gc, gland-cells.

which ends of nerves come to the surface. The structure of these
organs in Vespa vulgaris is shown in Figs. 49 and 50.

It is probable that organs of
touch are well developed in many
insects. Leydig, Hicks, and Vial-
lanes have described tactile hairs,
which are situated upon pores in
the cuticle, in which nerves end.
'^_4? Figure 51 is a diagram of one of
these hairs.

The Respiratory System. — If an
Fig. 51.— Diagram of tactile hair, c, cuticle; insect be carefully examined there

hy, hypodermis; 5m, basal membrane: /;,

hair; Ac, hair-cell; «, nerve; nc, nerve-cell. Can be found along the sides of the

body a series of openings. These can be easily seen in many cater-
pillars and other larvae; they are the openings of the respiratory sys-
tem, and are termed the spiracles.

The number of spiracles varies greatly in different insects.
There is, however, never more than one pair on a single segment of
the body. They do not occur on the head, but are borne by each
of the thoracic segments, and by the first eight abdominal segments.
Thus there are eleven segments that may bear spiracles ; but they
are always lacking on some one or more of these.

* For generalizations regarding these organs see Kraepelin, translated by Packard,
American Naturalist , 1887, p. 182.

\ Will, F. ^Das Geschmacksorgan der Insekten. Zeitschrift fur Wissen. Zool.
1885, p. 674.

THE ANATOMY OF INSECTS.

39

These spiracles are either simple openings into the respiratory
system, or are provided with valves, sieves, or fringes of hair for the
exclusion of dirt. They lead into a system of air-tubes termed tra-
chea. The accompanying figures will indicate the distribution of
the main trunks of these tracheae in a cockroach. There is a short
trunk arising from each spiracle ; these are all connected together
by a large longitudinal trunk on each side of the body, and by
numerous transverse trunks. From these large tracheae there arise
a great number of smaller ones, not shown in the figures, which
branch and subdivide, and extend to all parts of the body. When
one dissects an insect the viscera are found to be connected together
by the ramifications of these tracheae, so that in order to remove
any organ it is necessary to cut some of them. The smaller
branches of the tracheae are exceedingly minute, and are intimately

Fig. 52. — Tracheal system of Cock-
roach. The dorsal integument re-
moved and the alimentary canal
in place. (After Miall and Denny. i

Fig. 53.— Tracheal system of Cock-
roach. The alimentary canal re-
moved to show the ventral tra-
cheal communications. (After
Miall and Denny.)

associated with the various tissues. By means of these fine tracheal
trunks the air is carried to the various tissues; so that they are sup-
plied with oxygen directly from the air, without the intervention of
blood as in the higher animals.

The minute structure of the tracheae has been the source of
much discussion. But at last it seems to be well understood. The
walls of the tracheae are composed of three layers, which correspond
to the layers of the body-wall. In fact the tracheae are looked upon
as invaginations of the body-wall. The continuity of the mem-
branes of the tracheae and body-wall is shown diagrammatically in
Fig. 54. It should be observed that it is the inner layer of the wall
of the trachea that corresponds with the outer layer of the wall of the

40

AN INTRODUCTION TO ENTOMOLOGY.

body-wall. c. cuticle; ky, hypoder-
mis; dm, basal membrane; jr/, spiral
thickening of the intima.

body. This inner layer of the wall of the trachea, the Intima, like the
cuticle is chitinous, and is shed from the tracheae with the cuticle
when the insect moults. There is a peculiarity in the structure of the
chitinous layer of the wall of the tracheae that has attracted much
attention. It is furnished with thickenings which extend spirally.

These give the tracheae their characteristic
transversely striated appearance. If a
piece of one of the larger tracheae be
pulled apart the intima will tear between
the folds of the spiral thickenings, and
the latter will uncoil from within the tra-
chea like a thread. In some insects there
are several parallel thickenings of the in-
tima ; so that when an attempt is made
to uncoil the thread a ribbon-like band
is produced, composed of several parallel
threads. I have often observed this in the
fig. .54. -Section of trachea and larger tracheae of the larva of Corydalus.

The spiral threads are wanting in the
smaller terminal portions of the tracheae.
In many adult insects, especially those that have great powers
of flight, the tracheae are enlarged in many places so as to form
air-sacs. These doubtless tend to lessen the specific gravity of the
insect. The spiral thickenings are not developed in the intima of
these air-sacs.

Although insects are, strictly speaking, air-breathing animals,
many of them, as is well known, live in the water. The study of
the ways in which aquatic insects breathe is a very interesting one ;
it presents to us many wonderful modifications of structure. Some
of the more common of these are described in subsequent pages of
this book ; in this place I can only make a few generalizations.

The various modes of respiration of aquatic insects may be clas-
sified under two heads : first, those in which the insect obtains its
air from above the surface of the water ; second, those in which the
insect breathes the air that is mechanically mixed with the water.

With many aquatic insects the spiracles open beneath the wings,
which are folded upon the abdomen. The insect by coming to the
surface of the water and lifting the tips of its wings forms a cavity
beneath them into which the air rushes. The insect can then swim
through the water carrying this air with it in a position where it can
be respired. When the air becomes impure, the insect rises to the

THE ANATOMY OF INSECTS. 4 1

surface, forces out the air from beneath its wings and takes in a new-
supply. Water-beetles and aquatic bugs afford familiar examples of
this mode of respiration.

Some insects are provided with long tubes connected with their
spiracles by means of which they can draw their supply of air from
above the surface of the water while they crawl upon the bottom of
shallow ponds. Our most common illustrations of this arc bugs of
the family Nepidae ; but the most remarkable development of this
kind is exhibited by certain Dipterous larvae of the family Syrphidae,
known as Rat-tailed Maggots.

Although there are many insects that live in the water and draw
their supply of air from above it, the greater number of aquatic in-
sects breathe, as do fishes, the air that is mixed with the water. This
is accomplished by organs known as tracheal gills. These are hair-
like or more or less plate-like expansions of the body-wall, abun-
dantly supplied with tracheae. These tracheae divide and subdivide,
and their terminations or fine branches are separated from the
water that bathes the organ only by its thin walls. In this way the
air contained in the tracheae is separated from the air in the water
only by a delicate membrane which admits of the transfer of gases
between them. It will be observed that the difference between a
tracheal gill and a true gill (as of fishes, Crustacea, etc.) is that the
true gill is supplied with vessels containing blood, which is purified
by being brought in contact with the air in the water, while the
tracheal gill is supplied with tracheae containing air to be purified.

Tracheal gills are usually borne by the abdomen,
sometimes by the thorax, and \\\ case of one genus of
Stone-flies by the head. They pertain almost exclusively
to the immature stages of insects ; but Stone-flies of the
genus Pteronarcys retain them throughout their existence.

Tracheal gills vary greatly in form ; in Corydalus they
are hair-like and occur in tufts near the lateral margins
of the abdominal segments ; in the Caddice-worms they
are thread-like, more or less branched, and irregularly dis-
tributed over the surface of the abdomen ; and in certain
Dragon-flies (Agrionime) they are in the form of large
plate-like caudal appendages, Fig. 55.

The respiratory movements of insects have been carefully studied
by Plateau* and others. These movements consist in general of

* See account by Plateau, in " The Cockroach,'' by Miall and Denny, p. 159.

42 AN INTRODUCTION TO ENTOMOLOGY.

alternate contraction and recovery of the figure of the abdomen in
two dimensions, viz., vertical and transverse.

The Reproductive Organs. — In insects the male and female repro-
ductive organs are placed in different individuals. In many insects
there are marked external sexual differences of size, form, coloring,
or character of appendages. In others it is difficult to determine
the sex without dissection. The reproductive organs vary greatly in
form, but agree in certain general characteristics. They are con-
tained in the abdomen, are paired, and usually open by a common
duct near the caudal end of the body. (In the May-flies and Ear-
wigs the reproductive organs of each side have a distinct opening.)

In the female there is in the abdominal cavity on each side an
ovary. This is a compound organ consisting of a series of parallel
tubes opening into a common oviduct. Sometimes these tubes are
attached to each other so as to form a compact body ; in other spe-
cies each tube is free for a greater or less part of its length. These
tubes are tapering in outline, the larger end being joined to the ovi-
duct. Within these tubes, even in the larval state, may be found
the developing eggs, each tube containing a single row of them grad-
ually increasing in size from the small end of the tube towards its
opening into the oviduct. The oviducts of the two sides unite a short
distance from the external opening and form the vagina. There are
usually accessory glands opening into the vagina, whose secretions
serve to surround the eggs or to fasten them to the objects upon
which they are laid. Connected also with the vagina are one or
more pouches, the receptdcula scminis, within which the reproduc-
tive fluid of the male is received and stored. This fluid retains its
fertilizing properties for a long time. Thus the queen-bee or ant
pairs but once, though she may continue to lay fertile eggs for years.
The fertilization of the eggs of insects takes place at the time they
are laid. There is in one end of the shell of the egg one or more
pores known as mlcropyles. Through these the spermatozoa enter
the egg, as it passes the opening of the receptacula seminis.

In some cases, at least, it is not necessary that an egg should be
fertilized in order that the embryo should develop. This has been
proven with the Honey-bee. But so far as is known the unfertil-
ized eggs of the bee produce only males.

The organs of the male consist of a number of tubular glands,
often coiled together so as to form an apparently compact body,
the testes. These like the ovaries are paired and located in the
abdominal cavity. The efferent ducts of these glands, the vdsa defe.

THE ANATOMY OF IX SECTS. 43

rentia, like the oviducts unite and form an unpaired duct, the ductus
ejaculatorius. Accessory glands open into this duct.

All insects are developed from eggs. But there are some ap-
parent exceptions. Thus many flies retain their eggs till after they
are hatched, if a proper place for laying them is not found earlier;
and in some flies (the Pupipara) the young attain a considerable
development before they are born. In the Plant-lice (Aphididae)
there is a remarkable alternation of reproduction by budding with
the sexual reproduction.

CHAPTER III.
THE ORDERS OF THE HEXAPODA.

In a preceding chapter the distinguishing characters of insects
have been discussed. We have now to study the manner in which
the class Hexapoda is divided into its principal divisions or orders.
Regarding this subject, there is at the present time much difference
of opinion. Naturalists are not agreed as to the limits of the differ-
ent orders of insects. The number recognized in standard works
varies from seven to more than twice that number.

Although the question is an exceedingly difficult one, it is an
easy matter to state where the differences of opinion lie. And these
differences do not complicate the subject greatly.

More than a century ago Linnaeus recognized seven orders of
insects. These he named Coleoptera, Hemiptera, Lepidoptera,
Neuroptera, Hymenoptera, Diptera, and Aptera. Five of these
orders were well founded ; and two were not. The Aptera was soon
regarded as an unnatural group. It included various wingless in-
sects, which later entomologists have distributed among the other
orders. The Linnaean order Hemiptera included all four-winged in-
sects in which the front wings are half horny and half membranous.
But here Linnaeus by confining his attention to the wing characters
alone fell into error. The order Hemiptera as defined by him in-
cluded at least two distinct orders ; and those members of it with
biting mouth-parts were separated a little later by Olivier as the
order Orthoptera. Thus by the suppression of the Aptera, and the
erection of the Orthoptera, the number of orders remained the same
as proposed by Linnaeus. And with these two modifications the
Linnaean classification has been very generally accepted to this day.

The modified Linnaean system indicated above is very simple
and for this reason many entomologists are loath to propose alter-
ations in it. But there are certain places in which this classification
brings together insects which differ too widely to be classed in the
same order. The science of Entomology, however, is not yet far
enough advanced for any one to state with any degree of certainty
in just how many cases this is true.

One of the principal points in which there are differences of

THE ORDERS OF THE HEXAPODA. 45

opinion is in regard to the order Neuroptera. In this order as de-
fined by Linnaeus there are included insects with a complete meta-
morphosis as well as those with an incomplete one. So radical a
difference as this can hardly be expected to occur within the limits
of the same order.* For this reason those families in which the
transformation is an incomplete one were separated by Erichson as
the order Pseudoneuroptera ; and the term Neuroptera restricted to
those in which the metamorphosis is complete. This adds one to
the list of orders. In the following pages I have considered the
order Pseudoneuroptera, as distinct from the order Neuroptera.

Gerstaeker and some others of the German entomologists do not
stop with the separation of the Pseudoneuroptera from the Neurop-
tera. They hold that there is no important character separating the
former order from the Orthoptera ; and they therefore include in the
order Orthoptera not only the insects commonly placed there by the
English and American entomologists, but also those of the Linnaean
order Neuroptera in which the metamorphosis is an incomplete one.

We have, therefore, three slightly differing systems, which agree
as to the orders Hemiptera, Lepidoptera, Diptera, Coleoptera, and
Hymenoptera, but differ as to the other orders. These differences
are represented in the following table. It will be noted that al-
though the classification of Olivier and that of Gerstaeker present
the same names, these are used with widely different signification.
The Orthoptera of Gerstaeker includes much more, and the Neurop-
tera much less than in the classification of Olivier.

Olivier. Erichsox. Gerstaeker.

Orthoptera. Orthoptera. )

> Orthoptera.

( Pseudoneuroptera. )
Neuroptera. <

I .Yuroptera. Neuroptera.

Although the Linnaean system slightly modified in one or another
of the three ways just indicated is still very generally accepted,
there are many entomologists who hold that further modifications
should be made. There are certain families, as the Earwigs, Fleas,
Thrips, and others, each of which differs greatly from the typical
representatives of the order in which it was at first placed. Each
of these families have in turn been raised to the rank of an order.
But there is as yet little agreement among systematists as to how

* The males of the Coccids are the only insects which present an exception in this
respect.
4

46 AN INTRODUCTION TO ENTOMOLOGY.

many of them are entitled to this rank. In the following pages
most of these families are discussed under the head of the. orders in
which they have been most commonly placed ; in each case, how-
ever, the possible rank of the group as a distinct order is indicated.

There is one more proposed modification of the Linnaean system
which should be noticed in this place. Nearly all of the families in
the orders Pseudoneuroptera and Neuroptera are remarkably dis-
tinct. Each family differs from the other families in the same order
in much more important characters than usually distinguish families
in the other orders. At the same time the characters which distin-
guish either of these orders are not well marked. For these reasons
Professor Brauer holds that the Pseudoneuroptera and the Neurop-
tera are not natural orders, but that the former group includes four
and the latter three distinct orders.

Although in some respects (as, for example, in the classing to-
gether of the Termitidae, Psocidae, and Mallophaga as an order, the
Corrodentia) I cannot follow Professor Brauer, I am inclined to think
that in the main the school of entomologists which he represents is in
the right as regards the number and characters of the orders of the
Hexapoda. And I frankly confess that in adhering so closely to
the old classification I have been greatly influenced by a desire to
make my presentation of the subject as simple as possible, and by
the belief that an elementary text-book should follow rather than
lead in matters of this kind. I have, however, endeavored to pre-
sent the facts in such a manner as to clearly indicate the ideas of
the different schools.

On the following page two lists of orders are given. In the first
column are indicated the orders recognized in this work ; in the sec-
ond column are indicated the various other orders that have been
proposed. The reasons in each case for considering these smaller
o-roups orders is given later, under the special discussion of the
group.

LISTS OF ORDERS OF HEXAPODA.

I. II.

I. Thysanura. Thysanura.

f Plectoptera. {Ephemeridcz^
I Odonata. {Libellulidcei)
II. Pseudoneuroptera. - Plecoptera. (Perlida:)

Corrodentia. {Mallophaga, Psocidce, Ter-
[ nu 7 U'du-.)

THE ORDERS OF THE HEX A POD A. 47

I. II.

III. Orthoptera. \ Dekmaptera. {Forficulid^

( Orthoptera.

IV. Physopoda. Physopoda.

HOMOPTERA.

V. Hemiptera.

f Heteroptera.
f Neuroptera. {Sialida, Hemerobida.)
VI. Neuroptera. -j Mecaptera. (Panorpida.)

I Trichoptera. (Phryganeida.)
VII. Lepidoptera. Lepidoptera.

. TTTT _ S Diptera.

VIII. Diptera. < „ ... ,. ., .

( SlPHONAPTERA. (PltllCldce.)

I Strepsiptera. (Stylopidw.)

IX. Coleoptera. j Achreioptera. (Platypsyllida.)

[Coleoptera.

X. Hymenoptera. Hymenoptera.

It is not my purpose in this place to discuss the distinguishing
features of the orders of insects. But it seems worth while to
present here a brief tabular statement of the more important ordinal
characters. This table will aid the student in formulating his ideas
as to the characters of the .orders and as to the relations of the
orders to each other. It should be borne in mind, however, that a
linear arrangement is not a natural one ; it is simply a necessity of
book-making. The arrangement adopted here is the one that I be-
lieve best indicates the relative rank of the various orders taken as
a whole.

There is no doubt that the Thysanura is- the lowest of the orders. But the
position assigned to any one of the other orders is open to dispute. Thus we
find in the Orthoptera certain forms (the earwigs) which show as strong affini-
ties to the Thysanura as do any of the Pseudoneuroptera. And some entomol-
ogists hold that the Physopoda is the lowest of the orders of winged insects.

To enter into a detailed discussion of the reasons which have led me to
adopt the sequence of the orders given in the following pages would be beyond
the scope of this work ; but the following generalizations will indicate the
more important ones.

That series of orders in which the insects undergo an incomplete metamor-
phosis (the Ametabold) is undoubtedly lower than that (the Metabola) in which
the transformation is a complete one. The chief objection to placing the latter
series as a whole above the former is the wide separation thus brought about
between the Neuroptera and Pseudoneuroptera. I have felt, however, that
this was the least of two evils. Within the lower series the two orders in
which the mouth-parts are formed for biting are placed lower on this account
than the two orders in which the mouth is more highly modified. Of these

48 AN INTRODUCTION TO ENTOMOLOGY.

two orders of biting insects there can be but little doubt that certain members
of the Orthoptera (the crickets and katydids) reach a higher specialization in
structure than do any of the Pseudoneuroptera. The Physopoda are undoubt-
edly lower in structure than the Hemiptera; but they resemble that order
more closely than any other in the structure of the mouth-parts. The deter-
mination of the proper sequence of the orders of the Metabola is a much more
difficult question than that of the Ametabola. Of the five orders which con-
stitute the higher series, entomologists are agreed that the Neuroptera are the
lowest in structure. The Hymenoptera are placed highest with almost equal
unanimity ; not only do these insects exhibit a very high degree of organiza-
tion, but the development of the instinctive powers reached by bees, wasps,
and ants is greater than that attained by any other insects. The Lepidoptera
are placed next to the Neuroptera on account of the affinities between the cad-
dice-flies and moths. On the other hand, the higher Lepidoptera and the Dip-
tera resemble each other in the structure of the thorax. And the pupae of
certain Diptera (Cecidomyidae and Tipulidae) resemble more or less the pupae
of Lepidoptera. The Coleoptera are assigned to the next highest place, with the
belief that their complexity of structure entitles them to this rank ; but with
no intention of suggesting affinities with the Hymenoptera on the one hand
or the Diptera on the other.

Following the tabular statement of the more important charac-
ters of the orders of insects, there is given a table to aid the student
in classifying specimens. This table is purely artificial and includes
only adult insects. I have endeavored, however, to include in it all
of the aberrant forms, those which the young student would find
difficult to classify.

TABULAR STATEMENT OF THE MORE IMPORTANT CHARAC-
TERS OF THE ORDERS OF HEXAPODA.

A. Wingless insects which show no evidences of having descended from
winged ancestors {i.e., in which the thorax is simple in structure), and which
undergo no metamorphosis. (Synaptera.) I. Thysanura.

AA. Winged insects; or wingless insects in which this condition is the result
of a retrograde development, indicated by the complicated structure of the
thorax, or by the presence of wings in closely allied forms. (Pterygogenea.)
B. Insects with an incomplete metamorphosis. {Ametabola?)

C. Mouth-parts formed for biting ; i.e., with the mandibles and maxillae in
the form of jaws.
D. The two pairs of wings similar in structure, membranous.

II. Pseudoneuroptera.
DD. The first pair of wings parchment-like; the second pair membra-
nous, and folded in plaits longitudinally. III. Orthoptera.
CC. Mouth-parts intermediate in structure between those of the biting
insects and those of the sucking insects ■ viz., with bristle-like mandibles-
and with flat, triangular maxillae. IV. Physopoda.

THE ORDERS OF THE HEXAPODA. 49

CCC. Mouth-parts formed for sucking; viz., with the mandibles and max-
illae bristle-like. V. Hlmiptera.

BB. Insects with a complete metamorphosis. {Metadata.)

C. Mouth-parts formed for biting; viz., both mandibles and maxillae in the
form of jaws.

D. The two pairs of wings similar in structure, membranous, with many
veins and cells. VI. NEUROPTERA.

DD. The first pair of wings much thickened (horny) throughout their
entire length, and meeting in a straight line down the back ; the sec-
ond pair membranous. IX. COLEOPTERA.
CC. Mouth-parts formed for both biting and sucking; viz., with the man-
dibles in the form of jaws ; and with the maxillae and labium fitted for
taking liquid food. Both pairs of wings membranous, with few veins
and cells. X. Hymenoptera.
CCC. Mouth-parts formed for sucking.

D. With four wings clothed with minute imbricated scales ; mandibles
rudimentary; maxillae developed into a sucking tube.

VII. Lepidoptera.
DD. With only two wings ; the hind wings represented by a pair of
knobbed, thread-like organs ; mandibles and maxillae bristle-like.

VIII. DlPTERA.

TABLE FOR DETERMINING THE ORDERS OF HEXAPODA.

(This table includes only adult insects.)

A. Wingless or with rudimentary wings.

B. Mandibles and maxillae retracted within the cavity of the head so that
only their apices are visible. I. THYSANURA.

BB. Mandibles and maxillae more or less prominent and fitted for biting.
C. Head with long, trunk-like beak. (Boreus.) VI. Neuroptera.

CC. Head not prolonged into a trunk.

D. Louse-like insects of small size; body less than one-sixth inch in
length. {Book-lice and Bird-lice.) II. Pseudoneuroptera.

DD. Insects of various forms, but not louse-like, and, except in the case
of some ants, with the body more than one-sixth inch in length.
E. Abdomen with short, conical, compressed, many-jointed caudal
appendages. {Cockroaches.) III. Orthoptera.

EE. Abdomen without jointed caudal appendages.

F. Legs fitted for jumping. {Wingless Locusts, Grasshoppers, and
Crickets?) III. ORTHOPTERA.

FF. Legs fitted for running.

G. Abdomen broadly joined to thorax.

H. Body linear. {Walking-slicks.) III. Orthoptera.

HH. Body white and somewhat ant-like in form. ( Tcrmes.)

II. Pseudoneuroptera.

HHH. Body neither linear nor ant-like in form. ( Wingless

Fire-ply et a I.) IX. COLEOPTERA.

50 AN INTRODUCTION TO ENTOMOLOGY.

GG. Base of abdomen strongly constricted. {Ants et a/.')

X. HVMENOPTERA.
BBB. Mouth-parts formed for sucking.

C. Small abnormal insects in which the body is either scale-like or gall-
like in form, or grub-like, and clothed with wax. The waxy covering
may be in the form of powder, of large tufts or plates, of a continuous
layer, or of a thin scale, beneath which the insect lives. {Coccidce.)

VI. Hemiptera.

CC. Body more or less covered with minute scales, or with thick long

hairs. Prothorax not free {i.e., closely united with the mesothorax).

Mouth-parts usually consisting of a long " tongue" rolled beneath the

head. VII. Lepidoptera.

CCC. Body naked, or with isolated or bristle-like hairs.

D. Prothorax not well developed, inconspicuous or invisible from above.
Tarsi five-jointed. Mouth-parts developed into an unjointed trunk ;
palpi present. VIII. Diptera.

DD. Prothorax well developed.

E. Body strongly compressed ; tarsi five-jointed. {Fleas.)

VIII. Diptera.
EE. Body not compressed ; tarsi one-, two-, or three-jointed.

F. Last joint of tarsi bladder-like or hoof-like in form and without
claws; mouth-pans forming a triangular, unjointed beak; palpi
present. IV. Physopoda.

FF. Last joint of tarsi not bladder-like, and furnished with one or
two claws ; mouth-parts forming a slender, usually jointed beak ;
palpi wanting. V. Hemiptera.

AA. Winged.

B. With two wings.
C. First pair of wings transformed into club-shaped appendages. {Stylo-

Pidcs.) IX. COLEOPTERA.

CC Second pair of wings rudimentary or wanting.
D. Wings horny, leathery, or parchment-like.

E. Mouth-parts formed for sucking. Wings leathery, shortened, or
membranous at the tip. V. Hemiptera.

EE. Mouth-parts formed for biting. Jaws distinct.

F. Wings horny, without veins. Hind legs not fitted for jumping.

IX. COLEOPTERA.

FF. Wings parchment-like, with a network of veins. Hind legs
fitted for jumping. III. Orthoptera.

DD. Wings membranous.

E. Abdomen with caudal filaments. Mouth-parts rudimentary.
F. Halteres wanting. {Cloeon and Cams, in Ephemerida^)

IV. PSEUDONEUROPTERA.

FF. Halteres present (males of Coccidse). V. Hemiptera.

EE. Abdomen without caudal filaments. Halteres in place of second

wings. Mouth-parts formed for sucking. VIII. Diptera.

BB. With four wings.

C. The two pairs of wings unlike in structure. Prothorax freely movable.

THE ORDERS OF THE HEXAPODA. 5 1

D. Front wings leathery at base, and membranous at tip, often over-
lapping. Mouth-parts formed for sucking. V. HEMIPTERA.
DD. Front wings of same texture throughout.

E. Front wings horny or leathery, forming veinless wing-covers.
{Elytra.)

F. Abdomen with caudal appendages in the form of movable for-
ceps. {Earwigs?) III. Orthoptera.
FF. Abdomen without forcep-like appendages. IX. Coleoptera.
EE. Front wings leathery or parchment-like, with a network of veins.
F. Under wings not folded. Mouth-parts formed for sucking.

V. Hemiptera.
FF. Under wings folded lengthwise. Mouth-parts formed for biting.

III. Orthoptera.
CC. The two pairs of wings similar, membranous.

D. Last joint of tarsi bladder-like or hoof-like in form and without claws.

IV. Physopoda.
DD. Last joint of tarsi not bladder-like.

E. Wings entirely or for the greater part clothed with scales. Mouth-
parts formed for sucking. VII. Lepidoptera.
EE. Wings naked, transparent, or thinly clothed with hairs.

F. Mouth-parts arising from the hinder part of the lower surface of
the head, and consisting of bristle-like organs enclosed in a jointed
sheath. (Homoptera.) V. Hemiptera.

FF. Mouth-parts in normal position. Mandibles not bristle-like.
G. Wings net-veined, with many veins and cross-veins.
H. Tarsi consisting of less than five segments.

II. Pseudoneuroptera.
HH. Tarsi consisting of five segments.

I. Abdomen with setiform, many-jointed anal filaments.
(Certain May-flies?) II. Pseudoneuroptera.

II. Abdomen without many-jointed anal filaments.

VI. Neuroptera.
GG. Wings with brandling veins and comparatively few cross-
veins, or veinless.
H. Tarsi two- or three-jointed.

I. Posterior wings smaller than the anterior. {Psocidcei)

II. Pseudoneuroptera.

II. Posterior wings as large or larger than the anterior ones.
(Certain Stone-flies.) II. PSEUDONEUROPTERA.

HH. Tarsi four- or five-jointed.

I. Abdomen with setiform, many-jointed anal filaments.
{Certain May-flies.) II. PSEUDONEUROPTERA.

II. Abdomen without many-jointed anal filaments.

J. Prothorax horny. First wings larger than the second,
naked or imperceptibly hairy. Second wings without or
with few, usually simple, veins. Jaws (mandibles) well de-
veloped. Palpi small. X. HYMENOPTERA.

52

AN INTRODUCTION TO ENTOMOLOGY.

J J. Prothorax membranous or, at the most, parchment-like.
Second wings as large as or larger than the first, folded
lengthwise, with many branching veins. First wings
naked or thinly clothed with hair. Jaws (mandibles) in-
conspicuous. Palpi long. Moth like insects. {Phryga-
neidcE.) VI, Neuroptera.

CHAPTER IV.

Order I.— THYSANURA.*
[Bristle-tails, Spring-tails, Fish-moths, et al.)

The members of this order are wingless insects which undergo no
metamorphosis, the larval form being retained by the adult. The
mandibles and maxilUc are retracted within the cavity of the head,
so that only their apices are visible; they have, however, some freedom
of motion, and can be used for biting and chewing soft substances.
True compound eyes arc rarely present ; but in some genera there is a
group of agglomerated simple eyes on each side of the head. The
abdomen is sometimes furnished with rudimentary legs ; and in one
genus there arc well-developed abdominal legs.

This order comprises chiefly minute insects, which live on decay-
ing vegetable matter, and can be found
abundantly in damp situations ; some
species, however, live in warm and dry
places, and feed upon starched clothing,
the binding of books, and other dry
substances. In the more common spe-
cies, the body is either elongated, and
furnished with six well-developed legs,
and two or more long, many-jointed,
caudal appendages (Fig. 56) ; or short,

Fig. 56. — Lepisma. saccharina.
(After Lubbock.)

FlG. 57. — Papirius fuscus. (After
Lubbock.)

thick, and with a forked springing apparatus, bent under the
abdomen, instead of the thread-like caudal appendages (Fig. S7>-

* Thysanfira: thysanos (-Bvcravo?), a tassel; oura (ovpd), the tail.

54

AN INTRODUCTION TO ENTOMOLOGY.

Owing to the small size of these insects, the majority of them
escape the attention of all except the more careful students of
nature. The order is, however, of great interest to entomologists ;
for it includes the lowest or simplest of the true insects; and in it
are found forms which show close affinities to the next lower class,
the Myriapoda. It is thus one of the connecting links of which we
hear so much in these days; and in it are, doubtless, forms which
more closely resemble than any other living species those which in
ancient geological times were the first Hexapoda to appear on the
earth.

The low rank of these insects is indicated in many ways. The
mouth-parts are of a primitive form ; wings are never developed ;
and the insects undergo no metamorphosis, the larval form being
retained by the adult.

The absence of wings in this order is believed to represent the primitive con-
dition of these insects. None of the species show any indication of the devel-
opment of these organs. And the thorax does not present that complication
of structure which is the result of the development of wing-muscles. In each
of the higher orders we find wingless species; but in these cases there is good
reason for believing that the wingless condition is the result of a retrograde
development. In some cases this degradation is the result of parasitic habits,
as with lice, fleas, and mady other parasites; in other instances it is the result
of the separation of the species into several castes, of which some do not re-
quire wings, as the workers and soldiers among Termes, and the sedentary
generations of the Aphides.

Upon the distinction given above Professor Brauer separates the insects into
two classes. The first includes only the Thysanura ; this he calls the Afttay-

gogenea, or "originally wingless insects ;"
it coincides with the super-order Synap-
tera of Packard. The second class Brauer
terms the Pterygogenea, or " originally
winged insects."

The form of the mouth-parts of
the Thysanura is very different from
that seen elsewhere in the class
Hexapoda. Here the mandibles
and maxillae, although fitted for bit-
ing, are retracted within the head,
Fig. 58. T Mouth-pa«s of a Spring-tan, Ento- instead of being attached externally

tnobrytdie. (Drawn by J. M. Sled man, un- ° J

der the author's direction.) 8, labrum; to, as j s the case with the higher in-

mandible; n, maxilla; 12, labium; i?d, la- &

biai paipus. sects whose mouth-parts are formed

for biting. Fig. 58, I, shows the relation of the jaws to the wall of
the head in a common spring-tail, one of the Entotnobryidce. In this

THYSAXURA. 55

figure the mandibles are represented by a continuous line, and the
maxillae by a dotted one. It will be observed that only the tips of
these organs project from the cavity of the head.

There are, as pointed out by Meinert and by Lubbock, among the Hexapods
three principal forms of mouth :

" First, the mandibulate, in which the mandibles and maxillae are attached
externally, and are more or less powerful and adapted for biting and chewing.

" Second, the suctorial, in which the mandibles and maxillae are attached
internally, and are not opposite, but parallel, and intended for pricking.

"Third, the type presented by the Thysanura, in which the mandibles and
maxillae are attached internally, and are far from strong, but still have some
freedom of motion, and can be used for biting and chewing soft substances.

The Thysanura includes three sub-orders ; these can be separated
by the following table :

A. With well-developed abdominal legs, insect resembling a Myriapod in
form. I. SYMPHYLA.

A A. With only six well-developed legs.

15. Without ventral abdominal sucker. Caudal appendages bristle-like and
many-jointed, or in the form of a pair of forceps. II. Cinura.

BB. With a bifurcated sucker or tubercle on the ventral aspect of the first
abdominal segment. Abdomen with a springing apparatus, or without ap-
pendages. III. COLLEMDOI.A.

Sub-Order I. — SYMPHYLA.*

This sub-order has been erected for the reception of a single
genus, Scolopcndrclla. This genus includes certain minute insects
the zoological position of which is in doubt. All of the known species
are less than 7 mm. (.28 in.) in length. The general form of the
body resembles that of a Centipede ; and as with the centipedes,
each abdominal segment bears a pair of legs. But except in the
presence of these abdominal legs the structure of the bod)' is more
like that of the Cinura than that of the Myriapocls. And the legs
are five-jointed and end in two claws as in the Cinura ; while in the
Myriapoda there are six joints, and always a single large claw.

Sub-Order II. — ClNURA.f

{Bristle-tails and Fish-moths.)

Among the pests that annoy the housekeeper there is one which
is wingless, but can run rapidly, and which has long thread-like ap-

* Symphyla: syn (rrrc), together; phyla ((pv\t)), tribe.
f Cinura: cineo (Kiveoo), to move; oura (ovpa), a tail.

56

AN INTRODUCTION TO ENTOMOLOGY.

pendages at the caudal end of its body. This insect, on account of
the minute, shining scales with which its body is clothed, -is known
as the fish-moth. And it is the most familiar representative of the
sub-order Cinura. Other species occur beneath the bark of decay-
ing trees and in similar situations. The caudal end of the abdomen
is usually furnished with slender bristle-like appendages. These
suggest the popular name Bristle-tails applied to the sub-order as a
whole.

The body consists of the head, three thoracic and ten well-marked
abdominal segments. The antennae are large, many-jointed, some-
times longer than the body, and generally tapering towards the end.
The most remarkable character presented by this
order is a series of sub-abdominal appendages. These
are well shown in Machilis (see Fig. 59). Similar ap-
pendages are attached to the coxae of the second and
third pairs of thoracic legs. These abdominal appen-
dages are regarded as rudimentary legs. We have
here, therefore, a condition approaching that exhibited
by Scolopendrella.

The Cinura (Thysanura of Lubbock) is divided into
three families. These can be distinguished as follows:

A. Body not clothed with scales.

B. Caudal appendages unsegmented,
horny and pincer-like.

I. jAPYGID-iE.
BB. Caudal appendages many-jointed
and thread-like.

II. Campodeid^e.
A A. Body clothed with scales.

III. Lepismid.e.

Family I. JAPYGID^E. — The most obvious char-
acter of this family is presented by the caudal
appendages. These resemble those of earwigs,
being in the form of horny forceps. The body is
not clothed with scales; eyes are wanting. The F,G ^^^bbSf?*"'
palpi are short ; and the segments of the ab-
domen are of nearly equal width. The sub-abdominal appendages
are represented by groups of hairs.

Only a single genus, /d/>yx, has been described. Jdpyx subtcrrd-
neus " is found under stones at the mouth of a small grotto near the
Mammoth Cave."

Family II. CAMPODEID/E. — This family resembles the preced-

Fig. 59— Ventral
aspect of Jlfa-
c/it/is, showing
appendages.

THYSANURA.

57

Fig. 6i.

staphylinns.
Lubbock.)

Catnpodea
(After

ing in that the body is not clothed with scales, the eyes are wanting,

and the segments of the abdomen are of nearly

equal width. But the caudal appendages are

long, thread-like, and many-jointed. To each of

the first seven abdominal segments there is at-
tached a pair of ventral appendages, the rudi-
mentary legs already mentioned.

Two genera have been described. Campodea

has two caudal appendages, and the palpi are

minute. In Nicoletina there are three caudal

appendages, and the palpi are long.

Family III. LEPISMLLVE. — In this family the

body is clothed with scales ; the palpi are short ;

and the abdomen tapers towards the caudal end.

The eyes are large, compound, and contiguous in

MdcJiilis ; and small and far apart in Lcpisma.

The sub-abdominal appendages are well devel-
oped in Machilis ; in Lc-
pisma they are confined to
two of the posterior segments, and represented
by groups of stiff hairs on the anterior ones.
The three described genera are distinguished
as follows :

A. Prothorax much enlarged, and the abdomen ta-
pering rapidly, so that the body is almost heart-
shaped ; caudal appendages short. LEPISMINA.

AA. Body more elongated ; caudal appendages long.
B. Eyes large and contiguous. Machilis.

BB. Eyes small and far apart. LEPISMA.

The Fish-moth, Lepisma saccharina (Fig.
62), is a well-known pest in some parts of the
country. It is silvery white with a yellowish
tinge about the antennae and legs; it measures
8 mm. (.31 in.) in length. It injures clothing,
especially starched clothes ; and the bindings
of books. An instance was reported to me where they caused
the paper to cleave from the walls of a house by feeding upon
the starch with which it was fastened in place.

Fig. 62. — Lepisma saccha'
rina. (After Lubbock.)

58 AN INTRODUCTION TO ENTOMOLOGY.

Sub-Order I. — COLLEMBOLA.*

[Spring-tails^)

To this sub-order belong certain minute insects which have re-
ceived the common name Spring-tails. They are often of micro-
scopic size. The majority live on decaying matter ; and are very
common under stones and decayed leaves and wood, in the chinks
and crevices of bark, among moss, and on herbage in damp places.
Sometimes they occur abundantly in winter on the surface of snow ,
where they appear as minute black specks, which spring away on
either side from our feet as we walk. And some species collect in
great numbers on the surface of standing water.

The body consists of the head, three thoracic and six abdominal
segments. The abdominal segments are not well marked in some
forms. No compound eyes exist in this sub-order. There is, how
ever, usually a group of simple eyes on each side of the head. The
antennae consist of but few, four to eight, segments. The mouth-
parts are formed for biting, except in Anoura, where the mandibles
and maxillae are wanting.

The name Collembola refers to a curious organ situated on the
ventral aspect of the first abdominal seg-
ment, the ventral tube or sucker. " In
Podnra, Lipura, and the allied genera, this
organ is a simple tubercle ; divided into
two halves by a central slit ; in other
genera, as, for instance, in Orchesella and
Tomocems, the tubercle is enlarged, and
FlG ' ' ^tubbockT^ <After becomes a tube divided at the free end

into two lobes. In the Smynthuridae and
Papiriidae the organ receives a still further and remarkable devel-
opment ; from the end of the tube the animal can project two
long, delicate tubes provided at their extremity with two glands."
(Lubbock.) By means of this sucker and the fluid excreted by its
glands these insects are enabled to cling to the lower surface of
smooth objects.

The popular name Spring-tails was suggested for these insects
by a peculiar leaping apparatus which most of them possess. It
consists of a long appendage of either the fourth or fifth abdominal
segment, v/hich extends under the abdomen towards the head.

* Collgmbola. colon {KooXov), a limb; cmbole (eufioXr/), a throwing.

THYSANURA. 59

This appendage consists of a basal segment and two appendages ;
which are sometimes two-jointed, and sometimes consist of a single
piece each. This appendage constitutes the spring. On the ven-
tral side of the third abdominal segment in certain genera is also an
appendage, which is termed the catch. This catch passes between
the branches of the spring and holds it in place. By relieving the
spring and extending it suddenly the insect is able to throw itself to
a considerable distance.

Some of the Collembola are clothed with scales, resembling in
this respect butterflies and moths. These scales are very minute,
and wonderfully sculptured. The markings on them are so minute
that it requires a very good microscope to resolve them. On this
account they have been much used as test objects for microscopes
under the name of " Podura scales."

The most remarkable feature in the structure of the Collembola
is that in nearly the entire sub-order tracheae are wanting; while in
certain members, SmyntJirus, there is a well-developed respiratory
system. The difference is a great one to exist between genera other-
wise so closely allied.

In certain respects the Collembola is the lowest of the three sub-orders of
the Thysanura ; and it is so placed in some of the standard works on entomol-
ogy. The mouth-parts are very rudimentary in this sub-order; and the tra-
cheae are rarely developed. But it has seemed more natural to me to follow
the Myriapoda by Scolopendrilla ; and to place next the sub-order Cinura,
containing, as it does, forms with rudimentary abdominal legs. We have thus
an unbroken series from the Myriapodous to the Hexapodous condition. In
the Collembola we have insects which, while retaining a very primitive form
of the mouth-parts and of the respiratory system (the result of their con-
tinuing to feed on soft substances, and to live in damp situations), present a
much modified form of the body, and the development of peculiar special or-
gans, the spring and the ventral tube or sucker. We thus see well illustrated
the difficulties, referred to elsewhere, of any attempt to arrange animals in a
linear series.

The Collembola is divided by Lubbock into six families. These
can be separated by the following table :

A. Saltatorial.
B. Body globular.
C. Terminal segment of abdomen short, with whorls of hair.

1. Papiriid.e.
CC. Terminal segment long, ringed. 2. S.mvxthurid/E.

BB. Body cylindrical.

do AN INTRODUCTION TO ENTOMOLOGY.

C. The spring an appendage of the penultimate (fifth) abdominal segment.

3. Entomobryid^;.*
CC. The spring an appendage of the antipenultimate (fourth) abdominal
segment. 4. Podurid/E.

AA. Non-saltatorial.

B. Mouth mandibulate. 5. Lipurid^.

BB. Mouth suctorial. 6. Anourid^e.

Family I. PapirIid^E. — Two genera of this family have been
established. Papirius is characterized by four-jointed antennae ; and
Dicyrtoma by having the antennae eight-jointed. A large species
from Maine and Massachusetts, measuring 2^ mm. (o. 1 in.) in length,
is described by Packard under the name Papirius marmordtns. It is
marbled with deep dull lilac and pearl-colored lines and spots.

Family II. SMYNTHURID.E. — Only a single genus of this family,
Smynthurus, has been described. In this genus the antennae are
four-jointed, and the respiratory system is well developed. The
presence of tracheae enable these insects to live in drier situations
than can other members of the sub-order. The Garden Flea, Smyn-
thurus hortensis, is described by Fitch as occurring abundantly in
May and June, upon the leaves of young cabbage, turnip, cucumber,
and various other plants, and also on the ground. It is dull black,
with the head, legs, and bases of the antennae rust-color. Several
other species of this genus have been described by Fitch and
Packard.

Family III. ENTOMOBRYID^E. — This is by far the largest family
in this order; nine genera having been described. These can be
separated by the following table, which is from one given by Lub-
bock :

A. Antennae six-jointed. Orchesella.

AA. Antennae four- or five-jointed.
B. With scales.
C. Terminal segments of antennae ringed.
D. Two terminal segments ringed.

E. Eyes seven in each group. Tomocerus.

E. Eyes absent. Tritomurus.

D. Third segment simple. Templetonia.

CC. Terminal segment of antennae simple.

D. No eyes. Beckia.

DD. With eyes.

E. Head exposed. Seira.

* The Degeeriadae of Lubbock. The generic name Degeeria falls owing to its hav-
ing been previously used in the Diptera.

THYSAXURA. 6 1

EE. Head more or less concealed under the thorax. Lepidocyrtus.
BB. Without scales.

C. Abdominal segments unequal. Entomobrva.

CC. Abdominal segments subequal. Isotoma.

Family IV. PODURID^E. — The Poduridce comprises two genera,
Achoriitcs, in which the tarsi have two claws, and Podura, in which
there is but a single claw on each tarsus. Certain species of each
genus are found on the surface of standing water. Our common
" Snow-flea" is AcJiorutcs nivicola. This is sometimes a pest where
maple-sugar is made ; the insects collecting in large quantities in
the sap.

Family V. LlPURID^E. — The body is cylindrical in form ; there
is no saltatorial appendage ; and the mouth-parts are formed for
biting. Only a single genus, Lipura, has been described.

Family VI. AnOURID^E. — This family resembles the preceding
in the cylindrical form of the body, and in the absence of a saltato-
rial appendage ; but it differs from all other members of the Thysa-
nura, in having the mouth-parts formed for sucking. The mouth-
parts are exceedingly rudimentary; there being neither mandibles nor
maxillae. There is but a single genus, Anoura, known. The name
of this genus will doubtless be changed, as it is preoccupied by a
cenus of bats.

CHAPTER V.
Order VI.— PSEUDONEUROPTERA.*

{Dragon-flies, May-flics, Stone-flics, ct al.)

The members of this order have four wings; these are membran-
ous, and usually furnished with numerous veins. The mouth-parts
are formed for biting except in one family (Ephemeridce), where they
are rudimentary. The metamorphosis is incomplete.

The insects which are here classed as the order Pseudoneuroptera,
and those which in a later part of the book are termed Neuroptera
were formerly united in a single order, under the name Neuroptera.
This union was based upon the similarity of the characters presented
by the mouth-parts and the wings in the two groups. But there is
a radical difference in the nature of the transformations. In one
the metamorphosis is incomplete ; in the other it is complete.
Although it is difficult to find characters presented by the adult
insects which will separate these two groups, this difference in the
transformations indicates that they are not closely enough related
to be placed in the same order. The term Neuroptera has, there-
fore, been restricted to those with a complete metamorphosis ; and
the name Pseudoneuroptera, i.e., false Neuroptera, applied to those
with an incomplete metamorphosis.

