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APPLIED ENTOMOLOGY

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1

YPPLIED ENTOMOLOGY

4r

AN INTRODUCTORY TEXT-BOOK >^?7v

V

OF

INSECTS IN THEIR RELATIONS TO MAN

BY

H. T. FERNALD, Ph.D.

PROFESSOR OF ENTOMOLOGY, MASSACHUSETTS AGRICULTURAL COLLEGE, AND
ENTOMOLOGIST OF THE MASSACHUSETTS AGRICULTURAL
EXPERIMENT STATION

First Edition

McGRAW-HILL BOOK COMPANY, Inc.
NEW YORK: 370 SEVENTH AVENUE
LONDON: 6 & 8 BOUVERIE ST., E. C. 4

1921

Copyright, 1921, by the
McGraw-Hill Book Company, Inc.

JUTHSCA//^

4/

THE MAPLE PRESS TORE PA

TO THE MEMORY OF

yCly> ~3Fatl)er

Professor Charles H. Fernald:

the first teacher of Economic Entomology
to college students, in this country.

PREFACE

If one can judge from the answers to about fifty letters of inquiry
sent to teachers of Entomology in colleges in the United States, the
teaching of Entomology in this country at the present time is in a rather
chaotic condition. Very few of the answers received show much in
harmony in subject matter, methods of presentation, or even the line of
training the students should receive by a course in the subject.

The author believes that in agricultural colleges at least, two distinct
groups of students need a knowledge in Entomology, and rather early in
their course. One of these groups is composed of students who will
never specialize in the subject but need it as part of an agricultural
education, and particularly as a tool which they can use wherever insects
are related to their special lines of work. They are not particularly
interested in such details as the number of antennal segments in insects,
the number of branches of the radial vein, or how important a pest on
pigweed the insect is: they do not expect to identify insects beyond the
order or family at most, relying on specialists available at the State
Experiment Stations for such information. But they do desire a general
knowledge of the broad outlines of the subject, and a rather complete
knowledge of, and if possible, the ability to recognize particularly import¬
ant insect pests they are liable to meet in the course of their work.

The other group consists of those who expect to specialize in the
subject, becoming professional entomologists. Their needs will, of
course, be different from those of the other group, but an introductory
survey such as will meet the requirements of the rest will give the members
of this group an excellent foundation for further and more detailed work.

The present book is therefore offered as a classroom text for an
introductory course in the subject, which shall give a general idea of
insects, their structure, life histories and habits, with methods for the
control of insect pests in general, followed by a more thorough study of
the more important ones found in this country. For use, the writer
believes that in few places will all of the text be assigned. Instead, the
pests of the country as a whole (treated in large type) and those of the
particular region concerned (selected from among those printed in smaller
type) would naturally be the parts used in any one place, though the
book as a whole should be fairly well applicable to all sections of the
country.

The author is of the opinion that to avoid too much monotony, it
may prove wise to assign Chapters VI to IX inclusive, among those

vii

PREFACE

viii

immediately following. The treatment of the subject matter is such as
to permit this.

Many of the illustrations included are familiar. Where satisfactory
illustrations are already available, it is questionable whether new ones
are any gain, particularly when all are new to the student. In this
connection the author desires to express his grateful appreciation of the
kindness of Dr. W. E. Britton and the Connecticut Experiment Station,
and of Prof. J. S. Houser and the Ohio Experiment Station, for the pro¬
vision of cuts from the publications of those Stations. He is much
indebted to Prof. E. D. Sanderson for the use of cuts taken from “ Insect
Pests of Farm, Garden and Orchard” and from Sanderson and Jackson’s
“Elementary Entomology,” and to the publishers of these books, John
Wiley and Sons, Inc., and Ginn and Company respectively, as well as to
Dr. E. P. Felt who has kindly allowed the use of reproductions of illus¬
trations taken from his publications. Dr. J. W. Folsom’s kindness and
that of his publishers, P. Blakiston’s Sons and Company in permitting
the use of illustrations from Dr. Folsom’s book “Entomology with
Reference to its Biological and Economic Aspects,” is also much appre¬
ciated. Ginn and Company have kindly consented to the use of several
illustrations from Linville and Kelly’s “Textbook in General Zoology,”
and the side view of the parts of a grasshopper has been obtained by
permission of those in charge of the Natural History Survey of Connecti¬
cut. The largest number of illustrations secured, however, has been
obtained through the kind permission of Dr. L. O. Howard of the U. S.
Bureau of Entomology to use many which are the property of the Bureau.
Photographs from various Experiment Station Reports and Bulletins
have also been freely drawn upon. The source from which, each illus¬
tration has been obtained is indicated in every case. To all the persons
and companies above named, I desire to express my thanks.

Any book such as this is necessarily a compilation. Probably there
are very few if any entomologists in this country who have worked per¬
sonally on all the insects treated here. The only originality for it
which can be claimed therefore, is in the selection of the various topics
and their method of presentation. Errors have undoubtedly crept in,
and the author will appreciate having his attention called to any which
may be found.

The author desires to express his appreciation of the aid in the pre¬
paration of this book given him by his associates, Dr. G. C. Crampton,
Dr. W. S. Regan, and Mr. A. I. Bourne, who have gone over various
parts of it and have criticized and advised on those which they have
examined. Much of any value it may have is due to them, but for any
errors and incorrect statements which may be found, the author assumes
full responsibility.

Amherst, March 1, 1921.

H. T. Fernald.

CONTENTS

P

Preface,

CHAPTER I

Insects and other Animals .

The larger groups of animals — Their distinctive characters — The Arthropoda
— Its characters — Animals included — Subdivisions of the group — Their
distinctive characters — Tabular statement of the distinctive characters.

CHAPTER II

The Insect: Its External Structure .

The characters of insects— Number of segments in the embryo — In the
adult — The hypodermis — Sutures — Plates — Form of head — Structures on
the body — The antennse — Eyes — Mouthparts — Chewing mouthparts —
The thorax — Its appendages— Legs — Wings— The abdomen — Abdominal
feet — Ovipositor — Other appendages.

CHAPTER III

The Insect: Its Internal Structure .

Digestive organs — Breathing organs — Circulatory organs — The blood —
Excretory organs — Nervous system — Sense organs — Reproductive organs.

CHAPTER IV

The Development of Insects .

Egg-laying and viviparous insects— Description of insect eggs — Hatching —
Development of the insect — The Ametabolous development — Hemime-
tabolous development — Holometabolous development — Pupation and
cocoon making — Transformation of the pupa — -Emergence — -Common
names of Holometabolous larvae.

CHAPTER V

Losses Caused by Insects: Nature’s Control Methods .

Amount of the loss not generally realized — Its average amount— To crops —
To animals and their products — To forests and their products — To stored
materials — By disease — Total loss — Losses increasing — Causes — Intro¬
duction of foreign insect pests — Reduction in abundance of insectivorous
birds — A theoretic state of equilibrium upset by civilization — Nature’s
methods too slow — Artificial methods necessary.

CHAPTER VI

Artificial Methods of Control .

Two groups of methods — Farm practice — Healthy crops — Crop rotation—
Plowing — Time of planting — Resistant varieties of plants — Trap crops —
Special methods — Hand picking — Repellents — Trap lanterns — Burning —
Heat — Miscellaneous methods.

X

CONTENTS

CHAPTER VII

Page

Insecticides in General: Stomach Poisons . 43

Materials classified — Conveyance — Dusts — Sprays — Arsenic — Disadvan¬
tages — Paris green — Disadvantages — Standard formula — -Variations —
Arsenate of lead — Standard formula — Arsenate of lime — Standard formula—
Poison baits — Hellebore — Commercial Sodium Fluorid.

CHAPTER VI 1 1

Contact Insecticides . 49

Purposes of contact insecticides — Kerosene emulsion — Miscible oils —
Whale-oil soap — Common soap — Nicotine — Nicotine sulfate — Lime sulfur
wash — Dry sulfur compounds — Sulfur — Pyrethrum, insect powder, or
buhach.

CHAPTER IX

Insecticides and Fungicides: Fumigation . 54

Combinations of spray materials — Of insecticides — Of insecticides and
fungicides — Injurious combinations — Fumigation— Nature of its action —
Limits of availability — Carbon disulfid — Nicotine — Sulfur — Hydrocyanic-
acid gas.

CHAPTER X

The Relationships of Insects . 59

Classification — The development of animals in the past — Artificial and
natural classifications — -The original insects — The development of diversity
— Resultant groups — Relations of species, genera, families etc. — A sample
tree-like classification — Table of classification.

CHAPTER XI

The Apterygota . 62

General structure — Distinctive characters — General description — Divisions
of the group — Order Thysanura — Distinctive characters — The Silver Fish —
Order Collembola — General features — Distinctive characters — General
account.

CHAPTER XII

The Pterygota. The Ephemerida . 65

General considerations on the Pterygota — The Ephemerida — General
description and structure — Distinctive characters — Life and habits —
Importance.

CHAPTER XIII

The Odonata . 68

General description and structure — Distinctive characters — Groups of
dragon-flies — Habits — Their life and food — Importance — Abundance.

CHAPTER XIV

The Plecoptera . 72

General description of the group — Distinctive characters — Life and habits —
Abundance — Economic importance.

CONTENTS

xi

CHAPTER XV

The Embiidina .

General description — Economic importance.

CHAPTER XVI

Pace

74

The Orthoptera . 75

General description — Structure — Division into two sections — The Cursoria
— Distinctive characters — Families considered — -The Blattidae — Descrip¬
tion of Roaches — The German Roach — The American Roach — The Aus¬
tralian Roach — -The Oriental Roach or “black beetle” — Control of Roaches
— The Mantidse — General considerations — Common Mantids — The Phas-
midae — General description of appearance, life history and habits — Eco¬
nomic importance — Control — The Saltatoria — -General features — The Acri-
didae — Description of grasshoppers — Abundance — Economic importance —
Control — -Kinds of grasshoppers — Sounds produced — Organs of hearing —

The Tettigoniidse — General description of the family, habits, life history,
etc. — Economic importance — The Gryllidae — General statements — Sounds —

Ears — Economic importance — Kinds of crickets — Tree crickets — Control.

CHAPTER XVII

The Isoptera . 91

The colony — Its composition — Castes — Structures- — Distinctive characters
— Food — Swarming — Common species — Life and habits — Injuries — Control
— Zoraptera.

CHAPTER XVI II

The Dermaptera . 95

General description — Distinctive characters— Importance — Habits —

Different species — The European earwig — Injuries — Control.

CHAPTER XIX

The Coleoptera . 98

Structure — Distinctive characters — Life histories and habits — Division into
Coleoptera vera and Rhynchophora — Coleoptera vera — Lampyridae —
Carabidse — • Cicindellidse — Dytiscidae — Gyrinidae — Hydrophilidae — Staphy-
linidae — Silphidae — Dermestidae — Larder beetle — Buffalo Carpet beetle —

— Black Carpet beetle — Control— Buprestidae — Flat-headed Apple-tree
Borer — Elateridae — Wireworms — control — Scarabaeidae — June bugs — Rose
chafer — -Japanese Beetle — Chrysomelidae — -Colorado Potato Beetle —

Change of food a possible pest producer — -Striped Cucumber Beetle — Corn-
root Worms — Flea Beetles — Asparagus Beetles — Grape Root Worm — Elm
Leaf Beetle — Tortoise Beetles — Bruchidae — Pea Weevil — Bean Weevil — .
Broad Bean Weevil — Control of Weevils — Cerambycidae — Round-headed
Apple-tree Borer — Coccinellidae — Tenebrionidae — Yellow Meal-worm —

Meloidae — Rhynchophora — Plum Curculio — Plum Gouger — Cotton Boll
Weevil— White Pine Weevil — Alfalfa Weevil — Potato-stalk Weevil — Sweet-
potato Weevil — Ipidae — Fruit-tree Bark Beetle.

CONTENTS

xii

CHAPTER XX

Page

The Strepsiptera . 150

General description — Distinctive characters — Habits — Life history — Abun¬
dance — Importance.

CHAPTER XXI

The Thysanoptera . 153

General features — Structure — Distinctive characters — Habits — Subdivisions
— Wheat Thrips — Onion Thrips — Pear Thrips — Citrus Thrips.

CHAPTER XXII

The Corrodentia . 159

General description — Structure — Distinctive characters — Book lice —

Psocids — Importance of the group.

CHAPTER XXIII

The Mallophaga . 161

General features — Distinctive characters — Habits — Poultry lice — Control.

CHAPTER XXIV

The Anoplura . .-...• . 164

Description — Distinctive characters — Distribution — Life history — Body
louse — Relation of lice to disease — Crab louse — Lice on domestic animals —
Control.

CHAPTER XXV

The Hemiptera . 16S

General characters — Structure of mouthparts — Distinctive characters —
Distribution — Habits — Pentato midge — -Harlequin Bug — Cydnidse — Coreidse
- — Squash Bug — Pyrrhocoridge — Cotton Stainer — Lygseidae — -Chinch Bug
— The diseases of Insects— Tingitidse — Miridse — Meadow Plant Bug — Tarn¬
ished Plant Bug — Phymatidse — Reduviidse — Cimicida? — Bedbug — Gerridae
— Notonectidae — Corixidae — Nepidae — Belostomidae.

CHAPTER XXVI

The Homoptera . ISO

General statements — Distinctive characters — Variations in habits etc. —
Honey dew — Classification of the order — Cicadida? — -Periodical Cicada or
17-year Locust — Leaf Hoppers and Tree Hoppers — Apple Leaf hoppers —
Rose Leaf hopper — Chermidae — Pear Psylla — Aphididae in general — Apple
Aphids — -Grape Phylloxera — -Corn Root Aphis — Aleyrodidse — Coccidse
in general — -Armored Scales — Oyster-shell Scale — Scurfy Scale — San Jose
Scale — -Rose Scale — Pine Leaf Scale — Purple Scale — Red Scale — Soft
Scales — Black Scale — Terrapin Scale — Cottony Maple Scale — Hemispherical
Scale — Mealy Bugs — -Citrus Mealy Bug — Long-tailed Mealy Bug — Cottony
Cushion Scale— Introduction of enemies of introduced pests.

CONTENTS

xiii

CHAPTER XXVII

Page

The Neuroptera . 221

General features — -Distinctive characters — Economic value — Sialidae —
Corydalis — Chrysopidae or Aphis lions — Raphidiidae — Mantispidae — Myrme-
leonidae or Ant lions.

CHAPTER XXVI II

The Trichopteka . 220

General description — Distinctive characters — Life; and habits — Larval cases
— Importance.

CHAPTER XXIX

The Lepidoptera . 230

General features — Structure — Mouthparts — -Distinctive characters — Diver¬
sity in the order — Life history and development in general — Cossidae — -
Leopard Moth — Tineidre — Clothes moths and their control — Codling Moth
— Llgeridae — Peach Borers — Squash-vine Borer — Gelechiidae — Angoumois
Grain Moth — Pterophoridae — Pyralidae — Bee Moth — European Corn Borer
— Limacodidae — Psychidae — Geometridae — Canker worms — Bombycidae — -
Lasiocampidae — Apple-tree Tent-caterpillar — Forest Tent-caterpillar — Ly-
mantriidse — White-marked Tussock Moth — Antique or Rusty Tussock
Moth — Gypsy Moth — Brown-tail Moth — Notodontidae — -Dioptidae — Cali¬
fornia Oak Worm — Noctuidae in general — -Cotton Worm — Corn-ear Worm
— Army Worm — Fall Army Worm — Cutworms — Arctiidae — Fall Web-worm
— Ceratocampidae — Saturniidae — Sphingidae — Tobacco and Tomato Worms
— The Butterflies — Hesperiidae — Lycaenidae — Danaidae — Nymphalidae —
Satyridae — Pieridae — Imported Cabbage Butterfly — Sulfur butterflies — The
spreading over the country of introduced insects — Papilionidae — Black
Swallow-tail butterfly.

CHAPTER XXX

The Mecoptera . 300

General features — Distinctive characters — Habits — Food — Importance.

CHAPTER XXXI

The Diptera . 301

General description — Structure — -Mouthparts of adult — Larvae — Pupae —
Distinctive characters — Size and importance of the group — Tipulidae —
Culicidae — House Mosquito — Malarial Mosquitoes — Relation to malaria —
Yellow Fever Mosquito — Control of mosquitoes — -Itonididae — Clover-
flower Midge — Hessian Fly — Wheat Midge — Tabanidae — Simulidae —
Asilidae — Syrphidae — CEstridae — Ox Warbles— Trypetidae — Apple Maggot —
Muscidae — House Fly — Its relation to disease — Screw Worm Fly — Sarco-
phagidae — Tachinidae — Tsetse Flies — Anthomyiidac — Cabbage Maggot —
Onion Maggot — Pupipara — Sheep rl'ick.

CHAPTER XXXII

The Siphonaptera . 333

General description — Structure — Distinctive characters — Food— Life his¬
tory and habits — Relation to disease — Control— “Sticktight flea” — Chigoe.

XIV

CONTENTS

CHAPTER XXXIII

Page

The Hymenoptera . 338

General description and structure — Terebrantia and Aculeata— Develop¬
ment — Distinctive characters — Importance — Tenthredinoidea — Currant
Worm — Pear Slug — Wheat Stem Borers — Horn-tails — Ichneumonoidea —
Their importance — Methods of work — Long-tailed Thalessa — Cynipoidea —

Gall production — Alternation of generations — Inquilines — -Parasites — Impor¬
tance of galls — Chalcidoidea — Habits — Wheat Straw Worm — Wheat Joint
worm — Clover-seed Chalcis — Fig Blastophaga — Pteromalus puparum —
Serphoidea — Long-tailed Pelecinus — Variation in habits of parasitic Hymen¬
optera — Chrysidoidea — Sphecoidea — Vespoidea — Progressive development
as illustrated by Wasps — Apoidea — Solitary bees — Leaf-cutter bees —
Carpenter bees — Bumble bees — Honey bee — Life of a Honey bee colony —
Swarming — Value of bee products — Formicoidea — Composition of ant
colonies — Location of colonies — Swarming — Establishment of new colonies —

Ants and plant lice, etc. — Unusual habits — Argentine Ant — House Ants—

Ants in lawns.

APPLIED ENTOMOLOGY

CHAPTER I

INSECTS AND OTHER ANIMALS

Among the larger groups of animals now recognized by science, the
one known as the Chordata is naturally the most familiar, including the
mammals, birds, reptiles, fishes, besides numerous forms less well known.
Another group, also familiar, and called the Mollusca, includes the snails,
clam etc., while a third, the Annulata, contains most of the more
commonly seen worms. The starfish and sea urchins, often seen at the
seashore, belong with other similar animals, to a fourth group called the
Echinodermata, and a multitude of tiny beings almost all too small to be
seen without the aid of a microscope, are included in the group Protozoa.
A sixth large group is composed mainly of soft, jelly-like animals, the
more common larger members being called jelly-fish, and to this the
name Ccelenterata is applied, and several other groups of less familiar
forms are also known.

The largest group of all, however, is the Art.hropoda, its members
found in the seas, in fresh water, on land, or even flying freely; a group
with remarkable differences of structure, and so abundant that all the
other animals taken together are less than one-sixth as many as the
Arthropods. Well-known members of this group are the lobsters, cray¬
fish and crabs; scorpions, spiders, mites, ticks and “ daddy long legs;”
the centipedes and millipedes; and last and most abundant of all, the
Insects.

No one feature will serve to separate the Arthropods from all other
animals, but the possession by an animal of several of those here described
will enable the observer to determine in each case whether he is examin¬
ing one of this group. In Arthropods the body is composed of a series of
more or less similar pieces or segments, placed one behind another, the
line of attachment of these to each other being usually somewhat evident
on parts of the body at least. This character is also shown, and indeed
more clearly, in some members of the Annulata, such as the common
earthworm. Another character of the Arthropods is the presence of
jointed legs (or appendages of some kind), as is indicated by the name
of the group, and these are not possessed by Annulates. The surface of
the body is covered by a secretion which hardens on exposure to the air,

1

2

APPLIED ENTOMOLOGY

forming an outside shell or external skeleton (exo-skeleton), there being
practically no internal supporting structures except as ingrowths from
the outside. In the possession of this external skeleton these animals

have a seeming resemblance to the
shells (Mollusca), but the materials
of which it is composed are quite
different, being largely calcium car¬
bonate in the Mollusca, and chitin
which somewhat resembles horn in
its nature, sometimes with calcareous
salts deposited in it, in the Arthro-
poda. In its simplest members the
Arthropod body is also practically
bilaterally symmetrical, though this
condition is concealed somewhat by
secondary changes in many of the
group. The possession of a bilaterally
symmetrical body consisting of a
series of segments; an exoskeleton of
chitin, and the presence of jointed

Fig. i. Crayfish ( Crustacea ); about legs, are then, distinctive features of
one-half natural size. {Original.)

the Arthropods.

To separate the various groups of Arthropods, other characters must
be used. Aside from several small sections not often seen, there are five
large and important divisions which call for recognition. These are the
Crustacea, including the lobster, crab, beach flea, sow bug and many

Fig. 2. — “Sow-bug; a crustacean Fig. 3. — Millipede {Diplopoda); natural size,
living on land; about natural size. {From Folsom.)

{Original.)

others; the Diplopoda or Millipedes; the Chilopoda or Centipedes; the
Hexapoda or Insects; and the Arachnida, including the scorpions, pseudo¬
scorpions, spiders, mites, ticks, etc.

INSECTS AND OTHER ANIMALS

3

The Crustacea (Fig. 1) are mainly water-inhabiting animals which
breathe either by gills, or, in the smaller forms, through the surface of
the body. In those cases where its members live on land (Fig. 2) the gills
are still present, though in a somewhat modified condition. They have
numerous pairs of legs and generally two pairs of antennse (jointed
“feelers”)- Often some of the body segments are fused with the head
to form a cephalothorax.

The Diplopoda (Fig. 3) are land animals breathing by air tubes open¬
ing on the sides of the body and permitting the air to pass in to all the
internal parts of the animal. The head bears a pair of antennae and is
followed by a series of segments all practically alike and each, except

Fig. 4. — Centipede ( Chilopoda ); about three-quarters natural size.

(Original.)

the first three, with two pairs of legs. The reproductive organs open
far forward on the body. In most of the more common members of
this group the body is quite cylindrical and when disturbed the animal
usually curls up in a sort of close spiral. Small Diplopods about the
diameter of the lead of a pencil and gray in color are often found boring
into potatoes and roots in the ground in the fall, and are sometimes
wrongly called wireworms. The common name “millipede” refers to
the large number of legs possessed by these animals.

The Chilopoda are also land animals (Fig. 4). Like the Diplopods
they have antennse; breathe by air tubes, and the body segments are
practically all alike. The general form, however, is rather flattened;
each segment bears only one pair of legs, and the reproductive organs
open at the hinder end of the body. The front leg on each side is modi-

4

APPLIED ENTOMOLOGY

fied to serve as a poison claw. The numerous legs present in these
animals has resulted in their receiving the common name “centipede.”

Fig. 5. — Hairy Spider (Arachnida) ; about
natural size. (Original.)

Fig. 7. — Adult female castor-bean Tick
( Arachnida ); natural size. ( From U. S.
D. A. Farm. Bull. 1057.)

Fig. 6. — Large bodied Spider ( Arachnida );
about natural size. (Original.)

Fig. 8. — Adult female European dog
Tick (Arachnida) ; natural size. (From U. S.
D. A. Farm. Bull. 1057.)

Fig. 9. — Grasshopper (Insecta); with wings spread. (From Folsom.)

The Arachnida (Figs. 5, 6, 7 and 8) generally have the segments of the
body grouped into two sections called the cephalothorax and abdomen.

INSECTS AND OTHER ANIMALS

5

No antennae are present and the eight legs are all attached to the first-
named section. They breathe either by air tubes somewhat similar to
those of the other groups; by sacs containing many thin plates resembling
leaves of a book, whence these structures take the name of book-lungs;
or, in the smallest forms, directly through the body surface. In the
mites there is no evident division of the body into sections. Though
most of the group are land forms, a few are aquatic.

In the Hexapoda or Insects (Fig. 9) the segments of the body are
grouped in three distinct sections; the head, thorax and abdomen. A
pair of antennae is (with rare exceptions) present on the head; the six
legs are attached to the thorax as are the four wings usually present;
the animals breathe by air tubes; and while living under a great diversity
of conditions, the group as a whole is emphatically a terrestrial one,
though in many cases their early life is spent in water.

Distinctive Characters of the Main Arthropod Groups

Where

found

Body divisions

Antenna

I-egs

Breathe by

Reproduc¬
tive organs
open

Crustacea ....

Mainly in
water

Head and body:
often a cepna-
lothorax

Two pairs
generally

Numerous: may
be built for
swimming

Gills or through
body surface
(rarely by air
tubes;

Well forward

Diplopoda. . .

On land

Head and body

One pair

Many: two
pairs on most
body seg¬
ments

Air tubes

Near head

Chilopoda. . . .

On land

Head and body

One pair

Numerous: one
pair on each
body segment

Air tubes

Next to last
body seg¬
ment

Arachnida

Mainly on
land

Cephalothorax
and abdomen
(no divisions
in a few cases)

None

Eight: joined
to cephalo¬
thorax

Air tubes, book-
lungs or body
surface

Front part of
abdomen
(a few ex¬
ceptions)

Hexapoda. . .

Mainly on
land

Head, thorax,
abdomen

One pair

Six: joined to
thorax

Air tubes

Near hind end
of abdomen

CHAPTER II

THE INSECT : ITS EXTERNAL STRUCTURE

Bringing together the facts about insects already stated, we find that
an adult insect is a bilaterally symmetrical animal consisting of a series
of segments one behind another, and that these segments are grouped
into three regions, the head in front, followed in order by the thorax and
the abdomen (Fig. 10). Covering the animal is a skeleton, shell-like in
that it encloses the body, but horny in its nature. Attached to the seg-

Fig. 10. — Side view of Grasshopper with parts named. ( From, Walden, Conn. Geol. &

Nat. Hist. Surv., Bull. 16.)

rnents are three pairs of jointed legs, a pair of antennae, mouth parts and
usually two pairs of wings. It breathes through air tubes, and the
reproductive organs open near the hinder end of the body.

The adult insect does not show all the segments of which its body is
composed. In the embryo evidences of 21 have been found,1 but as the
animal progresses toward maturity some of these fuse with others. The
head of the adult, though apparently consisting of only one segment, is
now believed to be the product of the fusion of six: the three found in
the adult thorax seem to have always been that number; and the abdo¬
men, composed of 12 segments in the embryo appears to have been re¬
duced in the adult to a number varying from three to 11, partly by a

1 Som3 investigators believe that 22 segments are present, the head consisting of
seven, but this view is not universally accepted.

6

THE INSECT : ITS EXTERNAL STRUCTURE

7

ant.

mx.p.

lab.p.

' Ibr

Fig. 11. — Front view of head of a Grass¬
hopper showing a hypognathous head ; ant,
antenna; c. e., compound eye; ch, cheek; cl,
clypeus ;fr, irons; lab. p., labial palpus ; Ibr.,
labrum; md, mandible; mx. p., maxillary
palpus; o, ocelli; v, vertex.

process of fusion, partly by a sort of telescoping or the gradual shifting
of one segment within another until it is partly or entirely concealed.

The skeleton covering the body is generally considered to be a secre¬
tion from the outside living layer of cells, the hypodermis. This secre¬
tion gradually hardens on exposure
to the air, providing the support
necessary for the soft parts within.

Chemically it consists of chitin
(C15H26N2O10), which remains thin
and flexible at the movable joints
and wing articulations, but else¬
where becomes thicker and usually
darker in color. Here and there
over its surface are impressed lines
like scratches, very definite and
fixed in position in most insects,
and these are termed sutures, and
are of great use as landmarks in
description. These sutures have
such an arrangement that in an
ordinary segment of the body its
upper surface has often been re¬
garded as a plate or sclerite, the notum; one at each side, the pleuron;
and one beneath, the sternum. These plates may have sutures sub¬
dividing them.

In the head the sutures are few in number, and only a few plates or
sclerites are generally in evidence. In the thorax they are more numer¬
ous, while in the abdomen often
only a dorsal and ventral sclerite
for each segment are found.
Occasionally the weakly chitin-
ized areas are quite large (queen
white ant) and elastic. Usually
the elasticity of these places, as
for example, the portions con¬
necting the segments, is rather
slight. Spines, hairs, scales or
other structures are often present
on the chitin, sometimes entirely
concealing its surface and its
sutures.

The heads of different insects vary much in form and in the location
of the mouth (Fig. 11). In some cases this is on the underside (see Fig.
10), while in others (Fig. 12) it is practically on the front. Heads with

Fig. 12. — Side view of Beetle ( Lucanus
dama Fab.) showing a prognathous head.
{Original.)

8

APPLIED ENTOMOLOGY

the mouth beneath are called hypognathous: those with it in front are
prognathous.

Structures found on the head are a pair of antennae, the two compound
eyes, ocelli, and the mouth parts. On the thorax are the wings and legs;
and on the abdomen are various organs such as the ovipositor, sting, cerci,
st.yli, etc., present in some cases; absent in others.

Fig. 13<i. — Different forms of insect antennae. (Original.)

Antennae are nearly always present. They are usually slender, jointed
and therefore more or less flexible organs, varying greatly in the number of
segments composing them. They are sometimes very short; sometimes
long; often thread-like; sometimes enlarged near the tip; in many cases
with fine branches either on. one or both sides, so that they resemble
feathers or plumes; rarely they fork; in fact are of
many forms (Fig. 13). Sense organs are present on
them for the sense of touch, and probably also for
smell and hearing, at least in some cases.