The beginning student, in the classification of his specimens, will
find some difficulty in separating these two orders. But this can be
done by means of the table on pages 49 to 52. And as soon as one
becomes familiar with the families included in these orders there
will be no necessity for the use of the table.

In the linear arrangement I have adopted, these two closely-
allied orders become widely separated ; this results from the separa-
tion of the orders into two series, in one of which the metamorpho-
sis is incomplete, in the other complete.

The Pseudoneuroptera is not a well-marked order. Not only is
it difficult to distinguish it from the Neuroptera, but it includes
families which differ greatly from each other. The differences be-

* Pseudoneuroptera: pseudes (ipevdyS), false; Neuroptera.

PSE UDONE CROP TERA . 63

tween the families are much greater than is usual between the families
of the same order. On this account it is proposed by Professor
Brauer to break the Pseudoneuroptera up into at least four orders,
one for each of the first three families, and one for the last three.
It remains to be seen whether this multiplication of the orders will
be accepted by entomologists generally.

Owing to the great differences which exist between the families
of the Pseudoneuroptera, I will not attempt to make further gener-
alizations respecting the group in this place.

The Pseudoneuroptera is represented in this country by six
families. These can be separated by the following table :

TABLE OF FAMILIES OF PSEUDONEUROPTERA

A. With four or two well-developed wings.

B. Antennae inconspicuous, awl-shaped, short and slender.

C. First and second pair of wings nearly of the same length ; tarsi three-
jointed. 2. LlBELLULID/E.
CC. Second pair of wings either smaller or wanting ; tarsi four- or five-
jointed. I. EPHEMERID.E.
BB. Antennae usually conspicuous, setiform, filiform, clavate, capitate, or
pectinate.
C. Tarsi two- or three-jointed.

D. Second pair of wings the smaller. 5. PsociD/E.

DD. Second pair of wings broader, or at least of the same size as the

first pair. 3. Perlid.«.

CC. Tarsi four-jointed ; wings equal. 6. Termi 1 iii.E.

AA. Wingless, or with rudimentary wings.

B. Tarsi four-jointed. 6. Ter.mitid.e.

BB. Tarsi three-jointed.

C. Wingless, or with two rudimentary wings of a leathery substance.

5. PSOCID.E.

CC. Four rudimentary wings, still with distinct venation. 3. Peki.ii i.e.

BBB. Tarsi two- or one-jointed. 4. MALLOPHAGID^E.

Family I. — EPHEMERIDiE.f

Order PLECTOPTERA of some authors.^

{May -flics.)

The May-flies or Ephemerids are often very common insects in the

vicinity of streams, ponds, and lakes; frequently the surface of such

bodies of water is thickly strewn with them. They are attracted by

* After Baron Osten Sacken, in Hagen's Synopsis.

f Ephemeridae, Ephemera : ephemeron {ecprj/tiepov), a may-fly.

X Plectoptera ; plectos {itXeKvoi), plaited ; pteron {jcrepov), a wing.

6 4

AN INTRODUCTION TO ENTOMOLOGY.

lights; and it is not an uncommon occurrence in summer-time to see
hundreds of them flying about a single street-lamp.

They are very fragile insects,
with large delicate fore wings,
with the hind wings much smaller
or wanting, and with the abdo-
men furnished at its caudal end
with either two or three many-
jointed, thread-like appendages
(Figs. 64 and 64^).

The body is smooth, not

Fig. 64. — May-fly. Fig. 64a. — Ctznis.

clothed with scales or hairs. The head is free, with atrophied
mouth-parts, and inconspicuous antennae. These are composed
of two short stout segments succeeded by a slender many-jointed
bristle. The thorax is robust, with the mesothorax predomi-
nant. The great development of this segment is correlated
with the large size of the fore wings. The abdomen is long,
soft, and composed of ten segments. In the male there is a pair
of clasping organs placed ventrally at the extremity of the ninth seg-
ment ; these are usually two-, three-, or four-jointed, and are termed
the forceps-limbs. Just behind the forceps-limbs are the paired ex-
ternal sexual organs. The form of the external parts of the repro-
ductive organs is remarkable ; each vas deferens and each oviduct
has a separate opening. In the male these openings are between the
ninth and tenth abdominal segments, as indicated above ; in the fe-
male, between the seventh and eighth.

The May-flies have received considerable attention in popular
writings on account of their ephemeral existence in the adult state.
All have read of the insects that live but a day. Reference is made
in these accounts to members of this family ; and although the popu-
lar idea is fallacious, it has some foundation in fact. Strictly speak-
ing, the May-flies are long-lived insects ; some species appear twice
annually, once in the spring, and again in the autumn ; but as a rule
one, two, or even three years are required for the development of a

PSE UDONE CROP TERA . 6 5

generation. The greater part of this time is passed, however, beneath
the surface of water ; and after the insect emerges into the air and
assumes the adult form its existence is very brief. With many
species the individuals leave the water, undergo two transformations,
mate, lay their eggs, and die in the course of an evening or early
morning. And although the adults of many genera live several days,
the existence of these insects is very short compared with members
of other families.

The females lay their eggs in water. Some short-lived species dis-
charge the contents of each ovary in a mass. Specimens are often
found in which there project from the caudal end of the bod)- two
parallel subcylindrical masses of eggs, one protruding from each of
the openings of the oviducts. Egg-clusters of this kind " laid upon
the water rapidly disintegrate, so as to let the eggs sink broad-cast
upon the river-bed. The less perishable species extrude their eggs
gradually, part at a time, and deposit them in one or the other of
the following manners : either the mother alights upon the water at
intervals to wash off the eggs that have issued from the mouths of
the oviducts during her flight ; or else she creeps down into the
water — enclosed within a film of air, with her wings collapsed so as to
overlie the abdomen in the form of an acute narrowly linear bundle,
and with her setae closed together — to lay her eggs upon the under
side of stones, disposing them in rounded patches, in a single layer
evenly spread, and in mutual contiguity." (Eaton.)

With most May-flies the general form of the body in the immature
stages resembles somewhat that of the adult. The newly-hatched
nymphs respire through the integument at large. During the first
few clays after their birth the young cast their skin several times,
the intervals between the moultings lengthening by degrees. Rudi-
ments of tracheal gills begin to appear when the insect
is eight or ten days old ; they bud forth from the hinder
lateral angles of some or all of the first seven abdominal
segments ; and, like the parts of the mouth, are modi-
fied considerably in detail before they acquire their
ultimate shapes. They may be either thread-like,
tufted, or plate-like in form. In Oligoncura and folia
there is a pair of tracheal gills attached to the base of
the maxillae. This is a striking exception to the general Fig. 65.— Nymph

o I fc> of May-fly.

rule that external organs of respiration do not appear

on the head of insects. Fig. 65 represents a nymph of a May-

66 AN INTRODUCTION TO ENTOMOLOGY.

fly, a common representative of this family found under stones in
the beds of streams at Ithaca.

" May-fly nymphs mostly feed upon either mud or minute aquatic
vegetation, such as covered stones and the larger plants ; but (judg-
ing by their mandibles and maxillae) some must be predaceous.
Many of them live in concealment in the banks or under stones in
the bed of streams, rivers, and lakes ; others ramble openly amongst
water-weeds and swim with celerity." (Eaton.) The nymphs of
May-flies undergo many moults ; Cloeon, according to the observations
of Lubbock, sheds its skin twenty-one times. In this insects there
are no traces of wings until the ninth state ; then the hinder lateral
angles of dorsal aspect of the meso- and metathorax become slightly
produced. With each successive moult these prolongations become
more marked, until in the twentieth state, the last passed under
water, the rudimentary wings cover half or the whole of rhe third
abdominal segment. The wing-cases are not inverted (see page 6).

Most members of this family exhibit a remarkable peculiarity in
their development. After the insect leaves the water and has ap-
parently assumed the adult form, that is, after direct respiration
through the spiracles has been established, and the wings have be-
come fully expanded, it moults again. This is the only instance in
which insects with fully developed wings cast their skin. The term
subimago is applied to this stage between the nymph and the final
form of the insect. With some species the duration of the sub-
imago stage is only a few minutes ; the insect moults on leaving the
water ; flies a short distance; and moults again. In others this stage
lasts twenty-four hours or more.

The adults of the Ephemeridse eat nothing. Not only is the
period of existence in this state so brief that food in addition to
that taken in the nymph state is unnecessary, but the imperfect con-
dition of the mouth precludes the taking of nourishment. With
many species of May-flies there is great uniformity in the date of
maturing of the individuals. Thus immense swarms of them will
leave the water at about the same time, and in the course of a few
days pass away ; this being the only appearance of the species until
another generation has been developed. The great swarms of
" Lake-flies " {Ephemera simiilans), which appear along our northern
lakes about the third week in July, afford good illustrations of this
peculiarity. And an instance is on record where May-flies thronged
to the gas-burners in a store and actually quenched the flames.

The Ephemeridae are regarded as the lowest living representatives

PSEUDONEUROPTERA. 6?

of one of the lines of development of winged insects. This posi-
tion is indicated by fan-like form of the wings, which is characteristic
of the primordial insects, and by the paired openings of the repro-
ductive organs, a feature not found in highly developed animals.

Our representatives of this family have not been thoroughly
studied. Eaton in his monograph* enumerates less than one hun-
dred species from the whole of North America. But these he dis-
tributes among more than twenty genera. The following key is
based on the characters given for the genera and groups of genera
by this author. It will aid the student in classifying his specimens :
but it should be regarded as merely provisional.

In distinguishing subordinate groups in the Ephemeridae much use is made
of the venation of the wings. It is necessary here to describe only that of the
fore wings. The system adopted is that of Eaton.

The principal nerves of the fore wing show a tendency to be segregated into
three groups, as follows : (Fig. 66.)

CM. s.

a
Fig. 66. — Fore wing of May-fly.

Group I. — This group consists of three veins, which communicate directly
with the thorax. These are named the costa (c), subcosta (sc), and radius (r).
The costa is coincident with the anterior margin of the wing; and the sub-
costa and radius are nearly parallel with it ; the three veins are united near the
base of the wing by the great cross vein.

Group II. — This group also consists of three principal veins ; but the first of
these gives off a prominent branch before the middle of the wing, which is
termed the sector (s). The sector is a branch of the cubitus (cu) ; just behind
the cubitus is the fircebrachial (fir), and behind that the fiostbrdchial
This group of veins is annexed to the first group, or terminates in the wing
membrane adjacent to it, close to the base of the wing.

Group III. — The remaining veins constitute the third group. This is asso-
ciated with the prominent curved or angulated crease in the membrane of the
wing, which forms the boundary of a depression near the base of the wing.
The first vein of this group is the anal (a) ; the remaining ones are termed the
axillary veins (ax 1 , ax", ax % , etc). The anal vein as a rule subtends directly the
anal angle of the wing; in one group of genera it is joined at its base to the
postbrachial vein.

*A Revisional Monograph of Recent Ephemeridae or May-flics, by the Rev. .\. E.
Eaton. This work is to form Volume III. of the Trans, of the Linn. Soc. of London.
Only four parts have appeared at the present writing.

68 AN INTRODUCTION TO ENTOMOLOGY.

TABLE OF GENERA OF THE EPHEMERIDyE OF THE
UNITED STATES.

A. At the base of the fore wing the anal vein (a) meets the postbrachial (fio);
hind tarsi, when not atrophied, have four distinct joints.
B. Female with the hind legs longer than the other pairs ; male with the
forceps-limbs sessile upon the border of the segment.
C. Includes males only. Two caudal setae in both genera.

D. Hinder lateral angles of the 9th abdominal segment produced into a
short, tooth-like spine. Jolia.

DD. Hinder lateral angles of the abdominal segments subrectangular.

POLYMITARCYS.

CC. Includes females only.
D. Two caudal setae. Jolia.

DD. Three caudal setae. Polymitarcys.

BB. Fore legs of females at least as long as hind legs ; male with the forceps-
limbs inserted at the sides of the terminal border of a short transverse
laminar lobe prolonged from the segment.
C. Includes males only.

D. Median seta extremely rudimentary.

E. Fore leg nearly as long as body ; the tibia about i£ as long as

femur. Segments of caudal setae well marked. External sexual

organs strongly hooked. Hexagenia.

EE. Fore leg about half as long as body ; tibia about if as long as

femur. Segments of caudal setae inconspicuous. External sexual

organs nearly straight. Pentagenia.

DD. Median seta about as long as the others. Ephemera.

CC. Includes females only.

D. Median seta extremely rudimentary. Hexagenia.

DD. Median seta about as long as the others.

E. Abdominal segments 6-10 together constituting about f of the ab-
domen; segments of the caudal setae well marked. Ephemera.
EE. Abdominal segments 6-10 together constituting i of the ab-
domen ; segments of the caudal setae inconspicuous.

Pentagenia.
AA. Anal vein (a) of fore wing does not directly meet the postbrachial vein
(fio), but is connected with it by a more or less distinct channel of circula-
tion in the membrane.

B. The channel of circulation connecting postbrachial and anal veins ob-
solete (except in Cants, a two-winged genus). Hind tarsi with lour
distinct joints.

C. Hind wings well developed; with a sharply defined, almost right-an-
gled projection situated at about the first \ of the costal margin.

POTAMANTHUS.

CC. Hind wings of small or moderate proportions.

D. Hind wings either gently and on the whole continuously curved in
front, or else suddenly retracted in the middle of the fore margin.
E. Hind tibia usually longer than the femur, rarely subequal to it.

PSE UDONE UROP TERA . 69

F. Hind wings in front somewhat depressed in the middle.
G. Median caudal seta subequal to the others. Leptophlebia.
GG. Median caudal seta far shorter than the others. Blasturus.
FF. Hind wing strongly angulated in front.

G. Basal joint of forceps-limb about as long as the remainder ;
female with ventra'. lobe of segment 9 bifid and excised.

Habrophlebia.
GG. Basal joint of foreceps-limb very short ; joint 2 longer than
the remainder; female with ventral lobe of segment 9 obtuse.

Choroterpes.
E. Hind tibia rather shorter than the femur. Epiiemerella.

DD. Costal border of hind wings spurred or protuberant at about the
first \ of the wing's length.

E. Hind wings small, and extremely narrow; costal projection usually
very slender. Cextroptilum.

EE. Hind wings broad, oblong, and obtuse.

F. Hind wings with numerous cross-veins; costal projection large

and rounded. Callie.etis.

FF. Hind-wings with but few or no cross-veins; costal projection

small and acute or wanting. B.ETIS.

CCC. Hind wings wanting.

D. With two caudal setae. Clceox.

DD. With three caudal setae. \X'\%. €>\a.) Cexis.

BB. Channel of circulation connecting nerves 8 and 7 well defined; hind
tarsi with five distinct joints.

C. Space between anal (a) and first axillary {ax 1 ) veins subtended by the
outer half of the inner margin of the wing and the anal angle.
D. Tibiae of the hind legs longer than, or at least subequal in length to,
the tarsi.

E. Proximal joint of the hind tarsus shorter than the second joint.
F. Tarsal claws dissimilar ; costal dilatation of the hind wing acute.

COLOBURUS.
FF. Tarsal claws alike, narrow and hooked ; costal dilatation of the
hind wing obtuse. Chirotoxetes.

E. Proximal joint of the hind tarsus subequal to the second joint;
tarsal claws dissimilar; costal dilatation of the hind wing almost
right-angled. Ameletus.

DD. Tibiae of the hind legs shorter than the tarsi ; proximal joint of
the hind tarsus longer than the second joint. SlPHLURL'S.

CC. Space between anal (a) and first axillary {ax 1 ) veins subtended en-
tirely by a part of the terminal margin of the wing. B.etisca.
CCC. Space between anal and first axillary veins subtended by the anal
angle and a part of the terminal margin. IIeptagexia.*

* The American representatives of this genus have been distributed by Eaton
among five genera, which are distinguished by such slight and inconstant variations
in structure that I have been unable to express them in a tabular form.

70

AN INTRODUCTION TO ENTOMOLOGY.

Family II. — LlBELLULlD^E.*
Order ODONATA f of some authors.
{Dragon-flies.)
The Dragon-flies are very common insects in the vicinity of
streams, ponds, and lakes. Many of them are of large size ; and, as
they fly vigorously during the day-time, they are well known. They
have consequently received a number of popular names. The most
common of these used in this country are Dragon-flies, Darning-
needles, Spindles, and Snake-doctors.

The form of members of the Libellulidae is very characteristic
(Fig. 6y). The most striking features are the long, spindle-shaped

body, and the long, nar-
row, powerful wings ; of
which the second pair
are as large as or larger
than the first pair.

The head of a dragon-
fly is large, broad, often
semi-globose, and con-
cave behind. A con-
siderable part of its sur-
face is occupied by the
enormously developed
compound eyes. The
antennae are short ;
they consist of from five to eight segments ; of these the two basal
ones are thick, the others form a bristle-like organ. The mouth-
parts are well developed. The labrum is prominent; the mandibles
and maxillae are both strongly toothed ; and the labium consists of
three large lobes, which with the labrum nearly enclose the jaws
when at rest. The thorax is large. The wings are, as a rule, of
nearly similar size and structure; they are richly netted with veins;
and the front border of each is divided into basal and apical parts
by what is termed the nodus {n, Fig. 71). The veins and cells are
much used in classification ; the terms applied to them are given in
the explanation of Fig. 71. The abdomen is long, slender, and
more or less nearly cylindrical ; the caudal end is furnished with

Fig. 67. — Plathemis trimaculata. (From Sanborn.)

* Libellulidae, Libellula: libella, a water-level, on account of the position of the wings
during flight.

f Odonata: odons (oSovS), a tooth.

PSE UDOXE CROP TERA .

71

clasping organs. The most remarkable peculiarity of the order is
the fact that the copulatory organs of the male are distinct from the
opening of the vasa cleferentia ; the former are situated on the
second abdominal segment, the latter on the ninth. Before pairing
the male conveys the seminal fluid to a bladder-like cavity on the
second abdominal segment ; this is done by bending the tip of the
abdomen forward. The pairing takes place during flight. The
male seizes the neck of the female with his anal clasping organs :
the female then curves the end of her abdomen to the organs on the
second abdominal segment of the male

The eggs are laid in water. In some species the female flic-
back and forth over the surface of the water, sweeping down at in-
tervals to touch it with the tip of her abdomen, and thus wash off
one or more eggs into it. In other cases the eggs are laid in a mass.
On one occasion, in company with my class, I saw a dragon-fly pois-
ing herself in the air a short distance above the point where a water-
plant emerged from the water. At frequent intervals the insect de-
scended with a swift curved motion, pushing the end of her abdomen
into the water. On examination a large cluster of eggs were found
attached to the plant just below the surface. Professor Uhler has
observed a dragon-fly alight upon a water-plant, and, pushing the
end of her body below the surface of the water, glue a bunch of
eggs to the submerged stem or leaf.

The nymphs of dragon-flies (Figs. 68 and 69) pass their lives in

Fig. 68.— Nymph of Dragon-fly, Agrioninx-. Fig. 69.— Exuviae of nymph of Dragon-ily.

the water. They are predacious, feeding on such aquatic animals

72 AN INTRODUCTION TO ENTOMOLOGY.

as they can overcome. The form of the body varies greatly, some
species being quite slender, while others are nearly as broad as long.
These insects are, however, easily recognized. The general appear-
ance of the body is quite characteristic in spite of the variations in
its proportions. There are also certain well-marked structural char-
acters which distinguish the nymphs of dragon-flies from all other
insects. The most available of these characters is the form of the
mouth-parts. The mouth is furnished with well-developed mandi-
bles and maxillae, all of which are armed with strong teeth. But
none of these is visible when the insect is at rest. The lower lip is
greatly enlarged, and so formed that it closes over the jaws conceal-
ing them. For this reason it has been termed the mask. But it is
much more than a mask ; it is a powerful weapon of offence. It is
greatly elongated ; and is jointed in such a way that it can be thrust
out forward in front of the head. It is armed at its extremity
with a pair of sharp hooks, adapted for seizing and retaining its
prey.

An equally remarkable peculiarity of these insects in their
nymph stage is the form of the organs of respiration. The caudal
part of the alimentary canal, the rectum, is modified so as to con-
stitute a tracheal gill. It is somewhat enlarged ; and its walls are
abundantly supplied with tracheae. Water is alternately taken in
and forced out through the anal opening; by this process the air in
the tracheae, with which the walls of the rectum are sup-
plied, is purified in the same manner as in an ordinary
tracheal gill.

In addition to the rectal tracheal gill, certain dragon-
flies possess in their nymph stages other organs of respira-
tion. Thus, in the Agrioninae there are leaf-like caudal
tracheal gills (Figs. 68 and 70) ; in some of the Caloptery-
ginae we find lateral abdominal tracheal gills; and in cer-
tain forms there are even closing stigmata on the thorax
and abdomen.

Tracheal T\\q rectal tracheal gill of immature dragon-flies is an

r/ragon- organ of locomotion, as well as of respiration. By draw-
ing water into the rectum gradually, and expelling it
forcibly, the insect is able to dart through the water with consider-
able rapidity.

When the nymph of a dragon-fly is fully grown it leaves the
water to transform. The skin of the nymph splits open on the back
of the thorax and head, and the adult emerges, leaving the empty

PSE UDONE UROP TERA .

73

skin of the nymph clinging to the object upon which the transfor-
mation took place. Fig. 69 represents such a skin clinging to the
stem of a water-plant.

The dragon-flies are predaceous in the adult as well as in the
nymph state ; hence their vigorous flight and strong jaws render
them formidable foes of less powerful insects.

It is not strange that there should be many popular superstitions
regarding insects so conspicuous as these. It is a common belief
among children that they have the power of sewing up the ears of
people, hence the name darning-needle ; while the negroes in the
Southern States believe that the dragon-flies hover over dead snakes,
bringing them to life, and consequently call them snake-doctors.

The Libellulidae is a remarkably well-defined group of insects.
The wings are peculiar in form and venation, and especially in the
possession of the nodus ; the reproductive organs of the male are-
very distinct in form from those of any other insects ; and in the
nymph the structure of the mouth-parts and the organs of respira-
tion are equally peculiar. Owing to these important differences
which exist between the Libellulidae and the most nearly allied in-
sects, certain entomologists regard the group as an order, to which
they apply the name Odonata.

nS 44. sc. Sfl*. ms.fis. a.c. ss. *

\ I / / /

*tS A

Fig. 71. — Wing of Dragon-fly, sF.schna. A, arc or arculus; aa, anal angle; ac, antecubital cross veins;
am, accessory membrane or membranulc; at, anal triangle; ba, basal area or space ; c. c, costal
vein ; </, d, d, discoidal areolets ; it, internal triangle ; Is, lower sector of triangle, a prolongation of
pea; is', branch of Is ; »i, m, median vein ; »/,;, median area or space ; »is, ms, median sector; >:.
nodus ; >:s, nodal sector ; />ai, pea, postcostal area ; pco, postcostal vein, prolonged into Is ; pen,
postcubital cross-veins ; ps. ps, principal sector ; pt, pterostigma ; q, quadrangle or area above the
triangle ; sc, sc, subcostal vein ; sm, submedian vein, prolonged into us ; sns, subnodal sector ; ss,
ss, short sector; /, discoidal triangle, usually termed the triangle ; us, upper sector of the triangle,
a prolongation of s>n.

Figure 71 illustrates the nomenclature of the parts of the wing
in insects of this order.

74

AN INTRODUCTION TO ENTOMOLOGY.

TABLE OF SUB-FAMILIES OF LIBELLULIM:.

A. Wings alike, vertically folded in repose, (Eyes remote and peduncled.)
B. Antecubital cross-veins numerous, at least five in number. (Wings al-
most always not petiolated.) i. Calopterygin.e.
BB. Antecubital cross-veins two only. (Wings always distinctly petiolated.)

2. AGRIONINjE.

AA. Hind wings differently shaped from front wings ; all four wings carried
horizontally in repose.

B. Antecubitals of the first and second series not corresponding except at

base. Base of second series of postcubitals with cross-veins.

C Eyes remote. 4- Gomphusle.

CC. Eyes touching at a single point, the touching part of each forming an

acute angle. 5- Cordulegasterin^e.

CCC. Eyes touching for a considerable space, the touching part straight.

or at a single point {jEschina heros), the touching part rounded in a

single curve. 3. /EsCHiNiE.

BB. Antecubitals of the first and second series corresponding. Base of the

second series of postcubitals with no cross-veins.

C. Each eye laterally tubercled behind. 6. Cordulix.e.

CC. Posterior edge of each eye simple. 7. Libellulin.e.

CalopterygiNtE. — There are only two genera of this sub-family repre-
sented in our fauna. In Calopteryx the wings are very broad, and the basal
space has no transverse veins. Hcttxrina differs in having the wings rather
narrow, and with the basal space reticulated. In this genus the base of the
wings in the male is blood-red.

Agrionin^e. — The greater number of our species belong to Lestes and
Agrion. In Lestes the median and subnodal sectors arise from the principal
sector nearer the arculus than the nodus ; while in Agrion these sectors arise
under the nodus.

^EsCHNiN/E. — The greater number of our species belong to the typical genus
JEschna. In the males of this genus the anal angle of the posterior wings is
acute, the lower anal appendage is usually triangular, and the second abdom-
inal segment bears upon each side a little ear-like tubercle. Of the genus
Anax we have one common species, A. jiinius. This is a large insect, measur-
ing in length 68-74 mm., and having an alar expanse of 104.-110 mm. In the
males of this genus the anal angle of the posterior wings is rounded like that
of the females ; the lower anal appendage is short and truncate ; and the
second abdominal segment has not ear-like appendages.

Gomphin^E. — In the typical genus Gomphus the triangles of all of the wings
are without transverse veins ; this genus includes many species. In the genera
to which the following species pertain the triangles have transverse veins.
Taehopteryx tkoreyz'is a large insect expanding ioo mm.; it is remarkable for
the length of the pterostigma, which measures 9 mm. Hagenius brevistylus is
an even larger species, which expands 104-114 mm. The pterostigma meas-

* After B. D. Walsh, Proc. Ent. Soc. Phil. II. p. 259.

PSE UDOXE CROP 7 ERA .

/

ures only 6 mm., and the tarsi are very long. These two species are our most
common representatives of this division of the Gomphinse.

CORDULEGASTERIN/E. — Our only genus is Cordulegaster, of which but few
species are found in the United States.

Cordulin.e. — We have three genera of this sub-family, each of which is
well represented in our fauna. These are Macormia, Epitheca, and Cord&lia.

LibelluliN/E. — This sub-family is represented in our fauna by at least ten
genera.

Family III. — Perlid^E.*

Order PLECOPTERA of some authors.f

(Stone-flies?)

The family Perlidce includes comparatively few species ; but
members of it are common about any of our creeks. These insects
are called Stone-flies because the immature forms are very abun-
dant under stones in the bed of streams. The adults are found fly-
ing about or resting upon herbage in the vicinity of water.

The body is depressed, elongated, and with the sides nearly par-

Fig. 72. — Ptcronarrys regalis.

allel (Fig. 72). The prothorax is large. The antenna? are long,
tapering, and many-jointed. The wings are unequal, the second
pair being the larger, and lie upon the abdomen when at rest. The
tarsi are three-jointed ; and in most species the caudal mid of the
abdomen is furnished with two setae.

* Perlidre, Perl. 1 : a proper name.

f Plecoptera: plecos {nXeKoi), plaited; pleron (itrt <<<"'), a wing.

?6

AN INTRODUCTION TO ENTOMOLOGY.

Fig. 73. — Nymph of Stone-fly,
Acroneura.

It is easy to obtain the nymphs of these insects; by lifting
stones from the water of swiftly flowing streams the young stone-flies

may be found closely adhering to their lower
surface. They present a wonderfully flat-
tened appearance (Fig. 73) ; the body is de-
pressed, and closely applied to the stone ;
while the legs, antennae, and caudal setae ra-
diate from it on the surface of the stone. In
our common forms there is a tuft of hair-
like tracheal gills just behind the base of
each leg. And the more mature individuals
present conspicuous wing-pads.

The nymphs of stone-flies constitute an
important element in the food of fishes. I
have found them more often than any other
insects in the stomachs of brook trout.

When about to transform to the adult
state the insect crawls from the water upon a
stone or some other object. Their exuviae
are common in these situations. The females of certain exotic spe-
cies have been observed to carry their eggs about with them,
attached in a globular mass to the end of the abdomen, for some
time before they are laid in the water. Probably our species pre-
sent a similar habit.

The greater number of our species belong to the genus Pcrla.
In this genus the wings have but few transverse veins ; the anal
space of the posterior wings is large and folded ; the palpi are bris-
tle-like ; and there are two caudal setae. The genus Ptcrondrcys
(Fig. 68) is of great scientific interest, owing to the presence of
tracheal gills throughout the entire life of the insects. The gills of
Pteronarcys consist of little tufts of short slender filaments, of which
there is a pair on the ventral aspect of each thoracic, and the first
and second abdominal segments. The wings in this genus are
densely net-veined.

There are several species of stone-flies that appear in the adult
state upon the snow on warm days in the latter half of winter.
They become more numerous in early spring, and often find their
way into our houses. The most common one in Central New York
is the small snow-fly, Cdpnia pygma>a. It is black, with gray hairs.
The female measures 9 mm. in length, and has an expanse of wings
of 16 mm. The male measures only 4^ mm. (0.18 inch), and has

PSEUDONEUROPTERA. "jy

short wings which extend only two-thirds the length of the ab-
domen.

In England certain stone-flies are much used by anglers. One.
Chloroperla viridis, is well known under the name " Yellow Sally,"
and a species of Ncmoura is called the " Willow-fly.'

Family I V. — TERMITID^.*

{Termites, or White-ants^)

The Termites, or white-ants, are social insects, which live in large
societies, consisting of several distinct forms of individuals. They
are chiefly tropical; but there is one species which is commonly dis-
tributed over the United States east of the Rocky Mountains; and
several others occur farther west.

These insects can be easily recognized by the pale color of the
greater number of individuals of which a colony is composed, by the
fact of their living in large ant-like colonies, and by the form of the
abdomen, which is broadly joined to the thorax instead of being
pedunculate as in the ants.

The Termites are commonly called white-ants on account of
their color and of a resemblance in form and habits to the true ants.
These resemblances, however, are only very general. In structure
the Termites and ants are widely separated ; as the former are
among the lowest of winged insects, while the latter stand near the
head of the series. In habits there is little more in common than
that both are social, and the fact that in each the function of repro-
duction is restricted to a few individuals, while the greater number
differ in form from the sexually mature males and females, and are
specially adapted to the performance of the labors of the com-
munity.

This development of distinct castes for the performance of spe-
cial functions is carried much farther among the Termites than it is
among the ants and other social Hymenoptera. In the latter there
are only three forms : males, females or queens, and workers, which
are imperfectly developed females. With the Termites there are
nearly three times as many.

If a white-ants' nest be opened at any season of the year there
will be found a large number of individuals of a dirty-white color,

* Termltidae: Termes, a white-ant.

78

AN INTRODUCTION TO ENTOMOLOGY.

Fig. 74. — Termes fla-
vi/es, worker.

and of the form represented in Fig. 74. These are named the
workers, for upon them devolve nearly all the labors
of the colony. They may be looked upon as indi-
viduals, whose physical, and especially sexual, devel-
opment has been checked while yet nymphae and
never carried farther. But the development of their
instinctive powers is truly remarkable ; for it is this
caste that builds the nests, collects the provisions,
and cares for the young. A study of the internal
anatomy of workers has shown that both sexes are
represented in this caste; the reproductive organs
are, however, but little developed.
Associated with the workers, and resembling them in color and
in being wingless, there occur numerous representatives of another
caste, which can be recognized by the enormous size of their heads
(Fig. 75). These are the soldiers. Upon this caste
devolves the protection of the colony. And they are
well adapted for this work, their powerfully developed
mandibles rendering them formidable creatures. We
find among the soldiers, as among the workers, both
sexes represented. In some species the male and
female soldiers differ externally, so that they can be
distinguished without dissection. But here, as with
the workers, the reproductive organs are rudimen-
tary.

At a certain season of the year, late spring
or early summer for our common species, there
can be found in the nests winged individuals;
these are the males and females. These differ greatly in appear-
ance from the workers and soldiers. In our species, Termes ftd-
vipes, they are black or dark chestnut in color ; the body measures
5 mm. (0.2 in.) in length ; while the wings expand 16 mm. (0.63 in.).
The wings when not in use are placed lengthwise upon the back,
and project more than half their length beyond the end of the body.
The two pairs of wings are of nearly equal size, and are furnished
with numerous veins. In May or June these winged males and
females leave the nest in a body. Sometimes clouds of them ap-
pear. After flying a greater or less distance they alight on the
ground, and then shed their wings. At this time the males seek
the females, seizing hold of them with their mandibles ; but it is
believed that pairing does not take place till a later period. The

Fig. 75. — Termes fla-
vipes, soldier.

PSE CDOXE CROP PER A .

79

greater number of the individuals composing one of these swarms
soon perish. They fall victims to birds and other insectivorous
animals. But in a few cases a couple is taken in charge by some
workers; and thus is founded a new colon)-. There is usually at
the head of a colony only a single pair of sexual individuals. These
have been termed the King and Queen. It should be borne in
mind, however, that they are simply the parents of the community;
for all of the individuals in a colony, except the founders who
" elected " this King and Queen, are their offspring ; and in no case
among insects do we find rulers at the head of a community. It
would have been better in each case had the term Mother been ap-
plied to the individual at the head of a colon)- of Termites, ants, bees,
or wasps; as the function of such an individual is merely the produc-
tion of eggs. A cell is provided by the worker Termites for their
King and Queen. This is shaped like an inverted
watch-glass, and is furnished at first with a single
small opening ; later there are several. Within this
cell the royal pair remain prisoners ; but they are
carefully attended by numerous workers. As the
eggs develop in the body of the female her abdo-
men becomes greatly extended. Fig. 76 represents
such a queen, natural size. The specimen figured
is from India, and was kindly given to me by Dr.
Hagen. The dark spots along the middle of the
dorsal wall of the abdomen are the chitinized parts
of that region ; the lighter portions are made up of
the very much stretched membrane uniting the
segments ; along each side of the abdomen the spi-
racles are visible. This specimen is a comparatively
small one ; in some species the queens become six
or eight inches in length.

In addition to the winged males and females just
described, there are sometimes developed wingless sexual individuals
which never leave the nest. These are termed complemental males and
females ; and they serve as substitutes for the winged males or
females whenever a community does not find a true king or queen.
The complemental females produce comparatively few eggs, and
consequently never become as large as do the true queens. It re-
quires several of these to replace a queen. Fritz Mtiller found in
one case a king living in company with thirty-one complemental
females. As these wingless males and females never leave the nest,

r ic. 76. — Queen white-
ant, Termcs gilvus.

SO AN INTRODUCTION TO ENTOMOLOGY.

they pair with their near relatives. The development of winged
sexual forms is therefore necessary in order to provide for inter-
crossing of individuals not closely related. Doubtless here as with
the true ants the winged males and females emerge from many nests
at the same time and mingle in a single swarm: in this way there is
opportunity for intercrossing.

From the above it can be seen that among the Termites there
are four distinct castes; (i) Winged sexual forms or kings and
queens; (2) Wingless sexual forms or complemental males and
females ; (3) Workers ; (4) Soldiers. As both sexes are represented
in each caste, we have in all eight forms.

There is space here for but little regarding the habits of these
wonderful insects. In the tropics certain species build nests of great
size. Some of these are mounds ten or twelve feet in height. Other
species build large globular masses upon the trunks or branches of
trees. All of the Termites are miners, and all avoid the light.
They therefore build covered ways from their nests to such places
as they wish to visit. In some of the hot countries they are the
worst of all pests. They will feed upon almost any organic matter ;
they destroy wooden structures of all kinds, including buildings and
furniture. Libraries are often completely ruined by them. In in-
festing anything composed of wood they usually eat out the interior,
leaving a thin film on the outside. Thus a table may appear to be
sound, but crumble to pieces beneath a slight weight ; entrance
having been made through the floor of the house and the legs of the
table.

The mounds of Termites are composed chiefly of the excreted
undigested wood upon which the insects have fed.* This is moulded
into the desired form, and, on drying, it becomes solid.

Like other Pseudoneuroptera, the Termites undergo an incom-
plete metamorphosis. The eggs as soon as they are deposited by
the queen are carried away by the workers to other chambers. The
young are fed upon prepared food, which is stored up in the form
of very hard and tough rounded masses, evidently composed of com-
minuted wood. It is believed that the young Termites are also
fed on the sclerotia of some fungi. The young white-ants are ac-
tive; and all sizes, from the newly-hatched nymph to the full-grown

* That this substance is composed largely of woody tissue is easily seen by a micro-
scopic examination; and I am informed by Prof. J. C. Branner, who has observed these
insects in Brazil, that he has seen the Termites eject the matter from the caudal opening
of the alimentary canal and add it to the nest or covered ways which they were building.

PSEUDOXEUROPTERA. 8 1

worker, can be found in a nest at the same time. At certain sea-
sons of the year the nymphs of the kings and queens are present,
and can be distinguished by their wing-pads of greater or less length.

Termes ftavipes is common throughout the Eastern United States,
and it is the only species which occurs in this region. The workers
when full grown measure about 4 mm. 10.16 in.) in length, and are
of the form shown in Fig. 74. The soldiers are somewhat larger .
one is represented in Fig. 75. The winged males and females
are described above; they are often found in nests before they
have swarmed out, and swarms of them are frequently seen. But,
notwithstanding the abundance of nests of this species, the laying
queen has never been found. A specimen supposed to be a queen
was collected in Florida by Mr. Hubbard, and is in the Museum
of Comparative Zoology at Cambridge ; but this is believed by
Dr. Hagen to be merely a complemental female.

Tcrmcs flavipes is not a mound-builder. It makes its nests in old
logs, in stumps, in the ground under stones or other objects, and in
buildings or other wooden structures. It usually infests decaying
wood in the fields or forests; but I have known of several instances
where it has done serious injury to buildings; and I have also found
it infesting living plants. This habit of infesting growing plants is
manifested chiefly in the Southern States; but it has been observed
also in New England. I found the white-ants common throughout
Florida, infesting orange-trees, guava-bushes, and sugar-cane. In
this State these insects are generally recognized as important pests.
They are there known as " wood-lice," a name whose use is to be
deprecated, as it tends to create confusion.

When white-ants infest living plants, they attack that part which
is at or just below the surface of the ground. In the case of pampas-
grass the base of the stalk is hollowed ; with woody plants, as
orange-trees and guava-bushes, the bark of the base of the trunk is
eaten, and frequently the tree is completely girdled ; with sugar-
cane the most serious injury is the destruction of the seed cane.

The white-ants may be destroyed by water heated sufficiently to
kill the insects without injury to the infested plants. In the case of
orange-trees much can be done to prevent the attacks of these in-
sects. My experience convinces me that it is those trees about the
crown of whose roots the soil has been heaped that are most liable
to become infested. It follows that care should be taken to remove
such soil immediately after each cultivation of the grove, leaving the
crown of the roots exposed. It is also important to remove all old

82 AN INTRODUCTION TO ENTOMOLOGY.

wood, especially pine, from near the trees ; as such wood is liable to
become infested, and the white ants to spread from it to the orange-
trees.

The zoological position of the Termitidae is, like that of the Ephemeridae,
near the foot of the insect series. In fact, the form of the wings with Termes
is regarded as even more primitive than that of Ephemera; as is also the
structure of the thorax, with its equally developed and unusually distinct seg-
ments. But the wonderful development of instinctive powers and of separate
castes among the white-ants indicates that, although as shown by their struc-
ture, they represent one of the lowest groups of winged insects preserved to
this time, they constitute the highest development of their line. It is a sug-
gestive fact that Hagen, who is the best informed regarding the Termitidae,
considers them closely related to the Blattidae, to which the oldest known in-
sects belong.

Family V. — PSOCID^E*

{Book-lice ct al.)
The best known representatives of this family are the minute in-
sects common in old papers, books, and neglected collections ; and

which have received the name of Book-lice.
These low, wingless creatures form, how-
ever, but a small part of the family. The
more typical and winged forms (Fig. 77)
bear a strong resemblance to plant-lice or
Aphides. The body is oval, the head free,
and the prothorax is small. The wings
when present are of unequal size, the hind

Fig. 77. — Psocus venosus. , ., ,. n . ,

pair being smaller. When not in use the
wings are folded roof-like over the body, like those of the Aphides.
The tarsi are two- or three-jointed.

There are two sub-families, which are distinguished as follows :

A. Ocelli wanting; wings absent or incomplete. Atropine.

AA. Ocelli present ; wings well developed. Psocin^:.

ATROPINE. — Two genera of this sub-family are represented in
this country. In Atropos the wings are absent, the meso- and
metathorax are grown together, and the antennae are seventeen-
jointed. The common Book-louse is Atropos divinatoria. This species
is about 1 mm. in length ; it is grayish white, with black eyes. Closely
allied to this genus is ClotJiilla, in which the anterior wings are rep-
resented by small convex scales ; the meso and metathorax are free,
and the antennas are many-jointed.

*Psocidae, Psocus : psocho (tpooxa)), to grind.

PSEUDONEUROPTERA. 83

C.pulsatoria is a little more than 1 mm. in length. It is of a pale
yellowish white, and is found in similar situations as the book-louse.

PsOCINJi. — Here we find four well-developed wings. Usually
these extend much beyond the end of the abdomen. But short-
winged forms occur in species which ordinarily are long-winged. Of
course the young of all are wingless, and there is a gradual develop-
ment of the wings as the insect matures. The antenna; consist of
only thirteen segments ; this will enable one to separate the imma-
ture forms from the Atropinae.

The Psocinae occur upon the trunks and leaves of trees, on stones,
walls, and palings. They feed upon lichens, and probably other dry
vegetable matter. They are sometimes gregarious. I have often
observed communities of a hundred or more closely huddled together
on the trunks of orange-trees in Florida, feeding upon lichens.

The eggs are laid in heaps on leaves, branches, and bark ; the
female covers them with a tissue of threads. It is believed that
both sexes have the power of spinning threads similar to those spun
by spiders.

Several genera of Psocinae occur in the United States ; but the
greater number of our species belong to the genus Psocus.

Family VI. — Mallophagid.-e.*

Order MALLOPHAGA of some authors.

{Bird-lice?)

The MallopJidgidce are parasites which live on warm-blooded ani-
mals. They infest chiefly birds, and on this account the term Bird-
lice is applied to the entire group. A few genera, however, are
parasitic upon mammals. It is an interesting fact
that in the case of the genera that infest mammals
none of the species are found on birds; and of
those that live on birds none infest mammals.

The bird-lice resemble the true lice in form,
being wingless, and with the body more or less flat-
tened. Certain species which infest domestic fowls
are well-known examples. These insects differ from
the true lice in having biting mouth-parts. They
feed upon feathers, hair, and dermal scales, while the F Jgut* "^From Law'"
true lice (Family Pediculid;e, Order I [emiptera) have
sucking mouth-parts, feed upon blood, and infest only mammals.

* Maliophaga: malloi (jia\\6 c ), wool; phayein (fiayeiv), to eat.

84 AN INTRODUCTION TO ENTOMOLOGY.

Menopon pallidum is one of the species which infest the hen.
This is often a pest in hen-houses. It is to free themselves from
this and allied parasites that hens wallow in dust and scatter it
among their feathers. When fowls are confined so that they cannot
dust themselves they are very liable to suffer from bird-lice.

In order to protect fowls from these pests, cleanliness and the use
of proper insecticides are necessary. The house should be thor-
oughly cleaned at least twice each year, and the straw in the nests
burned. Sprinkling powdered sulphur in the nests, and oiling the
perches with kerosene, will do much to keep the lice in check. If a
house becomes badly jnfested it should be thoroughly white-washed,
and the fowls dusted with Persian insect-powder. Many writers
advise the use of kerosene upon infested fowls.

There is much doubt regarding the zoological position of the Mallophaga.
The placing of them in the Pseudoneuroptera must be regarded as a provi-
sional arrangement. They were formerly classed with the true lice, but they are
sharply distinguished from them by the structure of their mouth-parts. Both
of these groups have become so degraded as the result of their parasitic habits
that it will be very difficult if not impossible to definitely determine their
places in the insect series. Certain German entomologists class together as
an order the Termitidae, Psocidae, and Mallophaga under the name Corrodentia.
But this association does not seem to me natural.

TABLE OF GENERA OF MALLOPHAGA.

A. Antennae filiform, three- or five-jointed ; maxillary palpi invisible.

B. Antennae three-jointed; tarsi with a single claw. Parasites on mam-
mals, i. Trichodectes.
BB. Antennae five-jointed ; tarsi with two claws. Parasites on birds.
C. With movable appendages (trabiculae) on the head in front of the
antennae ; antennae nearly alike in both sexes. 2. Docophorus.
CC. Trabiculae absent, or if present not motile.
D. Antennae filiform, without sexual differences.

E. Head rounded behind ; last segment in the male rounded off.

3. Nirmus.

EE. Head abrupt angled behind ; abdominal segments fused in the

middle. 4. Goniocotes.