The eyes are of two kinds. There is a pair of com¬
pound eyes, each of which is a group of similar struc¬
tures which usually are like tall, slender pyramids in
form. Only the bases of these pyramids show on the
surface, the remainder being within the head. The
bases, closely pressed together, are usually more or
less hexagonal, and their outlines can often be easily
seen with a magnifying glass. They are called facets,
and the eyes themselves are sometimes termed the
facetted eyes.

The other kind of eyes, called ocelli, may be absent,
or if present, may vary in number in different insects,
three being perhaps the most usual. Each, as seen from the surface,
is a nearly circular, convex spot about the size of one of the facets of a
compound eye. It may be larger than this, but is never equal to an
entire compound eye in size. In some cases a cluster of ocelli or of the
pyramids of the compound eyes is found, not closely pressed together

Fig. 136 . — An¬
tennae of Cecropia
Moth. ( Samia ce¬
cropia L.) About
twice natural size.
(Original.)

THE INSECT: ITS EXTERNAL STRUCTURE

9

but somewhat separated, and such groups are called agglomerate eyes.
The chitin of the surface of the body is transparent where it covers
the surface of an eye, permitting access of light to the sensory struc¬
tures within: elsewhere it is usually pigmented and rather opaque.

The mouth parts of insects vary extremely in their structure. Appar¬
ently the original mouth parts were for biting and chewing, and this
type is very common. In some groups, however, they have been trans¬
formed into a sucking apparatus. Biting mouth parts, being the more

Fig. 14. — Three types of insect mandibles, greatly enlarged. Somewhat diagrammatic.

{Original.)

primitive and simple, are described here, while sucking mouth parts
having been differently transformed in different groups will be taken up
in connection with those groups.

In front of (in hypognathous heads), or above the mouth opening
(prognathous heads) is the front lip or labrum. It is a thin flap, hinged
to the skeleton of the head and
moves forward and backward. It
is often more or less divided by a
central notch at the middle of its
free edge. Its inner surface, form¬
ing the roof of the mouth, is often
called the epipharynx.

At the sides of the mouth open¬
ing, immediately behind the lab-
rum, is a pair of jaws, the mandibles.

These differ greatly in form in
different insects (Fig. 14). They
are often stout, heavy structures
with crushing faces bearing blunt
proj ections or teeth ; somet imes they
are long, curved and rather slender.

In general their form is adapted to the feeding habits of the insect.

Immediately behind each mandible at the side of the mouth is a
second appendage, the maxilla. This differs markedly from the mandible,
being much weaker, and composed of a number of pieces (Fig. 15). The
tips and outer internal margins of the maxillae usually bear numerous

Fig. 15. — Two types of insect maxilla
greatly enlarged. Somewhat diagrammatic.
(Original.)

10

APPLIED ENTOMOLOGY

spines or hairs, but this condition varies according to the nature of the
food of the insect. Attached on the outer side of each maxilla not far
from where the latter articulates with the head, is a sort of tiny antenna¬
like structure consisting of from one to six (usually five) segments, which
is called the maxillary palpus. The function of the maxillae appears to be
to hold and retain the food in the mouth while it is being worked upon
by the mandibles, and also to aid these in breaking it up. The presence
of sense organs on the maxillary palpi suggests that these are possibly
concerned with the sense of smell. Both mandibles and maxillae move
sideways.

Fig. 16. — Two types of insect labium much enlarged. Somewhat diagrammatic.

(Original.)

Behind the maxillae and closing the mouth opening behind, is the
hinder lip or labium (Fig. 16). This was evidently once a pair of jaws
somewhat similar to the maxillae, but with no mouth cavity between to
separate them, their inner edges have grown together to varying
degrees in different insects. In some, only one or two of the pieces
nearest the head have fused: in others, fusion all the way to the tip
has been accomplished, and all intermediate stages also occur, thus
producing a structure which now moves forward and backward like the
front lip, but which may be complete, partially, or almost entirely cleft
in the middle line.

Like the maxilla the labium has a palpus on each side arising from
near its base, and composed of three (rarely four) segments. The func¬
tion of these labial palpi appears to be similar to that of the maxillary
palpi.

Near the base of the labium on its inner or mouth side there is fre¬
quently a fleshy swelling more or less covered by bristles or hairs, which
is called the hypopharynx, lingua or tongue. It varies greatly in size
and form.

The thorax has its three segments usually quite clearly marked.
Each segment bears a pair of legs, but the prothorax, or first of the
three behind the head, bears no wings. On the second or mesothorax,
and on the third or metathorax, both wings and legs occur in the majority

THE INSECT: ITS EXTERNAL STRUCTURE

11

of insects. There is a tendency in some groups, carried farthest in the
higher Hymenoptera, for the first segment of the abdomen to consolidate
more closely with the metathorax than with the second abdominal seg-

Fig. 17. — Different forms of insect legs. A, Cicindela sexguttata Fab. (beetle); B,
Nemobius fasciatus De G. (cricket) hind leg; C, Stagomantis Carolina L. (Mantis) fore leg;
D, Pelocoris femoratus P. B. (carnivorous bug) fore leg; E, Gryllolalpa borealis Burm.
(mole cricket) fore leg; F, Canthon Icevis Dru. (a digging beetle) fore leg; G, Phanoeus
carnifex L. (a digging beetle) fore tibia and tarsus of female; H, same, fore tibia of male;
/, Dijtiscus fascivenlris Say, male (water beetle) fore leg; C, coxa; /, femur; s, spine; t,
trochanter; tb, tibia; is, tarsus. ( From Folsom.)

ment, which in such cases is often slender and gives thereby a semi¬
detached appearance to the rest of the abdomen, as though the line of
division between thorax and abdomen were at that place instead of

12

APPLIED ENTOMOLOGY

farther forward. The first abdominal segment when seemingly more a
part of the thorax than of the abdomen is called the median segment or
propodeum.

The three pairs of legs may be quite similar, or differ widely, according
to the uses to which they are put. In running and walking insects they
are usually most similar; but when for example, the fore legs are used
for capturing other insects, their form will depart greatly from that of the
others. The jumping power of the grasshopper is
due to the great development of its hind legs as
compared with its others. Different types of legs
are shown in Fig. 17.

Whatever may be the variations in form and
details of the legs, all are composed of a definite
number of pieces or segments, connected • by hinge
joints so arranged that by combining the motions of
these, a leg can be placed in nearly any position
desired.

The leg (Fig. 18) is composed of a coxa, a tro¬
chanter (two in a few cases), a femur, a tibia and a
tarsus. The last is really not a single segment but
a row of from one to five, small, and on the whole
rather resembling each other.

The coxa is the segment which articulates with
the body, frequently partly lying in a more or less
cup-shaped hollow of the latter. It may be short or
long, is generally freely movable on the body, and
powerful. The trochanter is usually small and may
not be visible on all sides of the leg. It is followed
s f by the femur, generally the largest and stoutest, but

Beetle showing parts. n°t often the longest leg segment. The tibia is in
c. coxa, cl, claws; f, m0st cases quite long, more slender than the femur,

femur; s, spine or , ,, • , , , ,1 • , •

spur; /M5, tarsal seg- and often provided with downwardly projecting

ments; tb, tibia; spines or other structures which are of assistance to

Foisoin.) the insect in climbing plant stems and other objects,

to help prevent slipping. The tarsal segments are

generally rather small, short, tend to be broadest at their outer ends, and

vary greatly in details of structure. At the end of the last a pair of

claws is generally found, and between them a sort of pad or cushion, the

pulvillus. Sometimes there are three of these, in which case the outer

ones are called the pulvilli and the middle one the empodium. Where

the tarsi are reduced to a small number of segments, only one claw may

be present.

The wings are chitinous outgrowths from the body which vary much
in size and form in different insects. Each consists of two delicate

THE INSECT: ITS EXTERNAL STRUCTURE

13

membranes in contact with each other except along certain lines (Fig.
19). Along these lines each membrane thickens and also rises above the
general surface, so that if the two membranes could be separated and
examined from the inner surface, they would appear uniform except for
grooves with thickened sides and bottoms, running here and there.

- - - - n _ Q n,

U TJ v—

Fig. 19. — Diagram of cross-section of an insect wing showing the two membranes
somewhat separated and the ways in which the veins are formed. ( Modified from Wood-
worth.)

When the membranes are brought together again, these grooves com¬
bining form hollow rods which, being stronger than the rest of the mem¬
brane, serve as its support and hold it stiff. These hollow rods are
usually called veins or nerves, though they are nothing of the sort.
The main and largest veins arise at the base of the wing and extend
outward, diverging as they go, and some branch several times before they

/A

Fig. 20. — Diagram of the margins and veins in the wings of moths. A, apex; a. an,
anal angle; c, costa; c.c., closed cell; /, frenulum; i.n, inner margin; o.m, outer margin; v,
vein. {Original.)

reach the wing margin (Fig. 20). Cross veins also occur, connecting the
radiating main veins or their branches. Areas of membrane between
veins are termed cells and where entirely surrounded by veins are called
closed cells. These may be relatively few or many, according to the
number of veins and their branches present. The arrangement and
number of the chief veins and their branches are of importance in
identifying insects.

14

APPLIED ENTOMOLOGY

There is usually a point or tip called the apex, somewhere along the
margin of the wing, though frequently the outline is so rounded that the
exact apex is uncertain. The front margin of the wing from where it
joins the body to where the edge begins to turn backward (in an extended
wing) is called the costa.

Wings are entirely absent in some groups of insects, and it is probable
that these are the direct descendants of the earliest forms, before wings
were developed. In other cases where they are absent this is associated
with a parasitic life where wings might be a distinct disadvantage, or
with peculiar habits which would render them useless or even inconvenient,
and in such cases they appear gradually to have become lost. In the
flies the hinder pair is modified, forming small structures not wing-like,
called halteres.

The abdomen does not usually show great differences in its seg¬
ments except those near the hinder end, which may be modified for
various purposes. Generally a dorsal plate and a ventral plate are the
only two skeletal plates evident in a segment. Small openings, usually
a pair in each, or at least in most, of the segments are the openings of the
breathing organs, and these also occur on some of the thoracic segments
where they are ordinarily less noticeable than on the abdomen.

Fig. 21. — Larva of Georopia Moth showing abdominal legs. Two-thirds natural size.

(Original.)

Legs are very rarely present on the abdomen in adult insects, but are
often found in the earlier stages' (Fig- 21). At the end of the abdomen
in the females of those insects which lay their eggs within objects, is a
combination of pieces known as an ovipositor. It usually consists of
about three pairs of parts, long or short, slender or stout as the case may
be, for the purpose of making a hole or sawing a slit in the object in which
the eggs are placed and in guiding the eggs into the hole thus made. In
one group which has apparently changed its habits and no longer needs
to make holes for egg laying, the ovipositor being unnecessary for this
purpose, has been transformed into a sting.

A pair of many-segmented, antenna-like structures, sometimes short,
sometimes long may occur at the end of the abdomen, and these are
called cerci. They probably serve as organs of touch, and possibly also
of smell in some cases.

CHAPTER III

THE INSECT: ITS INTERNAL STRUCTURE

Few of the internal structures of insects are of any great importance
from the standpoint of control methods, but some knowledge of them
and their arrangement is desirable.

Digestive Organs (Fig. 22). — The alimentary canal extends from the
mouth through about the center of the body to the anus at the hinder
end. In those insects whose food is most concentrated (Fig. 23), it is
in its simplest form and is but little if any longer than the body. In
those which feed on less concentrated food (Fig. 24), the necessity for a
greater digestive and absorptive surface has resulted in an increase
of its length and the accommodation of this within the body by the
production of loops and coils.

Fig. 22. — Diagrammatic longitudinal section of an insect to show the arrangement of the
internal organs. ( After Berlese.)

In the embryo the alimentary canal forms as three separate sections
which connect later. One of these is an ingrowth from the surface where
the mouth is to be; another and similar ingrowth occurs where the anus
forms; and a third forming earlier than the other two, arises as two
masses of cells, one near each end of the embryo, which move inward
and toward each other, unite, and surround the yolk. Later, when this
has been absorbed, a space is left with which the two ingrowths already
mentioned connect, the hollow centers of all three joining to form the
tube through which the food travels. The ingrowth from the mouth is
usually called the fore-intestine, the central portion the mid-intestine,
and the ingrowth from the anus the hind-intestine. The first and last

15

16

APPLIED ENTOMOLOGY

of these begin to grow inward from the surface of the body after that
surface has begun the formation of its chitinous exo-skeleton, and
accordingly also have this power, and line the inside of the parts of the
canal which they form, with chitin. In that portion of the canal termed
the mid-intestine, however, this power does not appear to be present, and
the mid-intestine is without this lining.

Fig. 23. — Alimentary canal of a Carnivorous Beetle, ad, anal glands; cd, stomach;
ed, hind intestine; in, crop; k, head and mouth parts; ce, oesophagus; pv, proventriculus;
r, rectum; vm, malpighian tubes. {Modified from Lang's Lchrbuch.)

The mid-intestine forms the stomach of the adult insect; the
fore-intestine forms those parts of the alimentary canal from the mouth
to the stomach; and the hind-intestine those from the stomach
to the anus. Each of these sections may sometimes have portions
differing in structure, producing a greater or lesser number of subdivisions.
Thus the fore-intestine, by differences of structure, may sometimes con¬
sist of a mouth cavity, oesophagus, crop and proventriculus: the stomach
may develop side pouches or gastric caeca; and the hind-intestine is often
separable by differences of structure into an ileum, colon and rectum.

Lined as these parts are by chitin which often bears rough, tooth-like
projections and spines, some persons have suggested that in insects where
these structures are present in the fore-intestine, the food is masticated
more thoroughly and mixed with digestive juices before it reaches the
stomach. In the stomach digestion is probably completed and absorp¬
tion at least begun, but the length of the hind-intestine in many insects

THE INSECT: ITS INTERNAL STRUCTURE

17

suggests the idea that absorption in those cases has not been completed
when the food leaves the stomach but continues in the hind-intestine.

Opening into the mouth is a tube leading to the salivary glands, which
generally lie in the front of the thorax and appear to have a similar func¬
tion to those in man. In some cases other glands for different purposes
are also present in the head or front of the thorax and open into the
mouth.

sp

It

sp

Fig. 24. — Internal anatomy of the Honey Bee showing alimentary canal, tracheal and
nervous systems, ce, compound eye; hi, hind intestine; hs, honey sac; It, lateral trachea
(enlarged); mt, malpighian tubes; rg, rectal glands; s, stomach; sp, spiracles. ( Modified,
from Leuckart’s Wandtafeln.)

Some of the poisons used in control measures are swallowed by the
insect, passing to the stomach and there are dissolved by the digestive
juices. Thus dissolved, they set up inflammation of the stomach walls
and finally cause death. Poisons acting in this way are called “stomach
poisons.”

Breathing Organs. — Respiration in insects is accomplished by a
method which is nearly unique. The oxygen needed, instead of being

S.

mt.