DD. Antennae of male forcipate by a process from the third segment.

E. Head angled behind ; terminal segments of female tubercle-like, of

male rounded off. 5- GONIODES.

EE. Head rounded behind ; terminal segment of male notched.

6. LlPEURUS.

PSE UDOXE CROP PEP A.

35

AA. Antennae clubbed, four-jointed ; maxillary palpi long, filiform, four-jointed.
B. Tarsi with two claws. Parasites on birds.
C. Mesothorax wanting ; antennae always concealed.

D. Head very broad ; no orbital sinus. 7. EUREUM.

DD. Head elongated, with lateral angles directed backwards.
E. With sharply marked off cypleus, and shallow orbital sinus.

8. LffiMOBOTHRIUM.
EE. With only wavy head-margins, and long lateral lobes on the
labrum. 9. Physostomim.

CC. Mesothorax present.

D. Mesothorax large, sharply marked off; head three-sided; antennae
concealed. 10. TRINOTUM.

DD. Mesothorax small, only indicated.

E. Orbital sinus deep ; antennae usually elongated and visible.

II. COLPOCEPHALUM.

EE. Orbital sinus very shallow or obsolete, antennae concealed.

12. Menopon.
BB. Tarsi with a single claw. Parasites on mammals. 13. Gyropus.

The following is a list of the described species of the Mallophaga which
infest domestic animals ; in each case the host is indicated:

1. TriCHODECTES. — Trichodectes hit us (Fig. 79), dog; T. rostrdtus, cat; T.
equi (Fig. 78), horse and ass; T. breviceps, llama; T. climax, goat; T. sphtro-
cephalus (Fig. 80), sheep; T. scaldris (Fig. 81), ox.

Fig. 79. — Trichodectes Fig. So. — Tricho- Fig. 8i. — Trichodectes Fig. 82. — Goniodes styli/er.
latus. (From Law.) dectes spheroce- scalaris. (From Law.) (From Law.)

fhalus. (From
Law.)

2. D0COPH0RLS. — Docophorus aJustus, goose; D. ict erodes, duck.

3. Nirmus. — Xirmus clavccformis, pigeon ; N. numidce, Guinea-fowl ; X.
tesselldttis, duck.

4. Goniochotes. — Goniochotes compar, pigeon ; G. sp.. Guinea-fowl ; G.
rectanguldtus, peacock ; G. chrysocephalus, pheasant ; (7. hologaster, hen.

5. Goniodes. — Goniodes numididnus, Guinea-fowl ; G. stylifer (Fig. 82),

86 AN INTRODUCTION TO ENTOMOLOGY.

turkey; G. falcicornis, peacock; G. colchicus, pheasant; G. dissimilis and G.
gigas, hen.

6. LlPEURUS. — Lipeiirus bacillus, pigeon; L. polytrapesins, turkey; L. sp.,
peacock ; L. heterdgraphus and L. variabilis, hen ; L. Idcteits and L. jcjilmis,
goose ; L. squalidus and L. variabilis, duck.

10. Trinotum. — Tr indium conspurca turn and T. squalidum, goose; T.con-
spurcdtum, swan ; T. litridum, duck.

ii. COLPOCEPHALUM. — Colpocephalum longicaudum, pigeon; C. minulum,
swan.

12. Menopon. — Menopon numidos, Guinea-fowl; M. stramineum, turkey;
M. phacoslomum, peacock; M. fuscomactddtum, pheasant; M. pallidiicm, hen.

13. Gyropus. — Gyropus gracilis and G. ovdlis, capybara.

CHAPTER VI.

Order III.— ORTHOPTERA.*

{Cockroaches, Crickets, Grasshoppers, Locusts, Earwigs, et al.)

The members of this order hare four wings: the first pair are
thickened, and usually overlap when at rest ; the second pair are
thinner, and are folded in plaits longitudinally. The mouth parts are
formed for biting. The metamorphosis is incomplete.

The order Orthoptera includes some of the very common and
best known insects. The most familiar representatives are the cock-
roaches, crickets, grasshoppers, locusts, and katydids.

Although the song of the katydid and the chirp of the cricket
are most often associated with recollections of pleasant evenings
spent in the country, we cannot forget that to members of this order
are due some of the most terrible insect scourges man has known.
The devastations caused by great swarms of migratory locusts are
not only matters of historical record, but are too painfully known to
many of our own generation in the Western States.

With the exception of a single family (Mantidse), the members of
this order are as a rule injurious to vegetation. And many species
are quite apt to multiply to such an extent that their destruction of
plant life becomes of economic importance.

In the Orthoptera the two pairs of wings differ in structure.
The front wings are leathery or parchment-like, forming covers for
the more delicate hind wings. These wing-covers have received the
special name tegmiua. Excepting in the first family (the earwigs),
the tegmina of the Orthoptera arc thickly reticulated with a net-work
of veins, and usually overlap at the tips. The position and struc-
ture of the tegmina differ in the different families, and afford good
characters for separating them. The more important veins of the
tegmina usually divide them into three more or less well-marked
fields or areas. These have been named, beginning with that bor-
dering on the front margin of the wing, the costal, median, and anal
areas, respectively. The hind legs are thickly netted with veins.

* Orthoptera: orthos (opOoS), straight; pteron (itvepov), a wing.

AN INTRODUCTION TO ENTOMOLOGY.

The principal ones are arranged somewhat like the bars of a fan ;
and the wings when not in use are folded in a fan-like manner. The
name Orthoptera is given to this order on account of this longitudi-
nal folding and position of the second pair of wings when closed.

There are many wingless genera in the order. A few species have
the anterior pair only; and in one instance at least, the first pair are
wanting while the second pair are present.

The mouth parts are all present, and are well developed. The
student who wishes to get a clear idea of the structure of a typical
insect's mouth cannot do better than to dissect the mouth of a cock-
roach or locust.

The appendages of the abdomen furnish important characters for

the purposes of classification. Thus the
form of the ovipositor is of great ser-
vice in distinguishing the families ; and
the cerci, a pair of appendages one on
each side near the caudal end of the
abdomen, are also much used in de-
scriptions.

In the Orthoptera the metamorpho-
sis is incomplete. In the case of those
species that never acquire wings the
change in form from the newly hatched
nymph to the adult is frequently in-
considerable. With others we see the
wings, developed by degrees, as de-
scribed in Chapter I. (Figs. 8 to 13).
There are many Orthoptera that have in the adult state only
rudimentary wings. These resemble very strongly immature insects.
It is often important to determine whether a short-winged speci-
men is an adult or not ; this is especially true in case of the Acridi-
dce, or locusts. Fortunately this determination can easily be made
with the Jumping Orthoptera (section Saltatoria). In case of these
insects the wing-pads of the nymphs are inverted, as shown by the
curving down of the extremities of the wing-veins instead of up, as
with the adult ; and the rudimentary wings are outside of the wing-
covers, instead of beneath them. There is also the distinction that
these rudiments of the second pair of wings are triangular in outline,
and are flat, not folded ; while the wings of the adult are more or less
folded, even when too small to be of use as organs of flight.

Certain species belonging to the three higher families, AcridicLx,

Fig. 83.— Mouth-parts of the Red-
legged Locust.

ORTHOPTERA. So,

Gryllidae, and Locustidae, are interesting on account of the sounds
which they produce. A very large proportion of the insect cries
heard in the late summer and autumn come from this source. The
organs by which these notes are made are chiefly the wing-covers.
It should be remembered that, owing to their peculiar mode of
breathing, insects have nothing that corresponds to our voice. It is
only the males of the Orthoptera that sing; and the musical appa-
ratus is different in each of the three families. Each form will be
described later.

In this connection perhaps reference should be made to the sup-
posed organs of hearing of these insects. In the Acrididaj there is
on each side of the first abdominal segment a pit, over the mouth of
which is stretched a membrane: this is termed the tympanum, and is
believed by some to be an organ of hearing ; it is doubtless a sense-
organ, but its function has not yet been determined. A pair of
similar organs occur near the proximal end of each tibia of the first
pair of legs in the Locustidae and Gryllidae.

The order Orthoptera comprises seven families. These have
been grouped into five sections by some writers ; and the names of
the sections occur frequently in entomological works. Each of the
first four sections includes only a single family ; the fourth section
includes the three remaining families. The names of the sections
except the first were suggested by the form of the legs in each.
The following are the names of the sections and the families which
they include :

I. Dermaptera ; includes the Fo)-ficulidce or Earwigs.
II. Cursor/a or Runners ; includes the Blattida or Cockroaches.

III. Raptoria or Graspers; includes the Mdntida or Rear-horses.

IV. Ambulatoria or Walkers; includes the Phdsmidce or Walking-
sticks.

V. Saltatoria or Jumpers; includes the Acridida or Locusts or
Short-horned Grasshoppers, the Locustidce or Long horned Grass
hoppers and Katydids, and the Gryllidcs or Crickets.

TABLE OF FAMILIES OF ORTHOPTERA.

A. Posterior femora fitted for walking, i.e.. resembling those of the other legs ;
ovipositor with the subgenital plate concealed ; organs of flight of immature
forms in normal position ; insects mute.

B. Anterior wings leathery, very short, without veins, meeting in a straight
line; posterior wings when present folded to the middle of the anterior

90 AN INTRODUCTION TO ENTOMOLOGY.

margin; tarsi three jointed, the pulvillus wanting; cerci hornv, resem-
bling forceps. i. Forficulid^.
BB. Anterior wings parchment-like, thickly veined ; posterior wings folded
to the base ; tarsi five-jointed ; cerci soft, jointed or without joints.
C. Body oval, depressed ; head wholly or almost wholly withdrawn beneath
the pronotum ; pronotum shield-like, transverse ; legs compressed ;
cerci jointed ; rapidly running insects. 2. Blattid^e.
CC. Body elongated; head free; pronotum elongated; legs slender,
rounded ; cerci jointed or without joints ; walking insects.
D. Front legs fitted for grasping; cerci jointed. 3. Mantid^e.
DD. Front legs simple; cerci without joints. 4. Phasmid^;.
AA. Posterior femora fitted for jumping, i.e., very much stouter or very much
longer, or both stouter and longer than the middle femora; ovipositor horny,
free (except with the mole crickets); organs of flight of immature forms
inverted; stridulating insects.

B. Antennae short ; tarsi three-jointed ; supposed organs of hearing situated
in the first abdominal segment; ovipositor short, composed of four sep-
arate plates; stridulating organs situated in hind femora and the costal
area of the tegmina. 5. Acridid.e.

BB. Antennae long, setaceous ; tarsi four- or three-jointed ; supposed organs
of hearing situated in the anterior tibiae and also in the prosternum ; ovi-
positor elongated (except in the mole crickets) ; composed of four connate
plates.

C. Tarsi four-jointed ; ovipositor (when exserted) forming a strongly com-
pressed, generally sword-shaped blade; the stridulating organs of male
limited to the anal area of the tegmina. 6. Locustidje.

CC. Tarsi three-jointed ; ovipositor (when exserted) forming a nearly
cylindrical, straight, or occasionally upcurved needle ; the stridulating
organs of the male extend across the anal and median areas of the teg-
mina. 7. Gryllid^e.

Family I.— Forficulid^.*

{Earwigs.)

This family includes only the earwigs. With these insects the

first pair of wings are leathery, very small,

^^•^^y^^s^^^^ without veins, and when at rest meet in a

%Py^^^^^— I j straight line down the back, partially cov-

$&MtyM \\^S^^ ering the second pair of wings. These

K/T^llli^^^y wing-covers strongly resemble those of the

^^j^XSjS^^^ rove-beetles. The second pair of wings

Fig. 8 4 .-win g of Earwig. differ from those of other Orthoptera (Fig.

84). They are furnished with radiating veins

which extend from a point near the end of the basal third of the

* ForficQlidae: forficula, a. pair of small shears.

ORTHOPTERA.

91

wing over the distal part of this organ. When the wing is not in
use this part is folded in plaits like a fan ; and the wing is folded
twice transversely. With other Orthoptera the longitudinal folding
extends to the base of the wing, and there is no transverse folding.
The tarsi are three-jointed ; and there are no pulvilli between the
claws. The most striking character of the family is the form of the
cerci, which are horny, and resemble forceps.

The earwigs are rare in this country, especially in the North. But
in Europe they are common, and are often troublesome pests.
They are nocturnal, hiding in the day-time among leaves and in all
kinds of crevices, and coming out by night. They feed upon the
corollas of flowers, fruit, and other vegetable substances. When
troublesome, they may be trapped with hollow objects into which
they can crawl and hide during the day-time.

The name of the typical genus, Forficula,
is the Latin word for scissors. It was sug-
gested by the curious form of the cerci. The
common name, earwig, has reference to a
widely spread fancy that these insects creep
into the ears of sleeping persons.

Our most common representative of the
family is the little earwig, Labia minor. This
is a small species; the body measures a little
less than 4 mm. (0.15 inch) in length ; the for-
ceps of the male, 1.25-2 mm. (0.05-0.08 inch) ;
and those of the female slightly less. The
head is blackish ; the pronotum is narrower
than the head ; and the wings protrude be-
yond the tips of the tegmina.

In 1876 only 13 species of this family were known to occur in
the United States. For a tabular synopsis of these by S. H. Scud-
der, see Psyche, vol. I. p. 177.

It is thought by many entomologists that this family should
rank as an order; and it is so classed in some of the text-books
under the name Dcrmdptera, and in others under the name Euplex-
optera.

Fig. 85.— An Earwig.

92 AN INTRODUCTION TO ENTOMOLOGY.

Family II. — Blattid^E*
(Cockroaches?)

The cockroaches are such well-known insects that there is but
little need for a detailed account of their characteristics. As already
indicated in the table of families, the body is oval and depressed ;
the head is nearly horizontal, and wholly or almost wholly withdrawn
beneath the pronotum ; the head is bent so that the mouth parts
project caudad between the bases of the first pair of legs ; the
antennae are long and bristle-like ; and the pronotum is shield-like.
This family includes only the cockroaches ; but these insects are
known in some localities as " black beetles," and our most common
species in the Northern cities bears the name of Croton-bug.

In the Northern States our native species are usually found in
the fields or forests under sticks, stones, or other rubbish. But cer-
tain imported species become pests in dwellings. In the warmer
parts of the country, however, native and foreign species alike swarm
in buildings of all kinds, and are very common out of doors.

Cockroaches are very general feeders : they destroy nearly all
forms of provisions, and injure many other kinds of merchandise.
They often deface the covers of cloth-bound books, eating blotches
upon them for the sake of the sizing used in their manufacture ; and
I have had them eat even the gum from postage-stamps. They
thrive best in warm, damp situations ; in dwellings they prefer the
kitchens and laundries, and the neighborhood of steam and water
pipes. They are chiefly nocturnal insects. They conceal themselves
during the day beneath furniture or the floors, or within the spaces
in the walls of a house ; and at night they emerge in search of food.
The depressed form of their bodies enables them to enter small
cracks in the floors or walls.

Not only are these insects very destructive to our possessions,
but owing to their fetid odor merely the sight of them awakens dis-
gust ; but it is due them to state that they are said to devour greedily
bed-bugs. This will better enable us to abide their presence in our
state-rooms on ocean voyages, or in our chambers when we are
forced to stop at poor hotels.

It is a curious fact in the life-history of cockroaches that the
female lays all of her eggs at once, they being inclosed in a purse-

* Blattidae: bldtta, a cockroach.

ORTHOPTERA.

93

Fig. 86.— Ootheca of a Cock-
roach.

like pod (Fig. 86). This pod varies in form in different genera ; but
is more or less bean-shaped. Upon one edge
there is a longitudinal slit. Within, the cap-
sule is divided into two spaces, in each of
which there is a row of separate chambers,
each chamber enclosing an egg. The females

carry this pod, or ootheca, as it is termed, about with them, pro-
truding from the end of the abdomen for several days.

The use of Pyrethrum or Persian insect-powder is the most effi-
cient means of ridding an infested house of these pests. It should
be sprinkled about their haunts at night, or blown into the cracks
from which they come. (See Chapter XIV., Pyrethrum).

The Croton-bug {Blatta germanicd). — This is the best known of all
of the cockroaches in our Northern cities. The above popular name
originated in New York City, and was suggested by the fact that
these pests are very abundant, in houses, about the
water-pipes connected with the Croton Aqueduct.
The adult insect varies in length from ii mm. to 13
mm. (0.43 in. to 0.51 in.). It is light brown in color,
with two longitudinal black stripes on the pronotum.
The wings extend beyond the tip of the abdomen.
This is an imported species, which has spread to
nearly all parts of the world, living upon ships, and
spreading from them. (Fig. 87.)

The Oriental Cockroach {Periplaneta orientdlis). —
This also is a cosmopolite, which, like the preceding
species, is a great pest in dwellings throughout the civilized world.
It is dark brown, and measures from 20 mm. to 23 mm. (0.8 in. to 0.9
in. in length). With the females the tegmina are only about 4 mm.
in length, and have no wings under them. In the males both pairs
of Wings are developed, but do not reach to the end ol the
abdomen.

Of our native species there are two which I have found very com-
mon at the North. Ectobia flavocincta is a blackish-brown species,
about 16 mm. (0.63 in.) in length, with a light stripe extending on
each side from the head along the margin of the pronotum and the
basal half of the tegmina. The wing-covers do not quite reach the tip
of the abdomen. Platamodes pennsylvanica is a much larger species.
with long delicate light-colored tegmina and wings. These extend
beyond the tip of the abdomen. The margin of the pronotum is
light, while the disk is dark ; and the lateral margins of the tegmina,
7

Fig. 87.— The
Croton buj, r .

94

AN INTRODUCTION TO ENTOMOLOGY.

especially at the base, are lighter than the discal portions. The
adult measures to the tip of the wings 25 mm. (1
inch) or more. Although this is a native species,
living in our fields, it is often found in our dwellings,
being attracted by lights at night.

Among our species of cockroaches are many
wingless forms. One of these is represented in
Fig. 88.

Fig. 88.— A wing-
less Cockroach.

Family III. — MANTID^E.*

{The Soothsayers or Praying Mantes.)

The members of this family have received many
popular names in the regions where they occur, owing to their gro-
tesque forms and strange attitudes. Among these are Rear-horses,
Race-horses, Camel-crickets, Praying Mantes, and Soothsayers. The

Fig. %Q.—Phasmomantis Carolina

species are usually of considerable size, so that they are conspicuous
objects. We have no representative of the family at the North ;
and there are but few species in our Southern States, they being
chiefly inhabitants of tropical countries.

The most striking characters of these insects are the great length
of the prothorax, it being the longest segment of the body, and the
enlarged front legs, which are fitted for grasping. With some spe-
cies the wings resemble leaves of plants in form and coloring. This
resemblance is protective, causing the insects to resemble twigs of

Mantidae, Mantis: mantis (/.lavrii), a prophet; also the Greek name for these in-

sects.

ORTHOPTERA.

95

the plants upon which they are. All of the species are carnivorous.
They do not pursue their prey, but wait patiently with the front
legs raised like uplifted hands in prayer, until it comes within reach,
when they seize it. This position which they as-
sume while waiting gives them most of their
popular names. The eggs of the Mantidae are
laid in clusters on twigs, and encased in a flattened
case or ootheca (Fig. 90). This differs from the
ootheca of the cockroach in being composed of
hardened silk.

The most common species of the Southern
States is Phasmomdiitis Carolina. This is shown
by Fig. 89. By referring to this figure the un-
usual development of the front legs can be seen.
The parts of the leg that are most strongly
spined are the femur and tibia ; the slender
tarsus appears as an appendage of the tibia ;
and the coxa is so elongated that at first sight
it would be mistaken for the femur.

Family IV.— Phasmid.-e."
( Wa/king-sticks.)

Even more grotesque in appearance than the
Mantidae are the insects constituting the family
Phasmidae, and commonly known as Walking-sticks,
or Spectres. They can be easily recognized by their
long, linear bodies, furnished with long legs and antennae. The
three pairs of legs are similar in form. Their wings, when present,
a/e small, or if large, very leaf-like ; resembling in some instances
fresh green leaves, in others, those that are dry and withered. The
wingless species often resemble twigs.

The Walking-sticks are strictly herbivorous ; the)' are slow in their
motions, and often remain quiet for a long time in one place. Their
eggs are large, oval, and are scattered on the ground beneath the
plants upon which the insects feed, the female, unlike most Orthop-
terous insects, making no provision for their safety.

These insects are chiefly tropical. Only a single species is com-
mon in the Northeastern United States. This is Diaphcromera fe-

Fic. go. — Egir-masses

of /'. Carolina.

(From Riley.)

* Phasmidrc, Phfisma: phasma {(pciaiicx), a spectre.

9 6

AN INTRODUCTION TO ENTOMOLOGY.

mordta. It is represented in Fig. 91, natural size. It is a quite
common insect ; and on several occasions has appeared in such great

Fig. 91. — Diafikeromera femorata. a, 6, eggs; c, young hatching. (From Riley.)

numbers as to be seriously destructive to the foliage of forest trees.
Probably the best way of destroying it when it becomes a pest is to
spray the infested trees or shrubs with Paris-green water, and its

ORTHOPTERA. 97

recurrence should be guarded against by burning the leaves upon
the ground under the infested trees in the autumn, thus destroying
the eggs.

Family V. — Acrididae.*
{Locusts or Short-horned Grasshoppers.)

The Acrididae and the two following families constitute the sec-
tion Saltatoria or Jumpers. The members of this section agree in
having the hind legs fitted for jumping, by being either very much
stouter or very much longer, or both stouter and longer, than the
femora of the other legs. The females are usually furnished with a
prominent ovipositor, and the wings of the immature forms are in
an inverted position.

In many species, especially of the Acrididae, the adult is fur-
nished with rudimentary wings ; and thus presents the appearance of
an immature form. But by means of the character just given it is
easy to distinguish the adult even in the case of these short-winged
species; for in the immature forms the tegmina are folded beneath
the wings, and the principal veins of both tegmina and wings curve
downward instead of upward.

The family Acrididce includes the Locusts or Short-horned Grass-
hoppers. These are common and well-known insects. They differ
from other Saltatoria in having the antennae much shorter than the
body, and consisting of not more than twenty-five segments. The
ovipositor of the female is short, and composed of four separate
plates, and the basal segment of the abdomen is furnished on each
side with a supposed organ of hearing.

The head is usually short, although in two of the sub-families it is
extended horizontally. Immediately under the vertex, but in some
cases above it, there is on each side a little space bounded by ele-
vated ridges. These spaces are termed the lateral foveolce ; their
variations in form afford characters which are much used in classifi-
cation. The front is generally traversed by three vertical keels or
carina ; the one on the middle line is termed the median carina
or frontal cost 'a, the others are the lateral carina. The pronotum
is divided into four lobes by three more or less well-marked trans-
verse sutures; it is also often furnished with a median crest. The
hind tibiae carry upon the upper side two rows of spines: the num-

* Acrididae, Acrldium: acridion (aKuidiuv), a small locust.

98 AN INTRODUCTION TO ENTOMOLOGY.

ber of these is of use in distinguishing species ; and the presence or
absence of the last spine in the outer row is of much greater impor-
tance. Besides these spines there are four articulated spurs, which
are situated in two pairs, one on the outer and one on the inner
side of the tibia. The sexes can be easily distinguished. In the
males the ventral surface of the abdomen consists of nine segments,
while in the females there are but eight. The caudal end of the
body in the females is furnished with four horny appendages, the
ovipositor; in the male the ventral pair of appendages is repre-
sented by a single plate.

With many species of the Acrididse we find the males furnished with stim-
ulating organs. These are not nearly so highly developed as those of mem-
bers of the two higher families, and are used only in the day-time. The
Locusts stridulate in two ways. Certain species rub the inner surface of the
hind legs against the outer surface of the wing-covers. With these insects
there is a thickening of one of the main longitudinal veins in the centre of the
wing-cover {vena radidlis), and a remarkable extension of the two areas be-
tween this vein and the costal margin of the wing cover {area scapu/dr/s and
area externomedid), which serves as a sounding-board, and which is wanting in
the female. The most common representatives of the insects which stridulate
in this way belong to the genus Stenobotkrus. According to Scudder, the
Stenobothri, when about to stridulate, place themselves in a nearly horizontal
position, with the head a little elevated ; then they raise both hind legs at
once, and grating the femora against the outer surface of the tegmina, produce
notes which in the different species vary in rapidity, number, and duration. The
first one or two movements are frequently noiseless or faint; and when the
sky is overcast, the movements are less rapid. Scudder has recorded the
songs of several species by means of a musical notation.*

The second method of stridulation practised by locusts is by rubbing
together the upper surface of the front edge of the wings and the under sur-
face of the wing-covers. Those which employ this method stridulate during
flight. Several common species pertaining to the CEdipodinae will serve as
illustrations : Chimarocephala viridifasciata. Eucoptolephus sordidus, and Dissos-
teria Carolina. Certain other closely allied species produce no sound whatever.

Locusts lay their eggs in oval masses, covered witha tough glutin-
ous secretion. Many species deposit them in the ground, the ovi-
positor of the female being well adapted for making the necessary
hole. The tips of the four horny appendages of which it is com-
posed can be alternately applied together and spread apart ; in this
way it is an easy matter to force the earth aside and press the end of
the abdomen into the ground. Fig. 97 represents the Rocky Moun-

* Proc. Bost. Soc. Nat. Hist., vol. XI.

ORTHOPTERA. 99

tain lccust in the act of ovipositing. Certain species make holes with
their ovipositor in a similar manner in fence-rails, logs, stumps, and
other masses of wood, in which they deposit their eggs. After the
eggs are laid, the entrance to the hole in the wood is closed with a
little plug of gummy matter.

The transformations of three of our more common species of
Melanoplus have been carefully studied by Riley.* These will serve
to illustrate the metamorphoses in this family. In each case there
are five nymph stages. In the first of these (Fig. 8), although the
insect would be readily recognized as a young locust, there is a
marked difference in the proportions of the body from those pre-
sented by the adult. This is especially noticeable in the large size
of the head, the relatively stouter thorax and hind femora, and in
the short abdomen. From this form to that of the adult there is
presented by the other nymph stages a very regular series of grada-
tions. The most striking change in the course of the development
of these insects is the growth of the organs of flight. In the first
nymph stage there is no indication whatever of wings ; in the
second stage the caudo-lateral angles of the mesonotum and meta-
notum are very slightly prolonged (Fig. 9). In the third stage these
prolongations are more marked, and are easily recognized as rudimen-
tary wing-pads (Fig. 10). In the fourth stage a remarkable change
has occurred in these organs : up to this point they have projected
downward and backward ; they are now turned up so that what was
their lower edges now meet on the narrow back, and the side of
each which was next to the body is now turned outward (Fig. 11).
While in this position the second pair of wing-pads is outside of the
first — the reverse of the relative positions of the fully developed
wings. In the fifth stage the wing-pads are longer, being now about
as long as the pronotum (Fig. 12). Up to this point the development
of the wings has been very gradual, the most pronounced change be-
ing the reversal of these organs between the third and fourth stages.
With the moult, which occurs at the end of the fifth stage, the insect
assumes the adult form (Fig. 13). The wings have now become
greatly elongated ; they are again reversed, so that the}- assume the
primitive position, with the second pair folded beneath the first.
This completes the changes through which these organs pass.

So far as my observations go, there is but a single generation of
each species of locust during a year. In the majority of cases at

See First Report of the U. S. Ent. Com., Plates I., II., and III.

IOO AN INTRODUCTION TO ENTOMOLOGY.

the North, the species winters in the egg state, and does not become
fully developed till the latter part of summer or in the autumn. A
few adults survive the winter ; and we have a few species in which
the eggs hatch in the autumn, and the insects pass the winter in the
nymph state.

Many of the Acrididae never acquire fully developed wings ; the
way in which these short-winged adults can be distinguished from
nymphs has been given in the generalizations regarding the order.

The locusts, or grasshoppers as they are commonly called, are of
first-class importance when viewed from an economic standpoint.
They feed on all kinds of vegetation, and they abound every year
in all parts of our country. Owing to their uniform abundance,
they have fallen into the category of the commonplace, and little is
said about them. I do not refer here to the migratory species, the
incursions of which spread consternation, but to the myriads that
swarm in our meadows and pastures every summer and autumn.

Although the injuries caused by our common locusts are very
great every year, they are more noticeable in seasons of drought.
It frequently happens at such times that every blade of grass is con-
sumed in extensive pastures. This results not merely from the
less luxuriant growth of the grass, but from the fact also that dry
weather is favorable to the development of these insects.

It follows from the above that such treatment of meadows and
pastures as shall best enable them to withstand droughts will also
serve to protect them from the ravages of locusts. Thus the
presence in the soil of a considerable amount of vegetable matter,
furnished in the form of stable manure or otherwise, which will
retain moisture, will have this tendency : or clover may be used ;
this will shade the soil, and will bring moisture and fertility from
great depths by means of its long roots. In case of heavy clay
lands, tile-draining has been recommended ; this prevents the pud-
dling and subsequent baking and cracking of the soil resulting from
surface drainage.

TABLE OF SUB-FAMILIES OF ACRIDID^.

A. Pulvilli present between the claws of the tarsi ; pronotum never extending
over the abdomen.
B. Prosternum unarmed.

C. Vertex and front of head meeting at an acute angle; vertex extending
horizontally ; front strongly receding. (Fig. 92.) I. Tryxalin.E.

ORTHOPTERA. IOI

CC. Head rounded at the union of the vertex and front ; front perpendic-
ular, or nearly so. (Fig. 93.)

D. The terminal spine of the outer row of the posterior tibiae wanting

(Fig. 94,/-') ; second abdominal segment smooth. II. CEdipodin.e.

DD. The terminal spine of the outer row of the posterior tibiae present

(Fig. 94, a) ; second abdominal segment granulated on the sides.

(Fig. 95.) III. Eremobix.e.

BB. Presternum tuberculate, or mucronate, or produced into a cone.

C. Head rounded at the union of the vertex and front; front slightly re-
ceding; antennae filiform. (Fig. 99.) IV. Acriiux.e.
CC. Vertex extending horizontally in front of the eyes ; front strongly re-
ceding ; antennae more or less flattened. (Fig. 102.) V. Opomaeix.e.
AA. No pulvilli between the claws of the tarsi ; pronotum extending over the
abdomen. (Fig. 103. ) VI. Tettigix.e.

Sub-family I. — Tryxalinae*

In the linear arrangement of the sub-families of the Acrididae
there are placed first, i.e., lowest, a series of sub-families in which the
prosternum is unarmed. The Tryxalinae differs from the other
members of this series in that the representatives of it have the ver-
tex, conical and elongated, the front strongly receding, and the an-
tennae flattened. The antennae are inserted between the middle of
the eyes or farther from the mouth than their middle ; the eyes arc
usually longer than that part of the genae below them ; the posterior
lobe of the pronotum is usually shorter than the anterior part ; the
median carina is not at all crested ; and the last spine of the outer
row of the posterior tibiae is wanting.

The characteristic difference between this family and the next,
the CEdipodinae, is in the joining of the vertex and front, as indicat-
ed in the table of sub-families given above. The following species
will serve to illustrate the Tryxalinae :

Ackurum brevipenne. — This is one of the most grotesque of all our
locusts. The body is excessively elongated, being almost linear. In
fully grown female specimens it measures more than 40 mm. (1.6 in.)
in length ; and about 3 mm. (0.12 in.) across in the widest part. The
males are somewhat smaller. The head is greatly elongated, and
ascending; the front is very strongly receding ; the antennae are a
little .shorter than the head and prothorax, broad near the base,
acuminate at the apex, and triquetrous. The wings are small',
when fully developed the tegmina extend a little beyond the third

Tryxalinae, Tryxaiis: tryxallis (rpvcaXXii), Greek name of these insects.

102 AN INTRODUCTION TO ENTOMOLOGY.

abdominal segment. The color of these insects is brown, sometimes
marked with minute dark specks.

This species is an excellent illustration of protective form and
coloring. I found it quite common in Florida upon the "wire-
grass " which grows in the sand among the saw-palmettoes ; and so
closely did their brown linear bodies resemble dry grass, that it was
very difficult to perceive them.

I have also collected this species near the coast as far north as
Maryland, but have no other information as to its distribution.

Among the more common representatives of this sub-family in
the Eastern United States are two species of the genus St enobot Ji-
ms. In each of these there is on each side on the margin of the
vertex in front of the eye a little oblong pit, the lateral foveolae ;
and the lateral carinae of the pronotum are incurved. The more
common of the two is the Short-winged Locust, 5. curtipennis. In
this species the lateral foveolae are linear; the tegmina are unspotted
and of a pale reddish brown. In some specimens the tegmina and
wings are shorter than the abdomen ; in others they are longer.
The males measure about 16 mm. (0.63 inch) in length ; the females,
21 mm. (0.82 inch).

The next species of this genus in abundance is the spotted-winged
locust, 5. maculipennis. In this species the lateral foveolae are shal-
low, and broader towards the eye than at the apex ; the tegmina are
green, with a median band of equidistant square black spots along
its whole extent ; sometimes the inner halves of the tegmina are
entirely of a rust-red color. Both the tegmina and wings extend
beyond the tip of the abdomen. This species is about the same
size as the preceding.

In the genus Clirysochraon the vertex is without foveolae; and
the lateral carinae of the pronotum are nearly parallel. One of the
species, the Sprinkled Locust, C. conspcrsiim, is very abundant. It

is brown, with the sides of the prono-
tum and the first two or three abdo-
minal segments shining black in the
male ; and with the body and teg-
mina of the female sprinkled or mot-
Fig. yi.—chrysochraon conspersum. tied with darker brown . The tegm ina

and wings are a little shorter than
the abdomen in the males, and much shorter in the females. The
female is represented by Fig. 92. The males measure 17 mm. (0.67
inch) in length; the females, 23 mm. (0.91 inch).

ORTHOPTERA. 103

Sub-family II.— CEDIPODIN/E.*

The second of the two more important sub-families in which the
prosternum is unarmed, the CEdipodincs, includes genera in which
the head is rounded at the union of the vertex and front; and in
which the front is perpendicular or nearly so. The antennae are
linear or sub-linear, and usually inserted nearer the mouth than the
middle of the eyes; sometimes they are inserted just in front of the
eyes. The eyes are small or of medium size; rarely longer than
that part of the cheeks below the eyes. The posterior lobe of the
pronotum is longer than the anterior part in the typical forms ; and
the median carina is frequently entirely or. partially crested. As
with the preceding sub-family, the last spine of the outer row of
the posterior tibiae is wanting.

We have many representatives of the CEdipodinae, and these are-
distributed by modern systematists among numerous genera. I
have selected a few of the more common species of the Eastern
United States as illustrations. These can be separated by the fol-
lowing table :

A. Wings with the disk yellow.
B. Apical half of wing dusky.
C. Dorsal aspect of head with a slight median carina, which is quite prom-
inent in the well-marked depression on the vertex (central fov<

Encoptdlophus serdidus.
CC. Dorsal aspect of head without median carina, or with merely an indi-
cation of one; central foveola less distinct. ChortopJiaga viridifascidta.
B. With a dark band across the wings. Spharagemon cequdle.

A A. Wings with the disk black. Dissostiria Carolina.

AAA. Wings with the disk red. Hippisais discoideus.

The Clouded Locust, Encoptdlophus sordidus. — This species is
very common in the Eastern Uni-
ted States during the autumn. It
abounds in meadows and pastures ;
and attracts attention by the
crackling sound made by the males
during flight. It is of a dirty-brown FlG . ^_ Encoptol

color, mottled with spots of a

darker shade. It appears somewhat like the variety infusedtaoi the
following species, but it can be easily distinguished by the charac-
ters given in the table above. Size same as following species.

* CEdipodinre, CEdipoda: oidos (oi'5o?), a swelling; pous (itOvZ), a foot.

104 AN INTRODUCTION TO ENTOMOLOGY.

The Green-striped Locust, ChortdpJiaga viridifascidta. — This is a
very common species from Maine to Florida. There are two well-
marked varieties. In one, the typical form, the head, thorax, and
femora are green, and there is a broad green stripe on each wing-
cover, extending from the horn to beyond the middle: this often in-
cludes two dusky spots on the edge. The second variety differs so
much in appearance, that it was described by Harris as a distinct
species under the specific name infuscdta. In this form the ground
color is dusky brown. Intergrades occur, in which the head and
thorax are of a reddish velvety brown. Length of male to end of
abdomen 20 mm. (.8 inch), to tip of wings 25 mm. (1 inch) ; length of
female to tip of wings about 30 mm. (1.4 inch).

The Barren-ground Locust, Sphardgcmon aqudlc. — This locust
occurs throughout North America east of the Rocky Mountains.
In the Northern United States it is found during the months of
July and August on dry, barren hills, and on sandy plains. It is
ash-gray in color, mottled with dusky brown and white ; the face is
whitish ; the wing-covers are marked with dusky bands, and are
semi-transparent at tip ; the wings are traversed by a dark band just
beyond the yellow disk. Length to tip of wings, male, 30 mm.
(1.2 inch) ; female, 35 mm. (1.4 inch).

The Carolina Locust, Dissosta-ia Carolina. — Notwithstanding its
specific name, this species is common throughout the United States
and Canada. At the North it is the largest of our common locusts,
but it is greatly surpassed in size by species found in the South. It
abounds in the highways and in barren places. It takes flight
readily, and the males stridulate while in the air. The color of this
insect varies greatly, simulating that of the soil upon which it is found.
It is usually of a pale yellowish or reddish brown, with small dusky
spots. The wings are black, with a broad, yellow margin, which is
covered with dusky spots at the tip. Length to tip of wings
35-45 mm. (1.4-1.8 inch).

Hippiscus discoldeiis. — This is the largest of our common repre-
sentatives of the CEdipodinse. It is a Southern species. I have,
however, specimens from as far north as New Jersey. In color it is
pale reddish or yellowish brown, with dark-brown spots ; the wing-
covers marked with strongly contrasting brown or blackish and white
spots or bands, the anal area reddish. The disk of the wings is red.
The body, especially of the female, is heavy, the thorax being both
broad and deep. Length to tip of wings, male 40mm. (1.6 inch);
female, 55 mm. (2.2 inch).

ORTHOPTERA. 105

Sub-family III.— EREMOBIN^; .*

This sub-family includes large, plump species, with the general
appearance of members of the GEdipodinae. They can be distin-
guished from the preceding sub-family by the presence of the ter-
minal spine of the outer row of the posterior tibiae 1 Fig. 940) ; also
by the presence of a rough plate on the side of the second abdominal
segment (Fig. 95). The vertex is usually broad, flat, or concave, and

a ^

I

Fig. 94. — Legs of Locusts. Fig. 95. — First abdominal segment of Eren

strongly declivous ; it is then suddenly narrowed and falls off verti-
cally to the plain of the antennas. In this place it forms a part ap-
parently of the frontal costa, from which it is separated anatomically
by a little transverse ridge. Below this ridge lies the middle ocellus.
The eyes are relatively small, and widely separated by the broad
vertex.

This sub-family is represented in our fauna by Eremcbia magna
from Arizona.

Sub-family IV.— Acridix.k.

Of the series of sub-families of Locusts in which the prosternum
is armed, representatives of but two have as yet been discovered in
our fauna. To the first of these, the Acridinae, belong some of
our most common and at the same time some of the most impor-
tant species. In this sub-family the head is short, and is rounded
at the union of the vertex and front. The front is slightly reced-
ing. The antennas are filiform; and the terminal spine of the outer
row of the posterior tibiae is usually wanting.

This sub-family is represented by many forms in this country.
Only those species that are most likely to attract attention are men-
tioned below. These can be determined generically by means of
the following table :

* Eremobln.'E, Erimobia: eremos (epijjuoi), a desert; bioS {fiiooo), to live.

io6

AN INTRODUCTION TO ENTOMOLOGY.

A. Wings as long as or longer than the abdomen.

B. Pronotum sloping from the median carina; lateral carinae wanting ; ex-
tremity of abdomen in males not swollen. i. Acridium.
BB. Pronotum somewhat flattened above; lateral margins angular; ex-
tremity of abdomen in the males much swollen. 4. Melanoplus.
AA. Wings of adult shorter than the abdomen or wanting.
B. Prosternal spine prominent.
C. Antennae tapering to the tip ; and with the segments very distinct.

2. DlCTYOPHORUS.

CC. Antennae thread-like, of nearly the same thickness throughout ; seg-
ments less distinct. 3. PEZOTETTIX.
BB. Prosternal spine slightly developed. 5. Brachystola.

I. Acridium. — The most common representatives of this genus
in the Eastern U. S. are A. alutdceum and A. rubiginosum. In the
Southern States the most conspicuous species is A. amcricdnum.

The Leather-colored Locust, Acridium alutdceum. — This locust
is dirty brownish yellow, with a paler stripe on the top of the head
and thorax; the wing-covers are semi-transparent, with irregular pale-
brownish spots, and with the sutural margins yellowish. Posterior
margin of each abdominal segment with a ring of black dots. The
wing-covers are longer than the abdomen. Length of body to end
of abdomen, female 43-50 mm. (1.7-2 in.), male 31 mm. (1.24 in.).

The Rusty Locust, Acridium rubiginosum. — The color of this
species is light rust-red ; the wing-covers are opaque, rather paler on
the overlapping portion than elsewhere, and sometimes with dim
spots, but usually without them. The wing-covers are about as long
as the abdomen. Length of female 35-40 mm. (.4-1.6 in.) ; males
much smaller.

The American Locust, Acridium amcricdnum . — This magnificent

icanum. (From Riley.)

species occurs in the Southern States. It can be easily recognized
from Fig. 96, which represents its natural size. This locust some-

ORTHOPTERA, \0"J

times assumes the migratory habit, and is sometimes injurious to
agriculture.

2. Dictyophorus. — This genus is represented by a very large and
clumsy locust, which occurs in the southern part of our country,
D. reticuldtus. The adult is yellow and black ; the tegmina and
wings are shorter than the abdomen ; the base and disk of the wings
are red, with the outer margin black. Length of body in female
about 60 mm. (2.4 in.), in male 50 mm. (2 in.). The nymphs of this
species differ remarkably from the perfect insect, being of a very deep
metallic bronze-green color approaching black, marked with yellow,
deepening into red in spots, or wholly with blood-red ; this is most
conspicuous in a slender dorsal stripe the whole length of the crea-
ture, and on the hinder edge of the pronotum. I found these
nymphs very abundant in May at Jacksonville, Fla.

3. Pezotettix. — To the genus Pezotettix belong a considerable
number of short-winged locusts, of medium or small size. More
than fort)- species have been found in the United States, but nearly
all of these are from the Far West or from the South. The mem-
bers of this genus, according to Brunner, with but few exceptions,
prefer cool and shady localities, and hence are often found among
or near rocks, on mountain slopes, in clearings or on the outskirts
of timber belts, and in meadows.

The only species of Pezotettix that has been taken at Ithaca in
considerable numbers,/ 5 . Scuddcri, occurs among scattered trees, on
the crests and slopes of our highest hills. This species can be easily
recognized by its close resemblance in form and appearance to the
Common Red-legged Locust, Meldnoplus femur-rubrum. The only
conspicuous difference is in the organs of flight : in P. Scuddcri the
wing-covers do not extend beyond the second abdominal segment.

In Pezotettix glacidlis the wings and wing-covers are wanting.
This species inhabits the mountains of New England ; it has also
been taken at Ithaca, N. Y.

Pezotettix pictus is the brightest colored of all our locusts. It is
bluish green, with bright red and yellow markings, and is found on
the plains sloping eastward from the Rocky Mountains.

4. Meldnoplus. — We have many species ol locusts, which belong
to this genus. Some of them are among the most common and
most destructive members of the family Acridiidx. Much has
been written concerning them; but as most writers have believed
that they belong to the genus Caloptenus, it will be necessary to

io8

AN INTRODUCTION TO ENTOMOLOGY.

look under that head in the older works for descriptions of them.*
The following table will aid in determining the males of the species
mentioned below ; as a rule there will be but little, if any, trouble
in assorting the females after the males are determined.

A. Apex of last abdominal segment of male distinctly notched.
B. Length of body to tip of wing-covers 29-35 mm - (1. 16— 1.4 inches).

M. SPRETUS.

BB. Length of body to tip of wing-covers 23-26 mm. (0.9-1.04 inches).

M. ATLANTIS.

AA. Apex of last abdominal segment of male entire or most obscurely notched.
B. Anal cerci enlarged at apex. M. FEMORATUS.

BB. Anal cerci tapering.

C. Species of medium size ; anal cerci much narrowed, but without a notch.

M. FEMUR-RUBRUM.

CC. Species of large size ; anal cerci suddenly narrowed, making a prom-
inent right-angled notch on lower side. M. differentials.

The Rocky Mountain Locust or Western Grasshopper, Melanoplus
spretus. — The most terrible of insect scourges that this country has
known have been the invasions of this species. Large areas of

Fig. 07.— Egg-laying of the Rocky Mountain Locust, a, a, a, female in different positions, oviposit-
ing ; b, egg-pod extracted from the ground, with the end broken open ; c, a few eggs lying loose
on the ground ; de shows the earth partially removed, to illustrate an egg-mass already in place,
and one being placed ; /"shows where such a mass has been covered up. (From RUey.)

country have been devastated, and the inhabitants reduced to a
state of starvation. The cause of all this suffering is not a large
insect. It is represented natural size by Fig. 97. It measures to

* For a statement of the reasons for the adoption of the name Melanoplus, see
paper by S. H. Scudder, Proc. Boston Soc. Nat. Hist., Vol. XIX. p. 261.

OR THOP TEKA. 1 09

the tip of its wing-covers 29-35 mm. (1. 16- 1.4 inches), and resembles
very closely our common Red-legged Locust, the most abundant of
all our species. It can easily be distinguished from this species by
the greater length of the wings, which extend about one third of
their length beyond the tip of the abdomen, and by the fact that
the apex of the last abdominal segment in the males is distinctly
notched.

The permanent home or breeding grounds of this species is in
the high dry lands on the eastern slope of the Rocky Mountains,
extending from the southern limit of the true forests in British
America south through Montana, Wyoming, the western part of
Dakota, and the Parks of Colorado. There are also regions in which
the species exists permanently west of the Rocky Mountains in
Idaho and Utah.

When the food of this insect becomes scarce in its mountain
home, it migrates to lower and more fertile regions. Its long wings
enable it to travel great distances ; and thus the larger part of the
region west of the Mississippi River is liable to be invaded by it.
Fortunately, the species cannot long survive in the low, moist regions
of the valleys. Although the hordes of locusts which reach these
sections retain their vigor, and frequently consume every bit of
green vegetation, the young, which hatch from the eggs that they
lay, perish before reaching maturity. In this way, the invaded
region is freed from the pest until it is stocked again by another
incursion. There is, however, a large section of country lying
immediately east of the great area indicated above as the permanent
home of this species, which it frequently invades, and in which it can
perpetuate itself for several years, but from which it in time dis-
appears. This sub-permanent region, as it has been termed, extends
east in British America so as to include nearly one third of Manitoba ;
and, in the United States, it embraces nearly the whole of Dakota,
the western half of Nebraska, and the north-east fourth of Colorado.

The temporary region, or that only periodically visited and from
which the species generally disappears within a year, extends east
and south so as to include more than half of Minnesota and Iowa,
the western tier of counties of Missouri, the whole of Kansas and
Indian Territory, and the greater part of Texas. The country lying
east of the section thus indicated has never been invaded by this
locust, and there is no probability that it will ever be reached by it.

The United States Entomological Commission has published

8

no

AN INTRODUCTION TO ENTOMOLOGY.

three large volumes regarding this insect. The student is referred
to them for a detailed account of it.

The Lesser Locust, Melanoplus atldntis. — This is a common
species, which is very closely allied to the Rocky Mountain Locust.
It can be distinguished, however, by its smaller size, as indicated
above, and by its shorter wings. The specific name is an inappro-
priate one; for the species occurs, throughout at least the northern
part of our country, from the Atlantic to the Pacific.

The Red-legged Locust, Melanoplus femur-rubrum. — This is the
most familiar member of the family Acridiidae throughout the
United States, except where M. sprctus occurs. It is more abundant

than any other locust east of the Missis-
sippi ; it is this and the preceding species,
which is usually confounded with it, that
ravage our meadows and pastures more
than all other species combined. The
female is represented natural size by Fig.
98.

-This species also extends from the

3. — Melanoplus femur-ru-
brutn.

Melanoplus fcmoratus.

Fig. 59 — M. femoratus. (From Riley.)

Atlantic to the Pacific. It is the largest representative of the genus
that occurs in the Eastern States. It is marked with a yellowish
stripe, extending along each side from the upper angle of the eye to
the tip of the elytra (Fig. 99). The length of the body to the tip

Fig. 100. — M. differentialis. (From Riley.)

of the abdomen varies from 25 mm. (1 inch) to 40 mm. (1.6 inches).
This species has been confounded in most of our works on Ento-

ORTHOPTERA.

Ill

mology with M. bivittatus, a closely allied species, which occurs in
the interior.

M. differ entialis. — This species is slight-
ly larger than the preceding ; it lacks the
prominent yellow stripes, and is confined
to the central portion of the United States
(Fig. ioo).

5. Brachystola. — This genus is repre-
sented by the " Lubber Grasshopper" or
Clumsy Locust of the plains, B. magna.
This insect is confined to the central
portion of North America, and it can be
readily recognized by the accompanying
figure (Fig. 101).

Sub-Family V. — Opomalix.e.' ;: "

This sub-family is closely related to the
Acrididae; and the members of it resemble
that sub-family in having the prosternum
armed. The Opomalinae are distinguished
by the vertex extending horizontally in
front of the eyes, by the strongly receding
front, and by the short fore and middle femora. The antennae are
usually more or less flattened ; and the terminal spine of the outer
row of the posterior tibiae is never wanting.

Several genera of this sub-family are represented in this country.
The species are more common in the South and West than in the

Fig. ioi. — Brachystola magna.
(From Riley.)

Fig. 102. — Leptysma marginicolle.

Northeast. Fig. 1 02 represents Leptysma marginicolle ; tin's species
occurs in Florida, and will serve as an illustration of the sub-family.

Sub-Family VI. — TETTIGINvE.f

The TettigincB includes small locusts of very unusual form. The
most striking character of the sub-family is the shape of the pro-

* Opomallnte, Opomala: ops (Mip), appearance; omalos (o//<t,ld?), plane,
f Tettiglnae, Tfittix: tettix (rerriq), the Greek name for these insects.

112 AN INTRODUCTION TO ENTOMOLOGY.

notum. This is prolonged backwards over the abdomen to or

beyond its extremity (Fig. 103). The head is deeply set in the

pronotum, and the presternum is expanded into

a broad border which partially envelops the mouth

like a muffler. The antennae are very slender and

„... short. The tegmina are rudimentary, being in the

riG. 103. — lettix. o J 1 o

form of small, rough scales, while the wings are usu-
ally well developed. These locusts differ, also, from all others in
having no pulvilli between the claws of the tarsi.

The Tettiginae are commonly found in low, wet places, and on
the borders of streams. Their colors are usually dark, and are often
protective, closely resembling that of the soil upon which the insects
occur. They are very active, and possess great leaping powers.

Three genera of this sub-family are represented in this country.
These can be separated by the following table :

A. Pronotum arched roundly, antennae 12-jointed. Batrachidea.
AA. Pronotum nearly or quite horizontal.

B. Antennae 13- or 14-jointed. Tettix.

BB. Antennae 22-jointed. Tettigidea.

Family VI. — LOCUSTID^E.*

{Long-horned Grasshoppers and Katydids.)

The members of this family are easily recognized. They differ
from the Acrididae in the great length of the antennae, which are
longer than the body. From the Gryllidae, which they resemble in
the length of the antennae, they are distinguished by the form of the
ovipositor, which is compressed and sword-shaped ; and by the four-
jointed tarsi. As with the Crickets, the tegmina of the males are
furnished with a musical apparatus. But this occupies a much
smaller part of the tegmina than with the Crickets. Excepting this
small area, the anal, the tegmina, when at rest, are vertical.

The name of this family, as is the custom, is derived from the
name of its typical genus, Locnsta. But the insects which are rightly
termed in popular language Locusts belong to the preceding family,
the Acrididae. That is, to that family belong the insects spoken of
in the Bible, and in modern European works, as locusts. In this
country, unfortunately, the term grasshopper has been used to in-
clude both the true grasshoppers, i.e., the Locustidae, and the true
locusts: while the term locust has been applied to an insect of an-

* Locustidse, Locusta: Locnsta, a locust.

ORTHOPTERA. 1 13

other order, the Cicada. In order to avoid confusion, I have referred
to the members of the Locustidae and the Acridiida; as Long-horned
Grasshoppers and Short-horned Grasshoppers respectively. It is
better, however, to call the former Grasshoppers, and the latter Lo-
custs. This last term should never be applied to the well-known
insect which appears once in seventeen years ; this is rightly called
the Periodical Cicada.

Representatives of each of the more common genera of the North-
eastern United States are mentioned below. These genera can be
separated by the following table :*

A. Wingless, or with rudimentary wings and wing-covers.
B. Pronotum not extended over the ineso- and metanotum.

i. Ceuthophilus.
BB. Pronotum extended over meso- and metanotum. 9. Thyreonotus.
AA. Winged.

B. Tegmina expanded in the middle.

C. Tegmina much broadened in the middle, concave. 5. Cyrtophyllus.
CC. Tegmina somewhat broadened in the middle, not concave.

D. Ovipositor very small. 7. Mjcrocentrum.

DD. Ovipositor of medium size. 6. Amblycorphya.

BB. Tegmina not expanded in the middle.

C. Vertex of the head with a conical projection forwards.

4. CONOCEPHALUS.

CC. Vertex of the head without a conical projection.

D. Ovipositor straight, or very nearly so ; insect small. 2. Xiphidium.
DD. Ovipositor curved ; insect large.

E. Ovipositor curved sharply upwards. 8. SCUDDERIA.

EE. Ovipositor sword-shaped. 3. Orchelimu.m.

In order to facilitate the study of the Locustarians, our common
genera can be arranged in four groups ; namely, the Cricket-like
Grasshoppers, the Meadow Grasshoppers, the Katydids, and the
Shield-backed Grasshoppers.

I. The Crickct-likc Grasshoppers.

1. Ceuthophilus. — To the genus Ceuthophilus belong certain
wingless grasshoppers, which bear some resemblance in form to
crickets (Fig. 104). They have a short, thick body and remarkably
stout hind femora, like a cricket, but are entirely destitute of teg-
mina and wings. All the species in our collection are cither of a
pale brown or dirty white color and more or less mottled with either

* After S. H. Scudder, Boston Journal Natural History, Vol. VII. p. 414.

U4

AN INTRODUCTION TO ENTOMOLOGY.

lighter or darker shades. These insects are found under stones and

rubbish in woods. Very closely al-
lied to them are the " Cave-crick-
ets." These belong to the genus
Hadencecus, H. caverndrum inhabits
the caves of this country ; it has very
long legs and antennae, is colorless
and blind.

Fig. \oi,.—Ceuthophilus,

Fig. 105. — Xiphidium.

II. The Meadow Grasshoppers.

2. Xiphidium. — From the middle of the summer to the autumn
there may be found upon the grass in our meadows and moist pas-
tures many light-green grasshoppers of various sizes. These, on ac-
count of the situations in which they are usually found, are termed
the meadow grasshoppers. A large proportion of the species belong
to the genus Xiphidium. This genus comprises the smaller of our
common species. The members of it do not have the head fur-
nished with a conical projection, and the ovipositor of the females
is straight and sword-shaped (Fig. 105).

We have three common species in the
Middle States. In one of them, X. fas-
eidtum, the tegmina and wings are long,
extending far beyond the tip of the ab-
domen. In each of the other species
the tegmina and wings are much short-
ened. X. ensifer is characterized by the great length of the
ovipositor, which is longer than the rest of the body ; while the
ovipositor of X. brevipennis is a little shorter than the hind femora.

3. Orchellmurn. — These insects differ from the other common
meadow grasshoppers in having the ovipositor curved. Our most
common species is O. vulgdre. This species measures from the ver-
tex of the head to the end of the abdomen 18 mm. (0.7 inch), or to
the tip of the wing-covers 25 mm. (1 inch). The brown line on the
dorsal aspect cf the head and thorax does not extend down upon
the front of the head ; in the males there are two short black dashes
on each of the tegmina ; the four form the angles of a square, inclos-
ing the musical apparatus. The wings equal the tegmina in length
or are a little shorter. Another common species is 0. glaberrimum.
This has the dorsal band and the musical apparatus of the males
bordered with black, and the ovipositor slightly expanded in the
middle. O. agile has a narrow dark streak down the middle of the

ORTHOPTERA. 115

front of the head. 0. concinnum is found in Massachusetts; this
also has a dark streak extending down the front to the labrum, but
it expands broadly in the middle of the face.

4. Conocephalus. — This genus includes the largest of our meadow-
grasshoppers. It differs from the genera already named in having
the head prolonged into a cone-shaped projection. The species are
found in trees as well as in grass, having a strong resemblance to the
katydids both in appearance and habits. The most common species
throughout the eastern part of our country is C. ensiger. Both sexes
have very long wings ; and the ovipositor of the female is remarka-
ble for its length. The length of the body from the tip of the head
to the end of the abdomen is 30 mm. (1.2 inches), while the distance
from the tip of the head to the end of the wings or ovipositor is twice
that amount. Two distinct forms of this species occur ; one is pea-
green, and the other is of a brownish straw color. C. robiistus is a
stouter species than the preceding, and has a shorter ovipositor.
This also exhibits dimorphism, being either pea-green or brown in
color. The specimens in our collection are from Cape Cod and New
Jersey. I have not seen any notice of its occurring in the interior.

III. The Katydids.

The song of the Katydids is known to every lover of Nature
that lives in the country. But the insects themselves are much less
familiar. Only the careful and patient observer succeeds in tracing
the well-known and oft-repeated " Katy-did, Katy-did " or " Katy-
she-did " to its source. The successful ones are rewarded by the
sight of a beautiful insect. The Katydids, of which there are in the
United States at least a dozen species, are large green grasshop-
pers with broad, leaf-like wing-covers and long, delicate antennae.
They differ from the meadow grasshoppers in being arboreal.
The}- are protected from observation by the color and shape of their
tegmina, which resemble the leaves of trees. Although the}- feed
upon the foliage of the trees which they inhabit, it is rare that they
are sufficiently abundant to be of economic importance. The only
locality in which I have known them to be injurious is Florida,
where the} - infest orange-trees.

Our species represent four genera. These can be separated by
the table given above.

5. Cyrtophyllus. — The true Katydid, the one whose song sug-
gested the popular name, is Cyrtophyllus concdvus. This has been

Il6 AN INTRODUCTION TO ENTOMOLOGY.

named the Broad-winged Katydid ; it occurs throughout the Central
and Eastern States. A closely allied species, C. pcrspicillat'ns, occurs
in the South. These differ from other Katydids in having the
wings shorter than the tegmina, and in having the tegmina very con-
vex, so that the insects have an inflated appearance, instead of a
narrow, compressed form, as is usually the case. The Southern spe-
cies has shorter tegmina, more robust legs, and the musical appara-
tus of the male is slightly broader than in the Northern form.

6. Amblycorypha. — We have at least four species that pertain to
this genus. The Round-winged Katydid, A. rotundifolia, is very
common throughout the Northern States and Canada. It is a
small species ; the length of the body is 20 mm. (0.8 inch), and of
the tegmina 25 mm. (1 inch). The tegmina are wide for their
length, as indicated by the specific name. The ovipositor is quite
broad, much curved, and roughly serrated. The Oblong-winged
Katydid, A. obloiigifolia, occurs in the same region as the preceding
species ; it is larger, has longer tegmina, and the ovipositor is less
serrate and less curved.* The Tailed Katydid, A. cauddta, occurs
in the South ; it is still larger than the preceding, and has a very
long ovipositor. The length of the body is 25 mm. (1 inch), of the
tegmina 37 mm. (1.5 inches), and of the ovipositor 20 mm. (0.8 inch).
Uhler's Katydid, A. Uhlerii, is our smallest species; it is common
in Maryland and about Washington.

7. Microccntrum. — -The Angular-winged Katydid, Microccntrum
rctincrvis, is the commonest species in the Western and Southern
States. It is especially abundant in Florida, where it often injures
the foliage of young orange-trees. Its eggs, which are deposited in
one or two rows upon twigs or the margin of leaves, frequently
attract attention on account of their large size and the remarkable
regularity of their arrangement. These are shown natural size on
Plate III. The adult female and several nymphs are represented at
the same place. Frequently the eggs of this species are infested by
a Chalcid parasite, Eupclmus mirdbilis, which is represented en-
larged on the same plate (2, female ; 2a, male). There is a closely
allied Katydid, M. affilidtum, occurring throughout the Eastern
United States, which is larger, and which differs in that the slightly-
hollowed front of the prothorax has a very small central tooth.
This is a rarer species than the preceding.

* Fig. 75 of Harris's " Insects Injurious to Vegetation" is of A. rotundifolia, and not
of this species as indicated in the text.

PLATE III.

JUn, j,t

Il8 AN INTRODUCTION TO ENTOMOLOGY.

8. Scudderia. — The Narrow-winged Katydid, Scudderia curvi-

cauda, is the common species of this genus. It is quite abundant in
many parts of the country. The tegmina are long and narrow,
hence the common name. The eggs of this species " are laid singly
in the edges of leaves, between the upper and lower cuticles, and
are so thin that they are not noticeable except when the leaf is held
between one's self and the light. They swell very considerably,
however, in the spring, before hatching." (Riley.)

IV. The Shield-backed Grasshoppers.

9. Thyreonotus. — These are wingless, dull-colored grasshoppers
which offer a striking appearance, owing to the great size of the pro-
notum. This segment is so enlarged as to extend back over the
other two thoracic segments. The ovipositor of the female is also
greatly developed, and is nearly straight. We have in the eastern
half of the United States two widely-spread species. T. dorsdlis has

Fig. 106. — Thyreonotus.

the pronotum well rounded behind. In T. pachymerus (Fig. 106)
it is nearly square. The hind legs and ovipositor are longer in T.
dorsalis than in the other species.

In the region west of the Mississippi River are found wingless
grasshoppers which are known as " Western crickets." These belong
to the genus Anabrus. This genus resembles TJiyreonotus in the
shield-like pronotum and the large size of the ovipositor, but differs
in having the presternum unarmed, while in the former genus there
are two spines between the base of the front legs. Three species of
Anabrus have been described. " A. colorddus is the smallest, and
has the abdomen distinctly marked by transverse bands; A. purpu-
rdscens, dark purplish brown, mottled with yellow; A. simplex, dark
shining brown. This species varies considerably in color, being
found of every shade from light brownish yellow to almost entirely
black ; specimens are sometimes found that are partly yellow and
partly black or dark purple." A. simplex is sometimes very destruc-
tive to crops.

ORTHOPTERA.

II 9

Family VII. — Gryllid^e.*

{Crickets.)

The Crickets constitute the last of the three families embraced
in the section Saltatoria. They agree with the members of the pre-
ceding family, the Locustidoe, in the possession of long, slender,
delicately-tapering antennae, and differ in the form of the tegmina,
the number of segments in the tarsi, and the form of the ovipositor.
The tegmina in the Gryllidae are horizontal, with the outer portion
bent abruptly downwards ; the tarsi are three-jointed, except in CEcan-
tJius, which has the hind tarsi four-jointed, and the ovipositor is
usually long and spear-shaped.

With most species of crickets the two sexes differ greatly in ap-
pearance. The female has a long ovipositor, and the venation of
the tegmina is simple, while the male has the veins upon the hori-
zontal part of the tegmina so modified as to admit of their being
used as a musical organ.

During the latter part of the summer and in the autumn, the air
is filled with the cries of the crickets. With care it is easy to ob-
serve these little fiddlers calling their mates. The common field-
crickets lurk in holes in the ground and under stones, or, emerging
from these retreats, run through the grass in search of food. At
the season indicated above, the male crickets spend much time at
or near the entrance of their
burrows, making their pecu-
liar calls. So intent upon
this are they, that by moving
quietly one can approach
sufficiently near to watch
them carefully. And even
when they are disturbed they
retreat into their holes only
for a short time, if all re-
mains still. At night they
can be observed by means
of a lantern, as light does
not disturb them. In order
to understand the manner
of making these calls, it is necessary to study the structure of
the tegmina. In the male crickets these organs differ greatly

Fig. 107. — Tegmina of male Gryllus.

* Gryllidae, Gryllus: gryllus, a cricket.

120 AN INTRODUCTION TO ENTOMOLOGY.

from the simple form seen in the females. In Fig. 107, a represents
the tegmina of a male Gryllus. It will be seen that the large veins
divide the wing into disk-like membranous spaces. If the principal
vein, which extends diagonally across the base of the wing, be ex-
amined with a microscope, it will be seen to be furnished with
transverse ridges like a file (Fig. 107, U). On the inner margin of the
wing, a short distance towards the base from the end of the principal
vein, there is a hardened portion which may be called the scraper.
This is shown enlarged at c in the figure. Each tegmina is therefore
provided with a file and scraper. When the cricket wishes to make
his call, he elevates his tegmina at an angle of about forty-five de-
grees with the body; then holding them in such a position that the
scraper of one rests upon the file of the other, he moves the tegmina
back and forth laterally, so that the file and scraper rasp upon each
other. This throws the tegmina into vibration, and produces the call.
The Gryllidae is a comparatively small family, but the American
species have not yet been monographed. The few genera which I
have selected as illustrations, and which are our most common ones,
can be separated by the following table:

A. Fore tibiae broad, fitted for digging. (Fossorial Crickets.)

B. Insect small ; antennae ten- to twelve-jointed. 1. Tridactylus.

BB. Insect large ; antennae many-jointed. 2. Gryllotalpa.

AA. Fore tibiae slender.

B. Hind femora stoutish. (True Crickets.)

C. Last segment of the maxillary palpi of the same length as the next

to the last. 3. Gryllus.

CC. Last segment of the maxillary palpi double the length of the next to

the last. 4. Nemobius.

BB. Hind femora slender. (Tree-crickets.) 5. CEcanthus.

The Fossorial Crickets. — We have two genera representing this
group ; they are commonly known as Mole-crickets. There are
species belonging to the next group, the true crickets, which burrow
in the ground ; but the mole-crickets, as their common name indi-
cates, are pre-eminently burrowers. The form of the body is that
suited to this mode of life. The front tibiae, especially, are fitted for
digging. They are greatly broadened, and shaped somewhat like a
hand, or the feet of a mole. Gryllotalpa is the better known of
these two genera, this is doubtless owing to the large size of the spe-
cies. The Northern Mole-cricket, Gryllotalpa borcdlis, inhabits nearly
the whole of the United States east of the great plains, from Lou-
isiana to Massachusetts. It is not a common insect, but occasion-
ally it is found in great numbers in a limited locality. It can be

ORTHOPTERA.

121

easily recognized by the accompanying figure, which represents the
insect natural size. They make burrows in moist places from six to
eight inches below the surface of the ground, and
feed upon the tender roots of various plants.
In Europe, where mole-crickets arc more abun-
dant, they are frequently serious pests in culti-
vated fields ; and in the West Indies there is a
species which is very destructive to sugar-cane.
The species of Triddctylus resemble Gryllotalpa
somewhat in form, but are very much smaller;
our species are all less than 10 mm. (0.4 inch) in
length. They also resemble the large mole-
crickets in habits, burrowing in similar places.
But they differ in having their hind legs formed
for leaping, and are able to jump as well as the
true crickets. At Ithaca we find Tridactylus
very local in its distribution. A large number
of specimens have been taken from a small FlG - Io8 ; — C'-yihtaipa

1 borealis.

spot on the margin of one of our streams, but

a most careful search has failed to reveal its presence elsewhere in

our region.

The True Crickets. — The true crickets abound everywhere, in
pastures, meadows, and gardens; and certain species enter our
dwellings. They are chiefly solitary, nocturnal insects ; yet many
can be seen in the fields in the daytime. They usually feed upon
plants, but arc sometimes predaceous. The eggs are laid in the
autumn, usually in the ground, and are hatched in the following
summer. The greater part of the old crickets die on the approach
of winter ; but a few survive the cold season. The greater part
of the species of our true crickets are included in the two genera
Gryllus and Nenwbius. To the former genus belongs our larger

species. The two larger of our
species are Gryllus luctuosus and
Gryllus abbreviates (Fig. \o%d). The
species of the genus Nemobius are
much smaller than Gryllus. and are
characterized by the greater length
of the last segment of the maxillary
palpi. The most common species,
and one that is very abundant in our fields during the latter part
of summer and autumn, is Nemobius vittatus.

Fig. ioSrt. — Gryllus abbreviatus.

122

AN INTRODUCTION TO ENTOMOLOGY.

The Tree-crickets. — Our common Tree-crickets belong to the
genus CEcanthus. The most abundant species is the Snowy Tree-
cricket, CEcanthus niveus (Fig. 109). This is a delicate greenish-
white insect. The male is represented
in the figure. The closely-folded wings
can be seen through the transparent
tegmina. The wings vary greatly in
length ; sometimes they are longer
than the tegmina, and sometimes not
as long. In the females the tegmina
are wrapped closely about the body,

Fig. 109. — CEcanthus niveus, male.

Fig

-Stem of blackberry with eggs of CEcanthu
mveus. c, egg enlarged ; d, ornamentation of egg
(From Rile v.)

making the insect much narrower than its mate. The female
lays her eggs in a longitudinal series in the twigs or canes of various
plants (Fig. no). She selects the raspberry more often than any
other plant ; and as that portion of the cane beyond the incisions
made for the eggs usually dies, it often happens that these crickets
materially injure the plants. In such cases the dead canes should be
cut out and burned early in the spring before the eggs hatch.

CHAPTER VII.

Order IV.— PHYSOPODA.*

(Thrips?)

The members of this order have four wings ; these are similar in
form, long, narrow, membranous, not folded, with but fezv or no
veins, and only rarely with cross-veins ; they are fringed with long
hairs ; and are laid horizontally along' the back when at rest. The
metamorphosis is incomplete. The mouth-parts are probably used
chiefly for sucking; they are intermediate in form between those of
the sucking and those of the biting insects ; the mandibles are bristle-
like ; the maxilUc are triangular, flat, and furnished with palpi ; and
the labial palpi are also present. The tarsi are two-jointed, bladder-
like at tip, and without claws.

These are insects of minute size, rarely exceeding 2 mm. or 3 mm.
in length. They can, however, be obtained easily from various
flowers, especially those of the daisy and clover. Ordinarily, it is
only necessary to pull apart one of these flowers to find several
specimens of Thrips. They are in many cases very active insects,
leaping or taking flight with great agility. In case they do not leap
or take flight when alarmed, they are apt to
run about and at the same time turn up the
end of the abdomen in a threatening manner,
as if to sting. In this respect they resemble
the Rove-beetles.

The body is long (Fig. in). The head
is narrower than the thorax, without any dis-
tinct neck ; the eyes are large, with conspic-
uous ocelli ; there are also usually three
simple eves. The ventral side of the head is

1 J IMG. 111.— Thrips.

prolonged into a conical beak, which extends be-
neath the prosternum. The form of the mouth-parts can only be
made out by dissection and the use of high powers of the micro-
scope. Fig. 112 represents the mouth-parts of one of our common

* Physopoda : physao (0rcr<i'oj), to blow up; pons (itovi), a foot.

124

AN INTRODUCTION TO ENTOMOLOGY.

Fig. ii2.— Mouth-parts of Thrips. (Drawn
by J. M. Stedman, under the author's di-
rection.) 8. labrum; io, mandible; n, max-
illa; i2, labium.

the wings sug-
TJiysanoptcra, by
is designated in

species. The mandibles are long, bristle-like, curved, and somewhat
flattened at the base ; the maxillae are broad at the base, and taper
to a point ; they are furnished with well-developed palpi ; the labial

palpi are distinct, but less conspic-
uous ; the labrum, in the form fig-
ured, is furnished with a curious
appendage at its tip ; and the la-
bium is deeply emarginate. The
three thoracic segments are well
developed. The wings are laid
horizontally on the back when not
in use ; they are very narrow, but
are fringed with long hairs, which,
diverging in flight, compensate for
the smallness of the membrane.
This fringing of
gested the name
which the order

many entomological works. In some
species the wings are wanting. The legs are well developed,
but are furnished with very peculiar tarsi ; these are two-jointed,
and are bladder-like at the tip. It is this character that suggested
the name Pliysopoda. The abdomen is more or less spindle-form ; it
is terminated in some genera by a long, slender segment ; in others,
the females are furnished with a four-valved ovipositor, which lies
in a groove on the ventral aspect of the abdomen.

" The larva resembles the perfect insect, but has a softer body,
with the mesothorax and metathorax distinct ; the mouth is like
that of the adult ; the antennae and legs are shorter; there are no
simple eyes ; and the compound ones are replaced by conglomerate
eyes. The pupa resembles the perfect insect, but the articulations
of the limbs are obscured by a film, and the wings inclosed in short
fixed sheaths. The antennae are turned back on the head, and the
insect, though it moves about, is much more sluggish than in the
other states." (Haliday.)

The different species of Thrips vary greatly in habits, some being
injurious to vegetation, while others are carnivorous. It should be
borne in mind that the insect commonly called The TJirips, that in-
fests the leaves of grape, is not a member of this order, but one of
the Leaf-hoppers (family Jassidae of the order Hemiptera). The

PHYSOPODA. 125

misapplication of the name Thrips to this insect is often the cause
of confusion.

In taking up the Physopoda, it seems very probable that \vc re-
turn again to near the foot of the insect series as represented by
living forms. This is indicated by the Campodea-like form of the
body, the presence of rudimentary abdominal legs in a European
species, and the Podura-like habit of jumping of many forms.

These insects have been placed in various positions. But the
structure of the mouth, and the character of the wings, throw them
out of any of the accepted orders. And now the majority of ento-
mologists agree in assigning them the rank of a distinct order. As
to the position of this order, it seems to me that it is the lowest
living representative of one of the lines of development of winged
insects, of which line the Hemiptera is the culmination.

The Physopoda has not been thoroughly studied. The most
important paper on the insects of this order is by A. H. Ilaliday.
This was published in the Entomological Magazine for 1836. It is
entitled An Epitome of the British Genera, in the Order Thysanop-
teret, with Indications of a few of the Species. Although this article
was published more than a half century ago, and was intended only
to include the British genera, it is the most complete account we
have of the order. The following classification is compiled from it :

Sub-Order I.— TUBULIFERA.*

This sub-order is characterized by the absence of a borer in
the females, and by having the last abdominal segment in both
sexes elongated, narrow, and tubular. The maxillary palpi are two-
jointed, with the first segment very short ; the wings are without
veins; the two pairs are of the same structure ; they are naked, ex-
cept the marginal fringe of hairs ; and when at rest, they arc crossed
so as to lie upon each other upon the abdomen.

This sub-order includes a single family, the Tubuliferida. And
only a single genus, Phlaeothrips, representing this family, was de-
scribed by Haliday.

Phlixothrips. — Here belong the more common of the black thrips
which abound in the flowers of clover and daisy; they are also
found, as their name indicates, under the bark of trees.

* Tubulifera: tubulus, a small tube; fero, to bear.

126 AN INTRODUCTION TO ENTOMOLOGY.

Sub-Order II.— TEREBRANTIA.*

This sub-order is characterized by the presence in the female of
a four-valved borer. The maxillary palpi are three-jointed; the two
pairs of wings differ somewhat in structure ; the first pair is some-
what longer, and wider, and usually also thicker ; sometimes they
are almost horny ; both pairs are clothed with numerous very fine
hairs ; the front wings have two parallel veins, the hind wings a
single vein or none ; the veins of the wings usually bear conspicu-
ous spines ; the wings, when not in use, are folded parallel to each
other on the abdomen.

The members of this sub-order are much more agile than those
of the preceding. They run rapidly, and spring, by bending under
the tip of the abdomen and suddenly straightening it out.

The Terebrantia includes two families ; these can be separated
as follows :

A. Females with borer curved downwards. Fam. II. — Stenopterid^e.

AA. Females with borer curved upwards. Fam. III. — Coleoptratid/e.

Family II. — STENOPTERiD.E.f

In the Stenopteridae the wings are narrow and are furnished
with one or two longitudinal veins ; but there are no cross-veins.
The longitudinal veins are usually fringed with spines. There are
two or three small indistinct segments at the end of the antennae.
And, as stated above, the ovipositor of the female is curved down-
wards. This family includes the greater number of the members of
the order. The following table will aid in determining the genera:

A. Body above netted with elevated lines. i. Heliothrips.
AA. Body smooth.

B. Abdomen clothed with silky hairs. 2. Sericothrips.
BB. Body glabrous.

C. Prothorax produced in front and narrowed. 3. Chirothrips.
CC. Prothorax not narrowed.

D. Last segment of abdomen armed with paired spines in the female ;

male wingless. 4. Limothrips.
DD. Last segment unarmed.

E. The last two segments of the antennae shorter than the sixth

segment. 5. Thrips.

EE. The last two segments of the antennae longer than the sixth

segment. 6. Belothrips.

* Terebrantia: terebro, to bore through.

f StenoptSridae: stenos (arevoS), narrow; pteron {nrepuv), a wing.

PHYSOPODA. 127

The most abundant members of this family pertain to the genus
Limothrips. There is a light yellow species which swarms in the
flowers of clover and daisies. Another common species I have desig-
nated, in my "Notes on Entomology," as The Grass-eating Thrips,
Limothrips podphagus. The injury caused by this pest often attracts
attention, although the insect itself is rarely observed. It infests
timothy and June-grass, causing the head to turn yellow and die
before maturing. These dead heads are very abundant every year.
By pulling the head from its sheath, the stalk will be found to be
shrunken in the tender part just above the joint, where the juice
has been sucked from it ; and in this place, if the examination be
made soon after the turning yellow of the head, the insect can also
be found. The adult female is light yellow in color, measures from
1 mm. to 1^ mm. (0.04 inch to 0.05 inch) in length, and is remark-
able in lacking the long spines on the veins of the wings.

Family III. — COLEOPTRATID/i:." :: "

This family is characterized by having the ovipositor of the
female curved upwards. The front wings are broader than in the
preceding family, and are furnished with both longitudinal and
cross veins. The following-named genera are indicated by Haliday :

A. Antennae with nine distinct segments. 1. MELANTHRIPS.

AA. Antennae apparently five-jointed, the last four segments being minute
and compact.

B. Body somewhat flattened ; mesothorax and metathorax broad ; front
wings without fringe on costal border, and with four cross veins; males
with lateral abdominal appendages. 2. COLEOTHRIPS.

BB. Body cylindrical ; mesothorax and metathorax constricted, wings rudi-
mentary. 3. iEOLOTHRIPS.

* Coleoptratidae: colcopteros (KuXeoTtrepoZ), sheath-winged.

CHAPTER VIII.

Order V.— HEMIPTERA.*

{Bugs, Plant-lice, Bark-lice, ct al.)

The members of this order have four wings; in one sub-order the
first pair of wings are of the same thickness throughout, and usually
slope at the sides of the body ; in another sub-order the first pair of
wings arc thickened at the base, with thinner extremities which over-
lap on the back. The mouth-parts are formed for sucking. The
metamorphosis is incomplete.

The Hemiptera comprises the insects which are properly called
bugs. This term is commonly applied to any thing that creeps or
crawls ; but the entomologist always refers to a member of this
order when he speaks of a bug. In addition to the general term
bug, the representatives of some of the families are known by special
names, as plant-lice, bark-lice, leaf-hoppers, water-boatmen, and
others. The order is a very important one ; it includes many spe-
cies injurious to vegetation, which often occur in such great numbers
as to destroy the plants infested. On the other hand, some of the
species are ranked among beneficial insects on account of their car-
nivorous habits ; while still others, as the cochineal and lac insects,
furnish us with useful products.

The name Hemiptera was suggested by the form of the front
wings in the sub-order Heteroptera ; here the basal half of these
organs is thickened so as to resemble the elytra of beetles, only the
terminal half being wing-like. The second pair of wings are mem-
branous, and are folded beneath the first pair. On this account, the
latter are often termed wing-covers ; they are also termed Jiemcly-
tra, a word suggested by their structure.

The wing-covers of the Heteroptera present characters much
used in classification ; and consequently special names have been
applied to the different parts. The thickened basal portion is

* Hemiptera: hemi- (f/fii-), half; ptcron {nrepoi'), a wing

HEMIPTERA.

129

composed of two pieces joined together at their sides ; one of these
is narrow, and is the part next to the scutellum when the wings are-
closed (Fig. 113, CI) ; this is distinguished as the cldvus:
the other broader part is the corium (Fig. 113, Co).
The terminal portion of the wing-cover is designated
as the membrane (Fig. 113, J/). In certain families, a f,,. ii 3 .—

, . . , r , . . Diagram of

triangular portion of the terminal part of the corium is wing-cover.
separated as a distinct piece (Fig. 113, Cu) ; this is the
cuneus. In certain other cases, a narrow piece on the costal mar-
gin of the corium is separated (Fig. 113, E) ; this is the embolium.
Both pairs of wings in the Homoptera and Heteroptera are furnished
with veins ; but it is not necessary for the purposes of this work to
discuss here the nomenclature of these veins.

The mouth-parts are formed for piercing and sucking. Without
dissection, they usually appear as a slender jointed beak, arising at
the base of a shorter pointed labrum. This beak consists of four
bristles inclosed in a fleshy, jointed sheath (Fig. 114).
Two of the bristles represent the mandibles, and two
the maxillae. The sheath is supposed to consist of the
labium and the grown-together labial palpi. This sheath
is usually four-jointed, and is never composed of more
than that number of segments. The maxillary palpi
are wanting.

Most of the Heteroptera protect themselves by the
emission of a disagreeable odor. This is caused by a
fluid which is excreted through two openings, one on
each side of the ventral aspect of the thorax, behind or
near the middle coxa. These openings are termed
'' a.' • u I4_ the osteoles. Each of these is usually in some kind of

Mouth- parts J

°ir'Muhr') U " an °P en channel styled the osteolar canal, and this is
surrounded by a more or less rugged and granulated
space, the evaporating surface. The legs of the Hemiptera vary
greatly in form, but the tarsi are never more than three-jointed.

The lateral margin of the abdominal segments is much devel-
oped in several families, and forms a flat, reflexed or vertical border
to the abdomen, which is called the connexlvum.

In their transformations the Hemiptera pass through an incom-
plete metamorphosis. The rudimentary wings of the nymphs lie
in the normal position, with the lower side of the wing next to the
body, and not inverted as with the Jumping Orthoptera. The

I30 AN INTRODUCTION TO ENTOMOIOGY.

males of the Coccidae present a remarkable exception in the nature
of their transformations, the metamorphosis being a complete one.

This order includes three well-marked groups ; these are ranked
as sub-orders, and are distinguished as follows :

TABLE OF SUB-ORDERS OF HEMIPTERA.

A. Wingless Hemiptera, parasitic upon Man and other Mammals, with a fleshy
unjointed rostrum.* I. Parasita.

AA. Hemiptera with or without wings, but with a jointed rostrum.

B. Wings of the same thickness throughout, and usually sloping at the sides
of the body; rostrum arising from the hinder part of the lower side of
the head ; head without neck, and so closely applied to the prothorax
that the first pair of coxae articulate with the cheeks. II. Homoptera.
BB. First pair of wings thickened at the base, and with thinner extremities,
which overlap on the back; rostrum arising from the front part of the
head ; head (except in Corisidce and Notonectida) with a more or less dis-
tinct neck, so that the cheeks and the first pair of coxae do not touch
each other. III. Heteroptera.

Sub-Order I.— PARASITICA.

The Parasitica includes certain parasites of Man and other Mam-
mals, commonly known as lice. All the species which have been
found in the United States belong to a single family, the Pedicu-
lidce. We will not, therefore, enter into a discussion of the charac-
ters of the sub-order, but pass directly to a study of this family.

Family I. — PEDICULID-E.f

{Lice.)

The lice are very small, wingless insects, which live on the skin of
Mammalia, and suck their blood. The mouth is furnished with a
fleshy, unjointed proboscis, which can be withdrawn into the head,
or extended to a considerable length. Within this proboscis are
two protrusible knife-like stylets ; and at its base, when extended,
there is a wreath of re-curved hooks. These hooks serve to anchor
firmly the proboscis when inserted in the skin of the infested ani-
mal. The eyes are two in number, small and simple. The antennae
have five segments. The legs are joined to the outer margin of the

* This is true of all forms that have been found in the United States. But in the
genus Polyctenus the rostrum is three-jointed. Two species of this genus are known ;
these infest bats ; one in the West Indies, the other in China.

\ Pediczdus, a louse.

IIEMIPTERA.

131

X&

Fig. i 15. — Hantatopinus
asini. (From Law.)

thorax. They are fitted for climbing, being furnished with a pow-
erful curved claw at the tip of the tarsus, which is opposed by a
toothed projection of the tibia. This arrange-
ment is admirably adapted for clinging to hairs.
The young do not undergo a metamorphosis.
Only a few species pertaining to this family are
known. The bird-lice, which differ from the
true lice in having biting mouth-parts, consti-
tute the family Mallophagidce, of the order
Pseudoneuroptera, and should not be con-
founded with the insects we are now de-
scribing.

Three species of lice infest man ; these are
as follows :

The head-louse, Pcdhulus capitis. — This
is the most common species infesting man.
It lives in the hair of the head, and is found upon all
races of men. It is most common upon the heads of neglected
children. Its general color is pale yellowish, with the outer edges
of the thorax and abdomen dark brown or gray, and the tarsal
claws pale brown. The eggs are oval, and are usually glued by the
pointed end to the hair of the host. These " nits" are said to hatch
under favorable conditions in about a week from the time they are-
laid. Under ordinary circumstances, cleanliness and the use of a
fine-toothed comb are all that is necessary to insure freedom from
this disgusting pest.

The Body-louse, Pediculus vestimenti. — This is somewhat larger
than the preceding species. Like the head-louse, it infests all races
of men. It is an interesting fact, however, that peculiar varieties
have been developed upon the different races. The variety which
infests the Whites in this country is yellowish, tinged with gray :
" that of the West African and Australian is nearly black; of the
Hindoo, dark and smoky; of the Africander and Hottentot, orange;
that of the Chinese and Japanese, yellowish brown; of the Indians
of the Andes, dark brown; of the Digger Indians of California,
dusky olive ; and that of the more North American Indians, mar the
Esquimaux, paler, approaching to the light color of the parasites of the
European." * This insect lives upon the skin of most parts of the
body; but especially selects the chest and back. It is often trouble-

* Andrew Murray, Economic Entomology, p. 39:

132

AN INTRODUCTION TO ENTOMOLOGY.

some on ships, in military camps, in prisons, and in the apartments
of uncleanly people who neglect to change their clothes. The fe-
male attaches her eggs to fibres in the seams of undergarments,
from which the larvae hatch in about a week. This species is ex-
ceedingly prolific. The method of destroying these vermin com-
monly employed in hospitals and poorhouses is to rub mercurial
ointment in the seams of undergarments.

The Crab-louse, Phthirius pubis. — The common name of this spe-
cies is suggested by the form of the body, which is nearly as broad
as long. When highly magnified, the resemblance of this insect to
a crab is quite striking ; but to the unaided eye it appears more like
a large scale of dandruff. These offensive vermin affect the pubic
region and armpits of man, stretching themselves out flat, holding
tight to the cuticle, and inflicting most irritating punctures. They
can be destroyed by mercurial ointment.

The true lice of cattle, of the horse, ass, swine, squirrel, etc., are
very closely allied to the head-louse and body-louse of man. They
have been placed, however, by systematists in a distinct genus,
Hcsmatopinus. The names of the more important species are as fol-

Fig. i\(t.—H. eurysternus. Fig. 117. — H.-uituli. Fig. 118 — H. sin's.

(From Law.; (From Law.) (From Law.)

Fig. 119. — H. piliferus.
(From Law.)

lows: louse of cow, H. eurysternus (Fig. 1 1 6) ; a second species
found on cattle, especially calves, is H. vituli (Fig. 117); louse of
horse and ass, H. dsini (Fig. 115); louse of swine, H. silt's (Fig 118);
louse of the dog, H.piliferus (Fig. 119); louse of rabbit, H. ventri-
cosus ; louse of monkeys, H. quadrumanus.

HEMIPTERA. 133

The reader should bear in mind that certain of the bird-lice, Mal-

lophagidte, infest cattle, the horse, ass, sheep, dog, and cat. These
pests have been discussed in an earlier chapter. The true lice of
the genus Hcematopinus can be recognized by the figures on the
two preceding pages.

For the destruction of these pests upon cattle, poisonous sub-
stances must not be used, as injur\- would result from the animals'
licking themselves. They may be safely treated by washing with a
strong infusion of tobacco leaves, or by rubbing with an ointment
made of one part sulphur and four parts lard, or by sprinkling with
Scotch snuff or powdered wood-ashes. The insecticide should be
applied thoroughly, leaving no spots untouched where the lice can
gather and remain, and from which the)- can spread over the body
again. The application should be repeated several times at inter-
vals of three or four days, in order to destroy the young which may
hatch after the first application. It is also necessary, in order to
make sure of eradicating the pests, to dress with similar agents, or
with strong lye, or kerosene, all places where the cattle have been in
the habit of rubbing, and the cracks in the stables where they have
stood ; or to whitewash the stables and rubbing-places.

Sub-Order II.— HOMOPTERA.*

The Homoptera is that division of the Hemiptera in which the
wings are of the same thickness throughout, and, when at rest, usu-
ally slope roof-like at the sides of the body. This sub-order is also
characterized by the absence of a neck, and the position of the
mouth-parts at the hinder part of the lower side of the head. So
closely is the head applied to the thorax that usually the front coxae
articulate with the cheeks, and in many forms the mouth-parts ap-
pear to arise from between the front legs.

Although the Homoptera is a well-marked group, so well defined
that by some it is considered a distinct order, the families of which
it is composed show great variations in structure, and modes of de-
velopment of the species. Some of the most interesting biological
problems presented by Entomology have arisen in the stud)' of this
sub-order.

TABLE OF FAMILIES Of HOMOPTERA.

A. Beak apparently arising from the sternum, or absent ; tarsi one- or two-
jointed : antennae usually prominent and filiform, sometimes wanting.

* Homoptera : homos (djuoi), same; ptcro>i (rrrt/joi'), a wing.