18

APPLIED ENTOMOLOGY

drawn into lungs and there being taken up by the blood and carried to
the parts of the body where it is needed, as in man, is carried directly
to those parts by a system of air tubes which open along the sides of
the body (Fig. 25). Here the air enters the tubes and proceeds through
them to where it is utilized. The openings by which the air enters are

called spiracles, and these occur in pairs
on some of the thoracic and most of the
abdominal segments, varying somewhat
in number and in position on the seg¬
ment in different insects. The spiracles
often have valves by which they can be
more or less completely closed at will.

Each spiracle opens into a short tube
or trachea which, with the others of
that side, soon joins a similar tube run¬
ning along the side of the body and
quite close to its surface. From these
longitudinal tracheae, branches pass off
in various directions, and in turn branch
again and again until every part of the
body is reached by its air supply. The
tracheae frequently enlarge here and
there, forming so-called air sacs.

The tracheae are lined by chitin con¬
nected with that of the surface of the
body. In these tubes, however, it is
formed with spiral thickenings which act
like a spring, keeping the tracheae open
when not under pressure. There is
probably considerable pressure on them

Img. 25.— Diagram showing ar- indifferent places by the movements of
rangement of the main tracheal tubes .

in an insect, a, antenna; b , brain; Various parts of the body 111 Walking

z, leg; n, nerve cord; P, palpus; s, and other activities, as well as by regular
spiracle; st , branch from main lateral .

trunk, t , to spiracle; v , ventral branch; respiratory movements, and the resulting

vs, visceral branch. ( After Kolbe, temporary variations in diameter aid in
from Folsom.) .

the circulation of air m these tubes.

Not only are the tracheae of use in carrying oxygen to all parts of the
body, but they also receive the carbon dioxid gas produced by the activi¬
ties of the cells and permit it to escape through the spiracles from the
body, thus performing both of the functions which the blood, so far as
gases are concerned, accomplishes in man. Blood then, in insects, does
not (except in a few cases perhaps) have a respiratory function.

The destruction of insects by fumigation is accomplished by the sub¬
stitution of a gas destructive to life, for the air, and this gas enters the

THE INSECT: ITS INTERNAL STRUCTURE

19

spiracles and follows along the tracheae to the living tissues, which take
it in place of the oxygen usually received in this way, and arc killed.

It was formerly supposed that certain materials called contact in¬
secticides which kill insects by contact with their bodies, caused death
by entering the spiracles and closing them up, thus producing suffocation.
This has now been proved to be incorrect.

Insects which in their early stages live in water, cannot of course
breathe air into their bodies through spiracles during that period of their
lives. These are closed in such cases and the animal obtains air usually
through special structures called tracheal gills. These will be described
in connection with the insects which possess them. In a few small
water-inhabiting forms, the chitin covering the surface of the body is so
thin that oxygen present in the water can pass directly through it into
the body and to the parts there which need it, and carbon dioxid passes
in the reverse direction.

Circulatory Organs. — Insects have only an incomplete system of blood vessels.
A tube lies in the middle of the body close beneath the back, beginning near the
hinder end of the animal and extending forward into the head (Fig. 26). In the
abdomen this tube is constricted, forming chambers, and the chambered portion
is called the heart. There is a pair of openings on the sides of each chamber
through which blood can enter, and valves there which prevent its going out
again. The walls of the heart contain muscles and these contract one after the
other, forming a sort of wave of contraction which begins at the hinder end and
travels forward. Blood in the heart, being unable because of the valves, to pass
out at the sides, is pressed forward by this contraction wave, and at the front end
of the heart finds itself in a tube without chambers or valves, called the aorta,
through which it is led to the head where the aorta may divide into a few short
• branches or may be unbranched. In either case, at this point the blood pours
out of it into the body, the system of blood vessels coming to an end. There is
now no definite and particular path for the blood to follow, but it would, in theory
at least, remain near where it escaped from the aorta, or gradually pass into any
spaces it might find unoccupied between the different structures in the head.
With each heart-beat, however, more blood is poured out of the aorta, increasing
the pressure upon that already in the head. It therefore is gradually forced
backward and to other parts of the body, each particle probably taking the path
where there is least resistance to its passage. In this way a general backward
direction is given to the flow.

As it approaches the heart, another influence appears. During each contrac¬
tion of the heart, it occupies less space, which leads to less than normal pressure
near it, and blood close by naturally flows closer to it. Upon its expansion again
and the opening of its valves, the direction of least resistance is now through the
valves and into the heart.

As the blood passes back through the body, a given particle may at one circuit
go over certain organs and at the next, over entirely different ones. All the
internal organs, however, have their surfaces bathed by blood and this as it
passes over the stomach or other parts of the alimentary canal will pick up any

20

APPLIED ENTOMOLOGY

food which having been digested has passed through the canal walls. Likewise
in passing over any organ needing this food, it is given up to those organs. The
blood therefore serves as a distributor of food from the place where it is digested
to all the parts which need it.

We have already seen that the living parts of the body — the cells — need
oxygen, and as the result of their activities give off carbon dioxid gas, but that
this exchange is accomplished by the aid of the tracheie. In a somewhat parallel
way, the cells which need food obtain it from the blood. The cells by their

Fig. 26.- — Diagram showing by the direction of the arrows the general course of the blood
flow in a Dragon fly nymph, a, aorta; h, heart. {Modified from Kolbe.)

activities produce not only carbonic acid gas but also waste material nitrogenous
in nature which must be removed like all wastes, from the body. This nitroge¬
nous waste is picked up at the cells by the blood and carried along , perhaps for
some time before a place to dispose of it can be found. Sooner or later, however,
a particle of blood containing this waste material will wash over certain structures
called Malpighian tubes, to be described in the next section, and the cells which
form these tubes have the power to collect this waste material from the blood as
it flows over them, thus purifying it.

The blood itself is usually a colorless (though sometimes yellowish, reddish or
greenish) fluid, in which are corpuscles resembling the white corpuscles of human
blood. It appears to serve to carry food to the tissues, and waste matter from
them, and therefore has no need of structures in it like the red blood corpuscles
of man, the work of which in insects is done by the trachea?.

THE INSECT: ITS INTERNAL STRUCTURE

21

Excretory Organs. — The organs which eliminate the nitrogenous wastes
from the body and correspond in function to the human kidneys, are
known as Malpighian tubes. These are blind-ended tubes, the walls
of which consist of a single layer of cells surrounding a central channel
which at one end opens into the hind-intestine, usually near its front,
just behind the stomach (Fig. 27). When blood containing nitrogenous
waste matter washes over the outer surface of a Malpighian tube, the
cells of which it is composed have the power of taking this matter out of
the blood into their own substance and passing it through themselves into
the channel between them, down which it moves
until it enters the mid-intestine, from which it
is finally expelled at the anus.

The Malpighian tubes may be few or many;
long or short (see Figs. 22, 23, 24). They show
a tendency to collect in groups and to unite near
the hind-intestine, so that their outlets into this
are much fewer than the number of tubes. It
seems possible that a certain amount of poison
entering the body by way of the stomach can
be eliminated by the Malpighian tubes, which
may explain the varying degree of resistance to
such poisons by different insects.

Nervous System. — The nervous system of insects
is located along the middle line of the body quite
near its under surface (Fig. 22). As in animals Fiq 27.-Portion of the
generally, it is composed of cells and fibres. The Malpighian tube of a fly,
former are for the most part gathered together in greatly enlarged, k, cell
clusters which are called ganglia, and from each of central canal; tr< trache®.
the cells in a ganglion, one or more nerve fibres ( Modified, from Gcgcnbaur.)
pass out, either to connect with some other nerve

cell or with some structure of the body. The larger nerves are really bundles
of these fibres running side by side like the wires of a telephone cable.

Apparently each segment of the insect body once had a nerve ganglion, but
with the fusion of the segments, many of these have also fused, reducing the
separate ganglia in adult insects to a smaller number, which varies in different
kinds. This fusion has been produced by the hinder ganglia moving forward until
in some cases none are found in the abdomen. Different degrees of this are
shown in Fig. 28.

Each ganglion is connected to the one in front and the one behind by one or
two bundles of nerve fibres which are called commissures. Each consists of
numerous fibres and these taken together form the means of communication
between the different parts of the system.

In the head, in front of or above the oesophagus, is the largest ganglion of the
body, called the brain, produced by the fusion of several ganglia. In addition to
its two commissures, which connect it with the ganglion next behind, it has nerves
which lead to the eyes, to the antennae and to other parts of the front of the head.

22

APPLIED ENTOMOLOGY

Below or behind the oesophagus is a second ganglion, also in the head, called
from its position the suboesophageal ganglion. As the oesophagus lies directly
between this and the brain, the commissures connecting the two do not lie close
together, but separate far enough to permit the oesophagus to pass between them.
The suboesophageal ganglion besides being connected with the brain in front,
and the first thoracic ganglion behind it, by commissures, sends nerves to the
mouth parts and other nearby regions of the head.

Fig. 28. — Diagram showing various degrees of concentration forward of four species of
flies. A, of Chironomus plumosus, little concentrated; B, Empis stercorea; C, Tabanus
bovinus; D, Sarcophaga carnaria , most concentrated. ( After Brandt, from Lang's Lekrbuch.)

The thoracic ganglia may be more or less separate or fused and may have fewer
or more of the abdominal ganglia added. Commissures, however, connect all
separate ganglia, and these also send out nerves to all the parts of the segments to
which they belong, no matter what their final location may be. In this way, the
wings, legs, muscles and other parts receive their nerve supply. A small “sympa¬
thetic nervous system” also present, appears to be concerned chiefly with the
nerve supply of the alimentary canal and tracheae.

Sense Organs. — All the more evident senses possessed by man appear to be
present in insects, but not in all cases in the same individual. Thus some cave-
inhabiting insects have no eyes. It is at least probable that insects may have
other senses not possessed by man.

Reproductive Organs. — Insects are of distinct sexes, male and female.
In many cases, however, individuals occur, incapable of reproduction,
their sexual organs not having become fully developed, and such insects
may be termed neuters. Most of these appear to be really undeveloped
females, though undeveloped males are also known. They are found in
colonial insects where division of labor occurs, as in the honey bee, ants,
termites, etc., and are known according to their duties, as workers, soldiers,

THE INSECT: ITS INTERNAL STRUCTURE

23

or by other names. Conventional signs for the various forms of insects
as a convenience, are: cfmale; 9 female; 9 worker.

In the female (Fig 29) the eggs are produced n a pair of ovaries located in
the upper front part of the abdomen. Each is a cluster of ovarian tubes whose
walls are cells. Some of these cells grow and separate from the others to lie in the
central cavity of the tube and then pass downward, growing till they reach its
hinder end, which connects with the similar ends of all the ovarian tubes of that
side to form a single tube called the oviduct. This extends downward and back-

o. s.

Fig. 29. Fig. 30.

Fig. 29. — Female reproductive organs of Honey Bee ( Apis mellifera L.) ; ag, accessoiy
gland; o, ovaries; od, oviduct; pg, poison gland; r, rectum, cut off and end bent back; sr,
seminal receptacle; v, vagina. (Modified from Leuckart's Wandtafeln.)

Fig. 30. — Male reproductive organs of Honey Bee (Apis Mellifera L.) ; ag, accessory
gland; ed, ejaculatory duct; s, spermaries; vd, vasa deferentia. (Modified from Leuckart’s
Wandtafeln.)

ward around the side of the alimentary canal, below which it joins with a similar
oviduct from the other side of the body to form a single duct, the vagina, which
lies below the alimentary canal, and extends backward to its outer opening which
is located in most cases, in front of the next to the last abdominal segment.
Surrounding this opening may be external structures (an ovipositor) for the pur¬
pose of together making holes in some object (the ground, wood, etc.) in which
to deposit the eggs. A side pouch (seminal receptacle) connected with the vagina
is for the storage of the sperms wh ch fertilize the eggs; a gland producing material
which forms the egg shell and is known as the shell gland, also opens into this
portion, and other glands similarly connected with the vagina, may also be
present.

24

APPLIED ENTOMOLOGY

In the male (Fig. 30) the arrangement of the organs closely corresponds to that
in the female. A pair of spermaries or testes is present in the upper front part
of the abdomen, each consisting of a rather closely-coiled mass of tubes, in which
the sperms are produced. The tubes on each side unite to form a single tube,
the vas deferens. These differ from the oviduct usually, in being much longer
and coiled or twisted. They pass downward and backward, however, and unite
on the middle line of the body below the alimentary canal, forming a single tube,
the ejaculatory duct, corresponding to the vagina in position, which leads back¬
ward to an opening in front of the last segment. An enlarged portion of the vas
deferens is often present, for the temporary storage of the sperms, and is termed
the seminal vesicle. Accessory pouches opening into the ejaculatory duct appear
to be in part at least, for the production of mucus and secretions to mix with the
seminal fluid.

CHAPTER IV

THE DEVELOPMENT OF INSECTS

Most insects lay eggs which hatch after a longer or shorter time into
the young. In some cases the egg appears to be retained within the
body of the parent until after it has hatched, and then the young are
produced in a stage able to move about. Insects in which this is true
are termed viviparous, the others being oviparous.

Insect eggs are usually very small ; vary greatly in form, and may be
laid singly or in clusters (Fig. 31). They are covered by a chitinous
shell, the chorion, which often bears markings in the form of ridges,

Fig. 31. — Eggs of various insects. A, butterfly; B, house fly; C, ohalcid ( Brucho -
phagus); D, butterfly; E, midge; F, bug ( Triphleps ); G, bug ( Podisus ); H, Pomace fly.
All much enlarged. ( From Folsom.)

reticulations, etc., and frequently they are also colored. At one place on
the surface is a minute opening or group of openings through the shell,
called the micropyle, believed to be for the entrance of the fertilizing
sperm. The length of time spent in the egg differs in different insects
from a few hours to many months, and in some cases the eggs do not
hatch until the second season after they are laid.

In hatching, the shell breaks and out of it crawls the young insect, in
the majority of cases quite unlike the adult it is to become. In order to
reach maturity it must now grow, and undergo changes in structure and
appearance. These together are expressed by saying that most insects
in order to become adult undergo a metamorphosis. In some of the
simpler insects, a few changes and growth only, are needed to make them
mature, and these are therefore usually grouped together as the Ameta-
bola, or insects having practically no metamorphosis.

25

26

APPLIED ENTOMOLOGY

The remaining insects, from this standpoint, form two groups: those
which on hatching show some resemblance to the adults and reach matu¬
rity by a certain series of changes; and those which on hatching are
totally unlike the adults and attain that condition in a different way.
These groups are known as the Hemimetabola or Heterometabola, and
the Holometabola respectively, these names suggesting the amount of
metamorphosis required for members of each group to become adult.

A member of the group Ametabola, upon hatching, will begin to
feed and grow. Growth, however, is restricted because the insect is
enclosed by chitin which, while elastic to some extent, at least at its
thinner portions, has its limitations in this regard. In some cases the
insect is able to reach its adult size within the chitin, but in other cases
this proves impossible, and a process called molting takes place. This is
begun by pouring out of fluid by the outside layer of living cells, the
hypodermis, between it and the chitin, separating the two. Next a
split in the chitin appears somewhere, usually along the back, and the
insect crawls out of its skin, i.e., molts. It is now soft and unrestricted by
an outer shell and grows rapidly. A new chitinous shell begins to appear
and is completed in a short time (within a day or so) and thereafter only
such growth is possible as the elasticity of the new shell will permit.

In most of the Ametabola, molting as thus described is not usual,
the shell being sufficiently thin to stretch the amount needed for growth
to adult size, though sometimes two or even three molts may occur.
In both cases, however, the reproductive organs appear not to be mature
at the time of hatching, and only gradually become so during the period
following. In a few cases molting seems to occur at intervals throughout
life.

In the Hemimetabola (or Heterometabola) the young insect on es¬
caping from the egg, though resembling its parent to some extent,
must nevertheless undergo many changes in structure and a considerable
increase in size as well, before reaching maturity. Thus a young short¬
horned grasshopper, on hatching, will need to grow to be about ten times
as long before becoming adult; it is without wings, which will need to be
developed; its reproductive organs are not mature and must become so,
and other differences occur. All of . these must be transformed into their
condition in the adult, and to accomplish this, energy is necessary. In
the egg the energy for development had been provided by the yolk:
after hatching the young insect must provide it by gathering food.

The young insect therefore, soon after hatching seeks for food, and
having found it begins feeding. The nourishment thus obtained results
in growth so far as this is possible within a shell which is tightly fitting
and only to some degree elastic. When no further growth in this way
can occur and the body has stored within it all the materials needed for a
greater increase in size, it proceeds to molt in the manner already de-

THE DEVELOPMENT OF INSECTS

27

scribed for the Ametabola. On escaping from its old skin or shell, how¬
ever, besides a rapid increase in size, changes of structure also occur,
so that a difference in appearance now becomes evident. These changes
must be produced quickly, as the hypoderma! cells of these parts, as
well as of all the surface, are producing a new chitinous skin, and when
this has once hardened, no further changes and little further growth are
possible. Molting then, marks the beginning of a brief period — a day,
more or less — of increase in size and of changes in appearance, these last
all being in the direction of making the young insect more nearly like the
adult it is to become. When the new shell has become hardened the
insect resumes its feeding.

After another feeding period the young insect is again confronted
with the same difficulties as before, and it meets them in the same way,
by molting, and immediately thereafter, before its new shell has hardened
it seizes the opportunity to grow and change its appearance further.
Finally, after some molt, full adult size for the insect is attained and all
its organs have also fully developed and matured, producing the adult
insect itself.

Thus the young insect becomes an adult by alternating periods of
feeding, with brief periods of molting, following which growth and change
take place, the total of which produces the adult.

The number of molts and consequent opportunities for change which
occur, varies in different Hemimetabola. There may be only two or
three in some kinds: five is perhaps the average number though more
are not uncommon, and 21 are known to occur in one species.

Certain names for these different conditions are convenient for use.

The feeding periods between the molts (or ecdyses) are called instars,
so that the progress of an insect from hatching to adult is by an
alternation of instars and molts. The insect itself, from hatching until
maturity is generally called a nymph. Figure 32 shows the changes in
size and appearance of a grasshopper after each molt.

With the remaining group of insects, the Holometabola, while there
is a little similarity in the metamorphosis to that in the Hemimetabola,
there are also many differences.

When a young Holometabolous insect hatches, it in no way resembles
its adult. A caterpillar is totally different in appearance from the butter¬
fly it finally becomes: the white grub in the earth is in no way suggestive
of the June bug (May beetle) into which it transforms. Nevertheless
it has to meet the same problems of growth and transformation to the
adult condition as do the Hemimetabola, and uses the same means for
accomplishing the needed results, viz., the utilization of the energy
derived from its food.

Accordingly, upon hatching, in the Holometabola, a feeding period or
instar comes first, followed by a molt and growth. At this point the

28

APPLIED ENTOMOLOGY

story of the metamorphosis differs from that of the Hemimetabola, for
after the molt no change in appearance to make the young insect more
nearly like the adult takes place. It may be different in some regards
besides size, from what it was before the molt, but these differences do not
increase its resemblance to what it finally becomes. This holds through¬
out the feeding period of its existence, so that after three, four or more
molts, a caterpillar is still a caterpilar, a grub is still a grub, and this is
equally true for all Holometabolous insects. Within the insect during
this period, however, changes not perceptible on the surface are taking
place, by the construction of portions of the adult which are forming as

Fig. 32. — Incomplete metamorphosis of a Grasshopper, a, first nymphal instar;
b, second instar; c, third instar showing beginning of wings; d, fourth instar; e, fifth instar;
/, adult. Figures not drawn to same scale. ( Modified from Packard’s Text-book
of Entomology by permission of the MacMillan Company , Publishers.)

buds or ingrowths from various parts of the body, and are termed imagi-
nal buds (from “imago,” the adult). They are closely compacted and
many at least are infolded somewhat like buds, becoming finally ready to
open when the proper time comes. And during its feeding instars, the
larva, as the young insect in the Holometabola is called, is not only
storing energy from its food for its growth at each molt, but also to carry
it on through a period yet to be described, during which it must transform
into the adult condition while unable to feed and obtain the energy needed
for this purpose.

After a varying number of feeding instars and molts, the young
insect or larva has grown sufficiently and has stored within it energy
enough to carry it through the remainder of its changes, and internally
the essential parts for the adult condition have been formed as far as

THE DEVELOPMENT OF INSECTS

29

possible under existing conditions. As the next change will produce an
animal practically helpless in most cases, and unable to protect itself
from its enemies, its next step is to find as much protection as possible.
Accordingly, the full-grown larva usually, though not always, leaves the
place where it has been feeding and elsewhere prepares for its next
change. Many larvse begin this by spinning around themselves a
thread of silk, produced by glands within the body and opening to the
surface on the lower lip. This thread is spun backward and forward and
around the body until it sometimes forms a complete outer covering,
entirely concealing the larva within, from view. This case or cocoon
appears to be protective in its function.

Some larvse go under ground for this change. Here a cocoon, as such,
seems unnecessary, but after digging into the earth a few inches, the
insect forms a little earthen chamber or cell in which to lie, and generally
lines this more or less densely with silk, probably to keep the eart hen walls
from falling in and crushing it. A larva transforming in tunnels in wood
where it has fed, may make a partial cocoon with more or less of the
chewed-wood fragments mixed in. One staying above ground but not
in tunnnels or otherwise protected, will spin more or less of a cocoon
as already described.

The completeness of the cocoon, however, varies greatly with differ¬
ent insects. Instead of being a thick, dense wrapping which entirely
conceals the insect, it may be so scanty that the animal within can be
seen to some extent. In other cases it is merely a sort of network, in no
degree giving concealment; and in still others, a few scattered threads to
hold the insect in place are all that represent it. Sometimes hairs from
the body of the larva, held together by silk, form most of the cocoon,
and in the case of butterflies, only threads enough to attach the hinder
end of the body at the place where it is to transform, and to form a
supporting loop around its middle, the ends of the loop also being fastened
to what it rests on, are produced. In some flies the larva shrinks within
its larval skin and transforms, this skin, now called a puparium, function¬
ing like a cocoon (see Fig. 33c).

The reason for such variations in a structure presumably formed for
the purpose of protection, can only be guessed at. Possibly in the course
of generations, some insects found less need of this than others and gradu¬
ally reduced it, thereby saving the vital energy so much needed for trans¬
formation, which would otherwise be expended in cocoon making.

Whether the larva forms a dense or scanty cocoon, or none whatever,
the next step in the process is a molt. When the insect escapes from this
skin, however, a great change in its appearance is evident, and it is now
called a pupa (Fig. 33a and b ). In a general way it may be said that it
has at this one molt changed more than half way to its adult condition.
This is due in part at least to the unfolding of the imaginal buds already

30

APPLIED ENTOMOLOGY

referred to, which contribute largely to form the new surface of the body
in which head, thorax and abdomen are evident, as are also the antennae,
legs, stubs of wings and other adult structures. Many of the internal
organs of the larva though, were necessary for use till the last moment
before it became a pupa. Then too, the arrangement of the muscles,
in the larva, would not be that needed by the adult. Accordingly, most
of the internal organs now gradually break down, losing all their earlier
form and structure, and new ones to meet the needs of the adult are con¬
structed to take their place.

a b c

Fig. 33. — Different types of pupation, a, pupa obtecta of a moth; b, pupa libera of a beetle;
c, puparium of a fly. a and b about natural size; c much enlarged. (Original.)

During this breaking down and the reconstruction period, the pupa
is practically helpless in most cases, hence generally the need for the
protecting cocoon or earthen cell it constructs.

When the structure of the adult insect has been completed, another
molt takes place, the pupa skin splitting and setting free the insect. If
it was enclosed in a cocoon it now produces a fluid which sufficiently
softens the silken threads so that it can push its way out and it escapes or
“emerges.” It is now soft, its wings are only partly expanded, as in
most cases there would be no room for full-sized wings in a pupa, and
because of its reconstruction there is considerable waste matter in its
body. The insect crawls upon whatever it may find to hold on to, expels
the waste matter, and its wings begin to grow rapidly. Drying out also
takes place and in a short time (a few hours) the adult thus produced is
in every way fully matured.

To summarize the differences in metamorphosis of the three groups it
may be said that in the Ametabola the insect hatches from the egg prac¬
tically in an adult condition, i.e., there is little or no metamorphosis. In
the Hemimetabola the insect hatches from the egg in a form somewhat
resembling the adult but much smaller. It becomes adult by alternating

THE DEVELOPMENT OF INSECTS

31

periods of feeding with molts, at which times growth and changes bringing
it nearer to the adult occur, the last molt completing the growth and adult
structure. In this life history we have a change, but as there was a
resemblance to the adult from the start, the change to it (metamorphosis)
is only an incomplete or partial one.

In the Holoinetabola the insect hatches from the egg in a form totally
unlike the adult, and while feeding periods followed by molts and growth
give increase in size, no external evidence of any changes making the
insect more like the adult can be found. These changes are largely made
after the end of the feeding and growing periods during a pupa (generally
quiet) stage, in which the breaking down of the larval, and construction
of the adult structures is completed. The difference between the larva
on hatching and the adult is so great that an entire change (complete
metamorphosis) takes place.

It should be evident from the foregoing that when the adult condition
is once reached, little if any growth is possible (except in rare cases)
and that the belief so common, that “big flies grow from little flies,”
is without any basis of fact.

The nymphs of the Hemimetabola appear not to have attracted
sufficient attention to have received any special common names. In
the Holoinetabola the larvae of various groups differ greatly in appear¬
ance; many are large and noticeable and some of them have, as a result,
received special names. Larvae of butterflies and moths are commonly
called caterpillars; those of beetles are usually called grubs; those of
flies are called maggots. Larvae found boring in wood, however, whether
they will become moths, beetles or other insects, are uniformly called
borers.

In the Hemimetabola then, the stages of life are: egg, nymph, adult ;
in the Holoinetabola they are: egg, larva, pupa, adult. Whether or not
the pupa is enclosed by a cocoon depends upon circumstances.

CHAPTER V

LOSSES CAUSED BY INSECTS : NATURE’S CONTROL METHODS

To ascertain how much man loses by the attacks of injurious insects
is a difficult task. The destruction, either partial or entire, of his crops
both growing and in storage; of household goods and of food; of our
forests and of the wood cut therefrom; injuries to our domestic animals
and their products: these and other injuries can be more or less accurately
estimated. But when we consider the attacks upon man by disease¬
carrying insects, resulting in loss of time from productive labor, or even
by death, and the actual costs connected with illness, the problem
becomes extremely complicated, and to determine how much financial
loss this country suffers from insects is a matter for the economist as
much as the entomologist.

Much of this loss we fail to appreciate, never having had a season
free from the attacks of insects which might serve as a standard for
comparison. If we could once have such a year entirely insect free,
however, the difference would at once force itself upon our notice.

Crop Losses. — Careful studies of the crops injured by insects have
now extended over quite a term of years, and the general conclusion
reached is that in an average year with no unusual attack, a crop will
generally produce only about nine-tenths as much as would probably
have been the case had insects not been present. When an outbreak
occurs, this will decrease production below that point, and instances
are far too frequent where for a single crop of some kind, production has
been only 20 or 30 per cent of the normal, and many cases are on record
where in some localities the destruction has been complete.

This estimate covers field crops; destruction of forests and forest
products; attacks on domestic animals and their products; articles in
storage; on shade trees, shrubs and ornamental plants; on farm wood
lots which are not included with the forests; on household goods and foods.
With fruit and truck crops the destruction and injury is believed to be
more than one-tenth generally.

Health Losses. — A number of serious diseases of man are due to
insects which serve as carriers of the disease-producing organisms.
Among these are malaria, the typhoid, typhus and yellow fevers, and the
bubonic plague, besides others of less importance. Illness with any
of these diseases means that the patient is not only unable to work but
is an actual cause of outlay for nursing, treatment, and possibly death
expenses also. With hundreds of thousands of illnesses from these

LOSSES CAUSED BY INSECTS. NATURE'S CONTROL METHODS 33

diseases each year, the loss of time from productive labor is, of course,
very large, and the country is that much poorer than it should be. Death
puts an end to any further production by those concerned, and here
also is a loss to the country. It has been estimated that the loss of
labor by sickness and death, caused by malaria alone, is at least $100,-
000,000, and by all insect-borne diseases is over $350,000,000 each year
in the United States.

In addition, there are many places in this country where the soil
is rich and would pay well if cultivated, but where man cannot live
under existing conditions because of the presence there of insects and
the diseases they carry.

Difficulties in Estimating Losses. — To fix a monetary value for all
this destruction and injury, however, is a difficult problem, so many fac¬
tors enter into it. It cannot be denied that insect attacks result in a
direct reduction of wealth to the country as a whole; that whatever food
material has been consumed by insects is not available for consumption
by the people, is self-evident ; and that if on account of a resulting scarcity
of any food the consumer pays more for it, he is thereby paying toward
the cost of the ravages by the insects. The producer of this food though,
may because of the reduced amount available, be getting as much or even
more than he would have received had insects not destroyed any of it. In
other words, while the destruction of any crop caused by insects is cer¬
tainly a loss to the nation as a whole, those fortunate individuals who suc¬
ceed in raising that crop may receive as much or more for the amount they
did produce than would otherwise have been the case. On the other hand
the man who starts to raise such a crop and loses a large percentage of it
by insect ravages, may not have a sufficient amount left to repay him
even at the higher prices, for his expenses.

It is evident then, that insect ravages while meaning a loss to the
country as a whole, may also mean either a loss to producers, a normal
profit because of a higher price on what part of the crop they have been
able to save, or even a better profit, due to higher prices than could other¬
wise have been obtained.