134 AN INTRODUCTION TO ENTOMOLOGY.

B. Tarsi one-jointed ; adult male without any beak and with only two wings :
female wingless, with body either scale-like or gall-like in form, or grub-
like, and clothed with wax. The waxy covering may be in the form of
powder, of large tufts or plates, of a continuous layer, or of a thin scale
beneath which the insect lives. 2. CocciDiE.

BB. Tarsi usually two-jointed; wings, when present, four in number.

C. Wings opaque, whitish ; wings and body covered with a whitish pow-
der. 3. Aleyrodid^e.
CC. Wings transparent.

D. Legs long and slender, not fitted for leaping ; antennae three- to
seven-jointed. 4. Aphidid/E.

DD. Hind legs fitted for leaping; antennae nine- or ten-jointed.

5. PSYLLID.E.

AA. Beak evidently arising from the mentum ; tarsi three-jointed : antenna?
minute, setiform.

B. With three ocelli, and the males with musical organs. Usually large
insects, with all the wings entirely membranous. 7. Cicadid^e.

BB. Ocelli only two in number, or wanting ; males without musical organs.
C. Antennae inserted on the side of the cheeks beneath the eyes.

8. FULGORID.E.

CC. Antennae inserted in front of and between the eyes.

D. Prothorax prolonged into a horn or point above the abdomen.

6. MEMBRACIDiE.

DD. Prothorax not prolonged above the abdomen.

E. Hind tibiae armed with one or two stout teeth, and the tip crowned

with short, stout spines. 9. Cercopid^e.

EE. Hind tibiae having a double row of spines below. 10. jASSlDiE.

Family II. — COCCID^;.*
{Scale-insects or Bark-lice, Mealy-bugs, et al.)

The family Coccidcs includes the Scale-insects or Bark-lice,
Mealy-bugs, and certain other insects for which there are no popu-
lar names. In many respects this is a very anomalous group, the
species differing greatly in appearance, habits, and metamorphoses
from those of the most closely allied families. Not only do the
members of this family appear very unlike other insects, but there
is a wonderful variety of forms within the family ; and even the
two sexes of the same species differ as much in the adult state as
members of distinct orders.

The males of Coccidse, unlike all other Hemiptera, undergo a
complete metamorphosis. The adult males have only a single pair

*Coccidae, C6ccus : coccum, "the berry that grows upon the scarlet oak." This sup-
posed berry was a bark-louse.

HEMIPTERA.

JD

of wings, the hind wings being represented by a pair of club-like
halteres. Each of these is furnished with a bristle, which in all of
the species I have studied is hooked, and fits in a pocket on the
wing of the same side (Fig. 120, id). The male in the adult state
has no organs for procuring food, as the mouth-parts disappear

vox Jd

Fig

120— A spidiotus nerii. i, scales on leaves of acacia, natural size ; ta, adult male, enlarged ; \b,
scale of male, enlarged ; i<\ scale of female, enlarged. (From the Author's Report for 1880.)

during the metamorphosis of the insect, and a second pair of eyes
appear in their place. The adult female is always wingless; and the
body is either scale-like or gall-like in form, or grub-like and clothed
with wax. The waxy covering may be in the form of powder, of
large tufts or plates, of a continuous layer, or of a thin scale, be-
neath which the insect lives.

Among the Coccidae are found many of the most serious pests of
horticulturists. Scarcely any kind of fruit is free from their attacks;
and certain species of scale-insects and mealy-bugs are constant pests
in conservatories. The ease with which these insects or their eggs
can be transported long distances while yet alive, on fruit or living
plants, has caused many species that infest cultivated plants to be-
come world-wide in distribution.

1 3t> AN INTRODUCTION TO ENTOMOLOGY.

During recent years, much attention has been paid to devising
methods of destroying these pests. The insecticides which are now
most widely used are alkaline washes and kerosene emulsion. (See
Chapter XIV.)

A number of useful insects belong to this family. Several species
furnish dye-stuffs. The best known of these is Coccus cacti, the
dried bodies of which are known as Cochineal. The stick lac of
commerce, from which sheli-lac or shellac is prepared, is a resinous
substance excreted by one of the Coccinae, Carteria lacca, which
lives on the young branches of several tropical trees. And the
bodies of this insect, which are obtained from the stick lac, furnish
the coloring agent known as lac dye. China wax is another sub-
stance for which we are indebted to this family. It is the excretion
of an insect known as Pe-la, Ericems pc-la. In fact, many species of
this family excrete wax in considerable quantities. I have found
three species in this country which, if they can be easily cultivated,
produce wax in sufficient quantities to be of economic importance.

The family comprises four sub-families. One of these includes
species that live in galls, and is confined to Australia. The three
sub-families which are represented in our fauna can be separated by
the following table : *

A. Body either naked or clothed wit-h a secretion ; the clothing, however, not
in the form of a scale composed in part of moulted skins.

B. Body of female usually remaining distinctly segmented,
and retaining the power of motion till maturity ; some-
times, however, it becomes more or less globular and fixed,
but in all cases the labium is composed of several seg-
ments, and there are no anal plates. (Fig. 121, ap.) The
abdomen usually ends in a pair of lobes, each furnished
with one or more bristles (Plate IV. Fig. le).

1. COCCINAE.
BB. Body of female changing much in form during develop-
ment, becoming scale-like or more or less globular, with
the segmentation absent or indistinctly indicated. The
Fig. m.—Leca- individuals usually become fixed to the plant upon which

"/,"anal pUtes. Ked ' they live ; sometimes they are enclosed in a covering of

wax. In all cases the labium is composed of a single seg-
ment ; the caudal opening of the alimentary canal in the adult female is covered
by a pair of subtriangular plates (Fig. 121, ap). 2 Lecanin^e.

* The characters given here for distinguishing the Lecaninrs and Coccinae are
merely provisional, as these groups are not yet well known.

PLATE IV.

•38

AN INTRODUCTION TO ENTOMOLOGY.

AA. Body of insect covered by a scale composed in part of moulted skins and
partly of a secretion of the insect. 3.- DiaspiNjE.

Sub-Family I. — CocciKrE.

The sub-family Coccina includes those Coccids of which the
females undergo the least change in form during their development.
The majority of them retain a form not much different from that of
the young larvae ; but in some genera the body becomes a globular
mass, with little or no indication of segmentation. The most im-
portant characters, as the family is now understood, are the multi-
articulate labium, and the absence of anal plates. Plate IV. \d rep-
resents the typical form of the female adult in this sub-family; le
represents the caudal end of the body of the same. The most com-
mon exception to this form is that of the genus Kermes described
below. In most genera of this sub-family the body of the female
becomes enclosed in a cottony or felt-like sac. In some, as ,the
mealy-bugs, this takes place just before they begin to oviposit ;
while in other genera the greater part of the life of the insect is
passed within the sac. In this and the next sub-family the caudal
style of the male is short ; and the last abdominal segment bears a
pair of long waxy filaments. Each filament is supported by one or
more hairs, at the base of which are the spinnerets from which the
wax is excreted (Plate IV. la and lb).

Mealy-bugs, Dactylopius.— T\\c mealy-bugs are the best known

members of this sub-family, as they are
the most common and most noxious of
green-house pests. Fig. 122 represents
D. lougifilis, a common species in green-
houses. D. destructor (Fig. 123) is an-

FlG. 122. — Dactylopius longifilis,
female, enlarged. (From the
Author's Report for 1880.)

FlG. 123. — Dactylopius destructor,
female, enlarged. (From the
Author's Report for 1880.)

other common species, which differs in lacking the long filaments

HEMIPTERA.

I 39

of the preceding species. This occurs in green-houses in the North,
and is also very destructive to orange-trees in Florida.

Cochineal, Coccus cacti. — This is a native of Mexico, but is now
cultivated in India, Spain, and other countries. It feeds upon vari-
ous species of the Cactaceae, more especially Opuntia coccinilifera.
I have received living specimens which were collected upon a wild
cactus in Florida. The dye-stuff consists of the female insects,
which, when mature, are brushed off the plants, killed, and dried.
The entire insect is used. From cochineal, lake and carmine are
also prepared. Cochineal is now being superseded by aniline dyes,
which are made from coal-tar.

Orthezia. — The members of this genus occur not uncommonly
on various weeds. They are remarkable for the calcareous secretion
with which the body is clothed. This is in the form of long plates.
Fig. 124 represents a nymph ; in the adult female, the excretion be-
comes more elongated posteriorly, and forms a sac containing the
eggs mixed with a fine down. Later, when the young are born,
they remain in the sac till the}- have themselves secreted a sufficient
amount of the lamellar matter to cover them.

Fig. 124. — Orthezia, enlarged. (From the
Author's Report for 1880.)

Fig. 125. — Icerya purchasi. Females, adult
and young, on orange. (From the Author's
Report for 1880.)

Icerya purcJiasi. — This beautiful insect (Fig. 125* is one of the
most dangerous pests infesting fruit-trees in California. The body
of the adult female is scale-like, dark orange-red, and has the dorsal
surface more or less covered with a white or yellowish-white powder.

The insect secretes a large egg-sac, which causes it to resemble l'ul-

140

AN INTRODUCTION TO ENTOMOLOGY.

vinaria, of the next sub-family. The egg-sac of Icerya, however, is
beautifully ribbed, while that of Pulvinaria is not of very definite
form. Icerya is an introduced insect from Australia.

Rhizococcus. — Two species of Rhizococcus are figured on Plate IV.
Fig. i represents R. araucarice, a species infesting Norfolk Island
pine {Araucaria excelsior) in southern California; and Fig. 2 is of
R. quercus upon oak from Florida. This genus is a good illustration

Fig. 126. — Kermes sp., on Quercus agri/olia. Adult females on stem ; immature males on leaves.
(From the Author's Report for 1880.)

of the forms that spend a greater part of their lives within sacs. A
more common illustration of this occurs in the genus Eriococcus, of
which we have a species, E. azdlecc, common upon azaleas in con-
servatories.

Kermes. — The most abnormal members of this sub-family consti-
tute the genus Kermes. Species of this genus are common upon

HEMIPTERA. 14I

oaks wherever they grow. These insects arc remarkable for the
wonderful gall-like form of the adult females. So striking is this
resemblance, that they have been mistaken for galls by man}- ento-
mologists. Fig. 126 represents a species of this genus upon Quercus
agrifolia. The gall-like swellings on the stem are the adult females;
the smaller scales on the leaves are the immature males.

Sub-Family II. — LECANIN^E *

In the present state of our knowledge of this sub-family there is
nothing to add to the characterization of it given in the table on page
136. The most available character for recognizing these insects is
the presence of the subtriangular anal plates (Fig. 121 1. Usually,
the body is elliptical or circular in outline, with a deep incision at
the caudal end, leading to the anal opening (Fig. 121). Although
as a rule these insects remain fixed to one spot after the wandering
larval stage, I have seen the adults of certain species move from one
place to another. It is a curious fact that in certain species, among
them the most common ones, as L. hesperidum, the males are un-
known. It seems probable that they rarely, if ever, occur. Only
three genera have been found in the United States. These are dis-
tinguished as follows :

A. Body naked or nearly so.

B. Female secreting a mass of cottony material in which the eggs are laid.
Fig. 127. 2. Pulvinaria.

B. Female laying her eggs beneath her body, not excreting a mass of cot-
tony material. 1. Lecaniu.m.
AA. Body covered with a layer of wax. 3. Ceroplastes.

Lccdnium. — The species of the genus Lccanium abound every-
where ; they occur on all kinds of plants both in conservatories and
in the open air. Some of them are known to gardeners as " Soft-
scales." The genus is one that is easily recognized, but no one has
yet found satisfactory characters for separating the closely allied
species. I have figured three of the more common forms. Plate
V. 2 is of Lccanium hesperidum. This is a representative of a group
that includes our most common species. They are an elongated
oval in outline, nearly flat, and smooth and shining.

Lecdnium hemisphcericum (Plate V. 3) is a much more convex
species, as its name indicates. It is common in conservatories.

* Lecanlnx, Lccanium : lecane {XeKCCVrj), a dish

PLATE V.

HRMIPTERA.

1 43

Lecdnium olcce also occurs in conservatories, but it is very common in
the open air in California. Here it is a serious pest of the orange,

Fig. 127. — Ptilvinaria innutnerabilis. Female on grape, natural size. (From the Author's Report

for 1880.)

olive, and other trees. It is very convex and marked with promi-
nent ridges (Plate V. 1). Especially prominent are two transverse
ridges and a longitudinal one which frequently form a raised surface
of the form of a capital H.

FlG 128. — Ceroplastes floridensis, adult and young
females on Ilex, natural size ; n, young female, en-
larged- /•, adult female, enlarged. (From the. Au-
thor's Report for 1880.)

TX -. J ,

, — Ceroplastes cirripediformis.

Adult females, natural size ; a. fe-
male enlarged. (From the Author's
Report for 1880.)

Ptilvinaria. — This genus is distinguished from Lecanium only by

144

AN INTRODUCTION TO ENTOMOLOGY.

the fact that the adult female excretes a large cottony mass in which
the eggs are laid. Fig. 127 represents Pulvindria innumerdbilis,
which is common on grape, maple, osage orange, and other' plants.

Ceropldstcs. — The species belonging to this genus are furnished
with a thick covering of waxy material, which does not, however,
adhere closely to the insect. Only two species have been found in
the United States. Both of these are Florida insects, and in each the
waxy covering is dirty-white in color. The most common species,
C. Floridensis (Fig. 128), infests a great variety of plants both wild
and cultivated. C. cirripediformis (Fig. 129) is not very common ;
it infests orange and quince. It is a beautiful species, as the waxy
excretion is in the form of regular-shaped plates.

Sub-Family III.— DlASPlNiE*

The Diaspince includes those species of scale-insects that form a
scale composed in part of moulted skins, and partly of an excretion of
the insect. This apparently trivial character is correllated with im-
portant structural characters, which mark a well-defined group. The

Fig. 130. — Organs of the last segment of adult females of the Diaspina. a, opening of oviduct ;
/>, anus ; d, d, ccphalo-lateral groups of spinnerets ; e, e, caudo-lateral groups of spinnerets ; /',
lobes ; k, spines ; /, plates (these are frequently described by authors as spines). (From a Report
by the Author, 1881.)

most important of the structural characters is the peculiar form of
the last segment of the body. This segment is highly specialized
for the excretion and manipulation of wax. It is furnished with
many openings and appendages. These vary greatly in number and
form, and afford good characters for distinguishing closely allied

* Diasplnse, Diaspis: dia (did,) through; aspis (acritis), a shield.

PLATE VI.

JharrM

I46 AN INTRODUCTION TO ENTOMOLOGY.

species. Figure 130 represents a common form of this segment.
But these special characters of this segment are not presented by the
larvae till after the first moult, nor by the male after the change to
pupa.

The following account of the metamorphoses of the Diaspinse is
quoted from my report on Scale-Insects in the Annual Report of the
U. S. Department of Agriculture for 1880.

The newly-hatched scale-insect is oval in outline, much flattened, furnished
with six legs, a pair of antennae, and an apparatus for sucking the juices from
plants. (See Plate VI. Fig. vc, young of Aspidiotus ficus.) At this stage of
its existence it is very small, a mere speck, which the untrained eye could only
with difficulty detect. By means of a lens, however, these minute creatures
can be seen crawling in all directions over the leaves or bark of an infested
tree. After wandering for a time, usually but a few hours or even less, the
young scale-insect settles on some part of the plant, inserts its beak, and draw-
ing its nourishment from the plant, begins its growth at the expense of its host.
In a short time there begins to exude from the body of the larva fine threads
of wax, which are cottony in appearance. The excretion of this wax continues
until the insect is completely covered by it. The rate at which this excretion
is produced varies greatly. Thus larvae of the red scale of Florida {Aspidiotus
ficus), which were only one day old, were found to be completely covered by the
cottony mass which they had excreted ; while the larvae of Glover's scale (Myti-
laspis Gloverii) did not become entirely covered until they were six days old.
Sooner or later the larva begins to excrete a pellicle, which, although very
thin, is dense and firm in texture. The mass of cottony fibres either melts or
is blown away, or, as in certain species of Aspidiotus, a portion remains as a
white dot or ring on the centre of the scale. After a period, which, in several
species that we have studied, is about one-half of the time from the hatching of
the larva to the emerging of the male, or one-third of the time from the birth
of the female to the date at which she begins ovipositing, the larva sheds its
skin. In some species this does not take place until after the beginning of the
formation of the permanent scale, and in such cases the moulted skin adheres to
the inner surface of the scale; and cannot be seen while it is in its normal posi-
tion on the plant. This is true of many species belonging to the genus Aspidi-
otus {A. ficus, A. citri, A. perniciosus, and others). In these species the position
of the exuviae is indicated by a nipple-like prominence, often marked by a
white ring or dot, which is the remains of the cottony mass first excreted. In
other species the moult takes place before the beginning of the excretion of the
permanent scale. In these, the larval skin is plainly visible either upon the
surface of the scale, as in certain species of Aspidiotus (A. nerii, Fig. 120), and
in Diaspis (Plate VIII. Fig. \a, 2a), or at one extremity, as in Mytilaspis (Plate
X. Fig. la). Sometimes, however, the larval skin is covered by a delicate trans-
parent layer, which, I think, is the melted or compacted remains of the cottony
mass excreted by the young larva (Plate X. Fig. 2a).

The change which the larva undergoes at this moult is a very remarkable
one, appearing to be a retrogression, instead of an advancement to a more

HEMIPTERA. 1 47

highly organized form, as is the rule in the development of animals. With the
skin are shed the legs and antennae.* The young scale-insect thus becomes a
degraded grub-like creature, with no organs of locomotion. The mouth-parts
remain, however, in a highly developed state and are well fitted to perform
their functions. This apparatus is not the least remarkable thing in the
structure of these insects. It is terminated by a thread-like organ, which is
frequently much longer than the body of the insect, and is composed of four
delicate hair- like bristles. By means of this organ the insect is firmly attached
to the plant, and draws its nourishment therefrom. From this stage the devel-
opment of the sexes differs.

The second and last moult of the female takes place, in those species which
we have studied most carefully, when she is about twice as old as when the
first moult occurred. The change in appearance at this moult presents nothing
remarkable. The second cast skin is joined to the first, and with it forms a
part of the scale which covers the body of the insect. Sometimes, as in the
genus Uhleria(Plate VII. Fig. 9), this moulted skin is very large and constitutes
the greater part of the scale; but more commonly the exuviae form but a small
proportion of the scale, the greater part of it being excreted subsequently to
the second moult. Soon after the second moult of the females takes place the
adult males emerge, and doubtless the impregnation of the females occurs at
once. After this, the body of the female increases in size, becoming distended
with eggs. The oviposition takes place gradually, and, in those species that we
have studied, begins when the female is about three times as old as when the
first moult occurred. The eggs are deposited beneath thescale, the body of the
female gradually shrinking and thus making room for them. (See Plate X.
Figs. \b and 2<r.) Some species, however, are viviparous.

The male scale-insect during the early part of its larval life is indistinguish-
able from the female. The first moult occurs at the same time and is accom-
panied by a similar change, the male larva, like the female, losing its legs and
antennae. The second moult is also synchronous with the second moult of the
female; but here the similarity in form between the two sexes ceases. Even
before this moult takes place there may be observed the formation of rudiment-
ary limbs beneath the transparent memberless skin of the larva; and alter this
skin is shed, the male, now in the pupa state, differs remarkably from the
female. The male pupa has long antennae, and its legs and wings, although in
a rudimentary state, are very large. The duration of the pupa state in those
species which we have bred, in short, lasting but a few days; and then, after a
third casting of the skin, the adult male appears.

The outline figures on Plates IV. VI., and IX. represent the insect in
this stage. The anterior wings, though very delicate, are large, and enable
the male to fly readily. The posterior wings are represented only by .1 pair of
halteres. These insects resemble in this respect the Hies, gnats, and other
insects belonging to the order Diptera, or two-winged insects. The posterior
end of the body is furnished with a stvle, which is sometimes nearly as long as
the remainder of the body, and is the external organ of reproduction. As our
figures represent only a dorsal view, the most remarkable character of the

* Rudiments of antennae are sometimes retained, as in certain species of Mytilaspis.

PLATE VII.

Jl.'&ComstctK. 2le\

\T~

Scales of the Diaspince, from camera-lucida drawings. i, Aspidiotus ficus, female ; la, male of
same ; 2, Aspidiotus iierii, female ; 2a, male of same; 3, Diaspis roste, female; 3^, male of
same; 4, Ckioiiaspis /urfurtts, female ; 4a, male of same; 5, Mytilaspis pomorum, female ;
5«, male of same; 6, Parlatoria pergandii, female; 6a, male of same; 7, Parlatoria proteus,
female; ja, male of same; 8, Parlatoria zizyphi, female ; 9, Uhleria camellia ; io, Aspidi-
otus ? parlaloroides, fema\e ; 11, Chionaspis ? biclai'is.

HEMIPTERA. 1 49

adult — the supplementary eyes which takes the place of the mouth-parts — is
not shown.

The genera of the Diaspinae are characterized chiefly by the form
of the scales, and the position of the moulted skins or exuviae upon
them. In the use of these characters it is necessary to distinguish
the sex of the individual by which a given scale was made. This
can be done as follows: In the scale of the fully developed female
there are two moulted skins, while in that of the male there is but
one. Our genera can be separated by the following table :" x '

A. Scale of female circular with the exuviae either central or more or less
nearly marginal.

B. Scale of male but little elongated, with the exuviae more or less central ;
scale usually resembling that of the female in color and texture (Plate
VII. Fig. 1a and 2a). Aspidiotus.

BB. Scale of male elongated, with the exuviae at one extremity.
C. Scale of male, white and carinated (Plate VII. Fig. yi). DlASPIS.

CC. Scale of male, not white and with no central carina (Plate VII.
Fig. 6a). PARLATORIA.

AA. Scale of female elongated, with the exuviae at one extremity.
D. Exuviae small.

E. Scale of male, white and carinated + (Plate VII. Fig. 4a); last

segment of female with five groups of spinnerets. CHIONASPIS.

EE. Scale of male white, but not carinated; female with eight groups

of spinnerets. POLIASPIS.

EEE. Scale of male similar in form to that of the female (Plate VII.

Fig. yi). Mytilaspis.

DD. Exuviae large.

F. Two moulted skins visible on the scale of the female (Plate VII.

Fig. 7, 8). Parlatoria.

FF. Second skin covered by a secretion (Plate I. Fig. 9). UHLERIA.

The accompanying illustrations, from my report on scale-insects
in the Report of the U. S. Dept. of Agriculture for 1 S80, will enable'
the reader to recognize the more important. species of this sub-family.

Aspidiotus. — This is the largest genus of the Diaspinae ; more than
twenty species have been observed in the United States. The one
which has done the greatest injury to citrus fruits on the Pacific
coast is tin- Red Scale of California. Aspidiotus aurantii (Plate VI. 1 ).
Closely allied to this is the Red Scale of Florida, A. flats 1 Plate VI.

* From the author's Second Report on Scale-Insects ; published in the Second Report
of the Cornell University Experiment Station. Ithaca, N. Y., [883.

f In Chionaspis ortholobis the scale of the male is not carinated. This species infests
willow in California.

PLATE VIII,

^<wt M

HEMIFTERA. 151

2). This also infests oranges; but its injuries are overshadowed in
Florida by those of other scale-insects; A. nerii (Fig. 120) is the
common white scale, which occurs on a great variety of plants. It
is an imported insect; but I have collected it throughout our country
from the Great Lakes to the Gulf of Mexico, and from the Atlantic
to the Pacific; in the colder parts of the United States it is, next to
the mealy-bugs and Lecanium, the most common Coccid on house-
plants. In northern California, and especially in the Santa Clara
Valley, is found A. perniciosus; this is a circular, grayish scale which
infests nearly all of the deciduous fruit-trees grown in that State. It
is the most destructive of the scale-making Coccids; and before the
fruit-growers awoke to the importance of fighting it, it came near
destroying the orchards of that section.

Didspis. — Our commonest representative of this genus is Didspis
rosiB (Plate VIII. 1); this is a snowy-white scale, which occurs
abundantly on neglected roses; I have found it also on raspberry,
and blackberry bushes. Didspis carueli (Plate VIII. 2) is common
in some localities on Juniper and allied plants.

Chiondspis. — The common white scale of pear and apple is CJii-
onaspis fur/urns (Plate IX. 1). Another common species which
occurs throughout the United States upon the leaves of pine and
spruce is C. pinifolii (Plate IX. 2). C. eudnymi (Plate VIII. 3) in-
fests Euonymus ; it is remarkable for having the scale of the female
of a dirty blackish-brown color, instead of white, as is the rule in this
genus. The common white scale of willow is C. sdlicis.

Mytildspis. — To this genus belong some of the best known Coc-
cids. Of those that occur on plants in the open air, only three
American species have been recognized. Two of these abound on
oranges. One of the orange species, M. gloverii, (Plate X. 2,) can be
easily recognized by the very narrow form of the scale, and the fact
that the eggs are laid in two rows beneath the scale ( Plate X. Fig. 2, c).
In the other orange species, M. citricola, (Plate X. I,) the scale of the
female is much wider, and the eggs are massed irregularly beneath
the scale. The Oyster-shell Park-louse of the Apple, M. pomdrum,
is distinguished from M. citricola only by minute characters. The
figure just referred to would serve equally well for this species, ex-
cept that it does not occur on the orange. It is the most common
scale of the apple in all parts of the United States in which that tree
grows ; it infests also a great variety of other plants.

The food-plants of the species figured on Plate VII., and not
named above, are as follows: Parlatoria pergdndii Occurs on Florida

PLATE IX.

-xncM.

HEMIPTERA.

3J

oranges. Parlatoria protcus has been found only on exotic plants
in conservatories. Parlatoria zizyphi is an exotic species which is
often found on imported oranges. Uhleria camellia is a trouble-
some pest of the camellia in conservatories. Aspidiotus parlato-
roldcs infest the Bay Tree in Florida. And Chiondspis bicldvis is a
remarkable species, which I found burrowing beneath the epidermal
layer of certain exotic plants in the conservatories at Washington.

Fig. 131. — Aleyrodes.

Family III. — ALEYRODID^E*
{Aleyrodes?)

The insects of the genus Aleyrodes were for a long time classed
with the Coccidae. In their immature state they are scale-like in
form (Fig. 131), and often somewhat resemble certain species of
Lecanium. But the mature insects differ so
much from Coccids that the genus has been
separated as a distinct family. They are very
small insects ; the species with which I am
acquainted have an expanse of wings of about
three millimeters. Both sexes are winged ;
and, as with other Hemiptera except the
Coccids, there are two pairs of wings. In the
adult state, all the species are of nearly the
same color; the wings are white, sometimes

spotted ; the body is usually yellowish, sometimes pinkish, and more
or less spotted with black. The most striking character presented
by the adults, in addition to the fact that both sexes are winged,
and each has two pairs of wings, is the presence of a whitish powder
with which the wings and body are covered. It is this character
which gives the name to the genus.

With the adults the eyes are reniform, and generally divided
into two portions, separated by a membrane ; in some species they
are more or less rounded or triangular. Above each eye there is a
minute ocellus. The rostrum is stout, and composed of three seg-
ments. The antennae are seven-jointed. The wings in repose are
carried nearly horizontally. The first pair are the larger, and are
traversed by two veins ; the first vein, which passes through the mid-
dle of the wing, is much the larger; the hind wings have only a
single vein.

* AleyrSdidae, AleyrOdes: aleurdd a li vpooSi Z), like flour.

PLATE X.

Ma da

HEMIPTERA.

3 3

Owing to their small size and similarity in color, it is difficult to
distinguish the different species of Aleyrodes in the adult state.
But the immature scale-like forms present considerable differences.
The most common form that I have met is very flat, nearly circular
in outline, and furnished with a beautiful white fringe (Fig. 131);
this fringe is composed of parallel fibres, which radiate from the
margin of the body ; and its white color contrasts strongly with the
dark color of the insect. The segmentation of the body is often
represented by prominent wrinkles, which give the insect a minia-
ture resemblance to the fossils known to geologists as Trilobites.
Sometimes the fringe of excretion is
wanting; and in a common species on
maple, the excretion from the margin of
the body, instead of extending laterally
and forming a fringe, is directed towards
the leaf upon which the insect rests,
and thus the body is lifted away from FlG - e^- --•<'<>; ><-./..- on maple.
the leaf, and perched upon an exquisite palisade of white wax
(Fig. 132).

The American species of this family have not been studied. In
case any of them become destructive to vegetation, they can proba-
bly be destroyed by strong alkaline solutions, as are Coccids.

Family IV.— Aphidid^.*
( Plant-lia . |

The plant-lice are well-known insects ; they infest nearly all
kinds of vegetation in all parts of the country. Our most common
examples are minute, soft-bodied, green insects, with long legs and
antenna', which appear on various plants in the house and in the
field. Among our common species are both winged and wingless
forms. There are a great number of species, nearly all of which
are of small size. The bodies of our largest species measure only 6
or 7 mm. (0.24 or 0.25 inch) in length.

The bod}- is usually more or less pear shaped. The winged
forms have two pairs of delicate, transparent wings. These are fur-
nished with a few simple veins; but the venation is more extended

' Aphldidae, Aphis: perhaps from apkysso (tx <pv o~ (Too), to drink up liquids.

156 AN INTRODUCTION TO ENTOMOLOGY.

than in either of the two preceding families. The first pair of wings
is larger than the other ; and the two wings of each side are usually
connected by a compound hooklet. The beak is two-jointed, and
varies greatly in length ; sometimes it is longer than the body. The
compound eyes are prominent ; and ocelli are also usually present.
The antennae are from three- to seven-jointed. On the dorsal aspect
of the sixth abdominal segment there is, in many species, a pair of
tubes, through which a sweet, transparent fluid is excreted. In
some genera these organs are merely perforated tubercles ; while in
still other genera they are wanting.

The fluid which is excreted through the abdominal tubercles is
the substance known as honey-dew. It is sometimes produced in
such quantities that it forms a glistening coating on the leaves of
the branches below the plant-lice, and stone walks beneath shade-
trees are often densely spotted with it. This honey-dew is fed upon
by bees, wasps, and ants. The bees and wasps take the food where
they find it, paying little, if any, attention to its source. But the
ants recognize in the plant-lice useful auxiliaries, and often care for
them as man cares for his herds. This curious relationship will be
more fully discussed under the head of ants.

In addition to honey-dew, many Aphids excrete a white sub-
stance. This may be in the form of a powder, scattered over the
surface of the body, or it may be in large flocculent or downy
masses; every gradation between these forms exists.

The plant-lice are remarkable for their peculiar mode of
development. The various species differ greatly in the details
of their transformations ; but the following generalizations can be
made.

At some period eggs are produced by impregnated females.
This ordinarily occurs in the autumn ; in which case the eggs do not
hatch till the following spring. From the fact that these eggs are
fertilized, they are frequently referred to as true eggs, in contradis-
tinction to pseudova, described later. These true eggs are also
known as winter eggs.

From the winter eggs there hatch in the spring a generation of
Aphids in which there is no distinction of sex. All are females ;
and each has the power of reproducing without the intervention of a
male. Such reproduction is termed agamic * reproduction, or repro-
duction by budding. And this term is also applied to the individu-

* Agamic: a (a), without; gamos (yajuoS), marriage.

HEMIPTERA 1 57

als that reproduce in this way. Usually, the agamic generation pro-
duced by the winter eggs is wingless. The agamic female which
hatches from a winter egg, being the starting point from which arise
the generations that intervene between this egg and the production
of other true eggs, is termed the stem-mother.

The offspring of the stem-mothers are wingless or winged or
both, and are agamic. In many cases they are born alive. This
can be seen by examining almost any colony of plant-lice during the
summer-time. While an agamic mother is unconcernedly feeding
or walking about, it may be giving birth to a young louse ; the lat-
ter can be seen with the unaided eye, but better with a lens, emerg-
ing from the caudal end of its mother, tail first, and kicking vigor-
ously, even before its head has been delivered. In other cases, the
agamic form produces egg-like bodies, which are termed pseudoi'a, to
distinguish them from the fertilized or true eggs. And, in still other
cases, they produce living young, which are enveloped in a pellicle,
from which they emerge in the course of a few minutes ; such an
enveloping pellicle with its enclosed young is also termed a pseudo-
vum.

The number of agamic generations that may follow without the
intervention of sexual forms varies with different species, and, in
some cases at least, varies in the same species, depending upon tem-
perature and other conditions. Thus Kyber, in the earl) - part of
this century, succeeded, by keeping the insects in a warm room, in
raising a series of agamic generations of two species of Aphids,
which extended through four years without the intervention of sex-
ual forms.

As already indicated, the agamic generations are of two forms,
wingless and winged. Each of these has a peculiar function in the
economy of the species. The wingless generations, which are usu-
ally the more numerous, by their great fecundity provide for the
enormous and rapid multiplication of individuals, which is so charac-
teristic of these insects. But this great increase of individuals would
be disastrous to the species, by the destruction of the infested
plants and the consequent starving of the insects, were it not sup-
plemented by other powers. We find, therefore, interspersed among
these wingless sedentary generations, generations which are winged
and migrating. Thus the spread of the species is provided for.

Generally on the setting in of cold weather, or in some cases on
the failure of nourishment, the weather being still warm, there is
produced a generation including individuals of both sexes. The
ii

158 AN INTRODUCTION TO ENTOMOLOGY.

males may be either winged or wingless ; but, so far as is known, the
females that pair with the males are always wingless. These
females, after becoming impregnated, produce the winter eggs; thus
is completed the cycle of changes through which the species passes.
In many cases, at least, the individuals of the agamic generation
that immediately precedes the sexual one produce but few pseudova ;
from these pseudova the sexual individuals emerge, not as larvae,
but as fully developed individuals, ready to pair and reproduce ; in
fact, in the cases referred to, the sexual individuals have the mouth-
parts in a rudimentary state, and take no nourishment. In many
species, the impregnated female produces a single egg, which is
nearly as large as the insect herself ; frequently this egg is not
laid, but remains throughout the winter in the dry skin of the dead
parent.

Agamic Aphides may hibernate, and may coexist with the sexual
generation of the same species.

From the above generalizations it will be seen that a single
species of plant-louse may present three distinct forms : first, a
sedentary, agamic, wingless form, furnished with mouth-parts ;
second, a migrating, agamic form, which is winged and furnished
with mouth-parts ; third, a sexual form, of which the females are
wingless, while the males may be either winged or wingless ; in cer-
tain cases, at least, the sexual forms are mouthless.

There is unfortunately a generalization in most of the text-books
on entomology that is incorrect. It is that the winged generation is
produced only on the approach of cold weather, and that this gen-
eration is the sexual one.

Plant-lice are often very destructive to vegetation ; they appear,
however, to be more liable to attack unhealthy plants than those
that are in good condition. The best method of destroying these
pests is by spraying with a strong solution of soap, or with kerosene
emulsion. (See Chapter XIV.) As plant-lice draw their nourish-
ment from below the surface of the plants they infest, they are not
injured by the application of poisons to the plants.

The Aphididse comprises four sub-families ; the following table
for separating these sub-families is published by Dr. Thomas, in the
Eighth Report of the State Entomologist of Illinois. It is necessary
here to give the names applied to the veins of the wings, as some of
them are used in this table. The principal vein of the front wing,
that which extends from the base to near the tip of the wing, (Fig.

HEMIPTERA.

!59

/ 2-

Fig. 133. — Wings of Plant-louse.

133, sc,) is the subcostal or submarginal vein. The distal end of
this vein becomes widened, and ex-
tends to the margin of the wing; this
part of it is the stigma (st). From the
stigma, a curved vein extends to the
tip of the wing; this is the stigmatic
or fourth vein. From the submarginal
vein there branch two or three veins
(in addition to the stigmatic vein),
which extend across the disk of the
wing ; these are the first, second, and
third discoidal veins. The third dis-

coidal vein is sometimes forked. The veins of the hind wing, so
far as they are present, are named in a similar manner.

A. Winged form known; species not subterranean, except in a few cases
where there are dimorphic forms.

B. Front wings with three discoidal veins ; antennae of the winged individu-
als, and generally of the apterous individuals, six- or seven-jointed.
C. Front wings with the third discoidal vein twice forked (except in Tox-
optera, which, however, has well-developed honey-tubes); posterior
wings with two discoidal veins ; honey-tubes various. 4. AphidiX/E.

CC. Third discoidal vein with one fork or simple ; posterior wings with
one or two oblique veins; honey-tubes tuberculiform or want-
ing. 3. Pemphigix.'e.
B. Front wings with but two discoidal veins, the third being absent ; an-
tennae never more than five-jointed, sometimes but three-jointed.

2. CHERMESIN/E.

A A. Permanently apterous ; at least no winged form has been observed : chiefly
subterranean, residing on the roots of plants. 1. Rhizobiix.e.

Sub-Family I. — RinzOBIIN/E.*

As indicated in the table above, this sub-family has been erected
for certain genera in which no winged forms are known. It is pos-
sible that some of the insects placed here are merely the degraded
wingless generation of species which have also higher developed
forms with wings, and which pertain to some one of the three higher
sub-families.

The Rhizobiina live in the ground upon the roots of plants.
Our best known representative is the Lettuce Earth-louse, Rhizobius
lactucce. This occurs on the roots of lettuce, often in great Hum-

* Rhizobilnse, Rhizobius; rhiza (pi%a), root; bios (fSiof), life.

i6o

AN INTRODUCTION TO ENTOMOLOGY.

bers. The mature lice measure 2 mm. (0.08 inch) in length. They
are oval, of a dull white color, with dusky legs and antennae, and
with the body dusted over with a white powder.

Other species of this sub-family are found on roots of grasses or
herbaceous plants, and usually accompanied by ants.

Sub-Family II. — Chermesinjl*
The CJiermcsinee includes those genera of plant-lice in which the
front wings have only two discoidal veins ; the antennae are from
three- to five-jointed.

This sub-family is represented by two common genera, Chermes
and Phylloxera. In Chermes the antennae are five-jointed, while in
Phylloxera they are only three-jointed.

Chermes. — The most common species of this genus is the Pine
Blight, Chermes pinicorticis. This, in its most conspicuous form, ap-
pears as patches of white, flocculent, down-like matter on the smooth
bark of young white-pine trees. Beneath these patches of white
substance the very minute young lice can be found. The winged
generation appears in early summer. A closely allied species, Cher-
mes abietieoleiis, infests the terminal shoots of spruce, producing
large swellings.

Phylloxera. — This genus contains many species ; one of them,

Phylloxera vastatrix, has
attracted so much atten-
tion by the great extent
of its ravages that it is
often referred to as the Phyl-
loxera. It is more properly
termed the Grape Phyllox-
era. We have space for only
a brief account of the his-
tory of this species.

The presence of this in-
sect is manifested by the
vines in two ways : first, in
the case of certain species of
grapes, there appear upon
the lower surface of the
leaves fleshy swellings, which are more or less wrinkled and hairy
(, Fig. 134); these are hollow galls, opening upon the upper surface

Fig. 134. — Leaf of grape with galls of Phylloxera.
(From Riley.)

* Chermeslnae, Chermes: Arab, kermes, Skt. krimi, a worm.

HEMIPTERA.

161

of the leaf, and containing a wingless agamic plant-louse and
her eggs ; second, when the fibrous roots of a sickly vine are
examined, we find, if the disease is due to this insect, that the
minute fibres have become swollen and knotty; or, if the disease
is far advanced, they may be entirely decayed. Upon these root-
swellings we also find an agamic, wingless, egg-laying plant-louse,
the author of the mischief.

The insects found upon the roots differ slightly from those found
within the galls; but their specific identity is now generally accept-
ed. A careful study of this insect has revealed still other forms.
So that now we can say that the species is presented to us under
the three distinct forms described below.

Of the first form there are two types: one, the root-inhabiting
type, which causes the knots on the roots; second, the gall-inhabit-
ing type, which produces the galls upon the leaves. The gall-inhab-
iting type is simply a dimorphic form, which does not constitute an
essential part in the cycle of changes through which the species must
pass. It only appears when the insect infests certain species of grapes.

The following epitomized account of the life-history of this spe-
cies is condensed from Dr. C. V. Riley's Sixth and Seventh Mis-
souri Entomological Reports:

Fig. 135. — Phylloxera root-inhabiting: form. a. roots of Clinton vine, showing the relation of swell-
ings to leaf-<,'alls. and power of resisting decomposition ; />. larva as it appears when hibernating ;
e, d, antenna and leg of same; e, f, g, forms of more mature lice; /;. granulations of skin, /,
tubercle ; j\ transverse folds at border of joints ; k, simple eyes. 1 From Riley. 1

The Grape Phylloxera hibernates upon the roots of the grape,
mostK' as a young larva of the first or sedentary, agamic, wingless
form (Fig. 135). With the renewal of vine-growth in the spring,

1 62

AN INTRODUCTION TO ENTOMOLOGY.

this larva moults, rapidly increases in size, and soon commences lay-
ing eggs. These in due time give birth to young, which soon
become agamic, egg-laying mothers, like the first ; and, like them,
always remain wingless. Five or six generations of these parthen-

Fig. 136. — Phylloxera, root-inhabiting form, a shows a healthy root ; b, one on which the lice are
working, representing the knots and swellings caused by their punctures; c, a root that has
been deserted by them, and where the rootlets have commenced to decay ; d, d, d. shows how
the lice are found on the larger roots; e, female nymph, dorsal view ; f, same, ventral view ; g ;
winged female, dorsal view ; /z, same, ventral view ; i, magnified antenna of winged insect ; j\
side view of the wingless female, laying eggs on roots ; k shows how the punctures of the lice
cause the larger roots to rot. (From Riley.)

ogenetic, egg-bearmg, wingless mothers follow each other, when
(about the middle of July, in the latitude of St. Louis) some of
the individuals begin to acquire wings. Thus is produced the second,
or migrating, agamic, winged form (Fig. 136). These issue from
the ground while yet in the pupa state ; as soon as they have ac-

HEMIPTERA.

16-

quired wings, they rise in the air and spread to new vineyards, where
they lay their eggs, usually in the down of the under sides of the
leaves. Each individual of this generation lays from three to five,
and sometimes as many as eight eggs. These eggs are of two sizes;
the smaller, which produce males, are about three-fourths the size
of the larger, which produce females. From these eggs are hatched,
in the course of a fortnight, the third, or wingless, sexual form. It is
a very remarkable fact that this form emerges from the egg not as
larvae but as fully developed individuals. These sexual individuals
are born for no other purpose than the reproduction of their kind, and
are without means of flight, or of taking food. After pairing, the body
of the female enlarges somewhat and she is soon delivered of a solitary
egg. This impregnated egg gives birth to a young louse, which devel-
ops into the first or sedentary, agamic, wingless form; and thus re-
commences the cycle of changes through which the insect passes.

It has been discovered that sometimes the first form, during the
latter part of the season, lays a few eggs, which are of two sizes, like
those of the second form, and like those also produce males and
females. These males and females are precisely like those born of
the winged form, and like them produce the solitary impregnated
egg. Thus the interesting fact is established that even the winged
form is not essential to the perpetuation of the species.

Fig. 137. — Phylloxera, gall-inhabiting form, a, b, newly hatched nymph, ventral and dorsal view ; .
epR- ; d, section of gall ; e, swelling of tendril ; f, ,<>, k. mother gall-louse, lateral, dorsal, and ven-
tral views ; /, her antenna ; /, her two-jointed tarsus. Natural sizes indicated at sides. (From Riley. 1

If to the above account we add that occasionally individuals
abandon their normal underground habit, and form galls upon the
leaves of certain varieties of grape-vine (Fig. 137), we have, in a
general way, the whole natural history of the species.

164 AN INTRODUCTION TO ENTOMOLOGY.

Owing to the great injury which the species has done to the vine-
yards of France, hundreds of memoirs have been published regard-
ing it. But, as yet, no satisfactory means of destroying it has been
discovered. The difficulty lies in the fact that the insecticide must
be one that can penetrate the ground to the depth of three or four
feet, reaching all of the fibrous roots infested by the insect. It
must be a substance that can be cheaply applied on a large scale;
and it must also be something that will kill the insect without injury
to the vine.

Where the vineyards are so situated that they can be submerged
with water for a period of at least forty days during winter, the
insect can be drowned. But this method is obviously of limited
application.

It is found that vines growing in very sandy soil resist the attacks
of the Grape Phylloxera. This is supposed to be due to the diffi-
culty experienced by the insect in finding passages through such
soil.

The method of destroying the pest which is most generally avail-
able is by the use of carbon bisulphide. See Chapter XIV.

Sub-Family III. — Pemphigin^e.*

The Pemphigince includes those genera of plant-lice in which the
front wings have three discoidal veins, and of which the third dis-
coidal vein has only one fork or is simple ; the honey-tubes are
tuberculiform or wanting.

In habits and transformations it is an unusually interesting group.
As a rule the species live above ground, although with some there
are root-inhabiting forms. Many species are remarkable for the
form and abundance of their excretions ; others cause abnormal
vegetable growths or galls within which they live. The galls made
by the different species vary greatly in form ; but each species pro-
duces a characteristic gall.

The species chosen to illustrate this sub-family represent two
sections of it, as indicated below :

Section I. — PEMPHIGIM.

This section includes genera in which the third discoidal vein of
the front wings is simple ; the antennae are six-jointed.

* Pemphiglnse, Pemphigus: panphix (n£f.i<pic,), a blister.

HEMIPTERA. 1 65

Three genera occur in this country. These can be distinguished
as follows :

A. Hind wings with two discoidal veins. 1. PEMPHIGUS.
A A. Hind wings with only one discoidal vein.

B. Antennae six-jointed. 2. TETRANEURA.

BB. Antennae five-jointed. 3. Hor.maphis.

Among the common representatives of this section are certain
species of Pemphigus, which make galls upon various trees of the
genus Populus. One of these, the Poplar-leaf Gall-louse, Pemphi-
gus populicaulis, is common on the leaves of cotton-wood and of
aspen. It makes a swelling the size of a small marble on the leaf at
the junction of the petiole with the blade. This gall is of a reddish
tint, and has on one side a slit-like opening. In the early part of
the season each gall is occupied by a single, wingless female, prob-
ably the agamic stem-mother, which, by midsummer, becomes the
mother of numerous progeny; these often amount to one hundred
and fifty in number.

A closely allied species occurs throughout the Western and South-
western States, which makes a similar gall near the base of the leaf
of Populus monolifera and P. balsamifera. This gall has a trans-
verse slit-like opening, which probably suggested the name of the
insect. Pemphigus populi-transversus. As in the preceding species,
the gall is started in the spring by a single, wingless stem-mother;
by the latter part of June the stem mother is surrounded with young
of various sizes, all covered with the usual white secretion, and
mixed with liquid globules. A generation of winged individuals is
produced in the autumn, sometimes not until the leaves have fallen.

Another of these species is known as the Vagabond Gall-louse,
Pemphigus va.gabii.ndus. It infests the tips of the twigs of certain
cotton-woods and the balsam poplar; here it makes large corrugated
galls, which somewhat resemble the flower of the double cockscomb
of our gardens. These galls turn black, and remain on the trees
during the winter. On opening the galls in midwinter I have found
many remains of winged lice in them.

Section II.— SCHIZONEURINI.

This section includes genera in which the third discoidal vein of
the front wings is forked ; the antennae are six-jointed. Two genera

1 66 AN INTRODUCTION TO ENTOMOLOGY.

occur in this country, ColopJia and Schizoneura. In ColopJia the hind
wings have only one discoidal vein ; in Schizoneura they have two.

The Cockscomb Elm Gall, ColopJia ulmicola. — Among the gall-
making species of this section this is probably the most familiar one.
The gall is an excrescence or follicle like a cock's comb, which rises
abruptly from the upper surface of the leaves of elm ; it is usually
about an inch long and a quarter of an inch high ; it is compressed,
and has its sides wrinkled perpendicularly and its summit irregularly
gashed and toothed ; it is of a paler green color than the leaf and
more or less red on the side exposed to the sun ; it opens on the
under side of the leaf by along slit-like orifice ; inside, it is wrinkled
perpendicularly into deep plaits. The complete life-history of this
species is not known. According to Riley and Monell there is a
winter egg, which is usually inclosed in the dry skin of a sexual
female. This can be found during winter in the crevices of the bavk
of the White Elm. The stem-mother which hatches from this egg
forms the gall. She gives birth to numerous offspring; these
become winged, and constitute the only generation produced within
the gall. These winged, agamic females issue from the slit-like
opening of the gall ; and each gives birth in the course of a day or
so to upwards of a dozen young. These are born as pseudova.
They have well developed mouth-parts ; and it is probable that
when fully grown they give birth to the sexual generation.

To the genus Schizoneura belong several of our most conspicuous
'Woolly Aphids." Among them are the following:

The Alder Blight, SchizoneTira tessclldta. — This woolly louse is
often found crowded together on the under side of the branches of
alder {AInns rubra), and concealed beneath a covering of downy ex-
cretion. It also excretes abundantly honey-dew. The result is
that the branches infested by this insect, and those beneath the
cluster of Aphids, become blackened with fungi that grow upon
this secretion. There is also a curious fungus which grows in large
spongy masses immediately beneath the cluster of plant-lice ; this is
known to botanists as Scorias spongiosum. It is evidently fed by
the honey-dew that falls upon it.

The Beech-tree Blight, Schizoneura imbricator. — This infests both
the twigs and leaves of beech. Like the preceding species it oc-
curs in clusters of individuals, each of which is clothed with a con-
spicuous downy excretion. These clusters often attract attention
by the curious habit which the insects have of waving their bodies up
and down, the plume-like masses of excretion rendering them very

HEMIPTERA. 1 67

conspicuous. When an infested limb is jarred, the Aphids emit a
shower of honey-dew. Owing to the abundance of this secretion,
the branches and leaves of an infested tree become blackened by
growths of fungi, as with the preceding species.

The Woolly-louse of the apple, Schizoneura laidgcra. — The
Woolly-louse of the apple is one of the best known pests of the
fruit-grower. In its most conspicuous form it appears on the trunk
and limbs of apple-trees. It congregates in clusters of individuals,
which are conspicuous on account of the woolly excretion with which
their bodies are clothed. They are especially injurious to young
trees, the bark of which becomes deeply pitted and scarred by their
attacks. The bark apparently ceases to grow at the point of attack,
but swells into a large ridge about the cluster of lice, leaving them
in a sheltered pit. The lice also frequently congregate in the axils
of the leaves and the forks of the branches. This species resembles
the grape Phylloxera in having a root-inhabiting form, which causes
knotty swellings on the fibrous roots. It is the presence of this form
which makes this pest such a difficult one to combat.

Although this insect has been known since the close of the last
century, its complete life-history has not been traced out. As with
all the Pemphiginae the transformations of which we know, and with
Phylloxera, there is in this species a generation of mouthless, wing-
less, and generally degraded sexual individuals. The females of this
generation produce each a winter egg. This can be found fn the
winter in the crevices of the bark, and in the pits caused by the
trunk form. It is frequently enveloped in the dry skin of the sexual
female. The trunk type at least of the wingless, agamic form gives
birth to living young not enveloped in a pellicle. As the season
advances there appears a generation of winged individuals. These
are probably agamic; but whether they produce the sexual genera-
tion directly or whether there intervenes one or more agamic genera-
tions has not been determined. At Washington I have seen both
the root and trunk type of the wingless, agamic form maintain them-
selves throughout an entire winter without the intervention of a
winter egg. I presume this is a common occurrence farther south.

As one form of this insect works deep in the ground upon the
fibrous roots of the trees, the same difficulties are nut in attempting
to destroy it that are presented by the grape Phylloxera. In fact,
except in case of an especially valuable tree, I do not believe that it
will pa\- to attempt to save a tree that has become badly infested by
the woolly aphis. It will be cheaper to dig the tree up ami burn it,

l68 AN INTRODUCTION TO ENTOMOLOGY.

and devote the ground to some other use. Some other species of
tree can be safely planted in the same place, but not an apple.
Great care should be taken in putting out trees from a nursery to see
that they are free from this pest. If there is any doubt, the trees
should be washed, roots and all, in a strong solution of soap. It is
well also to put in the fork of the trees a piece of hard soap, which
will be dissolved and washed down by the rains. This will serve to
prevent certain other pests as well as the woolly aphis from getting
a foothold. In case it is desired to rid an infested tree of this pest,
the trunk form should be washed off with a strong solution of soap
applied with a sponge, taking care to destroy all eggs; and the
ground should be treated with carbon bisulphide, as for the grape
Phylloxera.

Sub-Family IV. — Aphidin^:.

The sub-family Aphidinae includes those genera in which the third
discoidal vein of the front wings is twice forked ; the hind wings have
two discoidal veins ; and the honey-tubes are usually well developed,
sometimes tuberculiform or obsolete. The number of species belong-
ing to this group is very great ; it being the largest of the sub-families
of the Aphididae. Most of the species live above ground, on the
surface of leaves or twigs of woody plants or upon the leaves
and stems of the more succulent species. I do not know of any
species that produce galls.

Ldchnus. — The largest of our species of Aphididae belong to the
genus Lachnus. L. cdryce is found on the pig-nut
hickory, clustered on the under side of the limbs
in summer; it is interesting from being perhaps
our largest plant-louse, measuring to the tip of the
.—Lachnus. abdomen 6 mm. (0.24 inch), and more than 10 mm.
(0.4 inch) to the tip of the wings.
Aphis. — To the genus Aphis, in its restricted sense, belong a con-
siderable number of the important species of this sub-family. The
species that occurs in such immense numbers on cabbage is Aphis
brassiccz. It is the most common, and, perhaps, the most injurious
species that occurs in the vegetable gardens of this country. The
Corn Plant-louse is Aphis maidis. This species, according to the
observations of Forbes, winters in the wingless, agamic form in the
earth of fields previously infested. In the spring it appears to be
strictly dependent upon a species of ant, Lasias alienus, which mines
along the principal roots of the corn, collects the plant-lice, and

HEMIPTERA. 1 69

conveys them into these burrows, and there watches and protects
them. In a short time after the lice have been transferred to the
roots of the corn, they mature a winged generation, by means of
which adjacent fields ma)- be stocked. These facts indicate the
inadvisability of planting corn on a field that was infested by this
insect the previous year. The species of Aphis that has attracted
the most attention recently is Aphis mdli. This has occurred in im-
mense numbers on the young leaves of apple. Usually the injuries
of this species are confined to the terminal shoots of a few branches ;
but in seasons favorable to its development, the entire tree becomes
infested. It is necessary then to resort to the use of alkaline washes.
(See Chapter XIV.)

Myzus.- — Two species of Myzus are very common. One of these,
the Cherry-tree Aphis, Myzus cerasi, infests the leaves and twigs of
cherry. Sometimes it becomes so abundant that it completely covers
the infested tree. The other species referred to is the Peach-tree
Aphis, Myzus persicce. This lives on the under side of the leaves,
causing them to thicken and curl. Its injuries are usually confined
to the terminal portion of a few branches. The easiest way to
destroy this pest is to dip the infested branches into a pail of soap
solution. There is a serious disease of the peach which causes the
leaves to curl in a similar manner, and which is known as the curl-
leaf. This disease can be distinguished from the injuries of the
Peach-tree Aphis by the absence of plant-lice in the curled leaves.
It is caused by a fungus known as Exoascus deformans.

The Hop Aphis, Phorodoii humuli. — This species often swarms in
hop-yards to such an extent that it seriously injures the crop. An
interesting and important feature in its life-history is that it passes
the winter on plum-trees. As soon as the leaves of plum appear in
the spring, the first generation of this Aphid hatches from the winter
eggs on plum. The first and second generations are wingless, agamic
females, which live upon the plum; the third appears early in June,
is winged, and migrates to the hops. From this generation there
descend several generations of wingless, agamic females. Of these
there may be, according to Riley's observations, upon which this
account is based, as many as eight, making the last one the eleventh
of the season. Late in August and early in September the offspring
of the eleventh generation and of the members of the other genera-
tions that are still alive become winged. These winged individuals
are agamic females which migrate to plum-trees and there produce
wingless, sexual females. Late in September, there is produced on

170 AN INTRODUCTION TO ENTOMOLOGY.

the hops by some members of the eleventh agamic generation a
generation of winged males. These fly to the plum-trees and mate
with the wingless sexual females, which are already there. Soon
after this the eggs are deposited on the smaller twigs and branches
of the plum, in and around the angles formed by the buds and twigs.
Each female lays from one to three eggs.

If it should be proven that this species can winter only on plum,
the separation of plum and hop culture would be advisable. But
further observations are needed before we are warranted in advising
the destruction of plum-trees in the hop-growing sections. But we
can urge the careful destruction of all Aphids on plum-trees early in
the season. The most practicable way of doing this is by spraying
with a strong solution of soap or with kerosene emulsion. (See
Chapter XIV.)

Family V. — Psyllidae*

{Jumping Plant-lice^)

The Jumping Plant-lice are comparatively small insects; our
more common species measure only 3 or 4 millimeters in
length ; and our largest species, the giant, comparatively speak-
ing, measures only 6 mm. and has a wing-expanse of 12 mm.
They resemble somewhat the winged Aphids in appearance ; but
they look more like miniature Cicades (Fig. 139).
They are, however, closely allied to the Aphids ; but
they differ from them in the firmer texture of the
body, in the stouter limbs, in having the hind legs
fitted for jumping, and in the 9- or 10-jointed an-
tennae. The antennae are peculiar also in being
armed at the tip with two bristles, or less commonly
FlG 'enfarged?' //a ' with one. " The rostrum is short, three-jointed, and
placed almost between the fore coxae, where it fits into
a grooved space. Both sexes are always winged in the adult ; the
wing-covers are ample, and, while often transparent, are much thicker
than the wings, and furnished with stout curving veins, which
enclose a few areoles at the tip." (Uhler.)

The Psyllidae subsist entirely upon the juices of plants ; many
species form galls. But it is rare that any of them appear upon culti-
vated plants in sufficient numbers to attract attention, except in case
of the Pear-tree Psylla.

* Psyllidae, Psylla : psylla (ipvXXa), a flea.

HEMIPTERA. 171

The Pear-tree Psylla, Psylla pyri. — This is a minute species which
measures only 2.5 mm. (o. 1 inch) to the tip of the folded wings. It
invests the smaller limbs and twigs of pear-trees, causing them to
droop and fall off. It can be destroyed in the same way as recom-
mended for plant-lice in the same situation.

Family VI. — MEMBRACID^E.*

{Trcc-hoppcrs.)

We have many common representatives of this sub-family; and
the grotesque forms of certain species are sure to attract the attention
of collectors. The general outline of the body is usually triquetral,
that is, shaped like a beech-nut. But many of the species have one
or more of the angles prolonged, or are furnished with prominent
humps or tubercles. The most useful character for distinguishing
members of this family is the prolongation of the prothorax back-
ward above the abdomen. Sometimes it extends back to the tip of
the abdomen, and completely covers the wings. This development
of the prothorax reminds us of what occurs in the Tettiginae, of the
order Orthoptera.

Many species of the Membracidae live upon bushes or small trees ;
and all are good leapers. Hence the common name, Tree-hoppers.
Although these insects subsist upon the juices of plants, I have never
known them to occur in sufficient numbers to be of economic impor-
tance. Some members of this family excrete honey-dew, and are at-
tended by ants, as are the Aphids. The transformations of but few
species have been observed. Some of these make slits in twigs, in
which they lay their eggs. The immature forms of certain species oc-
cur upon plants in company with the adults. But the early stages
of the great majority of species are unknown to us.

The genus Darnis will serve as a good illustration of one of the
principal types of this family. Here the prothorax is nearly
all that can be seen of the body from above. It is very convex
in front, overshadowing the short, transverse, band-like head,
and tapers to a sharp point, which extends beyond the tip
of the abdomen. (Fig. 140.)

The Buffalo Tree-hoppers, Ccrcsa bilbalus, represents
another type belonging to this family. The popular name refers to
the lateral prolongations of the prothorax, which suggest the horns

* Membracidae, Membracis : membrax {nditfipaZ,), a kind of Cicada.

1 72

AN INTRODUCTION TO ENTOMOLOGY.

of a buffalo (Fig. 141). This insect lives on the sap of apple, pear,

and other trees. It is of a yellowish-green color. The eggs are laid in

little slits in the bark ; they hatch in the spring ; and the

young are very different from the adult, being furnished

with a pair of large spines upon each segment.

The Two-horned Tree-hoppers, Ccrcsa diceros, is also
a common species. It resembles the Buffalo Tree-hopper
in size and form. It is a pale, dirty yellow, spotted with
brown ; the lateral and caudal aspect of each horn is
brown ; the caudal tip of the prothorax, and a large spot
midway between the tip and horns are also brown. The insect is
densely clothed with hairs.

The genus EncJiendpa illustrates another strange form found in
this family. The Two-marked Tree-hopper, Enchcnopa binotdta, (Fig.
142,) abounds on various trees, shrubs, and herbaceous
plants. It is gregarious; and both adult and immature
forms are found clustered together. It is almost always
attended by ants. It lays its eggs in frothy masses, which
are very v/hite, and appear like wax. These egg-masses
have been mistaken for insects of the genus Orthczia.
Another very common species is E. carvdta. It is brownish, un-
spotted, and has a rather longer horn than the preceding species.

" To the genus Telamona (Fig. 143) belong our
indigenous humpback forms, of gray, claret, or
greenish colors, which live in June and July upon
oaks, hickories, and other forest trees. They gen-
erally rest singly on the limbs and branches of the
trees, with the head directed away from the trunk ;
but in the younger stages they keep together in small groups."
(Uhler.)

Fig. 142.— En-
chenopa bin-
otata.

Fig. 143. — Telamo-

Family VII. — ClCADlM:.*

{Cicadas.)

The large size and the well-known songs of the more common
species of this family render them familiar objects. It is only
necessary to refer to the Periodical Cicada (or the 17-year locust, as

* Cicadidae, Cicada: Cicada, Latin name of these insects.

HEMIPTERA.

173

Fig. 144. — Cicada tibicen.

it has been improperly termed) and to the Dog-day Harvest-fly
(Fig. 144) to give an idea of the more striking characters of this
family.

The species are generally of large size, with a subconical body.
The head is wide and blunt, with prominent
eyes on the outer angles, and three bead-like
ocelli arranged in a triangle on the vertex.
"The mesothorax is the largest segment, and
the metathorax is reduced to a narrow scale.
A very conspicuous feature in all of them is a
cross-like prominence on the hind end of the
former, which adds great firmness to this im-
portant part of the chest. The wing-covers
are nearly elliptical, longer than the body,
parchment-like, but generally transparent, and
with a series of eight areoles at the tip ; but the
hind wings are more membranous, scarcely ex-
ceeding half the length of the former, and with
an apical series of six areoles. Their legs are short and stout, not
fitted for leaping, the fore-thighs quite thick, armed with two or
more thick teeth ; also, the hind shanks are bristly, and have a series
of sharp spines on each side.

" But the most distinctive peculiarity, which has no parallel in
any of the other groups, appears in the organs of sound (of the
males). These consist of two large parchment sacs, ribbed and
gathered into numerous plaits, furnished with powerful muscles, and
situated in large cavities at the base of the abdomen. When in
action, the air is driven in great force against the ribbed surfaces, and
vibrations are set up which produce the sound in accordance with
the number and form of the fluted spaces and ribs." (Uhler.)

The Dog-day Harvest-fly, or Lyerman, Cicada tibicen. — The
shrill cry of this species, which is the most prominent of the various
insect sounds heard during the latter part of the summer, has
brought its author into prominent notice. This insect varies both
in size and colors. It commonly measures 50 mm. (2 inches) to the
tip of the closed wings; it is black and green, and more or less
powdered with white beneath. The transformations of this insect
are similar to those of the following species, except that it requires
only two years for its development. It differs also in seldom, if ever,
occurring in sufficient numbers to be of economic importance ; but a

174 AN INTRODUCTION TO ENTOMOLOGY.

brood of it appears each year. It is distributed from New York to
Rio de Janeiro.

The Periodical Cicada, Cicada scptcndccim. — This species is now
commonly known as the 17-year locust. But the term locust, as ap-
plied to it, is a misnomer, the locusts being Orthopterous insects.
I therefore adopt the more appropriate name, Periodical Cicada,
which has been proposed for it. This species is remarkable for the
long time required for it to attain its maturity. The eggs are laid
in the twigs of various trees ; the female makes a series of slits in
the twig, into which the eggs are placed. Sometimes this Cicada
occurs in such great numbers that they seriously injure small fruit-
trees, by ovipositing in the twigs and smaller branches. The larvae
hatch in about six weeks. They soon voluntarily drop to the
ground, where they bury themselves. Here they obtain nourish-
ment by sucking the juices from the roots of forest and fruit trees.
And here they remain till the seventeenth year following. They
emerge from the ground during the last half of May, at which time
the empty pupa-skins may be found in great numbers, clinging to
the bark of trees and other objects. The insects soon pair, the
females oviposit, and all disappear in a few weeks.

More than twenty distinct broods of this species have been traced
out ; so that one or more broods appear somewhere in the United
States nearly every year. In many localities, several broods coexist ;
in some cases there are as many as seven distinct broods in the same
place, each brood appearing in distinct years. There is a variety of
the species in which the period of development is only thirteen years.
This variety is chiefly a Southern form, while the seventeen-year
broods occur in the North.

Family VIII. — FULGORID.-E*

{Lantern-flics ct al.)

This family is remarkable for certain exotic forms which it con-
tains. Chief among these is the great Lantern-fly of Brazil, which is
figured in many popular works on insects. Scarcely less strange are
the Candle-flies of China and the East Indies. There does not seem

Fulgoridoe, FulgOra : fulgor, flashing lightning.

HEMIPTERA. 1/5

to be any typical form of the body, characteristic of this family. The
different genera differ so greatly that, on superficial examination, they
appear to have very little in common. Some even resemble butter-
flies and moths, while others might easily be mistaken for certain
Neuropterous genera.

The most useful character for recognizing these insects is the
form and position of the antennae. These are bristle-shaped, and
inserted into a button-shaped base on the sides of the cheeks beneath
the eyes. Although the Fulgoridae are vegetable-feeders, none of
our species have attracted the attention of agriculturists. There
are, however, certain exotic species which do great injur}- to
crops.

The Brazilian Lantern-fly, Laterndria phosphorca. — This is the
largest species of the family, and is one of the most striking in ap-
pearance of all insects. It has immense wings, expanding nearly
150 mm. (6 inches). Upon each hind wing there is a large eye-like
spot. But the character which makes this insect especially promi-
nent is the form of the head. There is a great bladder-like prolonga-
tion extending forwards. This prolongation has been aptly com-
pared to the pod of a peanut. In a specimen before me, the bod} - ,
exclusive of the head, measures 45 mm. (1.8 inches) in length ; while
the head alone measures 30 mm. (1.2 inches). The specific name
refers to the supposed luminosity of this part. Prof. Branner tells
us of various superstitions held by the Brazilians regarding this
insect. For example : " That it has great powers of flight, and when
in its wild career it strikes any living object — if an animal, no matter
how large or powerful — it falls dead upon the spot ; if a tree, it soon
wilts and dies."

The Chinese Candle-fly, Fulgoria candcldria. — This is another
very prominent insect, and also one that has the reputation of being
phosphorescent. It is commonly represented in collections of
exotic insects, and it is often figured by the Chinese. It is smaller
than the preceding species, measuring about two thirds as much in
length. The prolongation of the head is proportionately longer
than in the Brazilian insect; but it is more slender, and is conical.
The color of the insect is greenish or orange-yellow, with banded
wing-covers.

The following of our native genera will serve to illustrate some
of the variations in form represented in this country. Our species
are all small compared with the exotics described above.

176

AN INTRODUCTION TO ENTOMOLOGY.

Fig. ns.—Scolops.

Scolops. — In this genus the head is greatly prolonged (Fig. 145),
as with the exotic Candle-flies. Our more common species, how-
ever, measure only about 8 mm. (0.31 inch) in
length.

Otioccms. — In this genus, the body is oblong;
the head is compressed, with a double edge both
above and below, and the antennae are furnished
with tape-like appendages. " Otiocerus coquedertii is
a g a y lemon-yellow or cream-colored species, with a broad stripe on
the side of the face and wavy red forked lines on the wing-covers ;
the head, as seen from the side, is of the form of a ploughshare, with
little brown eyes standing out like beads. The antennae have three
bent appendages resembling strips of tape. It measures about
8 mm. (0.3 inch) to the tip of wing-covers, lives upon the leaves of
grape-vines, oaks, and hickory, in July, August, and September."
(Uhler.) It is distributed over the entire Eastern United States.

Ormenis. — In our common representatives
of this genus the wing-covers are broad, and
closely applied to each other in a vertical
position ; they are more or less truncate, and
give the insect a wedge-shape outline. O. sep-
tcntriondlis (Fig. 146) is a beautiful pale-green
species powdered with white, which feeds on
wild grape-vines, drawing nourishment from

the tender shoots and mid-ribs of the leaves, during its young
stages.

Fig. 146. — Ormenis septen-
trionalis.

Family IX. — CERCOPID^E*

{Spittle-insects or Frog-hoppa-s.)

This and the following family agree with the Membracidae in h?v-
ing the antennae inserted in front of and between the eyes. But the
Cercopidae differs from the Membracidae in lacking the backward pro-
longation of the prothorax, and from the Jassidae in the character of
the spines upon the hind tibiae. Here we find the tibiae armed with
one or two stout teeth, and the tip crowned with short, stout spines.
The Cercopidae "mark an important advance in the direction of the
Heteroptera by the large size of the prothorax and increased freedom
of the fore legs. This extensive piece is no longer a mere cap or

* Cercopidae, Cercopis : Cercops (KepKooip), one of a fabled race of men.

HEMIPTERA. 1 77

scale as in most of the Fulgoridae, nor yet a lid, case, or bubble-like
expansion as in the Membracidae, but is* an important regional por-
tion, exercising various important functions." (Uhler.)

Our most common representatives of the family are the insects

known as spittle-insects or frog-hoppers. During the summer months
one often finds upon various shrubs and herbs masses of white froth.
In the midst of each of these masses there lives a young insect, a
member of this family. In some cases as man)- as four or five insects
inhabit the same mass of foam. The froth is supposed to consist of
sap, which the insect has pumped from the plant, by means of its
rostrum, and passed through its alimentary canal. It is asserted
that these insects undergo all their transformations within this mass;
that when one is about to moult for the last time, a clear space is
formed about its bod}-; the superficial part of the foam dries, so as
to form a vaulted roof to a closed chamber within which the change
of skin is made. The adult insects wander about on herbage
and trees. They have the power of leaping well. The name frog-
hoppers has doubtless grown out of the fact that formerly the froth
was called "frog-spittle," and was supposed to have been voided by
the tree-frogs from their mouths. The name is not, however, inap-
propriate; for the broad and depressed form of our more common
species is something like that of a frog.

Our more common species of spittle-insects belong to the genus
Aphrdphora. The}- are mostly brownish insects, and are variously
banded and spotted. One of the common species of the Eastern
United States is Aphrdphora quadrangular is (Fig. 1471. The adult
of this species is a brownish insect, densely covered
with microscopic hairs, and black beneath ; the wing-
covers are marked with two oblique, brown bands,
which are confluent near the middle of the costal mar-
gin ; the humeral region is dusk}-; and the tip of F)G , 47 _ Aph _
each wing-cover is marked with a small blackish curve; 'ring..
the ocelli are black, but indistinct. This species
measures from 6 mm. to S mm. (0.24 to 0.31 inch) in length.
Somewhat resembling this species, and also common in the
East, is Aphrdphora quadranotdta. In this species the bodv is
pale; the wing-covers are dusk)-, each with two large hyaline costal
spots, margined with dark brown ; the ocelli are blood-red; and the
head and pronotum are furnished with a slightly elevated, median,
longitudinal line.

To the genus Clastoptera belong certain other common members

178 AN INTRODUCTION TO ENTOMOLOGY.

of this family. In this genus the body is short and plump, some-
times nearly hemispherical; 'the species are small, our common forms
ranging from 3 mm. to 6 mm. (0.12 to 0.24 inch) in length. Clastop-
tera protcus is a conspicuous species on account of its bright yellow
markings. It varies greatly in color and markings; but the most
striking forms are black, with three transverse yellow bands, two on
the head and one on the thorax; and with the scutellum and a
large oblique band on each wing-cover yellow. Another common
species is Clastoptera obtiisa. This occurs on black alder in summer
and autumn. " It is of a claret-brown color above, marked with two
pale bands on the vertex, two on the prothorax, and a wavy, broader
band on the wing-covers. The membrane is often whitish, the.
waved band is extended exteriorly, and there is a pale V-shaped
figure on the end of the scutellum."

Family X.— Jassid.t:.*
( Leaf -hoppers. )

This the highest family of the Homoptera is a very extensive one.
And it is also of considerable economic importance; for it includes
a number of species that are very injurious to vegetation. The body
is more slender than in the preceding family; with which this agrees
in the insertion of the antennae in front of and between the eyes,
and in the absence of a prolongation of the prothorax above the
abdomen. But the most salient character which distinguishes the
Jassidae is the structure of the hind tibiae. These are nearly or
quite as long as the abdomen, curved, and armed with a row of
spines on each margin. The form of the body " is commonly long
and slender, often spindle-shaped, with a large transverse prothorax
not much wider than the head. The front is generally an oblique,
cross-ribbed, inflated prominence, with the cheeks touching the
anterior coxae, but rarely, if ever, restraining their movement. They
have a rather large triangular scutellum ; the wing-covers curve over
the sides of the abdomen, appear as tapering towards the tip, and
the membrane is distinguished from the more leathery corium."
(Uhler.)

The Jassidae are able to leap powerfully ; and, as they are more
often found on the leaves of herbage and on grass than elsewhere,
they have been termed leaf-hoppers.

Jassidae, Jassus : Jassus, a proper name.

HEMIPTERA. 179

The family has been divided in various ways by different writers.
It seems best to recognize in this place only two sub-families ; although
seven are proposed by Stal. These two sub-families can be distin-
guished as follows:

A. Ocelli placed on the front rim of the vertex close to the eyes, or on the

front, but never on the disk of the vertex. I. jASSlNiE.

AA. Ocelli placed upon the vertex. II. Tettigoxin.k.

Sub- Family I.— J ASS IX. k.

The more important members of the Jassinae from an economic
standpoint are the following:

The Destructive Leaf-hopper, Cicadula exitiosa. — During the
winter of 1879-80 much damage was done to winter grain in the
Carolinas and Georgia by this species. It is a small, active, brownish
insect, which measures with its wings folded about 5 mm. (0.2 inch) in
length. Its general form is well indicated by the enlarged figure (Fig.
148). It is very quick, a good flyer, and a great jumper.
It injures grass or grain by piercing the midrib of the
leaf and sucking the juices from it. Upon the planta-
tion where I studied this insect there was observable a
most exact line between the eaten and uneaten portions of
the wheat-field. Instead of spreading themselves over
the field indiscriminately, or half eating a patch here and
there, the leaf-hoppers ate the wheat down to the ground M
as they progressed. They are very shy, however, and fly FlG m8 _
away on the least disturbance. Judging from the known exlf/'J*.
habits of allied species, the eggs are doubtless laid in the A^tho'r's
stems of grasses close to the ground. The young hoppers iSyg )' 1
when hatched are almost precisely of the same appearance
as the old ones, except that they lack wings. The time occupied in
attaining full growth probably does not exceed a month, so that
there are several broods a year. These insects are readily attracted
by light; and probably many of them could be destroyed by trap-
lanterns, or by building bonfires at night. It is possible, also, that
many could be destroyed by spraying with some of the alkaline or
other washes described in the chapter on remedies. In those cases
where the line of injury is a well-marked one, only a small part of
the field would need to be sprayed.

The Grape-vine Leaf-hopper, Erythroneura litis. — There are

l8o AN INTRODUCTION TO ENTOMOLOGY.

several species of Leaf-hoppers that infest the leaves of grape, and
are known to grape growers as the " Thrip." These all belong to
the genus Erythroneura. The most common one is E. vltis. It is
a little more than 3 mm. (0.12 inch) in length, crossed by two blood-
red bands, and a third dusky one at the apex. These insects pass
the winter in the perfect state, hibernating under dead leaves or
other rubbish ; in the spring they deposit their eggs on the young
leaves of the vine. The larvae hatch during the month of June, and
resemble the adult insect except in size and in being destitute of
wings. The insects feed together on the under side of the leaves,
and are very quick in their movements. Like the preceding species
this insect can be destroyed by trap-lanterns or by washes.

The Rose Leaf-hopper, Empoa rosce. — " Swarms of these insects
may be found, in various stages of growth, on the leaves of the rose-
bush, through the greater part of the summer, and even in winter
upon housed plants. Their numerous cast skins may be seen adher-
ing to the lower sides of the leaves. They pair and lay their eggs
about the middle of June, and they probably live through the winter
in the perfect state, concealed under fallen leaves and rubbish on the
surface of the ground." Although this is a very common pest, it
does not seem to have received much attention from entomologists
since the time of Harris, from whom the above account is quoted.
It should be combated in the same way as the leaf-hoppers already
described.

Sub-family II. — TETTIGONIN^E.*

The members of this sub-family are mostly small or medium-sized
insects, with long narrow bodies. But we find here some forms
which resemble certain genera belonging to the Cercopidoe. Thus
Penthimia includes plump, short-bodied insects, which remind us of
Clastoptera; and the genus Gypona includes a large number of species,
some of which resemble very closely certain species of ApJirophora.
It is, however, hardly necessary to remind the student that a glance
at the posterior tibiae of these leaf-hoppers will enable one to dis-
tinguish them from the Cercopids, which they so closely resemble.

The genus DiedrocepJiala includes grass-green, or pale-green,
spindle-shaped species which represent better the typical form of
this sub-family. The members of this genus may be recognized by
the long, triangular head as seen from above. One of the species,

* Tettigonlnae, Tettigonia : tettix (rerTig), a cicada; gonia (yoovia), a corner.

HEMIPTERA. 151

D. fidviceps, sometimes greatly injures fields of grain in the South.
The most common species in New York is D. novcboracciisis.

The genus Proconia includes species in which the head is more
blunt than in the preceding genus, and is wider across the eyes
than the thorax. P. unddta (Fig. 149) is a common species. '"Its-
body, head, fore part of thorax, scutellum, and legs
are bright yellow, with circular lines of black on the
head, thorax, and scutellum. The underside of the
abdomen is banded, and the breast and legs speckled
with black. The wing-covers are bluish purple, when
fresh, coated with whitish powder." (Uhler.) It FlG . J 49-— Proc °-

1 v ' ma undata.

measures 12 mm. (0.47 inch) to the tip of the wing-
covers. It is said to lay its eggs in single rows in grape canes ; and
to puncture with its beak the stems of the bunches of grapes, caus-
ing the stems to wither and the bunches to drop off.

Sub-Order III.— HETEROPTERA.*

The Heteroptera includes those members of the order Hcmip-
tera to which the general name Bug is most frequently applied.
These insects are characterized, as already indicated, by having the
first pair of wings thickened at the base, and with thinner extremi-
ties, which overlap on the back ; and by the position of the rostrum,
which arises from the front part of the head. The head is furnished
with a more or less distinct neck, so that the cheeks and the first
pair of coxse do not touch each other.

In this sub-order we find variations in structure which corre-
spond closely with variations in habits. There are certain families
the members of which are truly aquatic, living within the water,
through which they swim, and to the surface of which they come
occasionally for air. There are others which are truly terrestrial,
living upon the surface of plants, or in other positions away from
waterr There are still other families the members of which hold an
intermediate position between the aquatic and the terrestrial forms,
living upon the surface of water, or in marshy places.

In a systematic arrangement of the Heteroptera the aquatic
forms are placed first or lowest ; the terrestrial forms, highest ;
and the semiaquatic forms hold an intermediate position.

* Heteroptera : heterosis tepui), diverse ; pteron (itrepov), awing.

1 82 AN INTRODUCTION TO ENTOMOLOGY.

TABLE FOR DETERMINING THE FAMILIES OF HETEROPTERA.

A. Antennae short, and nearly or quite concealed beneath the head.

B. Ocelli wanting; insects aquatic, and, excepting Nepidae and Naucoridae,
with legs fitted for swimming.

C. Head overlapping the prothorax ; fore tarsi flattened, consisting of one
segment, and ciliated. Fam. XL— Corisidae.

CC. Head inserted in the prothorax ; fore tarsi normal.

D. Body thick, dorsal aspect of abdomen very convex. Insects which

swim upon their back. Fam. XII.— NotoneCTID^e.

DD. Body either flat or elliptical in outline, or much elongated; caudal

end of abdomen furnished with a respiratory tube composed of a

pair of grooved filaments. Fam. XIII. — NEPID/E.

DDD. Body flat, oval or ovate, without respiratory filaments.

E. Abdomen with a pair of strap-like caudal appendages (these ap-
pendages ate retractile, and are frequently withdrawn from sight);
legs flattened for swimming. Fam. XIV. — Belostomatid^E.

EE. Abdomen without caudal appendages; legs fitted for crawling
rather than swimming. Fam. XV. — Naucoridae.

BB. Two ocelli present ; insects aerial, although living near the water ; body-
short and broad ; eyes very prominent. Fam. XVI. — Galgulidae.
AA. Antennae prominent, free, rarely (Phymatidae) fitting in a groove under
the lateral margin of the pronotum.
B. Body linear ; head as long as the three thoracic segments.

Fam. XX. — Limnobatidae.
BB. Body of various forms, but, when linear, with head shorter than the
thorax.

C. Distal segment of the tarsi more or less bifid, with the claws inserted
before the apex.

D. Body usually elongated, prothorax narrow ; rostrum 4-jointed ;
second and third pairs of legs extremely long and slender.

Fam. XIX. — Hydrobatid^e.
DD. Body usually stout, oval, and broadest across the prothorax; ros-
trum 3-jointed ; legs not extremely long. Fam. XVIII. — Veliad/E.
CC. Distal segment of the tarsi entire; claws inserted at the end.
D. Antennae 4-jointed.*

E. Wing-covers reticulated, and of one uniform thin substance
throughout ; very rarely (Piesma) with a distinction between the
corium and membrane. Fam. XXVI. — Tingitid.e.

EE. Wing-covers of various forms or absent, but not of the form pre-
sented by the Tingitidae. See Fig. 171.
F. Rostrum 3-jointed.
G. Ocelli wanting.

H. Wing-covers rudimentary, with only corium (Acanthiin^.

Fam. XXVII. — Acanthiid.e.

* In certain families there are minute intermediate joints between the principal joints
of the antennae. For the purposes of this table these intermediate joints are not counted.

HEMIPTERA. 1 83

HH. Wing-covers well developed.

I. Body linear. Fam. XXI. — EMESID/E.

II. Body not linear.

J. Body greatly flattened. Fam. XXV. — Akadiim

JJ. Body of ordinary form (Saicinse,).

Fam. XXII. — ReDUVIIDjE.
GG. Two ocelli present, though sometimes difficult to see; wing-
covers well developed.
H. Wing-covers with embolium, Fig. 151. (Anthocorinae.)

Fam. XXVII. — ACANTHIID 1
1 1 H. Wing-covers without embolium.

I. Rostrum long, reaching to or beyond the intermediate
coxae. Fam. XVII. — Sw.ihi>i

II. Rostrum short.

J. Front legs with greatly widened femora.

Fam. XXIV. — Phv.mai id.k.
JJ. Front femora somewhat thickened, but much less than
half as wide as long. Fam. XXII. — Reduviid.e.

FF. Rostrum 4-jointed.

G. Membrane of wing-covers with longitudinal veins ; legs either
raptorious or ambulatory.

H. Membrane usually with four long veins bounding three
discal cells, which are often open. From these cells diverge
veins all around and form several marginal cells (Fig. 1501;
legs raptorious. Fam. XXIII. — Nahid.*:.

HH. Membrane with 4 or 5 simple or anastomosing veins
arising from the base; or with a larger number of veins aris-
ing from a cross vein at the base ; legs ambulatory.

I. Ocelli wanting ; membrane with two large cells at the base ;
and from these arise branching veins (Fig. 153).

Fam. XXIX. — Pyrrhocorip.v .

II. Ocelli present.

J. Head with a transverse incision in front of the ocelli.

Fam. XXXI.— Bkrvti U.K.
JJ. Head without transverse incision.

K. Membrane with 4 or 5 simple veins arising from the
base of the membrane; the two inner ones sometimes
joined to a cell near the base (Fig. 154).

Fam. XXX.— Lyc.mi. E.
KK. Membrane with many, usually forked, veins, spring-
ing from a transverse basal vein (Fig. 155).

Fam. XXX II. COREIDJE.

GG. Membrane of wings-covers with one or two closed cells at

its base, otherwise without veins (Fig. 152); legs ambulatory.

Fam. XXVIII.— Capsi d.k.
GGG. Membrane of wing-covers without any veins ; legs ambu-
latory. Fam. XVIII.— Hkbriim..

1 84

AN INTRODUCTION TO ENTOMOLOGY.

DD. Antennae 5-jointed.*

E. Lateral margin of scutellum with 9. furrow in which the edge of
the wing-cover fits when closed.
F. Scutellum nearly flat, attenuated posteriorly.
G. Tibiae unarmed or furnished with very fine short spines.

Fam. XXXIIL— Pentatomid^e.
GG. Tibiae armed with strong spines in rows.

Fam. XXXIV.— Cydnida:.
FF. Scutellum very convex, covering nearly the whole abdomen.

Fam. XXXV.— CORIMELiENID^E.

EE. Lateral margin of the scutellum without a furrow ; scutellum
very convex, covering nearly the whole abdomen.

Fam. XXXVI.— Scutellerid/E.

Fig. 150. — Na- Fig. 151. — An- Fig. 152. — Ca/>-
kidce. thocorinee. sidtr.

Fig. 153.— Pyr- Fig. 154. — Lygce-
rkecorida'. idee.

Fig. 155. — Co-
reidce.

Family XI. — CORISID/E.f
( Water-boat men?)
To the Corisidce belong certain aquatic Heteroptera which are
very widely and commonly distributed throughout our country.
They are of medium or small size, and of somewhat elongated oval
form. They occur in lakes, ponds, and streams, in both stagnant
and running water, and even in the salt lakes of Utah and Califor-
nia.

All of the North American species of this family belong to the
genus Corisa. Fig. 156, which represents a
species of Corisa, illustrates the form of the
body. These insects may be distinguished by
the peculiar tarsi of the front legs. These
tarsi are flattened or scoop-like in form ; each
consists of a single segment, and bears a comb-
like fringe of bristles. The structure of the
head of these insects is quite unusual. In-
stead of being inserted in the prothorax, the
head overlaps that segment. The position of
the mouth-parts is also peculiar ; these are pushed through an open-

Fig. 156. — Corisa undulata.

* In certain families there are minute intermediate joints between the principal joints
of the antennae ; for the purposes of this table, these intermediate joints are not counted,
f Corisidae, Corisa: coris (ko/jiS), a bug.

HEMIPTERA. 1 85

ing in the clypeus instead of being articulated to its tip. In the
males of Corisa the abdominal segments, especially the four caudal
ones, are very unsymmctrical, being upon one side broken into
irregular-shaped fragments.

These water-boatmen have the body flattened above, and swim
upon their ventral surface ; they differ in these respects from the
members of the next family. They swim with a quick, darting mo-
tion ; they use for this purpose chiefly their long, oar-like posterior
legs. When in their favorite attitude, they are anchored to some
object near the bottom of the pond or aquarium by the tips of their
long, slender, intermediate legs, at such times the fore legs hang
slightly folded, and the posterior legs are stretched out horizontally
at right angles to the length of the body. The body of these in-
sects with the air which clings to it is much lighter than water;
consequently, whenever the)' loose their hold upon the object to
which they have been clinging, they rise quickly to the surface, un-
less they prevent it by swimming. They occasionally float on the
surface of the water, and can leap into the air from the water and
take flight.

The bodies of these insects, as they swim through the water, are
almost completely enveloped in air. The coating of air upon the
ventral surface and sides can be easily seen, for it glistens like silver.
By watching the insects carefully, when they are bending their bod-
ies, air can be seen to fill the spaces between the head and prothorax,
and between the prothorax and mesothorax. The space beneath
the wings is also filled with air. When these insects are in impure
water, they must come to the surface at intervals to change this sup-
ply of air. But I have demonstrated that in good water it is not
necessary for them to do this. The air with which the body is
clothed is purified by contact with the fine particles of air scattered
through the water; so that the insect can breathe its coat of air again
and again indefinitely.*

The Water-boatmen are carnivorous, feeding upon other insects.
They attach their eggs to aquatic plants; and the young arc found
in the same situations as the adults.

" In Mexico, the eggs of a species of corisa are said to be gathered
from water-plants, and used as an article of food by the dwellers-
near the lakes where they abound. The natives cultivate a sedge
upon which the insects will deposit their eggs. This sedge is made

* See account of my experiments in American Naturalist, June, 18S7.

1 86 AN INTRODUCTION TO ENTOMOLOGY.

into bundles, which are then floated in the water of a lake until cov-
ered with eggs. The bundles are then taken out, dried, and beaten
over a large cloth. The eggs being thus disengaged, are cleaned and
pounded into flour." (Glover.)

Family XII. — NOTONECTID^E.*
(Back-swimmers or Back-swimming Water-boatmen^)

The Notonectidtz differ from all other aquatic Heteroptera by the
fact that they always swim on their back. And there is a corre-
sponding difference in the form of the body. This is much deeper
than in the allied families, and is more boat-shaped.
The back, from the peculiar attitude of the insect
when in the water, corresponds to the bottom of a
boat, and is sloped so as to greatly resemble in
form this part (Fig. 157).
FlG ' lHLfaiJa. nect " The eyes are large, uniform, twice sinuated

on the outer side, and project a little way over
the front margin of the prothorax. The prothorax has the
lateral margins sharp and projecting. The legs are all long ; the
hind pair are much the longest and fitted for swimming.
The tarsi consist each of three segments, but the basal segment
is so small that it is often overlooked. There is a ridge along the
middle line of the venter which is clothed with hairs.

These insects are predaceous, feeding upon insects and other
small animals. In collecting them, care must be taken or they will
inflict painful stings with their sharp and powerful beak.