No crop producer can as yet foretell whether he in any given year will
be one who will lose, receive a normal return, or do better than usual on
any of his crops. He can only be prepared for insect attacks if they come,
and save all he can by proper methods of protection and repression, know¬
ing that the vast majority of the people will do little or nothing in this
line and that in consequence he will be among those losing least; will have
proportionally more to sell, and that he will therefore receive the benefit
of any higher prices coming from a reduced production.

Against what he will gain in this way must be offset the cost of his
protective and control measures. If these are too expensive he will gain
nothing, but in most cases their cost is small as compared with the value

3

34

APPLIED ENTOMOLOGY

of the product saved, and such measures used with judgment represent
one of the cheapest and most successful forms of crop insurance.

It is certain that the time will never come when protection of crops
from insect ravages will ever be so universal and successful that to produce
crops will not pay, for with our increasing industrial population to be fed
the demand is more likely increasingly to exceed the supply, even though
every crop producer should finally come to the protection of what he raises,
from insects. At present the farmer who adopts modern methods against
insect injuries is certain in any term of years to raise more and to sell at
higher prices than one who trusts to chance or “luck” in this phase of his
industry.

Figures on Losses. — From the above it becomes evident that no
accurate figures as to the losses caused by insects can be given. We can
only recognize that everything produced which is destroyed by these pests
is thereby lost to the country as a whole, even though some individuals
may profit. To value this destruction we have only the prices for which
crops sell, as a criterion, and the point has already been brought out that
if the tenth destroyed had been saved, the price of the whole might have
been no greater than it was for the nine-tenths actually produced. Tak¬
ing this unreliable standard, however, in order to get some slight idea of
the amount of destruction ordinarily caused by insects, we may bring
together the following statement, based on the average value of the crops
for the five years 1913-1917 as given in reports of the United States
Department of Agriculture and from other sources.

Field crops . $833,660,000

Animals and their products . 431,450,000

Forests, forest products and materials in storage . 300,000,000

Loss by human disease and death . 350,000,000

Farm wood lots . 100,000,000

Extra losses on fruit and truck crops . ?

Shade trees and ornamental shrubs and plants . ?

Household goods and foods . ?

Altogether, if we may accept figures based on the assumption, as has
been indicated, that if no losses had occurred the value of the whole
would be at the same rate as the actual price for what was obtained, it is
safe to estimate the loss in the United States due to injurious insects as
being not far from two billion dollars each year. How nearly correct this
is, however, no one can tell, so many factors enter into the problem.

Causes of Increased Injury. — Losses to crops, forests and other mate¬
rials are increasing, for several reasons. Before the settlement of this
country there were, of course, native insects attacking the various plants
growing here. When settlements were established new plants were intro¬
duced by the settlers and grown in greater abundance than if they were

LOSSES CAUSED BY INSECTS: NATURE'S CONTROL METHODS 35

wild and scattered. An insect finding in any of these a food acceptable
to it, would at once also find a more abundant supply, and a rapid multi¬
plication would become possible, resulting in their increase to injurious
abundance. A second factor has been the introduction of many insects
from foreign countries. In the United States such forms have sometimes
entirely failed to maintain themselves. Unfortunately, as has more fre¬
quently happened, they have found all conditions favorable to a rapid
increase, unchecked by their enemies which in most cases have not also
been brought to this country with them. A third factor has been that
with the increasing occupation of this country, much of its wild bird life
has either been destroyed or has been driven away from the neighborhood
of man. Many insect feeders among birds, once quite common, must now
be sought in remote woodlands and thickets, and rarely show themselves
near settlements. Some kinds have adjusted themselves to the new
conditions and among these may be mentioned the robin, chipping
sparrow, blue bird and a few others. But to too great a degree the insec¬
tivorous birds are becoming either fewer in number or afraid to visit the
settled districts where cats and people are numerous, even though in such
places the gardens and trees may be thickly populated with insects.

With modern agricultural methods distinctly favoring a rapid in¬
crease of insects by providing an enormous acreage of a single crop;1 with
an addition to our worst native pests of at least as many more from other
countries, which have escaped their enemies by coming here; and with
our birds becoming less effective in their work, it is only natural that losses
by the attacks of insects should be great and increasing in importance.

Control by Natural Methods. — In countries undisturbed by man
and his industries it is probable that destruction or serious injury from
insect attacks would usually be rather small, particularly in a series
of years. The saying in Physics that “Nature abhors a vacuum ”
seems to be paralleled in Biology by the paraphrase, “Nature abhors
extermination.” Accordingly, insects appear to be more or less com¬
pletely held in balance by natural factors, some of which may be briefly
considered here.

Plants of various kinds form the food of most of the insects which
we regard as pests, and in a country entirely under natural conditions,
plants of any one kind are liable to be more or less scattered, no large
number being close together. Under such conditions a search for the
proper food plant is necessary to an insect as a preliminary to egg-
laying, and in many instances these may be too scarce to provide for all
the insects. In any case, where the food supply is scanty, an insect

1 As an example of this, apple orchards containing thousands of trees are now
common. It is stated that one year in a single valley in California, there were three
wheat fields each containing over twenty thousand acres.

36

APPLIED ENTOMOLOGY

species feeding wholly on that kind of plant will be more rare than where
its food is abundant. If, on the other hand, there is an abundance of
the food plant, there is a greater probability of the survival of more of
the insects. But this brings its disadvantages. Increase in the number
of the insects will result in more food being needed, and finally this will
become insufficient and will be followed by the failure of many to find
food, death resulting. In this way a balance may be finally secured,
though it will not be permanent, the process being repeated in the
subsequent years.

Weather conditions are also a factor in Nature’s control. Some
insects find in a wet season conditions favoring the survival of a large
proportion of those which appear, while for others such a season produces
heavy mortality. A severe winter with many and marked fluctuations
of temperature may put an end to the rapid increase of some species
which because of preceding favorable winters, has been becoming more
abundant. Other meteorological factors also enter into the subject of
insect control.

Birds and other animals which feed on our insects must also be con¬
sidered in this connection. When insects acceptable to these animals are
abundant, more will be eaten and in any case many will be destroyed in
this way. Where insectivorous birds have an abundant food supply
more will survive, which will result in more individuals to be fed. Thus
an abundance of insects may lead to a corresponding increase in abun¬
dance of their enemies.

Parasites and diseases play their part too in this competition. The
more abundant an insect becomes, the more food is thereby available
for its parasites, and fewer of these will fail to find an insect to attack.
Finally the parasites may become so numerous that practically all the
insects of the kinds they attack will be found and killed. The next
generation of parasites following this, will, of course, consist of many
more individuals than the one preceding, but now so many of their
food insects or “hosts” have been killed in producing them that there are
practically none left, and most of these parasites die for lack of food.
Thus, under these conditions, a sort of “balance of Nature” develops,
and though the scales may tip first to one side and then to the other,
this balance is usually preserved if periods of a number of years at least,
are considered.

But when man with his many lines of activity appears in the field,
introducing and raising millions of plants of the same kind in small
areas, instead of scat tering them here and there, thus furnishing enormous
quantities of food for insects; and when he brings in many pests from
foreign countries, no matter how unintentionally, which in their new
home are not beset by the foes present in their native land; and when

LOSSES CAUSED BY INSECTS: NATURE’S CONTROL METHODS 37

his manner of life is such as to drive away birds which might be valuable
aids in his struggle against pests, the situation changes rapidly for the
worse.

Those who look on the bright side are confident that in time Nature
will reestablish a balance, and this is probably true. But Nature works
in centuries, and man cannot wait so long for results.

Under these conditions artificial measures as contrasted with natural
ones must be taken if crops are to be raised, food obtained, and if health
is to be preserved, and these artificial methods for the control of injurious
insects need to be known, and the nature of their action understood.

CHAPTER VI

ARTIFICIAL METHODS OF CONTROL

It has been indicated that Nature has methods for the control of any
continued undue abundance of insects, by a resulting scarcity of food;
by weather conditions; by insectivorous birds, and other animals; by
parasites and diseases; and probably in other ways also. But it seldom
pays to wait for the results so obtained, as they generally require a num¬
ber of years for completion, and measures which may be termed artificial,
inasmuch as they are used by man, also have their value.

These measures may be divided into two groups, viz., those which
aim to establish conditions unusually favorable to the plants or un¬
favorable to the insects; and those which attempt either to poison or
otherwise directly kill the insects. In some cases perhaps, a given treat¬
ment might seem to belong as properly in one of these groups as in the
other, but in general the line of separation is quite distinct.

Whatever the method and its effectiveness may be, there is always
the cost of using it to bear in mind. When this cost is greater than the
loss would otherwise probably amount to, it is evident that little will be
gained by treatment, except that in such cases possibly, omitting it for
this reason one year may result in such an increase of the pest as to pro¬
duce serious results the following season. In other words, treatment
costing more than the probable loss may sometimes pay as a sort of in¬
surance. In general, though, in every case where insect attack occurs,
the estimated cost of the treatment should be weighed against the
probable loss without it, in deciding whether to treat or not.

GENERAL FARM PRACTICES

These are chiefly methods for raising crops which distinctly increase
their vigor and growth or remove conditions favorable to insects.
Healthy crops, clean culture, the rotation of crops, late or early plowing,
and the time of planting are the chief farm practices which belong here.
Special methods for particular cases, directed more with reference to the
insects than to the handling of the plants, such as hand picking, the use
of repellents, burning insects, heat, trap lanterns, etc., may also be in¬
cluded here, leaving the measures dealing with insects by the use of poisons
and by fumigation for later consideration.

38

ARTIFICIAL METHODS OF CONTROL

39

Healthy Crops. — In the majority of cases a vigorous, thoroughly
healthy plant is not only better able to withstand insect injury but is
also less liable to attack than one enfeebled or not thriving for any reason.
Thorough cultivation, the use of fertilizers and the removal or repair of
injured or diseased parts or plants as soon as these appear, will aid
greatly in insuring the desired results.

Clean culture is also an important factor. Weeds not only interfere
with successful crop growth but may in some cases at least, consume
plant food in the soil which might otherwise be utilized by the crop,
thus reducing its vigor, and in addition they provide wintering places
for many insects. Rubbish left on a field after the harvest often serves
the same purpose: insects frequently find protection during the winter
in tall grass too often left surrounding the trunks of fruit trees, and
many serious pests winter close to the ground in grass fields. Decaying
fruits and vegetables harbor insects and should be composted. Weeds
should therefore be killed and burned and the grass kept down in or¬
chards. Burning over grass fields in early spring in the Northern states at
least, choosing a time when the dead growth is dry enough to burn while
the living parts of the grass are still so wet as to be uninjured by the heat
is often a valuable way in which to destroy many pests which winter
there. Clean culture in all its forms, not forgetting fence-line and road¬
side growth will do much to reduce loss by insects.

Crop Rotation. — The rotation of crops often has an important bearing
on insect control. Any crop attacked by a particular species of insect
should not be followed by another, either of the same kind or by a differ¬
ent one which is also fed upon by that species of insect. How far this
principle can be carried out in practice, however, is a different matter.
To break up sod land and plant corn for the first crop is merely to follow a
mixture of grasses with a single kind of a grass and from the standpoint of
insect control at least, is unwise. It is the usual practice though, and
how far it would be wise to depart from it, planting beans, buckwheat or
perhaps potatoes instead, is a question, though these last-named crops
would be much more likely to be free from insects. The entire subject
of crop rotations which are satisfactory from the standpoint of agri¬
culture and are also correct when insect problems are considered, is still
in a far from settled condition, and needs prolonged investigation.

Plowing.— Many serious pests winter in the ground. Fall plowing
after they have formed the cells in which they pupate or winter, as the
case may be, will break many of these and remove the protection they
give: eggs laid in the ground will often be buried so deeply that the larvae
if they hatch in spring will be unable to reach the surface. Similarly,
thorough cultivation in the summer, where it is possible, besides being
good for the crop, has an injurious effect on insects there.

In some cases early fall plowing gives the best results : in others, late

40

APPLIED ENTOMOLOGY

fall is the best time. Sometimes disking with a harrow can be done
where plowing cannot, and is of value.

Time of Planting. — This is sometimes of importance as a protection
against pests. Thus, in general, wheat sown after September 20 will
escape the attacks of the Hessian fly : early planting will often give
cotton an opportunity to obtain the greater part of its growth before the
boll weevil has progressed far in its ravages, particularly if early maturing
varieties of cotton are planted. It follows from this that, a choice of
the variety to plant is also often of importance, and insect-resistant
varieties of our various crop plants and trees should be selected as far as
any are known, if they are otherwise satisfactory. The “ bugless potato,”
while perhaps non-existent, expresses an idea which should be kept in
mind, and resistant varieties of plants should be watched for and
preserved.

Trap Crops. — In some cases trap crops can be made use of to advantage.
A small patch of kale planted in the fall, or of mustard planted early in
spring will attract the Harlequin cabbage-bugs as they leave their winter
quarters, and on these they can be destroyed, as they seem to prefer
such plants to the young cabbages. Several similar cases are also known
where trap crops work well.

Hand Picking. — In some cases, where the pest is large, easily seen,
or not present in large numbers, hand picking is the easiest method of
control. Egg clusters are often of such a color, size, or have such notice¬
able features that they are not difficult to find, and the convenience of
destroying several hundred eggs at a time, as compared with killing the
same number of insects after the eggs have hatched and the young have
scattered, is evident. Larvae feeding in groups together are also often
most easily destroyed by hand picking.

Repellents. — Inert materials, such as air-slaked lime, flour, or even
fine road dust, thickly spread over plants will, in certain cases, act as
repellents, driving insects elsewhere to a greater or lesser degree. Car¬
bolic acid, naphthaline, oil of citronella, and other materials having an
objectionable odor act as repellents to some insects.

Trap Lanterns. — These have been quite extensively tested, but have
failed to be as successful as was expected. Though many insects are
attracted to such lights, the greater number are found to be beneficial,
while of the injurious kinds a large number have already laid their eggs
and are therefore no longer of any importance, and most of the serious
pests are not attracted at all. On the whole it is doubtful if the use of
trap lanterns ever pays.

Burning Insects. — Gasoline torches for burning egg clusters, cater¬
pillars, scale insects, etc., on trees, have also been tried, but the time
necessary to kill the insects in this way is often long enough to injure
the tree where the blast hits it, and this method must be regarded as at

ARTIFICIAL METHODS OF CONTROL

41

least exposing the plant treated, to the risk of greater injury than that
caused by the insects.

Heat. — Heat can sometimes be used to advantage for the destruction
of insects. A temperature of 125°F. is enough, if maintained for 3 or
4 hr., to kill insects infesting grain, seeds, etc., and also almost all house¬
hold pests at least. Where heat can be applied in this way, therefore, it
is a special method of control of considerable value.

Miscellaneous Methods. — Borers in trees present particular difficul¬
ties, being so hard to reach, and cutting them out by hand is frequently the
best control method. Protective coverings over or around plants may
sometimes be used to advantage, as for example, netting over young
cucumber and squash plants. Sticky bands placed around the trunks of
trees keep insects which cannot fly from crawling up to the leaves.
Pieces of bark or boards on the ground near plants, under which insects
may crawl for protection at night, as some do, are good traps for such
insects, if these traps are visited early in the morning and the insects
destroyed before they scatter again for the day. Burlap bands around
tree trunks attract many caterpillars as being good hiding places during
the day. These and numerous other special methods for the control of
insects are made use of, many being based on some peculiarity of habits
of the special pest for which they are used.

Still other methods will be considered later, in connection with the
insects against which they are used.

In order to make proper use of the above methods of Farm Practice,
a clear understanding of the life and habits of the insect to be controlled,
must be had. Failure in this might easily lead to doing just the wrong
thing.

The control of insects is at the present time very unequally developed
for different crops. Naturally the insects of those which are most
valuable have been most carefully studied, those of less importance
having been given much less attention. Fruit and market-garden crops
have a high value and the insects which attack them have been carefully
investigated, though the area they cover is very small as compared with
the wheat acreage of this country, for example. Trees, bushes or other
plants, whether growing alone or in rows with cultivated land or grass
surrounding them are accessible as units on which to work, but a 10-acre
field of clover, wheat or any other crop, is a totally different proposition.
The former can be reached in all its parts by a spray or other treatment:
a wheat plant in the middle of a field may need treatment but to reach
it would probably cause a greater amount of injury than would be saved
by the treatment.

Field crops and particularly grain crops therefore, present distinct

42

APPLIED ENTOMOLOGY

problems, and here Economic Entomology and Practical Agriculture
have failed to work as closely together as should be the case, and our
present methods for controlling field crop insects are less effective than
with most others.

The same thing is true with our forests. The shade tree can be
sprayed if that is a desirable treatment, but the spraying of forests even
if practicable from the standpoint of expense, is frequently impossible
because of the nature of the ground on which the forest stands, density of
growth and other factors, and other and more indirect methods of insect
repression then must be resorted to.

CHAPTER VII

INSECTICIDES IN GENERAL: STOMACH POISONS

Though the farm practices and special methods outlined in the pre¬
ceding chapter are of great importance for the control of insect pests
in many cases, they are ineffective and cannot be made use of in many
others. Under these circumstances other methods of attack must be
resorted to, and in general, insecticides of various kinds, fitting the
particular nature of the injury and of the insect causing it in each case,
have proved successful. Insecticides are substances which may be
placed upon a plant, or elsewhere, to be eaten by the insect and which
when eaten, kill the insect; or materials which on coming in contact with
the body of the insect, kill it as a result of that contact. Poisonous
gases and vapors would also be included as insecticides, as thus defined.

CLASSES OF INSECTICIDES

The materials used as insecticides fall into two general groups: (1)
Those which are placed upon the food eaten by the insect, swallowed
with it, and which upon entering the stomach are dissolved, producing
inflammation and finally death. Such poisons can, of course, be used
only for insects with chewing mouth parts which bite off and swallow
solid food, such as pieces of leaves, stems, etc.; (2) Those which, when
they come in contact with the body of an insect either enter the spir¬
acles and penetrate their chitinous lining and kill the tissues beyond;
or which corrode the body; deprive it of oxygen; or by softening the
coverings over the body (scale insects) cause these to adhere to the
plant it is on, killing the insect in any case. The materials of the first
group are usually called stomach poisons; those of the second, contact
insecticides. The latter could also be used for biting insects but the
difficulties in the way of their being successfully applied are such that
stomach poisons are used whenever possible.

In reaching the insects concerned, either with stomach poisons or
contact insecticides, the methods of conveying the material to where
the insect is, and of an even and thorough distribution of it are important.
Those substances which are solids in the form of fine powders can be
blown onto the tree or whatever the insect may be on, but some are
liquids. Accordingly, “powder guns” for spreading the poisonous
dusts have been used with considerable success, and pumps with a fine
nozzle at the end of a line of hose are used for the liquids.

43

44

APPLIED ENTOMOLOGY

With stomach poisons, however, the poison is not necessarily eaten
by the insect as soon as it falls on the plant, but must or should remain
there for some time, as the insects may appear during a period of several
days or even weeks. During this time much, probably most, of the
poisonous dust would be blown off and the treatment be of little value.
In spite of this difficulty, much successful work has been done with dry
stomach poisons, and they have many advantages over sprays under
certain conditions.

It has been found that when stomach poisons are mixed with water
and sprayed onto plants in the form of very fine droplets, the spray
appearing like a fine mist, each droplet soon dries, leaving behind it
the poison it contains, adhering to the leaf, where, unless washed off by
rain, it will remain a long time. This has led to the general adoption of
spraying, both with stomach poisons and contact insecticides, despite
certain difficulties which have developed.

STOMACH POISONS

Arsenic is the basis of nearly all the commonly used stomach poisons,
for though probably more than 50 materials have been tested, only a
few have proved at all satisfactory, and with two or three exceptions,
useful only under special conditions, they have all been arsenical com¬
pounds. It would seem natural under these circumstances to use
common white arsenic (As203) as the stomach poison, it being, when
pure, 100 per cent arsenic (arsenious oxid). But it is found that arsenic
dissolves to some extent in water, and that thus dissolved it destroys
(“burns”) the places on the leaves on which it falls. This result is as
bad for the plant as it would be to have the leaves eaten, for the object
of spraying is to prevent injury or loss of leaf surface. Because of its
solubility in water, therefore, arsenic, as such, is not employed as a spray,
but combinations of it with other materials, not, or only very slightly
soluble, have been selected for use instead. This produces another diffi¬
culty. A combination with lead can be obtained for example, which is
almost absolutely insoluble in water and therefore entirely safe for use
as a spray. But in this material only about one-quarter of it is arsenic,
so that an insect, speaking in a general way, would be obliged to eat
about four times as much before being poisoned, as would be the case had
the material been arsenic instead. By the use of more or less insoluble
combinations of arsenic* with other substances, then, reduced injury to
the foliage can largely be secured, but a larger leaf surface is consumed by
the insect before the poisonous dose is obtained. This is a small matter,
however, as compared with the protection of all the foliage on a tree from
injury by the spray.

Another difficulty in the use of sprays is the weight of the poison
mixed in and carried by the water. It has just been pointed out that

INSECTICIDES IN GENERAL: STOMACH POISONS

45

the poison must not dissolve, or burning of the foliage will result. The
poison, instead, must be suspended in the water, which acts merely as a
carrier from the pump to the plant over which it distributes the poison.
This distribution should be as uniform as possible in order that all parts of
the plant may be equally well protected and covered. If the poison be
heavy, settling quickly to the bottom of the pump, uneven distribution
will result, some parts of the plant receiving too much of the poison while
others will get but little. The best stomach poison from this standpoint
therefore, is one which is so light that after mixing it with water it will
take a long time to settle to the bottom.

The chief stomach poisons now in use in the United States are Paris
green, Arsenate of lead, Arsenate of lime, Hellebore, and Sodium fluorid,
the last two having only a limited application. Standard formulas for
these are given below. Variations from them will be found in connection
with the special cases where change from the standard is desirable.

Paris Green. — This was probably the first stomach poison used against
insects, having been first employed about 1868 for the treatment of the
Colorado potato beetle. Chemically, it is a combination of copper,
arsenic and acetic acid, containing when pure, nearly 60 per cent of arsenic,
which is high as compared with the other arsenicals in use, and this gives
the substance its chief value.

Paris green has three serious disadvantages. One of these is that
some of the arsenic will dissolve in the water it is mixed with, causing
injury to the foliage. This can in part be avoided by the addition of lime,
which combines with any of the arsenic that separates from its combina¬
tion with the copper and acetic acid and would cause burning, converting
it into arsenite of lime which is only slightly soluble under such circum¬
stances. Sometimes though, a slight burning takes place, even under
these conditions. By Federal law, not over 3 per cent should be soluble.

A second disadvantage is that Paris green is a heavy substance,
settling quickly through the water to the bottom of the pump, which
results in an uneven distribution over the plant.

The third disadvantage is that it does not adhere well to foliage, being
easily washed off by rains. This means that more frequent sprayings are
necessary for the protection of the plants than would otherwise be the
case, involving greater cost for material and labor.

A standard formula for Paris green is:

Per Barrel Per Gallon

Paris green . Y lb. Y teaspoonful (level)

Quick lime . 1 lb. 1 teaspoonful (level)

Water . 50 gal. 1 gal.

Use fresh stone lime, slaking this in some of the water: work up the Paris
green to a paste in a little of the water: add the lime slaked, to the rest of
the water, then stir in the Paris green paste. It is not advisable to mix

46

APPLIED ENTOMOLOGY

this long before it is to be used, nor to mix more than will be used the
same day.

Although the addition of lime to the Paris green reduces the danger
of injuring foliage, some plants even then, are liable to be burned some¬
what. Accordingly, the amount of the poison to use per barrel will vary.
Thus, for potatoes the Paris green can usually be increased to \L2 lb. per
barrel, while for the peach it is not safe to use more than }/§ lb. It
should not be used on evergreens.

Applied as a dust it is usually thoroughly mixed with flour, plaster or
air-slaked lime, in about the proportion of 1 part of the Paris green to
from 6 to 10 parts of the other, by weight.

Paris green is unsafe to apply on stone fruit foliage, and because of the
danger of burning in general, it is now less used than was once the case,
arsenate of lead having largely replaced it as a spray.

Arsenate of Lead. — The value of this material as a spray against insects
was discovered about 1892 in the course of the work conducted by the
State of Massachusetts on the control of the gypsy moth, and it has now
been generally adopted as being, under ordinary conditions, the best
stomach poison to use. Two forms of it are available: the basic or neu¬
tral (ortho) arsenate, Pb3(As04)2 and the acid arsenate, PbHAs04. In
pure condition the former is about 25 per cent arsenic oxid and the latter
about 33 per cent. The latter is the form in most general use, but on the
Pacific Coast, because of local conditions, the former appears to be re¬
garded with more favor.

Arsenate of lead may be obtained both as a paste and as a powder.
By law the paste must not be more than half water, but with about this
amount present the percentage of arsenic oxid in it is reduced to from
12 or 13 to 19 or 20 per cent. In the powder, water being practically
absent, about 32 to 33 per cent is arsenic oxid. As the average in the
paste is usually 16 per cent and the price of the powder is about double
that of the paste, there is little choice between the two so far as the arsenic
is concerned. The Federal law requires that in the paste no more than
0.75 per cent of the arsenic oxid shall be soluble in water.

Either form of arsenate of lead shows well on the foliage, which is
useful, enabling the sprayer to see parts he has missed in spraying, and
to “touch up” those places. It is also very light, settling slowty in the
pump. Under most conditions arsenate of lead does not burn the leaves,
being in fact, the safest of the stomach poisons in this regard, and it
adheres to the leaves longer than the others (stomach poisons). On
the other hand, it acts slowly on insects because of its rather low arsenic
content

As a pound of the paste is approximately one-half water, it is necessary
in spraying a given area to use twice as much (by weight) as of the
powder, in order to supply equal amounts of the poison.

INSECTICIDES IN GENERAL: STOMACH POISONS

47

A standard formula for arsenate of lead is:

Per Barrel Per Gallon

Arsenate of lead paste . 3 lb. 3 teaspoonfuls (level)

Water . 50 gal. 1 gal.

Arsenate of lead powder . lb. teaspoonfuls (level)

Water . 50 gal. 1 gal.

In mixing the paste it is well to add some water and stir thoroughly
before adding the rest of the water, in order to get a more uniform mix¬
ture. If it is allowed to dry it will not work up well thereafter by adding
water, and it is also injured by freezing.

Arsenate of Lime. — This substance has come into use since about
1914, because of the rapidly increasing cost of arsenate of lead. It
is Ca3(As04)2 and may be obtained, like arsenate of lead, either as a paste
or a powder. The former contains about 18 per cent of arsenic oxid,
and the latter about 44 per cent, thus being slightly higher in paste form,
and considerably higher in powder form, than arsenate of lead. As the
costs of the two forms differ correspondingly, there is little choice between
them from this standpoint, but convenience and other factors give a slight
preference to the powder. Being stronger than arsenate of lead, less
needs to be used in order to supply an equal amount of poison to a given
area.

Arsenate of lime is not safe for use on foliage, and particularly that of
stone fruits, unless an excess of lime is present. Accordingly, as was the
case with Paris green, lime must be added to the mixture.

A standard formula for arsenate of lime is:

Per Barrel Per Gallon

Arsenate of lime paste .

. 2

lb.

IK teaspoonfuls

Quick lime .

. 2 to 3

lb.

2 teaspoonfuls

Water .

. 50

gal.

1 gal.

Arsenate of lime powder .

. H

lb.

teaspoonfuls

Quick lime .

. 1

lb.

9 teaspoonfuls

Water .

. 50

gal.

1 gal.

The quick lime, which should be fresh stone lime, is slaked in some of
the water, then added to the rest, and the arsenate of lime thoroughly
stirred in.

While this material is cheaper than arsenate of lead and perhaps
kills a little more quickly, it has not been in use long enough to be certain
just what results may be expected in all cases. At least it may at the
present time be termed a very promising insecticide.

Poison Baits. — These are included here, as, in most cases at least,
they contain an arsenical poison. They are used mainly for the control
of cutworms and grasshoppers. There are several formulas proposed,

48

APPLIED ENTOMOLOGY

but those consisting of bran or horse manure, poisoned with arsenic or
Paris green, and made attractive to the insect by adding strong-smelling
molasses (syrup) and the juice of citrus fruits, have in general been the
most successful. Detailed consideration of them will be given in con¬
nection with the insects for which they are used.

Hellebore. — This is the powdered roots of the plants Veratrum
album and Veratrum viridis. It is a mild stomach poison and can
therefore be used with safety to man, on plants soon to be gathered for
food, as it loses its strength quite quickly on exposure to the air. It is
sometimes difficult to obtain fresh.

It may be dusted over the plants, sticking on best if applied while dew
is on them, or it may be mixed with from one to three times its bulk of
flour or plaster, for this purpose. It may also be used as a spray by
steeping an ounce in a quart of water and then adding another quart of
water. At the rate of half a pound in 10 gal. of water it is effective against
house-fly maggots in manure piles. It is too expensive to use except on a
small scale.

Commercial Sodium Fluorid. — This substance has recently been found
to be effective for some insects, acting apparently both as a stomach
poison and as a contact insecticide. It is applied as a dust, either
pure or mixed in about equal parts, with flour or plaster. Details are
given in connection with the insects against which it is used.