The favorite attitude of the Back-swimmers is floating at the
surface of the water, with the caudal part projecting sufficiently to
admit of the air being drawn into the space beneath the wings.
When in this position, their long oar-like hind legs are stretched out-
ward and forward ready for action. When disturbed, they dart
away toward the bottom of the pond, carrying a supply of air for
respiration beneath their wings. As in the Corisidae, the body of
these insects with the air which they carry for respiration is much
lighter than water ; consequently, the moment they stop swimming,
they rise to the surface of the water if they do not cling to some
object to prevent it. Occasionally these insects will float on the
surface of the water with their dorsal aspect uppermost ; and, like the

Notonectidae, Notongcta: notos {voJroS), back; nectos {vrjKroi), swimming.

I1EM1PTERA.

lS 7

Water-boatmen, they can leap into the air from the water and take
flight.

There are three genera in North America. The greater number
of our common species belong to Notonecta. The following table of
the genera is from an unpublished work by Professor H. E. Sum-
mers :

A. Apices of hemelytra entire ; the three pairs of legs similar in shape. Plea.
AA. Apices of hemelytra notched ; le^s dissimilar.

B. Hemelytra much longer than abdomen; fourth segment of antennae

longer than third. ANISOPS.

BB. Hemelytra but little longer than abdomen; fourth segment of antennae

shorter than third. NOTONECTA.

Family XIII. — NepidA*

( Water-scorpions.)

The members of this family can be distinguished from other
aquatic Heteroptera by the presence of a long respiratory tube at
the end of the abdomen. This tube con-
sists of two long filaments, each with a
groove on its mesal side. By applying
these filaments together the grooves form
a tube, which conducts the air to two
spiracles situated at the caudal end of the
abdomen. By means of this apparatus
these insects are able to rest on the bot-
tom of a shallow pond, or among rubbish
or plants in water, and by projecting this
tube to the surface obtain what air they
need.

With regard to the form of the body
two very different types exist in this fam-
ily. In one, represented by the genus
Ncpa, the body is a long-oval, flat and thin:
in the other, represented by the genus
R&natra, the body is almost linear and
cylindrical (Fig. 158).

The Water-scorpions are carnivorous; and with them the first
pair of legs is fitted for seizing prey. In these legs the coxae

—lianatra fusca.

* Nepidae : Nepa, a scorpion.

1 88 AN INTRODUCTION TO ENTOMOLOGY.

are very long, especially in Ranatra : the femora are furnished with
a groove into which the tibiae and tarsi fit like the blade of a pocket-
knife into its handle.

Although the Nepidae are truly aquatic insects, the second and
third pairs of legs are fitted for walking rather than swimming.

Of the genus Nepa we have only a single species, N. apiculata.
This insect is about two-thirds of an inch in length, not includ-
ing the respiratory tube, which measures a little more than one-
fourth of an inch. It lives beneath stones and rubbish in ponds,
and in the quiet parts of our streams.

Of the genus Ranatra, our most common species is R. fiisca
(Fig. 158). This insect lives in the same situations as Nepa. Owing
to the linear form of its body, and to the dirt with which it is
usually covered, it is quite difficult to detect the presence of this
insect among the rubbish where it is found. Doubtless this resem-
blance to a dirty stick aids it greatly in the capture of insects, fish,
and other unwary animals upon which it preys.

Family XIV. — BELOSTOMATlDJi*
{Giant Water-bugs.)

" The family Belosto matidce contains the largest Heteroptera now
in existence. These are all wide and flat-bodied aquatic insects, of
more or less ovate outline, furnished with powerful flattened swim-
ming-legs, the fore tibiae curved as in the preceding family, and fitted
for seizing and holding tightly the victims, upon which they pounce
from their hiding places in the rubbish or among the branches of
water-plants. A remarkable feature of all the genera is in the pres-
ence of a pair of flattened, narrow, strap-like appendages at the end of
the body, which are extensile, but not concerned with respiration, as
in members of the foregoing group". (Uhler.)

These insects are rapacious creatures, feeding on other in-
sects and small fish. Some of the species are of great size. One
found in Guiana and Brazil sometimes measures four inches in length.
We have in our fauna two common species of the larger Giant Water-
bugs. They are Belostoma atnericdnum and Bendcus griseus. These
two species so closely resemble each other that they are commonly
confounded.

*Belostomatidse, Belostoma: belos (/3eXoS), a spear ; stoma (orofta), a mouth.

IIKMIPTERA.

I89

Belostoma americdnum (Fig. 1 59) varies greatly in size. Specimens
before me as I write this range from 44 mm. (1.75 in.) to 60 mm. (2.4
in.) in length. It is of a pale dirty-brown
color, mottled with dark brown ; the ven-
tral aspect of the body is speckled with
dark brown. The anterior femora are
furnished with a groove for the reception
of the edge of the tibiae.

Bendcus griseus can be distinguished
from Belostoma by the absence of the
femoral groove. In Benacus the ventral
aspect of the thorax is marked by five
interrupted longitudinal stripes of dark-
brown.

To the genus Zditha belong our more
common representatives of the smaller
members of this family. The common
species of the Eastern United States is

Zditha flltminca. This measures about FlG - 159— Belostoma americanut

nine-tenths of an inch in length, and bears

a round scar on each side of the prothorax (Fig. 160). The
females of this species la} - their eggs upon
their own backs. These eggs are set upon
end, and placed in transverse rows, by means of
a long protrusile tube or ovipositor, which the
insect can extend far over her own back. The
eggs are fastened to the back of the mother by
a very thin layer of a waterproof gum secreted by
the insect. At about the time when the young
brood begins to hatch, the mother sheds the

Dim-

Fig. 160. — Zaitha Jlu-
minea.

entire layer of eggs from her back,
mock.)

Family XV. — NatjcoriDjE*

The Nancoridoe includes flat-bodied, chiefly oval insects, which
are of smaller size than the members of the preceding family. The
abdomen is without caudal appendages , and the legs are suited for
crawling rather than for swimming. The front legs, however, are fitted
for grasping, the femora being greatly thickened. There are no

* Naucoridae, Naucoris : naus (vavi), a boat ; coris (Kopii), a bag.
13

I9O AN INTRODUCTION TO ENTOMOLOGY.

ocelli ; the antennae consist of four simple segments, are very short,
and well concealed beneath the eyes. The rostrum is three-jointed,
and covered at the base by the large, transverse, triangular or rounded
labrum, and the wing-covers are furnished with a distinct embo-
lium.

The members of this family are predaceous ; and, according to
Uhler, they are fond of reedy and grassy, quiet waters, where they
creep about like the Dyticid beetle's, creeping and half-swimming
around and between the leaves and sprays of the submerged plants,
and suddenly seizing any unlucky Corisa or other insect that happens
to be within reach.

The family is a small one ; as yet, less than fifty species have been
described. These are distributed among twelve genera. Of those
that occur in the United States, only five species, representing two
genera, have been described. But one of these is found in the States
on the Atlantic coast. This is Pelocoris femordta. It measures
about 9 mm. (0.35 in.) in length, and after death is pale yellow or
brownish in color, with black or dark-brown markings. The remaining
species are found in the Western States, and belong to the genus
Ambry sus. This genus differs from Pelocoris in having the front
margin of the prothorax very deeply sinuate.

Family XVI. — GalguliD/E.*

The Galgalidce is the concluding member of the series of fami-
lies of Heteroptera characterized by short antennas, nearly or quite
concealed beneath the head. This family differs from the other
families of the series in that the species present a pair of ocelli. In
the more typical forms, the body is very broad and short, and the
eyes are prominent and projecting. Fig. 161 represents
the characteristic form of these insects.

The Galgulidae differ from the other short-horned bugs
in habits. Whilst the members of the preceding families
are truly aquatic, these insects pass their lives on the
muddy margins of streams, or about the other parts of
marshes, where the soil is moist but not continuously
submerged. Some of them make holes for themselves,
and live for a part of the time beneath the ground.

This is a small family, containing only about a score of known

* Galgulidas: galgnlns, the witwall or yeilow thrush.

HEMIPTERA. 191

species. Of these, only three, representing three genera, have been
catalogued from the United States. Our forms can be separated
by the following table :

A. Fore-legs stout, fitted for grasping.

B. Anterior tarsi with a single claw. MONON\ x.

BB. Anterior tarsi with two claws. Galgulus.

AA. Fore-legs slender, fitted for running. PELOGONUS.

Our three species are Mononyx stygicus, Galgulus oculdtus, and
Pelogonus americdnus. Fig. 161 represents the Galgulus; the Mon-
onyx closely resembles this in form ; while the Pelogonus is a smaller
insect, with a more oblong body, and of a velvety black color. All
of the species are predaceous.

Family XVII. — Saldid.i:.-

With the Sdldida we reach the beginning of the extensive series
of families of Heteroptera, in which the antenna- are prominent and
are not concealed beneath the head. In this family the insects are
of small size, and of dark colors, with white or yellow markings.
The head stands out free from the thorax on a cylindrical base.
The antennas are four-jointed ; there are two ocelli ; the
rostrum is three-jointed and very long, reaching to or
beyond the middle coxae. The membrane of the wing-
covers is furnished with looped veins, forming four or
five long cells placed side by side. Occasionally there
is little or no distinction between the corium and mem-
brane. Two forms sometimes occur in the same species,
one with a distinct membrane, and another with the membrane
thickened and almost as coriaceous as the corium proper.

In regard to the habits of the Saldidae, Uhler states as follows:
" In the present family we have types which, like Galgulus, make
links for themselves, and live for a part of the time beneath the
ground. Like the members of that genus, too, a majority of these
inhabit damp soils, and are often found in countless numbers on the
salt or brackish marshes of our sea-coasts. Their manners strongly
recall those of the Tiger-beetles that inhabit the same places. When
approached, or in any way disturbed, the}' leap from the ground,
arise a few feet into the air by means of their wings, and alight a

Saldidae: Salda, a proper 1.

192 AN INTRODUCTION TO ENTOMOLOGY.

short distance away, taking care also to slip quickly into the shade
of some projecting tuft of grass or clod where the soil- agrees with
the color of their bodies."

About thirty species have been described from the United States
and British America. These all belong to the genus Sdlda.

Family XVIIL— Veliadae.*

The Veliada includes insects which are very closely allied to the
water-striders both in structure and habits. In both families, the
distal segment of the tarsi is more or less bifid, and the claws are
inserted before the apex. These characters distinguish these two
families from all other Heteroptera. In the Veliadae the body is
usually stout, oval, and broadest across the pro-
thorax, (Fig. 163). The rostrum is three-jointed,
and the legs are not extremely long. In fact,
the legs are fitted for running over the water, in-
stead of for rowing, as with the Hydrobatidae.
The Veliadae " pass most of their lives upon
,Ua the surface of the water, but always near the
banks of the stream or pond ; but they also make
excursions beyond the limits of the water, and move with great free-
dom upon the land." (Uhler.)

Less than a dozen species have been described from the United
States ; but these represent six genera.

Family XIX. — HYDROBATID^.f

( Waters triders.)

This family includes elongated or oval insects which live upon
the surface of water. Several species are very abundant on our
ponds and streams. They run over the surface of the water very
rapidly ; and, like the Whirligig-beetles, often congregate in great
numbers. The head is inserted in the thorax up to the base of the
eyes ; these are round and prominent. The antennas are long, and
consist of four segments. " The thorax usually widens backwards,
and its thickness is increased by the prominent middle and posterior
coxae, which project beyond the sides. No scutellum is apparent
(except in Stephanid), but in its place the end of the dorsal plate of

* Veliadae: Velia, a proper name.

f Hydrobatidae, Hydrobates: hydor (vdoop), water; bates {fl art] i), one that treads.

HEMIPTERA.

J 93

the mesothorax is scale-like, narrowed, rounded, and depressed
around the tip. Behind this, the abdomen tapers more or less to-
wards the last segment, which is usually armed each side with a
tooth-like process. The under side of the bod)- is generally min-
utely pubescent and sericeous like satin, and this is sometimes con-
tinued along the sides of the thorax. There are commonly two
forms of the adult belonging to the same species, the winged and
unwinged. These do not necessarily co-exist. During some years,
only the winged forms appear ; while in others, and especially if the
spring and summer are cool, the individuals will all be unwinged.
Often in sunny, protected places, where the food is abundant, all
will be winged, while, in exposed localities, the same species will be
found unwinged, with, perchance, a single, more vigorous specimen
winged. In some parts of the Southern States three forms occur,
those before cited and another which has the wing-covers of scarcely
half length." (Uhler.)

The water-striders prefer quiet waters, upon which they rest, or
over which they skim rapidly. They jump from the water to capture
flies or other insects for food. Fig. 164 represents a species of Hy-
grotrcchus. " These insects stow
themselves away under the banks
of streams, in the mud beneath
leaves or rubbish, or at the bottom
of water under stones and roots of
trees when the autumn begins to
be cold ; and from thence they
reappear upon the surface of the
water as soon as the warm weather
of spring returns. Soon after this,

the eggs are attached by a sort of glue to the leaves and stems
of aquatic plants. They are whitish translucent, long, cylindrical,
more blunt at the end from which the young emerge than at the
somewhat tapering, but round, opposite extremity. If the weather
continues to grow warmer, these eggs mature in about two weeks."
(Uhler.)

Five genera occur in our fauna; these can be separated by the
following table : *

Fig. 164. — Hygrotrechus conformis.

A. Body oval, less than three times as long as broad ; pronotum not h
than broad.

This table was prepared by Professor II E. Summers.

IQ4

AN INTRODUCTION TO ENTOMOLOGY.

B. Second segment of antennae longer than either the third or fourth.

JVIetrobates.
BB. Second segment of antennas shorter than either the third or fourth.

Stephania.
AA. Body elongate, more than four times as long as broad ; pronotum much
longer than broad.

B. Antennas longer than head and pronotum together ; the posterior tibiae
and tarsi together much longer than the intermediate tibiae.

LlMNOPORUS.

BB. Antennae shorter than the head and pronotum together ; the posterior
tibiae and tarsi together but little longer than the intermediate tibiae.
C. First segment of antennae nearly equal in length to the fourth.

LlMNOTRECHUS.

CC. First segment of the antennae considerably longer than the fourth.

Hygrotrechus.

Closely allied to Stephania, and resembling it in the form of their
bodies, are the species which constitute the genus Haldbatcs. These
are truly pelagic insects, living on the surface of the ocean, often
hundreds of miles from land. They are most abundant in the region
of calms near the equator; they feed on the juices of dead animals
floating on the surface, and probably attach their eggs to floating
sea-weed {Sargassum).

Family XX. — LlMNOBATlD^.*

The members of this family are very long, slender insects, with
linear legs and antennae. The head is nearly
cylindrical, and longer than the thorax ; the eyes
are round, projecting, and placed a little nearer
the base than the tip of the head. These insects
creep slowly upon the surface of the water; they
carry the body considerably elevated ; and are
found mostly where plants are growing in quiet
waters. "They delight to remain at rest, with
perhaps a single claw hooked to some projecting
object. When disturbed, they move very slowly,
and seem disposed to save themselves rather by
concealment among rubbish or tangled growths
than by active movements. The young forms
are so very slender that they can only be detected
with great difficulty in the places to which they resort." (Uhler.)

Fig. 165. — Limnobates
lineata.

* Limnobatidae, Limnobates: limne (Xiixvrj), a salt marsh; bates {(idriji), one that
treads.

HEMIPTERA. 1 95

I find no observations regarding the food of these insects; but they
are probably herbivorous.

Only a single species has been found in the United States. This
is Limnobates linedta. It is a small insect less than 12.5 mm. (0.5 in.)
in length. The legs and antennae are extremely slender, being hair-
like in form. Fig. 165 represents this species greatly enlarged.

Family XXI. — Emesid.k."

The Emesidce includes a small number of insects in which the
body is very slender, and the middle and hind legs are thread-like.
The front legs are less thread-like, and fitted for grasping. They
suggest by their form the front legs of the Mantidae; the coxa is
very greatly elongated, more than four times as long as thick; the
femur spined ; and the tibia shut back upon the femur.

This family is very closely allied to the one following. In
fact, by some authors the two are united. They agree in having
the rostrum short, attached to the tip of the head, and with the
distal end when not in use resting upon the prosternum, which is
grooved to receive it. The great length of the fore coxa easily dis-
tinguishes this family from any of our species of the Reduviidae,
and in the Emesidae there are no ocelli. Only seven species of this
family are catalogued from the United States.

Our most familiar representative is Emesa longipes. This insect,
by its elongated form and slender legs, at first sight reminds one of
the walking-sticks. But the raptorial fore legs, the wings, and the
rostrum, really give this species a very different appearance from
those insects. Its body measures about 33 mm. (1.3 in.) in length;
the middle and hind legs are each about 40 mm. (1.6 in.) long;
while the narrow wings are only one-fourth as long as the legs. As
indicated by the structure of the fore legs, these insects are
predaceous.

Four genera are represented in our fauna ; these can be separated
as follows : f

A. The pre-tibia- and pre-tarsi together not shorter than the pre fem.ua.
B. Eyes large, very prominent ; when seen from the side, occupying the whole

side of the head. 1. Li 1 1 v \.

BB. Eyes small, slightly prominent; when seen from the side, not occupying

more than half of the side of the head. 2. Cr.RASCOPUS.

* Em&sidae: Emesa, a proper name.

f Table prepared by Professor II. E. Summers.

I96 AN INTRODUCTION TO ENTOMOLOGY.

AA. Pre-tibia and pre-tarsi together shorter than the pre-femora.

B. Pre-tarsi one-clawed. 3. Barce.

BB. Pre-tarsi two-ciawed. 4. Emesa.

Family XXII. — ReduviiD/E*

The Reduviidce is a large family, including numerous genera of
diverse forms. Many of the members of it are insects of considerable
size; and some are gayly colored. They are predaceous, living on
the blood of insects. In some cases, they attack the higher animals;
and, occasionally, even man suffers from them. As already stated,
this family is closely allied to the preceding. But the species differ
from the Emesidae in having the body and legs thicker. The front
coxae are shorter, being never more than two or three times as long
as broad ; and, in the case of the species found in the United States,
two ocelli are present. These insects agree with the Emesidae in
having the rostrum short, three-jointed, attached to the tip of the
head, and with the distal end, when not in use, resting upon the
presternum, which is grooved to receive it.

In Uhler's Catalogue of the Hemiptera of North America (1886),
fifty genera of the Reduviidae representing nine sub-families, are
enumerated. Only a few of the more familiar species can be referred
to in this place.

The Masked Bed-bug-hunter, Opsiccetus personatus. — The member
of this family about which probably most has been written is the one
for which I propose the popular name given above. The species is a
European one, and is described in nearly all of the European text-
books of entomology under the name Reduvius personatus. But it is
now placed in the genus Opsiccetus. A variety of this spe-
cies occurs in the Atlantic region of our country. Fig.
166 represents the adult insect. It measures from 15-20
mm. (0.6—0.8 inch) in length. It is black, or of a very
dark brown. The prothorax is strongly constricted
in the middle, rounded in front, and has a prominent
groove on the middle line.

There are two marked peculiarities of this species
which has caused it to attract much attention: first, in

Fig. 166.— Op

sicoetus per- its immature stages, the body is covered with a viscid

sonatus. ° J

substance which causes particles of dust and fibres
to adhere to it ; not only the body proper, but the legs and

* Reduviidae, Reduvius: reduvia, a hang-nail.

HEMIPTERA. 19-

antennae also are masked in this way: second, tin's species infests
houses for the sake of preying upon the bed-bug. It feeds also upon
flies and other insects. Dr. Le Conte, in writing of this insect, states
that it is remarkable for the intense pain caused by its bite; that,
when caught or unskilfully handled, it always stings. In this case.
the pain is almost equal to that of the bite of a snake, and the swel-
ling and irritation which result from it will sometimes last for a week.
In very weak and irritable constitutions it may even prove fatal.

The Big Bed-bug, Conorhinus sanguisiigus. — Closely allied to the
masked bed-bug-hunter is a large bug which insinuates itself into
beds for a less commendable purpose than that of its ally; for it
sucks human blood at first hand.

This insect measures 25 mm. (1 inch) in length. It is black,
marked with red. The prothorax is triangular, with a tubercle in
front on each side, slightly constricted before the middle, in front
with two raised lines diverging backwards, and most raised in front,
margined with red ; scutellum with two raised diverging lines directed
forwards and joined at the base ; wing-covers with two triangular red
spots on each, one at the base, the other near the middle on the
outside ; abdomen with six red spots on each side, both above and
below. The species was first described from Georgia; but it occurs
also in the more Northern and Western States. It, too, is re-
markable for sucking the blood of mammals, particularly chil-
dren. Dr. Le Conte, who first described this insect, says that
it, like the preceding species, inflicts a most painful wound. And
that he has known its bite to be followed by very serious conse-
quences, the patient not recovering from its effects for nearly a year.
He states his belief also that the accounts which we have of persons
being bitten by spiders are based on stings of these or allied insects.

Although the species referred to above will serve to illustrate the
form of the members of this family, they are exceptional in habits.
I know of no others that habitually enter the dwellings of man.
Usually the members of this family pass their lives upon trees,
shrubs, or herbage, adroitly catching their prey. They feed upon
various insects both in the larva and adult states. Numerous
instances are on record of their destroying the Colorado potato-
beetle, the Rocky Mountain locust, and other important pests.

The wheel-bug, Prionidus cristdtus (Fig. 167) furnishes a good
illustration of the habits of the predaceous members of this family.
This is a common insect in the South. The adult, a cluster of eggs,
and several nymphs are represented in the figure. The hexagonal

198

AN INTRODUCTION TO ENTOMOLOGY.

masses of eggs are deposited on the bark of trees, on fence-rails, under
the eaves of out-buildings, or wherever the female chances to be

Fig. 167. — Prionidus cristatus. (From Glover )

at the time of oviposition, to the number of 70 or more. The
nymphs when young are blood-red, with black marks, and do not
resemble the adult insect excepting somewhat in form and in habits.
Both the nymphs and adults feed upon all other insects they can
overcome, not even sparing their own kind. " They kill their prey
by inserting into it the proboscis, which ejects a most powerful
poisonous liquid into the wound. The victim thus pierced dies in a
very short time. They then leisurely suck the juices out, and drop
the empty skin. The perfect insect is of a gray color, and has a high
semicircular ridge or projection on the crest of its thorax." (Glover.)

Family XXIII.— Nabid.e *

We have but few representatives of the Nabidce ; but some of
them are very common. In this family the body is oblong, and

* Nabidae: Nabis, a proper name.

HEMIPTERA. 199

somewhat oval behind. The rostrum is long, slender, and four-
jointed. The wing-covers arc longer than the abdomen, or arc very
short. In the long-winged forms the membrane is usually furnished
with four long veins bounding three discal cells, which are often
open. From these cells diverge veins all around and form several
marginal cells. (Fig. 168.)

Only three genera occur in our fauna ; these can be separated by
the following table :*

A. Pre-acetabula remote from each other. Clavus and corium semi-transparent.
(Sub-family Coriscinae.) i. CORISCUS.

A A. Pre-acetabula close together. Clavus and corium opaque. (Sub-family
Nabinse.)
B. Joint 2 of rostrum longer than joint 3; joint 2 reaching base of head.

2. Pag as a.

BB. Joint 2 of rostrum shorter than joint 3 ; joint 2 not reaching base of

head. 3. Nabis.

Coriscus ferus is one of our most common species. This insect
measures about 8 mm. (0.3 in.) in length. It is pale yellow with nu-
merous minute brown dots. The veins of the mem-
brane are also brownish. This species is widely dis-
tributed both in this country and in Europe. It
secretes itself in the flowers or among the foliage
of various herbaceous plants, and captures small wing-cover

insects upon which it feeds. Fig. 168 represents the %>us° r ' scus
wing-cover of this species.

Coriscus subcolcoptrdtus is another very common species, and one
that is quite likely to attract attention. Although I have collected
very many specimens of it, I have met with only the short-winged
form. This is of a shining, jet-black color, with the edge of the
abdomen and the legs yellowish. The specimens before me have
short wing-covers which barely extend to the second abdominal seg-
ment. Uhler says that the long-winged form is much narrower
behind, and the wing-covers and abdomen are rather dusky, or pice-
ous, than black.

Family XXIV.— Piivma rnu . »

The Phymatida is even more poorly represented in this country
than the preceding family; but, as in that case, some of the species

* Prepared by Professor II E. Summers.

f Phymatidae, Phymata: phyma (<J>vjxa), a tumor.

200 AN INTRODUCTION TO ENTOMOLOGY.

are very common. Here we find the body extended laterally into
angular or rounded projections, suggesting the name of the typi-
cal genus. But the most striking character which distinguishes this
group is the remarkable form of the front legs. These are fitted for
seizing prey. The coxa is somewhat elongated ; the femur is greatly
thickened, so that it is half or two thirds as broad as long ; the tibia is
sickle-shaped, and fits closely upon the broadened and curved end
of the femur ; both tibia and femur are armed with a series of close-
set teeth, so that the unlucky insect that is grasped by this organ
is firmly held between two saws ; the apparently useless tarsus is
bent back into a groove in the tibia. Another striking character
is presented by the antennae : the terminal segment is more or less
enlarged into a knob. Under the lateral margin of the pronotum
there is on each side a groove into which the antenna fits.

Only two genera are represented in our fauna. These can be
distinguished as follows:

A. Scutellum short; head with a bifid prolongation above the insertion of the
antennae. Phymata.

AA. Scutellum very long, extending to the tip of the abdomen ; head without
bifid prolongation of the antennae. Macrocephalus.

Our most common species is Phymata Wolffii (Fig. 169). It is
a yellow insect, greenish when fresh, marked by a broad
black band across the expanded part of the abdomen.
It conceals itself in the flowers of various plants, and cap-
tures the insects which come to sip nectar. It is remark-
able what large insects it can overcome and destroy.
Cabbage-butterflies, honey-bees, and large wasps are
overpowered by it.

Family XXV.— Aradid.£.*

The Aradid<z are very easily recognized by the depressed form
of the body. In fact they are the flattest of all Heteroptera. They
live in the cracks or beneath the bark of decaying trees ; and the
form of the body is especially adapted for gliding about in these
cramped situations. They are usually of a dull brown color ; some-
times they are varied with reddish or pale markings. Unlike the pre-
ceding family, the legs are all of similar form. There are no
ocelli ; the antennae are four-jointed ; the rostrum three-jointed ; the
wing-covers are usually well developed, with distinct corium, clavus,

* Aradidae, Aradus: aradus (dpdSoS), a violent disturbance of the stomach.

HEMIPTERA.

201

and membrane ; and the tarsi are two-jointed. The species are said
to feed upon fungi. It is desirable that observation should be made
upon their habits. The family is not a large one. Only a little
more than a score of species are now catalogued from the United
States. They are of medium or small size; our largest one meas-
ures less than half an inch in length. Fig. 170, Aradus
acictus, will serve to represent the form characteristic of
the family.

Our genera can be separated by the following table :*

A. Rostrum reaching only about to base of head, ventral surface FiG.170.—
of thorax and abdomen not furnished with a fine mesal furrow. acutus.

(Sub-family Brachyrhyxchix.i i.

B. Joint 4 of antennae much longer than joint 3 ; scutellum transverse, broad

caudad, caudal angle obtusely rounded. 1. Aneurus.

B. Joint 4 of antennae not longer than joint 3 ; scutellum scarcely transverse,

triangular, caudal angle acute. 2. BRACHYRHYNCHUS.

AA. Rostrum reaching about to caudal margin of prosternum or beyond it;

ventral surface of abdomen and thorax furnished with a fine mesal furrow.

(Sub-family Aradinse.) Aradus.

Family XXVI. — TlNGITIl >.!..+

The Titigitidce are doubtless the most easily recognized of all
Heteroptera. The reticulated and gauze-like structure of the wing-
covers, usually accompanied by expansions of the prothorax of a
similar form, gives these insects a characteristic appearance which
needs only to be once seen to be recognized
in the future. Fig. 171 represents one of
these insects greatly enlarged, the hair-line
at the side indicating the natural size of the
insect. They are generally very small insects.
But they occur in great numbers on the
leaves of trees and shrubs.

In this family the ocelli are wanting; the
rostrum and the antennae are both four-
jointed: the scutellum is wanting or rudi-
mentary, replaced by the angular hind portion
of the pronotum ; and the tarsi are two-
jointed.
The family is one of considerable size. There are about forty

Fig. 171. — Corythuca. arcu-
ata. (From ihe Author's
Report for 1879.)

* This table was prepared by Professor H. E. Summers,
•f Tingitidae . Tlngis, a proper name.

202 AN INTRODUCTION TO ENTOMOLOGY.

known genera, including hundreds of species. Less than a score of
species are now catalogued from the United States ; but- doubtless
many more will be found.

There are two well-marked sub-families.

Sub-family I. — Tingitin^e.

This division includes nearly all of the known species. Here the
scutellum is usually covered by an angular projection of the pro-
notum ; and the wing-covers have no distinction between the clavus,
corium, and membrane.

The genera that occur in the United States can be separated by
the following table :*

A. Discoidal and costal areas of hemelytra rarely jointly elevated ; when so
elevated, the lateral margins of pronotum never broadly foliaceous, nor with
the narrow foliaceous parts (when they are present) produced cephalad.
B. Rostral sulcus of the sternum not interrupted by a transverse ridge (be-
tween the mesosternum and metasternum).

C. Costal area of hemelytra furnished with a regular single or double
series of areoles.

D. Costal area with a single series of areoles. i. Teleonemia.

DD. Costal area with a double series of areoles. 2. TlNGIS.

CC. Costal area of hemelytra, at least in part, furnished with a triple or
multiple, sometimes confused, series of areoles.
D. Joint 1 of antennae not twice as long as joint 2.

E. Pronotum with a single longitudinal mesal ridge (carina) ; third

joint of antennae not at all slender. 3. Leptoypha.

EE. Presternum with three parallel longitudinal ridges (carinae) ; third

joint of antennas slender. 4. Physatochila.

DD. Joint 1 of antennae at least twice as long as joint 2.

E. Oblong, anal margins of hemelytra somewhat concave.

5. Leptostyla.

EE. Oval, anal margins of hemelytra convex. 8. Acalypta.

BB. Rostral sulcus of the sternum interrupted between the mesosternum

and metasternum by a transverse ridge. 6. Gargaphia.

AA. Discoidal and costal areas of hemelytra jointly elevated ; lateral margins

of pronotum broadly foliaceous, produced cephalad. 7. Corythuca.

The following species will serve as an illustration of this sub-
family.

The Hawthorn Tingis, Corythuca arcudta. — This I found very
abundant in Washington, puncturing the under surface of the leaves

* Prepared by Professor H. E. Summers.

HEMIPTERA.

20-

Fig. 172. — Eggs and
nymph of Corythuca
arcuata, (From the
Author's Report for
1879.)

of different species of Cratagus. The infested leaves have a brown
and sunburnt appearance. All stages were found together. The
adult is represented much enlarged by Fig. 171. In Fig. 172 the
eggs and immature form are shown. The eggs are
smooth, whitish, glistening, semitransparent, and
ovoid in shape. Their average length is 3 mm.
(0.12 in.). They are deposited on their broad end,
and seem to be somewhat inserted into the sub-
stance of the leaf ; they are covered completely
by a brown, sticky substance, which hardens soon
after oviposition. It adheres so firmly to the egg,
especially to the upper portion, that it is impos-
sible to remove it without crushing the egg.
At its upper end this covering of the egg is squarely
truncate, giving the whole mass the appearance
of a frustum of a cone with a porous lid. From
the funnel-shaped summit the young insect makes its exit. The eggs
are usually laid, in groups of from ten to thirty, along both sides of
some prominent leaf vein. They bear a much greater resemblance
to certain forms of fungi, notably the genus PJiowa, and to certain
young Homopterous galls, than they do to eggs of any sort.

The immature insect is of the same dirty brown color as the sub-
stance covering the egg, and but little darker than the withering
leaf. It is of a broad, flat, oval shape, and spines seem to project
from almost every portion of its body. It looks under the micro-
scope more like a lobe of prickly cactus than anything else I can
think of. The cast-off skins stick to the leaf, and give it the appear-
ance of being much more seriously infested than it really is.

The dead leaves under the bushes during the winter have been
often found to contain the living and healthy eggs of the Tingis ;
but the customary method of hibernation is in the adult state alone.
This form can be found during the winter under the loose bark of
the tree, and under sticks and stones on the ground. These insects
can be destroyed by strong alkaline washes or by kerosene emul-
sions. But it is probable that if the leaves and rubbish underneath
the trees are destroyed, either every fall or every spring, a necessity
for remedies will not arise.

Sub-Family II. — Piksmiwk.

This division includes a single aberrant genus, Piestna, of which
but few species are known. Here the scutellum is not covered ; the

204 AN INTRODUCTION TO ENTOMOLOGY.

wing-covers have a distinct clavus, with a well-marked claval suture ;
the clavus is furnished with one, and the corium with three longi-
tudinal veins which are much stronger than the network of veins
between them. In long-winged specimens the tip of the membrane
lacks the network of veins and appears like the membrane in other
families. As yet but a single American species has been described.
The Ash-gray Leaf-bug, Picsina cincrea. — This measures about
3 mm. (0.12 in.) in length, and is of an ash-gray color. The prothorax
is deeply pitted, so that it presents the same appearance as the base
of the wing-covers. The head is deeply bifid at tip, and there is a
short robust spine between the eye and antenna of each side. This
species sometimes infests vineyards to an injurious extent, destroy-
ing the flower-buds in early spring.

Family XXVII.— ACANTHIID^.*

The Acanthiidae comprises two closely allied groups, which have
been considered as distinct families, but are now ranked as sub-
families. These are the AcantJiilnce and the Anthocorince. As these
have been separated in the table of families, I will at once proceed to
the discussion of them.

Sub-Family. I.— Acanthiin^E.

(Bed-bugs?)

The AcanthilncB is represented in this country by a single species,
the Bed-bug, Acdnthia lectuldria. This species is a well-known pest
over the greater part of the world. It is reddish-brown in color, and
measures in length when full grown from 4 to 5 mm. (0.16 to .018 in.).
It presents the following characters, which are those of the sub-family
Acanthiinae: The body is ovate in outline and is very flat (Fig.
173). It is wingless or with very short and rudimen-
tary wing-covers. The labrum is triangular. There
are no ocelli. The rostrum consists of three seg-
ments ; the antennae, of four ; and the tarsi, of
three.
FlG /- 173-— f ^."- The bed-bug is a nocturnal insect, hiding by day

thia lectularia. fc> .

in the cracks of furniture and beneath various
objects. Ordinarily it is found only in the dwellings of man.
But it has been known to infest chicken-coops and pigeon-

* Acanthiidae, Acanthia : ac&ntha (aKav&a), a thorn.

HEMIPTERA. 205

houses. And the opinion is held that it also infests bats and
may be brought into our dwellings by these creatures. I have,
however, found no well-authenticated instance of its occurring
upon these animals, or of its being found in saw-dust, or under the
bark of trees, as has been reported. The means commonly empli tyed
to destroy this pest is to wet the cracks of the bedstead and other
places in which it hides with corrosive sublimate dissolved in alcohol.
This is sold by druggists under the name of bed-bug poison. As
this substance is a virulent poison, it should be used with great care.
A safer substance to use is 1'yrethrum. In case of a badly infested
room, it should be thoroughly cleaned; fumed with sulphur; the
walls re-papered, kalsomined, or whitewashed ; and the wood-work re-
painted. In travelling where one is forced to lodge at places infested
by this insect or by fleas, protection from them can be had by
sprinkling a small quantity of Pyrethrum powder between the sheets
of the bed on retiring.

Sub-Family II. — AnthocoriN/E.*
( The F/ozccr-bngs.)
In the AntJiocorince the wing-covers are almost always fully de-
veloped ; and are furnished with an embolium (Fig. 174). The
ocelli are present, though sometimes difficult to see.
As in the preceding sub-family, the rostrum consists
of three segments; the antenna,-, of four; and the
tarsi, of three. F,r ;- 174- —

Wing - cover

The species are small. They are found in a great <>* Triphiefs.
variety of situations, often upon trees and on flowers,
sometimes under bark or rubbish. They are predaceous.

Nearly thirty species have been catalogued from the United
States. The best known of these is the Insidious Flower-bug.
Trlplilcps insidiosus. This is often found preying upon the leaf-in-
habiting form of the Grape Phylloxera ; it is also often found in com-
pany with the Chinch-bug, upon which it preys, and for which it is
sometimes mistaken.

Family XXVIII.— CAPSID/E.f

This is one of the large families of the Heteroptera. Nearly a hun-
dred genera are catalogued from North America alone. The >pecies

* Anthocorinre, Anthocoris : ant ho s (ar&oS), ;i llower ; ton's (Kopti), a bug.
f Capsidae, Capsus : cu/'sits, a wagon-body, an enclosure.

14

206 AN INTRODUCTION TO ENTOMOLOGY.

are usually of medium or small size ; there is a great variation in the
form of the body, which makes it difficult to characterize the family.
The most available character for distinguishing these insects is the
structure of the wing-covers. These are almost always complete, and
composed of clavus, corium, cuneus, and membrane. At the base
of the membrane there are one or two cells ; otherwise the mem-
brane is without veins. See Fig. 175. Other characters of the fam-
ily are as follows : The ocelli are wanting ; the rostrum
and antennae are each four-jointed ; the coxae are sub-
elongate ; and the tarsi are three-jointed.

It is impracticable to discuss here the divisions of
F w1ng- I cov^ : this family ; I can only refer to a few of the more
^ asci/ffca ^ m common species.

The Four-lined Leaf-bug, Pcccilocapsus linedtus. —
This is a bright yellow bug, marked with black. It measures about
8 mm. (0.31 in.) in length. There are four longitudinal black lines
which extend over the prothorax and the greater part of the
wing-covers (Fig. 176). There is in many specimens
a black dot on the cuneus of each wing-cover ; and
the membrane is also black. This insect infests
various plants, but abounds most on the leaves of
currant-bushes and of sage. It punctures the
young and tender leaves, causing small brown Fu . i^-Pvcii-
spots ; but these are sometimes so numerous and °iut us h " ea ~

closely placed that the leaves become completely
withered. This insect is sometimes very abundant during the spring
and early summer; and occasionally does great injury. No efficient
means of destroying it has been devised except to collect it by
jarring the bushes early in the morning while it is torpid.

The Tarnished Plant-bug, Lygiis prataisis. — The Tarnished Plant-
bug is a very common member of the Capsidae. It is smaller than
the preceding species, measuring 5 mm. (0.2 in.) in length, and 2\ mm.
(0.1 in.) in its greatest width. It is exceedingly variable in colorand
markings. It ranges from a dull bark brown to a greenish or dirty
yellowish brown. In the more typical forms the prothorax has a
yellowish margin and several longitudinal yellowish lines; there is
a V-shaped yellowish mark on the scutellum ; the distal end of the
corium is dark ; and the cuneus is pale, with a black point at the apex.
This species has been reported as injuriously infesting the young
leaves of the expanding buds of pear, and also the unopened buds.
Sometimes a whole branch will be thus affected, and will die as the

HEMIPTERA.

207

result of the injury. This species passes the winter in the adult state.
When it becomes injurious, the insects should be shaken from the
trees upon a sheet, earl}- in the morning-, while they are torpid, and
destroyed.

The most abundant species of the Capsidae in the Northeastern
United States is one for which I know no popular name, Leptopterna
dolobrdta. In sweeping the grass of meadows, in early summer, in
this locality, frequently more specimens of this bug are taken than
of all other insects. This species is very different in form from the two
preceding, the body being long and narrow. Full)- developed speci-
mens measure 9 mm. (0.4 in. > to the tip of the wing-covers ; and are but
little more than 2 mm. (.08 in.) in width. The color is greenish
yellow marked with black. The markings of the head vary greatly ;
there are two longitudinal black stripes extending from the eyes
over the prothorax and scutellum. The central part and apex of
the scutellum is light-colored. There is a variety in which the cor-
neous part of the wing-covers is rust-red.

Fig. 177. — Wing-
cover of Dys-
dercus.

Family XXIX.— Pvrrhocorid^; *

The members of this family are very different in appearance from
those of the preceding family. They are larger, stouter, and more
heavily built, and are generally marked with strongly contrasting
colors ; red with black or brown are the most usual
combinations. In coloring these insects resemble some
of the larger species of the following family. The
Pyrrhocoridae can be distinguished from the Lygagidae
by the absence of ocelli, and by the peculiar venation
of the membrane of the wing-covers (Fig. 177). At

the base of the membrane there are two large cells;
and from these arise branching veins. Only twenty-
five species of this family are catalogued by Uhler
from North America ; and of these but seven are
credited to the United States. Our forms occur in
the Southern and Western States.

Our most important species, from an economic
standpoint, is the Red-bug or Cotton-stainer, Dysdercus
suturellus. This species serves well as an illustration
of the appearance of the members of this family
(Fig. 178). "It is oblong-oval in form, of a red color; the wing-cov-

Fig. 178.— Dysder-
cus suturellus.

*Pyrrhoc6ridre, Pyrrhocoris : pyrrhos (rtvppoS), reddish : coris (KopiS), bug.

208 AN INTRODUCTION TO ENTOMOLOGY.

ers and an arc on the base of the prothorax, and also the scutellum,
are pale brown. The wing-covers have the costal .margin, a
narrow line bordering the base of the membrane and continuing
diagonally along the outer margin of the clavus, and also a slender
streak on the inner margin of the clavus, pale yellow. It varies
much in size, ranging from 10 mm. to 16 mm. (0.4 in. to 0.63 in.) in
length." From time immemorial this has been one of the worst
pests with which the cotton-planters of Florida and the West Indies
have had to contend ; it would be difficult to estimate the immense
loss it has occasioned. It does much damage by piercing the stems
and bolls with its beak and sucking the sap, but the principal injury
to the crop is from staining the cotton in the opening boll by its ex-
crement. I found also in Florida that this insect is sometimes very
injurious to oranges; it punctures the rind of the fruit with its ros-
trum ; and soon decay sets in, and the fruit drops. The principal
injury seems to have been done where cotton was planted in close
proximity to the orange-groves. On one occasion I received the
eggs of this insect from Florida ; they were laid in a group of
twenty-one upon the under side of an orange-leaf. They were am-
ber colored, and oval in shape ; they appeared smooth and glistening
to the naked eye, but an examination with a lens showed them to be
densely covered with hexagonal impressions. The young bugs are
bright red with black legs and antennae. These insects can be trapped
in cotton-fields by laying chips of sugar-cane upon the earth near
the plants; in orange-groves small heaps of cotton-seed will be found
useful, as well as pieces of sugar-cane. The insects which collect
upon these traps can be destroyed with hot water.

Family XXX. — LYG/EID/E.*

The Lygaeidae is another one of the large families of the Heter-
optera. It includes certain forms which closely resemble members
of the preceding family in size, form, and strongly contrasting colors.
But the great majority of the species are of smaller size and less
brightly colored ; and all differ from that family in presenting dis-
tinct ocelli. The membrane of the wing-covers is furnished with
four or five simple veins, which arise from the base of the mem-
brane; sometimes the two inner veins are joined to a cell near the

^Lygaeidae, Lygasus : lygceos (AvyaioS), dark.

HEMIPTERA. 209

base (Fig. 179). The antenna of each side is inserted below an
ideal line extending from the eye to the base of the
rostrum. And the vertex is not constricted in front of £25$^.
the ocelli. X2=5c^=St

There is a great variety of forms in this family; Fig. i 79 .— Wing-
the North American species are distributed among ^° ver of Ly&a! ~
nearly fifty genera, representing nine sub-families.

The first sub-family, Lyg<2in<2, includes the forms, referred to
above, that resemble the Pyrrhocoridae in coloring. These are chief-
ly red insects, banded with black across the wing-covers. Among
our most common species are the three following:

Oncopcltus fascidtus. — This is a large red and black insect, measur-
ing 16 mm. (0.63 in.) in length. It has the following-named parts
black: legs, antennae, rostrum, sides, and middle line of the head,
disk of the prothorax, scutellum, most of the ventral aspect of the
thorax, dots along the lateral edge of the abdomen, the tip of the
abdomen, and two spots on each side of the ventral aspect of the
same region. There is a broad black transverse band across the middle
of the wing-covers; and the membrane is also of the same color. This
species " is pretty generally distributed throughout the warm and
sheltered parts of this continent, and wherever the larger varieties of
Asclepias flourish, either on the coast or inland." (Uhler.)

Lygceus reclivdtus. — This is smaller than the preceding species,
measuring from 10 to 12 mm. (0.4 in. to 0.47 in.) in length. The
head is black, with red spots on the vertex ; the thorax is black,
with a transverse red band on the disk of the pronotum ; this
band is sometimes twice interrupted, so that it is represented by
three dots ; the abdomen is bright red, with the apex, a row of
small dots on the lateral edges, and a row of spots on each side of
the venter, black; the wing-covers are black, with a red arc opening
outwards on each ; the free margin of the membrane, a pair of spots
on the disk, and two or more irregular spots on the basal margin of
the membrane, are snowy white.

A variety occurs in which the white spots on the disk of the
membrane are wanting. This variety is the most common represen-
tative of the Lygaeinae which I find in central New York. A few
of the New York specimens show the white spot; while in a large
series of this species in our collection from Arizona these spots are
invariably present.

Lygmis t&rcicus. — Tins species is very closely allied to the pre-
ceding, if not identical with it. Here the red spot on the vertex is

2IO AN INTRODUCTION TO ENTOMOLOGY.

Y-shaped, and includes the antennal tubercles. The membrane of
the wing-covers lacks the discal white spots, and the basal half of the
clavus is red.

Among the many smaller representatives of this family the fol-
lowing is the best known :

The Chinch-bug, Blissus Icucoptcrus. — This well-known pest of
grain-fields is a small bug, which when fully grown measures a little
less than 4 mm. (0.16 in.) in length. It is blackish in color, with con-
spicuous snowy- white wing-covers. There is on the costal margin of
each wing-cover near the middle of its length a black spot ; from each
of these spots there extends towards the head a somewhat Y-shaped
dusky line. The body is clothed with numerous microscopic hairs.

In Fig. 180 this insect is represented natural size

and enlarged. The species is dimorphic, there being

a short-winged form.

There are two generations of the Chinch-bug each

year. The insects winter in the adult state, hiding
Fig. 180T— bus- beneath rubbish of any kind; they even penetrate

sus leucopterus. .

forests and creep under leaves, and into crevices in
bark. In early spring they emerge from their winter quarters
and pair ; soon after the females begin to lay their eggs ; this
they do leisurely, the process being carried on for two or three
weeks. The eggs are yellowish ; about 500 are laid by a single in-
sect ; they are deposited in fields of grain, beneath the ground upon
the roots, or on the stem near the surface. The eggs hatch in about
two weeks after being laid. The newly-hatched bugs are red ; they
feed at first on the roots of the plants which they infest, sucking the
juices; afterwards they attack the stalks. The bugs become full-
grown in from forty to fifty days. Before the females of this brood
deposit their eggs, they leave their original quarters and migrate in
search of a more abundant supply of food. About this time the
wheat becomes dry and hard ; and the migration appears to be a
very general one. Although the insects sometimes go in different
directions, as a general rule the masses take one direction, which is
towards the nearest field of oats, corn, or some other cereal or grass
that is still in a succulent state. At this time many of the bugs
have not reached the adult state ; and even in the case of the fully-
winged individuals the migration is usually on foot. In their new
quarters the bugs lay the eggs for the second or fall brood.

Satisfactory means of preventing the ravages of this insect are

HEM1PTERA.

211

yet to be discovered. Something can be done by burning in au-
tumn all rubbish about fields, in fence-corners, and in other places
where the bugs have congregated to pass the winter. The march-
ing of the spring brood into new fields has been stopped by means
of ditches, as is done with the Army-worm. Some farmers have ac-
complished the same purpose by making a line of gas-tar on the
ground ; the bugs will not pass such a line, but it is necessary to re-
place it frequently. In some cases kerosene emulsion can be used
to advantage.

Family XXXI.— BERYTID/E.*

The Bcrytidce consists of a small number of species, which on
account of their attenuated forms are very striking in appear-
ance. The body is long and narrow ; the legs and antennae are also
long and extremely slender. There is a transverse incision in the
vertex in front of the ocelli. The antennae are four-jointed, elbowed
at the base of the second segment, and with the tip of the first seg-
ment enlarged. The rostrum is four-jointed ; and the membrane
of the wing-covers is furnished with a very few veins.

Only two genera are catalogued from
the United States, each represented by a
single species, Jdlysus spinosus and Neides
muticus. These can be separated as follow s:

In Jdlysus (Fig. 1 8 1) neither the corium
nor the venter is punctate ; and the ver-
tex is not furnished with a prominent
spinous process extending cephalad.
There is, however, a small spine on the
scutellum, and one on each side of the
thorax in front of the coxa. J. spinosus
measures about 8 mm. (0.3 1 in.) in length.

In Neides the corium and venter are
strongly punctate; the vertex is furnished
with a prominent spinous process extend-
ing cephalad. This genus lacks the spines of the scutellum and
thorax characteristic of the preceding genus.

Fig. 181. — Jalysus .v

* Berytidae, Berytus : (5i)pvro?, Greek name of Beyrout.

212 AN INTRODUCTION TO ENTOMOLOGY.

Family XXXIL— COREID^E *

The Coreidae is one of the most extensive of the families of
Heteroptera ; and the members of it vary greatly in form. Some
of the species are among the most formidable in appearance of all
of our Heteroptera; while others are comparatively weak and in-
conspicuous. The family is characterized as follows : The antennae
are inserted above an ideal line extending from the eye to the base
of the rostrum, and are four-jointed ; the vertex is not transversely
impressed ; the ocelli are present ; the rostrum is four-jointed ; the
scutellum is small or of medium size ; the wing-covers are usually
complete, and composed of clavus, corium, and
membrane ; the membrane is furnished with many
veins, which spring from a transverse basal vein,
Fig 182.— an d are usually forked (Fig. 182); the tarsi are

Wing- cover thrpp ininreH

of Leptocoris. ini ee-joiniea.

This family contains both vegetable feeders and
carnivorous forms ; in some cases the same species will feed upon
both insects and plants.

The most common and best known species is
the Squash-bug, Anasa tristis. The form of the
body of the adult insect is represented in Fig.
183. In this stage the insect appears blackish-
brown above and dirty-yellow beneath. The
ground color is really ochre-yellow, darkened by
numerous minute black punctures. Upon the
head are two longitudinal black stripes; the lat- FlG lg _ Anasa
eral margins of the prothorax are yellow, owing
to the absence along a narrow space of the punc-
tures ; and the margin of the abdomen is spotted with yellow from
a similar cause ; the membrane of the wing-covers is black.

This species winters in the adult state. In early summer it lays
its eggs in little patches on the young leaves of squash and allied
plants. The young bugs are short and more rounded than the
adult insects. There are several generations of this species each
year.

This is one of the most annoying of the many pests of the
kitchen-garden. The most satisfactory way yet devised for pre-
venting its ravages is to protect the young plants by means of

* Coreidae, Coreus : probably from coris {KopiS), bug.

HEMIPTERA.

213

—Metafiodius femoratus.
(From Glover.)

boxes or frames covered with netting. After the plants have ob-
tained a good start they are not easily destroyed by this bug.

Metapodius femoratus (Fig. 1 84) is a rep-
resentative of a group which contains the
largest members of this family. This
species is distributed from North Carolina
to Florida and Mexico. It was observed
by Prof. Trelease to destroy the Cotton-
worm {Aletid).

Family XXXIII. — PENTATOMID/E *

With the Pentatomidce we reach a
series of families, four in number, in which
the antennae are five-jointed. I have
found no exception to this character
within the United States, although there Fig. ij
are forms which occur just south of our
border in which the antennae are only three- or four-jointed. This
group of insects is very easily recognized ; but the student may
have at first a little difficulty in separating the families. The
body is short, broad, and rather thick The scutellum is al-
ways large ; we find two types of this part, each characteristic
of two families. The first type is presented by the Penta-
tomidae and Cydnidae ; here the scutellum is more or less flat-
tened, and triangular in outline, being attenuated posteriori)-. In
each of these families the lateral borders of the scutellum are
furnished with a groove into which the wing-cover fits when not in
use.

The form of body presented by the great majority of the mem-
bers of the Pentatomidae is well shown by Fig. 185.
It is broad, short, and but slightly convex ; the head
and prothorax form together a triangle. In this family
the tibiae are unarmed, or are furnished with very fine-
short spines. This is the most available character for
separating this from the following family. Of the
Pentatomidae, the genus Dinidor, which occurs in
Mexico, and certain other exotic forms have only
four-jointed antennae.

As with the Coreidae, the members of this family vary greatly in

Fig
l'entatomid.

* Pentat5midae, Pentatoma: petite (nevre), five; tome (TOJUtf), section.

214 AN INTRODUCTION TO ENTOMOLOGY.

their habits; some are injurious to vegetation; others are preda-
ceous ; while some species feed indifferently upon animal or vege-
table matter.

The Harlequin Cabbage-bug, Murgantia histronica. — Among the
species of the Pentatomidae that feed upon cultivated plants, the
Harlequin Cabbage-bug, or " Calico-back" as it is called in some
sections, is the most important pest. This is a very common insect
in the Southern States. It occurs from New Jersey southward and
westward. I have specimens from Colorado, and Arizona. It feeds
upon cabbage, radishes, turnips, and other Curciferous plants ; it is also
found sometimes on plants not closely related to cabbage. The
adult bug measures about 10 mm. (0.4 in.) in length. It is polished
blue black, banded striped, and margined above with yellow, orange,
or red ; on the venter it has seven lines of yellow and orange spots ;
and the head has generally two white spots on the front. The relative
proportions of the black and the light colors vary greatly indifferent
specimens. This bug winters in the adult state ; in early spring it
emerges and lays its eggs on the young plants. The eggs are usually
attached to the lower surface of the leaves in two parallel rows of
about six each. The young larva is of a uniform pale-green color,
marked with black ; with the successive moults the various orange
markings appear. In the immature stages the antennae are only four-
jointed. This insect develops very rapidly ; the eggs hatch on the
third day after they are laid ; and it is said that the bugs will pass
through all of their moults and be ready for reproduction in two
weeks. There is a series of generation extending through the en-
tire summer. This is an exceedingly difficult species to contend
against. Much can be done by trapping the bugs that have
hibernated by placing turnip or cabbage leaves in the garden in early
spring.

As if to atone for the destruction caused by their relative, the
Harlequin Cabbage-bug, there are many members of this family
which aid the agriculturist, by destroying noxious insects. I can-
not, without going into details inappropriate here, point out so that
they could be recognized the predaceous members of this family.
And it would hardly be worth while. It is only in case of excep-
tional species, like that just described, that these insects occur in suf-
ficient numbers to invite the attention of the agriculturist. They are
usually found wandering singly over the plants which they attack or
upon which they search for their prey.

The species of the genus Podisus have been reported more often

HEMIPTERA.

215

Fig. 186.— Po-
iHsus spino-
sus 1 From
Glover j

than any other as destroying the Potato-beetle, currant-worms, and
other well-known pests. The form of the body of members of this
genus resembles quite closely that of the insect represented by Fig
186. In P. spinosus, the best-known member of the
genus, the caudo-lateral angles of the prothorax are pro-
longed into spines.

Among the smaller members of this family there are
two common species which are so well marked that
they may be mentioned here.

Cosmopepla cdrnifcx is the more common of the
two species. It measures about 7 mm. (0.28 in.) in
length ; and is of a shining black color, with the body
densely punctured. The lateral margin of the body, including
the prothorax, basal half of wing-covers, metathorax, and abdo-
men, is red or orange ; the disk of the pronotum is crossed
by a transverse and a longitudinal line of the same color; the
longitudinal line is widened at its cephalic end so as to cover half of
the cephalic margin of this segment. There are also two red or
orange spots near the tip of the scutellum.

Mormidea liLgens is the other species. This also measures about 7
mm. (0.28 in.) in length. The body is densely punctured ; it is olive
brown above, and darker beneath. The lateral margin, including the
same parts as in the preceding species, is light yellow ; the cephalic
margin of the prothorax is of the same color ; and there is a trans-
verse yellow line on the pronotum a short distance behind its front
margin ; the scutellum except its cephalic margin is also bordered
with yellow.

The

Family XXXIV.— Cydxid.e.*

characters of this family have been discussed somewhat in
the characterization of the preceding one. In the
Cydnidaewe find the outline of the body more generally
oval, rounded, or elliptical, and the form more convex,
than in the Pentatomidae. The tibia; are closely armed
with strong spines, in rows (Fig. 187), and, with but a
single known exception in our fauna, the anterior pair
are fitted for digging, being more or less flattened. The
scutellum is either broad and bluntly rounded or tri-
angular, with the apex pressed down ; the lateral margins are fur-

Fir.

Cyr tome-
is us mira
bills.

* Cydnidae, Cydnus : Cydnus, a proper name.

2l6 AN INTRODUCTION TO ENTOMOLOGY.

nished with a furrow into which the margin of the wing-cover fits
when not in use. The antennae are five-jointed except in the
exotic genera Adrisa and Pachymeroides ; the distal three seg-
ments are usually united by slender threads.

The species are generally black or very dark brown. They are
found burrowing in sandy places, or on the surface of the ground
beneath sticks and stones, or at the roots of grass and other herb-
age. A European species is said to suck the sap from various plants
near the ground. It is desirable that further observations be made
upon the habits of this family.

Family XXXV— CORiMELiENlDiE.*

( The Negro-bugs.)

This family is represented in our fauna by a single genus,
Corimeltzna. They are mostly black, beetle-like in appearance ;
some have a bluish or greenish tinge, and all are very convex. The
form of the body is similar to that seen in the next family. It is
short, broad, and very convex, in fact almost hemispherical. The
scutellum is very convex, and covers nearly the whole of the
abdomen. At the base of the scutellum there is on each side a
short furrow into which the edge of the wing-cover fits when at rest.
This character allies this family to the two preceding,
and separates it from the following. These insects
infest various plants ; and often injure raspberries,
and other fruit, by imparting a disagreeable, bed-bug-
like odor to them. Fig. 1 88 represents Corimelcena

Fig. iSS. — Con- o r

meitena atra. atra, somewhat enlarged ; this is a common and widely
distributed species.

Family XXXVI— Scutellerid^e.

The Scutelleridae resemble in the form of their body the pre-
ceding family. They are turtle-shaped bugs; that is, the body is
short, broad, and very convex. The scutellum is very large, cover-
ing nearly the whole of the abdomen. The lateral margin of the
scutellum is not furnished with a groove for receiving the edge of
the wing cover, as is the case in the three preceding families. The

* Corimelaenidae, Corimelaena : coris (Kopi?), bug ; me/as (ueXaS), black,
f ScutellSridae, Scutellera : scutclla, little plate.

HEMIPTERA.

217

antennae are five-jointed, except in the genus A agocoris, which occurs
in Mexico and in the West Indies, and in certain
South American forms; in these they are three-
jointed. Fig. 189 represents Eurygdster alterndtus
somewhat enlarged, and serves to illustrate the
typical form of members of this family.

I have met no account of any of our species of
this family occurring in sufficient numbers to be

of economic importance.

Fig. 189. — Eurygas
ter alternatus.

CHAPTER IX.
Order VI.— NEUROPTERA*

{Ant-lions, Scorpion-flics, Caddicc-flics, ct a I.)

The members of tins order have four zvings ; these are membra-
nous, and usually furnished with numerous veins. The mouth-parts
are formed for biting except in one family (Phryganeidae), where they
are rudimentary. The metamorphosis is complete.

The term Neuroptera, or nerve-winged insects, is applied to the
members of this order on account of the numerous veins or nerves
with which the wings are strengthened. In this character there is,
however, a close resemblance between the Neuroptera and the
Pseudoneuroptera. Regarding the relations of these two orders the
reader is referred to the remarks on page 62.

It is not certain that the Neuroptera as limited here is a natural
group. One family, the Caddice-flies (Phryganeidaj), differs so
greatly from the other families that it has long been separated as a
distinct order; and more recently it has been proposed for similar
reasons to treat another family, the Scorpion-flies {Panorpidaf), in a
like manner. This multiplication of the orders has not yet been
generally accepted.

Owing to the great variations in structure exhibited by the dif-
ferent families, it is not easy to make generalizations regarding this
order. I will, therefore, reserve the more detailed discussions of
the structure of these insects for the special treatment of the indi-
vidual families.

The Neuroptera includes four families. These can be separated
by the following table :

TABLE OF FAMILIES OF NEUROPTERA.f

A. With well-developed wings.

B. Posterior wings with no anal space; not folded.
C. Mouth prolonged into a rostrum. 3. Panorpid^e.

* Neuroptera: neuron (vevpov), nerve; pteron (7trepov), wing,
f After Baron Osten Sacken in Hagen's Synopsis.

NEUKOPTERA.

219

CC. Mouth not prolonged into a rostrum.
BB. Posterior wings with a folded anal space.*
C. Wings reticulate. Prothorax large.
CC. Wings with rather few transverse veins.

AA. Wingless, or with rudimentary wings.
B. Mouth prolonged into a rostrum.
BB. Mouth not prolonged into a rostrum.

2. Hemerobiad.i..

1. Si ALU). E.
Prothorax small.

4. Phryganeid 1

3. Panoki'id.e.
4. Phryganeid.*.

Family I. — SlALin.E.f
{The Dobson et a I.)

There is no common name by which the members of this family
as a whole are known. The}' are, however, easily recognized.
Although the typical genus, Sialis,
includes insects of moderate size,
our most common forms are large.
All are characterized by having the
second pair of wings with a folded
anal space, and by having a large
prothorax. This segment is either
quadrangular or cylindrical and long

The larvae of all of the forms
occurring in the Eastern United
States are aquatic, living chiefly
under stones in the bed of swiftly-
flowing streams. They are carniv-
orous.

This family is represented in our
fauna by four genera. These can
be separated by the following table :

A. Wings without pterostigma ; prothorax
quadrangular.
B. No ocelli. Sevlis.

BB. With three ocelli.

C. Latero-caudal angles of head un-
armed. Transverse veins of wings
slender. Ch ^uliodes.

CC. Latero-caudal angles of head with a sharp tooth. Transverse veins of
wings Stout. CORYDAl IS.

AA. Wings with pterostigma ; prothorax cylindrical and long. R.APHIDIA.

Fig. 190. — Corydalis cornuta, adult.

* The anal space is absent in a few Phryganeidse.
f Sialidse, Slalis : sialon{cria\ov), saliva.

220 AN IXTRODUCTIOX TO EXT0M0L0GY.

'.is. — This genus includes the smaller of our representatives
of the family, those having an expanse of wings of about 25 mm.
The prothorax is nearly or quite equal in width to the
head : there are no ocelli : the antennae are filiform ; the wings are
irregularly reticulated with stout veins; and the fourth segment of
the tarsi is dilated and bilobed. Our common species is ^. in-
fumdta. This is black, with the head not narrowed posteriorly ; the
prothorax is a little wider than the head ; and the feet and wings
are black. I find the larva of this species common in the swiftly-
flowing creeks about Ithaca, adhering to the lower side of stones in
the bed of the streams. It resembles in form a young Corydalis,
or " Dobson." It has a pair of long tapering appendages on each
of the first seven abdominal segments, similar to those of Cory-
dalis. It differs from Corydalis in that the caudal end of the body
is terminated by a very long tapering appendage ; and there are no
tufts of tracheal gills. It is probable that when the larva is full
grown it leaves the water and transforms in an earthen cell without
a cocoon, as is the case with well-known European species.

Chauliodcs. — The species of Chauliodes are larger than the mem-
bers of the preceding genus, measuring from 30-60 mm. (1.2 in-
2.4 in.i in length, and having an alar expanse of from 60-100 mm.
2.4 in.- 4 in.). They differ also in having ocelli; three in number,
and placed close together. This genus closely resembles the follow-
ing one. but can be distinguished by the characters given in the
table above. The two genera also differ in that the caudal appen-
dages of the male are conical and simple in Chauliodcs ; while they
are in the form of forceps in Corydalis. The larva of Chauliodcs
also greatly resembles that of Corydalis. The abdomen is furnished
with similar lateral filaments, and anal pro-legs furnished with hooks.
But there are no tufts of tracheal gills as in Corydalis. The larva
of Chauliodes are aquatic, and probably carnivorous.

Chauliodcs pccticornis is a common species with grayish wings
and feather-like antennae. Chauliodcs scrricornis is also common ;
this is a brownish-black species with the wings spotted with white,
and with serrate antennae.

Corydalis. — The characters by which this genus can be recog-
nized have been given in the table above, and in the discussion of
the preceding genus. We have but a single common species, the
Hellgrammite-fly, Corydalis cornuta. This is a magnificent insect,
having an alar expanse of from 100-135 mm. (4 im-5.4 in.). The
male is remarkable for the great size of its mandibles, which are

NEUROPTERA.

221

more than half as long as the rest of the body. This species is
common throughout the greater part of the United Stale-. The
larvae are called " Dobsons" by anglers, and are used by them for
bait, especially for bass. Fig. 191 represents a fully grown Dob-
son, natural size. There is on each abdominal segment a pair of
long tapering appendages ; those of the ninth
abdominal segment are carried back so as to
project from the sides of a pair of anal pro-
legs. These pro-legs project caudad, and are
furnished each with a pair of claws. At the
base of each lateral appendage on the first
seven abdominal segments there is a tuft of
hair-like tracheal gills. The larva also has
spiracles; a remarkable instance of an insect
provided with both organs for aquatic and
aerial respiration. The spiracles are probably
not used till the insect is fully grown and
leaves the water to undergo its transforma-
tions. These larvae live under stones in the
bed of streams. They are most abundant in
the swifter parts of the stream. The}- are
carnivorous, feeding upon the larvae of Stone-
flies, May-flies, and other insects. When
about two years and eleven months old, the
larva leaves the water and makes a cell under
a stone or other object on or near the
bank of the stream. This occurs at Ithaca during the latter part
of May or early in June. By the middle of June the majority of
these larvae have transformed to pupae. These are of a yellowish-
white color. The\- are furnished with rudimentary wings and legs.
and quite long antennae. During the last half of June the pupae
change to the adult .-rate. The eggs are soon laid. These are-
attached to stones or to other objects overhanging the water.
They are laid in blotch-like masses, which are chalky white in color
and measure from 12 to 20 mm. in diameter. A single mass con-
tains from two thousand to three thousand eggs. When the larvae
hatch they at once find their way into the water, where they remain
till full}- grown.

Rapliidia. — This genus is represented in this country only on the
Pacific Coast. It is distinguished from the other members of the
family by having the prothorax cylindrical, and in having the wings
15

Fig. ioi. — CorydalU cornu-
rva.

222 AN INTRODUCTION TO ENTOMOLOGY.

furnished with a pterostigma. The anal space of the second pair
of wings is small. The third segment of the tarsi is dilated and
bilobed ; and the fourth is very short. The abdomen in the female
is furnished with a long ovipositor. The larvae differ from all other
Sialidae in not being aquatic; they are found under bark.

Those species of this genus that have no ocelli have been placed
by some writers in a distinct genus, Inocellia.

Family II. — HEMEROBIADAE*

{Ant-lions, Lace-winged Flies, ct al.)

The Hemerobiadae is a family of considerable extent ; and repre-
sentatives of it are very common throughout our country. As a
rule they are delicate insects, with large, gauzy wings. These wings
are narrow, having no anal space ; in this respect they resemble the
wings of the Panorpidae. But the members of this family differ
from the Panorpidae in not having the mouth-parts prolonged into
a rostrum. The larvae of the Hemerobiadae are predaceous ; and
they are remarkable for having the mouth-parts formed for sucking.
They thus form an apparent exception to the characters of the order
Neuroptera. The form of these mouth-parts is a very unusual one.
It is well shown in the larva of the Ant-lion, where these organs are
large enough to be easily studied. The mandibles are very long;
on the ventral aspect of each there is a furrow the entire length ;
into this furrow the long and slender maxilla fits. In this way the
mandible and maxilla of each side form a tube through which the
blood of the prey of the insect can be drawn.

Five sub-families are represented in our fauna. These can be
separated by the following table :

TABLE OF SUB-FAMILIES OF HEMEROBIAD^.

A. Prothorax not greatly elongated ; the three pairs of legs similar in structure.
B. Wings with very few veins, and covered with whitish powder.

I. CONIOPTERYGIN/E.

BB. Wings with numerous veins, and not covered with powder.
C. Antennae without terminal enlargement.

D. Subcostal vein joined to the median before the end of the wing; the
principal sector parallel to the median vein and giving rise to the
other sectors.! {Sisyra, Polyst&chotcs.) 2. Hemerobiin/E.

* Hemerobiadae, Hemerobius: hemera {rjuepa), day; bios (fSioS), life,
f For explanation of terms see Fig. 71, p. 73.

NEUROPTERA. 223

DD. Subcostal and median Veins separate.

E. Some of the transverse veins between the costal and subcostal
forked. {Micromus, Hemerobius.) 2. HemerobiinjE.

EE. Transverse veins between the costal and subcostal veins simple.

3. Chrysopix.k.
CC. Antennae gradually enlarging towards the end, or filiform with a ter-
minal knob. 4. MYRMELEONINjE.
AA. Prothorax greatly elongated ; first pair of legs fitted for grasping.

5. MaNTISPINjE.

Sub-family I . — C o x 1 o pt e r v ( _; 1 x . 1 •: .
( Mealy-winged Neuropteral)

This is a sub-family of limited extent ; and it includes only small
insects. They are characterized by a very small number of veins in
the wings, and by having the body and wings covered with a whitish
powder. The larvae are said to have the peculiar form of sucking
mouth-parts characteristic of the Hemerobiadae; and they probably
feed upon small plant-lice.

Two genera have been described. Aleuronia has reniform eyes
and ciliated wings ; in Coniopteryx the eyes are globose and the
wings are not ciliated. Our common species is Aleuronia westwoodii.
This occurs in the adult state in June and July ; it is black, with the
abdomen yellowish ; and measures to the tip of the wings 2\ mm.
(0.1 inch).

Sub-family II. — HEMEROBIIN.dE.

To this sub-family belong many genera, of which several are repre-
sented in this country. The antennae are setiform or moniliform
without any terminal enlargement. The wings are furnished with
numerous veins, and are not covered with powder. Our genera fall
into two groups; the first is represented by Sisyra and Polystce-
c/iotcs, and the second by Micromus and Hemerobius. These groups
are separated in the table of sub-families given above. The genera
in each group can be separated as follows : The costal space'-' of the
front wings of Sisyra has no recurrent vein at the base: while in
Polystcechotes the first transverse vein of this space curves towards
the base of the wing, and gives off several branches in its course.
The same difference exists between Micromus and Hemerobius ;
the former is without the recurrent vein, while it is present in the
latter.

* The costal space is the area between the costal and subcostal veins.

224 AN INTRODUCTION TO ENTOMOLOGY.

The genus Sisyra is anomalous in that its larvae are aquatic. We
have a single species described from Georgia. This is a small insect,
having an alar expanse of only 9 mm. (0.35 inch).

Polysiccchotcs is confined to this continent. These are larger
insects, having an alar expanse of from 50 to 75 mm. (2 to 3 inches).
They are nocturnal, and are attracted to lights. Two species have
been described. P. punctdtus is our most common one ; it is black-
ish, with three longitudinal lines on the disk of the prothorax, and
the lateral margins of this segment yellowish. P. vittdtus is pale
yellowish, with a black stripe on the sides of the thorax, and with
the abdomen dark brown. The larva of neither of these species is
known. They are probably aquatic.

Micromus includes smallish species having an alar expanse of
from 10 to 20 mm. (0.4 to 0.8 inch). My personal experience leads
me to believe that they are rare ; and I find no published accounts
of the appearance and habits of the larvae.

Hemerobius is much better known ; although the species of this
genus are not common. More than twenty North American species
have been described. These are also smallish insects ranging in
alar expanse from 8 to 20 mm. (0.3 to 0.8 inch). They occur in
forests, and especially on Coniferous trees. The larvae bear a strong
resemblance to the Aphis-lions ; and like them feed upon Aphids
and other small insects. After sucking the fluids from their victims,
they make a cloak for themselves of the empty skins.

Sub-family III. — CHRYSOPINiE.

{Lace-winged Flics or Aphis-lions.)

Nearly all of the species of this sub-family pertain to the genus
Chrysopa. These insects are known in the adult state as Lace-winged

Fig. 192. — Chrysopa, eggs on stalks, larva, and adult..

Flies, and in the larval form as Aphis-lions. The antennae of the
adult are longr and setaceous; the venation of the wings resembles
somewhat that of the preceding sub-family ; but the subcostal and

NEUROPTERA.

-^

median veins are separate, and the transverse veins of the costal
space are not forked.

The lace-winged Flics are very common insects throughout the
summer months upon herbage and the foliage of trees. They are
usually of a light green color or yellowish. While alive their eyes
are very bright ; and on this account they have also received the
popular name of Golden-eyed Flies. Some species, when handled,
emit a very disagreeable odor. A remarkable fact in the history of
these insects is the way in which the female cares for her eggs.
Winn about to lay an egg she emits from the end of her body a
minute drop of a tenacious substance; this is drawn out into a
slender thread by lifting the abdomen : then an egg is placed on the
summit of this thread. The thread dries at once and firmly holds
the vgg in mid-air. These threads are usually io to I 5 mm. (0.4 to 0.6
inch) in length, and occur singly or in groups. It is probable that
this placing of the eggs on stalks protects them from the ravages of
predaceous insects, including the aphis-lions themselves. When the
young aphis-lion hatches it crawls down the thread that held up the
egg, and starts in quest of some small insect or egg which it can
feed upon. While doing so it may wander through a forest of egg-
stalks, not observing the eggs far above it. The larv;e are spindle-
form, and have long, sickle-shaped mandibles. The) - feed chiefly on
plant-lice, but will eat such other insects as they can overcome. The
cocoon in which the pupa state is passed is spherical, and composed
of dense layers of silk. In order to emerge the insect cuts a circular
lid from one side of the cocoon.

Sub-family IV. — Mvrmeleoxix.e.
(Ant-lions et a I.)

The members of this sub-family can be distinguished from other
Hemerobiadre by the form of the antennae. Two types of antennae
exist in the sub-family, but in each the organs are enlarged at or
near the tip: while in other He'merobiadaj the antennae are with-
out a terminal enlargement.

The genera of this sub-family constitute two group-, each oi
which is represented in our fauna by a well-known genus. These
two genera include nearly all of our species. The first group is
represented by Myrmeleon. Here the antenna- are short and gradu-
ally thickened towards the tip. In the second grc up, represented

226

AN INTRODUCTION TO ENTOMOLOGY.

by Ascd/apfctiSfthe antennae are long, filiform, and suddenly enlarged
at the end.

The Ant-lions. Myrmeleon. — This is a large genus ; Hagen, in
his Synopsis published in 1861, describes twenty-five American
species. The adult insects are graceful creatures, with long, narrow,
delicate wings and slender bodies. The larvae have broad and
somewhat depressed bodies which taper towards each end. The
form of the mouth-parts has been described in the generalizations
regarding the Hemerobiadae. The interesting habits of these larvae
have attracted much attention since the earliest times. They live in
sandy places, where they dig pitfalls for trapping their prey. In
making these pitfalls the sand is thrown out by an upward jerk of
the head, this part of the body serving as a shovel. The pits differ
greatly in depth, according to the nature of the soil in which they
are made. Their sides are as steep as the sand will lie. When an
ant. or other wingless insect, steps upon the brink of one of these
pits, the sand crumbles beneath its feet, and it is precipitated into
the jaws of the ant-lion, which is buried in the sand, with its jaws at

Fig. 193. — Myrmeieon.

the bottom of the pit. In case the ant does not fall to the bottom
of the pit, the ant-lion undermines it by throwing out some sand
from beneath it. I have even seen an ant-lion throw the sand in
such a way that in falling it would hit the ant and tend to knock it
down the side of the pit. These larvae can be easily kept in a dish
of sand, and their habits watched. The pupa state is passed in a
spherical cocoon, made of sand fastened together with silk, and
neatly lined with the same material. This silk is spun from a spin-
neret, placed at the caudal end of the body, the caudal part of the
alimentary canal being transformed into a silk gland. The food of

NEUROPTERA. 22 7

these larvae is of such a nature that it can all be absorbed, and thus
the rectum is not needed for the passage of waste matter.

Ascdlaphus. — As already stated, this genus differs from the ant-
lions in the form of its antennae. The body is short, and the wings
are less densely veined than in Myrmeleon. The early stages of our
species have not been observed. In case of certain European
species the eggs are laid upon the stems of grass ; and the larvae
live upon the ground, hiding under stones, and seizing, by stepping
forward, insects that pass near them.

Sub-family V. — MANTISPIN^E,
{The Mantis-like Neuroptera.)

This remarkable sub-family is represented in our fauna by a single
genus, Mantispa. These insects present an unusual form of the
prothorax and the first pair of legs: a form that strikingly resembles
the shape of these parts in the family Mantidas of the order Orthop-
tera. The prothorax is elongated, cylindrical, and more or less
trumpet-shaped. The first pair .of legs are enlarged and fitted for
grasping. The wings are narrow, the two pairs similar ; and the
costal and subcostal veins are confluent near the middle of the costal
margin.

As indicated by the form of the grasping legs, the adult Mantispa
resembles the true Mantis in its predaceous habits. The trans-
formations of these insects are of unusual interest. It was acci-
dentally discovered that the larvae were parasitic in the egg-sacs of
spiders of the genus Lycosa. These are the large black spiders that
are common under stones, and which carry their egg-sacs with
them. Brauer obtained eggs from a female Mantispa kept in con-
finement. These eggs were rose-red in color, and fastened upon
stalks, like the eggs of Chrysopa. The eggs w ere laid in July : and the
larvae emerged 21 days later. The young larvae are very agile crea-
tures, with a long, slender body, well-developed legs, and long,
slender antennae. They pass the winter without food. In the
spring they find their way into the egg-sacs of the above-named
spiders. Here they feed upon the young spiders; and the body
becomes proportionately thicker. Later the larva moults and un-
dergoes a remarkable change in form, becoming what is known as
the second larva. In this stage the bod} - is much swollen, resem-
bling in form the larva of a bee. The legs are much reduced in
size; the antennae are short: and the head is very small. When

228

AN INTRODUCTION TO ENTOMOLOGY.

fully grown this larva measures from 7 to 10 mm. (0.3 to 0.4 in.) in
length. It then spins a cocoon, and changes to a pupa within the
skin of the larva. Later the larval skin is cast ; and, finally, after
being in the cocoon about a month, the pupa becomes active, pierces
the cocoon and the egg-sac, crawls about for a time, and then
changes to the adult state.

Family III. — PANORPIDiE.*
Order MECOPTERAf of some authors.
{Borcus, Scorpion-flics, ct al.)
is a small family ; but it is composed of very remarkable
insects. The most striking character common to all
is presented by the mouth. This is prolonged into
a rostrum, as shown in the figure. The body is
cylindrical or conical ; the head is exserted ; the
prothorax is small ; and the tarsi are five-jointed.
So far as is known the members of this family
are carnivorous. There are only four described
genera. These can be separated by the following
table :

This

Fig. 194. — Head
and tail of Pa-
norpa.

BOREUS.

Panorpa.

BlTTACUS.

Merope.

A. Wingless or with rudimentary wings.
AA. With well-developed wings.
B. Wings narrow ; antennae setaceous.
C. Tarsi with two serrated claws.
CC. Tarsi with a single simple claw.
BB. Wings broad ; antennae short, thick, the apex narrowed.

Borcus. — Among the few insects that occur on the snow, in the
winter, in our Northern States, are two species of the genus Boreas.
In this genus the wings of the female are very rudimentary; those
of the males are about half as long as the abdomen, narrow, stiff,
and entirely useless for flight. Borcus nivoriiindus, the Snow-born
Boreus, is shining black or brownish black, with the rudimentary
wings, thorax above, and the rostrum and ovipositor excepting their
tips, tawny. The male measures 3 mm. (0.12 in.) in length; the fe-
male, including the ovipositor, 4^ mm. (0.16 in.). The Midwinter
Boreus, B. brumalis, is smaller; the male measuring 2^ mm. (o. 1 in.),
and the female 3 mm. (0.12 in.), in length. This species is deep black-

* Panorpidse, Panorpa: pan (tzocv). all; horpe = harpe (apmf), a sickle,
f Mecoptera, incorrectly written Mecaptera: mecos (juf/KoS), length ; pteron {nrepov),
wing.

NEUROPTERA. 220,

green ; with the legs, antennae, rostrum, and ovipositor black, and
the rudimentary wings brownish black. Both species are found
on the snow throughout the entire winter. They also occur in moss
on tree-trunks. It is not known whether they feed on the mi
upon Thysanurians and other small insects which they find there.
These insects have long legs, and are able to leap to a limited ex-
tent. The females are furnished with a long, curved ovipositor, re-
sembling that of a cricket. The early stages of our species have
not been studied. The larva of a European species has been found
throughout the summer in the ground and upon stones under Liver-
worts.

The Scorpion-flies, Panorpa. — These are our most common rep-
resentatives of the family. They are called scorpion-flies on account
of the peculiar form of the caudal part of the abdomen of the male.
Tlx*3 at first sight suggests the corresponding part of a scorpion :
but in reality the form is very different. The last
segment, instead of ending in a sting like that of a
scorpion, is greatly enlarged, and bears a pair of clasp-
ing organs. The wings are narrow, but are well
developed, being longer than the body. In our
more common species they are yellowish spotted
with brownish black. The earl)' stages of several
European species have been studied. The eggs FlG ^ 95 a ^ u y 1 t"' < ""
are laid in a mass in a shallow hole, which the female
bores with her abdomen in damp earth. The larvae are remarkable
on account of their great resemblance to caterpillars."" Not only is the
form of the body like that of Lepidopterous larvae, but the abdomen
is furnished with fleshy prop-legs. There are, however, eight pairs
of these ; while caterpillars never have more than five pairs. The
larvae which were kept in confinement were fed raw beef; the}' made
horseshoe-shaped mines in the earth, one end of which opened be-
neath the meat. Their natural food is unknown.

Bittacus. — The insects of this genus resemble the scorpion-flies
in having long, narrow wings, three ocelli, and very slender, seta-
ceous antennae. But the caudal appendages of the male are not
enlarged as in Panorpa. The legs of Bittacus are very long; this
with the narrow wings and slender abdomen cause these insects to
resemble Crane-flies. They are predaceous, the European species

* The larv.-E of three species are figured by Kraucr, Verhandl. der k. k. zool. bot.
Gesellsch., Band XIII. taf. 13.

230 AN INTRODUCTION TO ENTOMOLOGY.

having been observed to capture and destroy flies. Brauer figures
the larva of one species, and represents it with six true legs and
eight pairs of conical prop-legs. Unlike the larvae of Panorpa, this
did not mine in the ground, but remained on the surface hiding
under dry leaves and other rubbish.

Mcropc. — This genus was established for a very rare and remark-
able species. The wings are broad, with many transverse veins ;
the ocelli are absent ; the eyes are large, kidney-shaped, and united
at the vertex ; the antennae are short, thick, and with the apex nar-
rowed. The abdomen of the male has very large forceps.

Family IV. — Phryganeid/£.*

Order Trichoptera of some authors.f

( C add ice-flies))

The Caddice-flies are moth-like insects, which are common in the
vicinity of streams, ponds, and lakes ; and they are also frequently

attracted to lights at night. But the larvae
of these insects are much better known
than the adults ; for the curious houses
of the caddice-worms have attracted at-
tention wherever there are observers of

Fig. 196.— Caddice-fly.

insects.

In the adult insect the body-wall is soft, being membranous or at
the most parchment-like, and is thickly clothed with hairs. There
are usually four ample wings. These are membranous ; but the
anterior pair are more leathery than the posterior. When not in
use they are folded against the sides of the abdomen, in an almost
vertical position, and give the insect a narrow and elongated appear-
ance. The wings are more or less densely clothed with hairs. In
some cases the hairs are scale-like in form. The second pair of
wings are generally broader than the front wings, and are often longi-
tudinally folded in repose. All have numerous longitudinal veins ;
but the transverse ones are few.

The head is small ; the antennae are sectaceous, and frequently
several times as long as the body; the labium is usually elongate;
the mandibles are mere tubercles at the base of the labium ; the
maxillae are small, and ordinarily furnished with an obtuse maxillary

* Phryganeidae, Phryganea: phryganon ((ppvyavov), a dry twig,
f Trichoptera: thrix (Gpz'c), a hair; pteron {7trepov), a wing.

NEUROPTERA. 23 1

lobe ; the maxillary palpi are well developed, and furnish characters
which are much used in classification ; the labium is usually well
developed, and bears three-jointed palpi.

The females deposit their eggs in masses enveloped in a gelati-
nous covering. These are often found adhering to the end of the
body in captured specimens. It is supposed that these eggs are
usually deposited on aquatic plants ; but it is known that in some
cases the females descend below the surface of the water to oviposit.

The larva; are long, cylindrical, soft-bodied, and furnished with
six well-developed thoracic legs and a pair of anal legs. The abdo-
men bears a greater or less number of hair-like tracheal gills. These
larvae protect themselves by building a case about the body, in which
they live during the larval and pupal stages. These cases vary
greatly in form, and in the materials used in their construction ; but
in general those made by the larvaj of any given species are very
similar.

One of the most interesting topics which a young entomologist
can take for study is the habits of these insects. The larvae can be
easily found throughout our country. Man}' species can be kept in
aquaria; but others, those that live in swiftly-flowing water, must be
observed in their native haunts. I will indicate a few of the general
features in the economy of these insects. The facts given here can
be easily supplemented by any careful observer.

Among the simplest of the various forms of houses built by
caddicc-worms are those made by certain species that live under
stones in rapid streams. These consist merely of a few pebbles
fastened to the lo.wer surface of a larger stone by threads of silk.
In the space between these stones the worm makes a more or less
perfect tube of silk, within which it lives. Very little respect for
the architectural skill of these builders is commanded by their rude
dwellings. But if one looks a little farther, something will be found
that is sure to excite admiration. The dweller within this rude re-
treat is a fisherman ; and stretched between two stones near by can
be seen his net. This is made of threads of silk extending in two
directions at right angles to each other, so as to form meshes of sur-
prising regularity. It is as if a spider had stretched a small web in
the water where the current is the swiftest. In the streams about
Ithaca these caddice-worm nets are very abundant. They occur in
the rapids between stones, but are to be found in greater numbers
along the brink of the falls. Here the}- are built upon the surface
of the rock, in the form of semi-elliptical cups, which are kept <lis-

232 AN INTRODUCTION TO ENTOMOLOGY.

tended by the current. Much of the coating of dirt with which
these rocks are clothed in summer is due to its being caught in these
nets. I have not yet observed the owners of the nets taking their
prey from them ; but I cannot doubt that they are made to trap
small insects or other animals that are being carried down stream,
for the larvae of the sub-family to which these net-builders belong,
the Hydropsychince, are known to be carnivorous. It should be
noted here, however, that the greater number of caddice-worms are
herbivorous.

There are many caddice-worms that build their cases of stones ;
some of these cases are very regular in form. One of the common
kinds resembles a slightly tapering cornucopia, made of small grains
of sand, cemented together with great regularity. Another consists
of a shorter tube, to each side of which are fastened one or two
larger stones, as if to keep it in position (Fig. 197). But more re-

Figs. 197, 198.— Cases of Caddice-worms.

markable than either of these is the case (Fig. 198) which sc closely
resembles in form the shell of a snail that it has been described as
such by several conchologists.

We find among the caddice-worms carpenters as well as masons.
And there exists among the builders of wood as great a variety of
architectural tastes as among the builders of stone. Probably the
most familiar of the forms of cases made of wood is that represented
in Fig. 199. This is made of irregular pieces of wood arranged in a

Figs. 199, 200.— Cases of Caddice-worms.

longitudinal manner. Much more likely to attract attention is the
case composed of sticks placed at right angles to the body (Fig. 200).

NEUROPTERA. 233

These remind one of the cob-houses of our childhood. Fortunately

the species that make this style of case live in stagnant water, and
may, therefore, be kept alive in aquaria. A case closely resembling
this in plan but differing in appearance is made of bits of moss.
Sometimes leaves are used ; these are either fastened so as to form
a fiat case ; or are arranged in three planes, so as to form a tube, a
cross section of which is a triangle.

Whether stones or wood are used, the material is fastened to-
gether by silk, which the larvae spin from the mouth in the same
manner as caterpillars. In some species the case is composed en-

Fig. 201. — Case of Caddice-worm.

tirely of silk. Fig. 201 represents the form of such a case, which is
common in Cayuga Lake.

Before transforming to pupae, the caddice-worms partially close
their cases, so as to keep out intruders; but provision is made for
the ingress of water for respiration. Thus the owner of the silken
case to which reference has just been made, when read}- to trans-
form, fastens its case to a stem of the grass which grows in the
lake, and then closes the entrance to the case with a lid having a
slit-like opening in the centre. The worms making the casus shown
in Fig. 199 build a grating in each end of the case.

It would naturally be supposed that the caddice-worms would
escape the attacks of Ichneumon-flies, living as they do beneath
water, and within well-built tubes. But this is not so. And curi-
ously enough, in certain species at least, the parasitized individuals
differ from others in fastening their cases by means of a long band,
when about to transform, instead of attaching them directly to the
supporting object.

In the Phryganeidse we find another group which differs in such important
characters from the most nearly allied insects that many entomologists bi
it should he classed as a distinct order ; and long ago the name Trichoptera was
proposed for this order. The rudimentary mouth-parts of the adult eaddice-
llies and the structure of the wings separate them from the other Neuroptera,
and suggest affinities with the Lepidoptera ; on the other hand, the anal legs of
the larva- with hooked claws resemble those of the Sialidae. As indicating the
strength of the tendency to recognize the order Trichoptera. it isonly nei
to name Hagen, McLachlan, and Brauer as among those that shaie this v iew.

234 AN INTRODUCTION TO ENTOMOLOGY.

The American species of the Phryganeidae have not been monographed.
One hundred and fifty species are described in Hiigen's Synopsis of the North
American Neuroptera; comparatively little has been written regarding the
American forms during the quarter-century that has elapsed since the appear-
ance of that work. The student who wishes to make a special study of this
group should possess the great work of Robert McLachlan, A Monographic
Revision and Synopsis of the Trichoptera of the European Fauna. There is
also a paper by Friedrich Brauer which is very useful. This is entitled Ver-
zeichniss der bisjetzt bekannten Neuroptera im Sinne Linne's, and is published
in the Verhandlungen der Zoologisch-Botanischen Gesellschaft, XVIII. (1868).
It contains analytical keys to the sub-families, and to all of the genera described
at that time.

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An introduction to entomology.

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