CHAPTER VIII

CONTACT INSECTICIDES

For insects which do not feed upon solid food, stomach poisons are
useless, and sprays which come in contact with, and kill them in one or
another of the ways already indicated, must be used. This is unfortunate
for it means the most thorough kind of work if all the insects are to be
reached by the spray. It is among such insects too, that the greatest
difficulties in accomplishing this, occur. Some, though large enough to be
almost certainly reached by the spray have a particularly thick outer
shell: others are exceedingly small and thus can find protection under
buds, in crevices of the bark and in other places where the spray may not
reach them: still others form protective coverings (scales) over them¬
selves, which fit tightly to the objects they may be on, so that a successful
spray must be very strong and penetrating: and finally, many of the
smallest and also of the scale-protected insects have marvelous powers of
increase, so that if even a single individual escapes treatment, a few
days or a week or two will find the plant again swarming with these
insects.

Every insect therefore, which can be killed by a stomach poison is
best controlled by such materials. For the others, oils, soaps, nicotine,
sulfur compounds and a few other substances of minor importance serve
as contact insecticides.

Considering the oils first, there are several which are of use. Among
mineral oils, crude petroleum and kerosene are destructive to insect life
but so dangerous to plants when of full strength, that some method of
dilution becomes necessary.

Kerosene Emulsion: standard formula:

Common laundry soap . 3*2 Ik-

Soft water . 1 gal.

Kerosene . 2 gal.

Dissolve the soap in the water (best by shaving it into hot water) :
then add the kerosene and with a small hand spray pump having a fine
nozzle, draw the mixture into the pump and out through the nozzle back
into the dish from which it was drawn. In a few minutes it should
become creamy and then begin to thicken. When it has become so
thick as to go hard through the pump, this process has been completed,

49

4

50

APPLIED ENTOMOLOGY

giving a Stock Solution in which the oil, broken up into very tiny droplets,
will not run together again and the water can dilute the mixture. For use
against soft-bodied insects, 1 part of the Stock Solution is mixed with
about 9 parts of water to spray, while for tougher insects, 1 part is diluted
with 4 or 5 parts of water, though this strength may sometimes injure
the plants somewhat. The Stock Solution, if well prepared, should keep
before breaking down (shown by a film of oil appearing on the surface)
for at least a month or two. If the materials fail to thicken in the pump
it is probably because the water is “hard water.” In that case add a
little borax or soda to soften it.

Crude Petroleum can be used in place of kerosene in preparing this
emulsion, provided the right grade can be obtained, but this is often
difficult, and so is not frequently done.

Miscible Oils. — These are stronger than kerosene emulsion. They
contain mineral oils, a small amount of vegetable oil, naphthaline in
some cases, some alkali, and water. Properly made they dilute readily
with water.

A number of brands of miscible oils are on the market, prepared
mainly as sprays for the control of scale insects. For winter use against
scales they are generally diluted at the rate of 1 part of the oil to 12
to 14 parts of water. When used in summer against plant lice the dilu¬
tion should be about 1 part to 35 to 40 parts of water.

The material should not be used if free oil stands on it, as this shows
that it has broken down and is not safe on the plants. If sprayed on trees
in freezing weather it may gather and freeze in cracks of the trees, in¬
juring them. It is easy to handle and spreads readily from where it
strikes, covering more than would otherwise be the case, but it has been
claimed, with considerable evidence to support it, that repeated treat¬
ments with miscible oils cause a cumulative injurious effect on trees.

Among soaps, common laundry soap and whale-oil (generally fish-oil
now) soap are the usual materials used as insecticides.

Whale-oil Soap. — This is a soap made by combining fish oil with an
alkali, preferably potash. It is usually diluted at the rate of 1 lb. to 5
or 6 gal. of water to apply against plant lice and similar soft-bodied
insects in summer, but is also a fair winter application for scale insects,
at the rate of 2 lb. per gallon of water, though more costly than other,
equally good materials.

Common Soap.— This is a fairly good material at the rate of 1 lb. in
3 to 5 gal. of water for summer use against plant lice and other soft-
bodied insects but is not as effective as whale-oil soap and is mentioned
only because the latter cannot always be obtained.

Nicotine. — This is an alkaloid which occurs in tobacco. It can be
obtained by soaking tobacco stems in warm water till a dark brown liquid
containing nicotine is obtained, and this is of some value as an insecticide.

CONTACT INSECTICIDES

51

Tobacco dust is also used around plants as an insect repellent as well as a
fertilizer.

Nicotine obtained as above indicated, is variable in its strength and
the amount it should be diluted for use is uncertain. It is also quite
volatile and this is a disadvantage when it is used as a spray. Com¬
mercial nicotine compounds on the market avoid these difficulties by
supplying a material containing a fixed percentage of nicotine combined
with sulfuric acid, known as nicotine sulfate 40 per cent. This can be
diluted to the proper strength with accuracy, and does not pass off into
the air rapidly. Nicotine uncombined, of the same strength, can also
be obtained, but shoidd be used for fumigation and not as a spray.

Nicotine sulfate is an excellent material to use for plant lice and other
delicate insects. It is generally diluted at the rate of 1 gal. to 800 or
1,000 gal. of water, and in some cases a greater dilution even, than this is
possible. Sometimes dilution at the rate of 1 to 500 is desirable.

Standard formula for nicotine sulfate 40 per cent, 1 part to 800 of
water:

Per Barrel Per Gallon

Nicotine sulfate, 40 per cent . ^2 pint 1^ teaspoonfuls

Soap . 2 to 3 lb. 1 oz.

Water . 50 gal. 1 gal.

Three-eighths of a pint in 50 gal. of water, or 1 teaspoonful in a
gallon, gives nearly a dilution of 1 to 1,000. The addition of soap
causes the material to spread more and adhere better.

Among the various sulfur compounds, those with lime have thus far
been found to be the most successful.

Lime-sulfur Wash. — This is prepared by boiling lime and sulfur
together in water. Several substances are produced by this boiling,
but apparently its insecticidal value is determined by the quantity of
calcium polysulfids (CaS4 and CaSs) and possibly the calcium thiosulfate
(CaS203) which are formed in the mixture. The wash can be made at
home but it is generally easier to buy it in concentrated form and dilute
as needed. It will vary in specific gravity in different cases, and its
reading must be taken (a Beaume hydrometer is generally used for this
purpose) in order to dilute it properly. The range in readings of differ¬
ent lots may vary as much as 5° or more, but is usually about 33°Be.
Thus, a sample of this density should have 6 x/± gal. mixed with 43 gal.
of water to be of the proper strength for use as a winter spray for the
San Jose Scale, when this insect is dormant; while if its density is 30°Be.,
7 gal. should be mixed with 43 gal. of water. Tables of density, Beaum6
readings, and the amount of concentrate to add to water to make a total
of 50 gal. of spray, both for winter use and as a foliage spray in summer,
can be obtained by applying to any state experiment station or to the
U. S. Bureau of Entomology.

52

APPLIED ENTOMOLOGY

The Lime-sulfur wash is used both as a strong spray against insects
during their dormant season, and as a weaker one for general purposes
during the summer. In the latter case, besides being a contact insecti¬
cide, it has a little value as a stomach poison. It cannot safely be used
on stone fruits or potatoes, however.

This material must be kept in air-tight containers as it decomposes
on standing when exposed to the air. A film of some vegetable oil over it,
for partly filled containers, will give this protection. It should not be
allowed to freeze.

For stone fruits where a summer treatment seems necessary, self-
boiled lime-sulfur may be used. This is. prepared by slaking 8 lb. of
fresh stone lime in a barrel, in enough water to nearly cover it. Eight
pounds of fine sulfur should be gradually added to this, as soon as the
lime begins to slake, running the sulfur in through a sieve to break up any
lumps. This mixture should be constantly stirred and more water
added to form first a thick paste, then gradually a thin one. The heat
produced by the lime in slaking will cause the mixture to boil for several
minutes. When slaking is at an end, cool the mixture rapidly by adding
considerable water, then strain into the pump to remove lumps of lime,
but working any lumps of sulfur through the strainer; then dilute with
water to a total of 50 gal.

Dry Sulfur Compounds. — These substances have recently appeared
in competition with the lime-sulfur wash, the advantages claimed for
them being ease of handling, reduction of shipping charges, no deteriora¬
tion on standing, and equal efficiency at lower cost.

These substances are sulfid combinations with either potassium,
sodium, barium or calcium. The amount of sulfur present varies greatly
in different brands. They do not contain as much of the polysulfids
which appear to be the actual insecticides of the lime-sulfur wash as the
liquid wash, and even the amount of sulfur present in them, after the
addition of water according to directions, is less than in an equal quantity
of the wash, so that basing efficiency on the amount of sulfur, regardless
of its form, the amounts of these dry materials would have to be greatly
increased to equal that of the wash, and would therefore seriously increase
their cost. At the present time their value cannot be considered as
having been finally settled though in many cases field tests of them have
given good results. Continued studies and tests of these materials are
needed to determine their real value.

Sulfur. — This substance in the form of a very fine powder, can be
dusted over plants for the destruction of red spiders and other mites,
or it may be made into a paste with soapy water, using 10 lb. of sulfur
and 2 lb. of soap in 50 gal. of water, and applied as a spray Its use is
rather limited and its actual value somewhat questionable in many cases.

CONTACT INSECTICIDES

53

Pyrethrum, Insect Powder or Buhach. — This is made by grinding
up the blossoms of certain plants, which contain an essential (and volatile)
oil effective against insects but not injurious to man. Its use is mainly
limited to small areas, and best, those which can be tightly closed.

Various other materials will be considered in connection with the
particular insects, for the control of which they are used.

CHAPTER IX

INSECTICIDES AND FUNGICIDES: FUMIGATION

COMBINATIONS OF SPRAY MATERIALS

The greater part of the cost of spraying comes from the time and
wages of the workers, the materials used being rather inexpensive in
comparison. Wherever it is possible therefore, to make two or three
applications at once by using combined sprays, the cost is much reduced.

Frequently there are cases where the application of a stomach poison
for chewing insects and of a contact insecticide for sucking forms, can
be made at about the same time. Treatment for fungous diseases may
also be desirable, and a satisfactory mixed spray for all three purposes
can often be given. Certain precautions must be taken in mixing sprays,
however, as in some instances the materials of two or more sprays, when
combined, will undergo changes, producing substances injurious to the
plant or affecting the value of the spray for the purpose for which it was
intended.

No spray material containing soap should be combined with one con¬
taining lime, as when these materials are brought together, a calcareous
and insoluble soap is formed. Thus, when nicotine sulfate is used with
lime-sulfur or Bordeaux mixture, the soap usually added to the former
must never be put in. Arsenate of lead and compounds containing
sodium or potassium sulfid, when mixed, produce sodium or potassium
arsenate which is very soluble and will injure foliage, so this combination
should also be avoided.

Bordeaux mixture, a fungicide, combines well with most of the insec¬
ticides except those containing soap, but as it contains lime, an insec¬
ticide with soap is not safe for this combination. In most cases the
Bordeaux mixture ready for spraying can be regarded as an equivalent
amount of water, to which to add the insecticide. For example, in
combining Bordeaux and arsenate of lead, simply add 3 lb. of the paste
to 50 gal. of the Bordeaux.

Bordeaux mixture will safely combine with any of the arsenical
poisons given in this book, and also with nicotine sulfate if the soap
be omitted. Lime-sulfur at summer strength may be used with arsenate
of lead or nicotine sulfate, leaving out the soap, though in the former
case a decomposition is liable to take place which reduces the value
of the material. Lime-sulfur at winter strength when added to the

54

INSECTICIDES AND FUNGICIDES: FUMIGATION

arsenate of lead brings about a decomposition, as a result of which con¬
siderable soluble arsenic is formed, and the efficiency of the lime-sulfur
is also reduced about one-third. This may be avoided, however, by
slaking 5 lb. of quick lime and adding this to the lime-sulfur before putting
in the arsenate of lead.

Lead arsenate can be combined with nicotine sulfate, and in some cases
at least, with kerosene emulsion. With soap, acid lead arsenate decom¬
poses to some extent forming a soluble arsenate which is dangerous on
foliage. Small amounts of soap added as a “sticker,” however, are often
advantageous even in spite of this decomposition and are frequently
recommended, the gain by the addition of the soap being greater than
a small injury by burning.

FUMIGATION

In theory, fumigation is the best method for the control of insects.
A gas will reach every portion of a room or a plant, penetrating where no
spray can reach, so that insects no matter how well concealed in crevices,
under bark or in other locations, will be reached. Still, practical diffi¬
culties in the use of poisonous gases are numerous and result in a restricted
use of this method of treatment.

The gases used for the destruction of insects act either as actual
poisons which enter the body through the tracheal system and directly
attack the tissues, or combine with the oxygen of the air and thus remove
it from availability by the insect, which suffocates in consequence. In
either case, successful fumigation depends upon the liberation of a suf¬
ficient quantity of the gas or vapor to make it strong enough to kill the
insect.

This at once eliminates trees, bushes and crops growing out of doors
from consideration, unless they or their products are so valuable as to
make the use of gas-tight tents to cover them during treatment worth
the expense, which is considerable. Accordingly, fumigation is generally
made use of only with citrus trees, and in houses, greenhouses or other
places capable of being tightly closed. Under the conditions mentioned,
however, it is an excellent method for insect control, though where plants
are to be fumigated, it is usually done at night as the gases or vapors are
less liable to cause injury then.

The fumigants most often used are carbon disulfid, nicotine, sulfur
and hydrocyanic acid gas.

Carbon Disulfid (CS2). — This is obtained in liquid form but becomes
a gas on exposure to the air. Impure grades are as good for fumigation
as the purified article. The number of cubic feet in the space to be fumi¬
gated is calculated, and in general from 10 to 20 lb. of the disulfid
are used for each 1,000 cu. ft., though if the place is very tight, less than
this will be needed. As the gas is considerably heavier than air, the usual

56

APPLIED ENTOMOLOGY

practice is to put the liquid in rather flat dishes close to the top of the
place to be fumigated, as the gas will develop more rapidly in such dishes
and work downward from its source. All openings into this place must
then be tightly closed at once and everything be left undisturbed for from
24 to 48 hr. Ventilate well from outside before entering.

The chief disadvantage in the use of this gas is that it is quite inflam¬
mable and cannot be used near where there is a fire or highly heated pipes
of any kind. In such quantities as the operator is likely to inhale while
using it, a headache is generally the most serious result, though persons
with heart trouble of any kind should not work with it as it has some effect
on that organ.

Carbon disulfid is used chiefly against clothes moths, carpet beetles,
stored grain pests, pea, bean, and other seed pests, ants, and borers in
trees. It cannot safely be used in greenhouses or with plants. Details
of its uses in different cases will be given in connection with the different
insects concerned.

Nicotine. — Nicotine as a vapor may be obtained by evaporating the
decoction of it mentioned in the last chapter, in a dish over a lamp, but
the uncertainty as to its strength makes treatment in this way liable to
prove unsatisfactory.

Nicotine 40 per cent, both in liquid form and as paper rolls saturated
with it, are on the market and supply a material of known strength with
which to work. It is of value as a treatment for plant lice and other
delicate insects. A fluid ounce added to a little water, and this evapo¬
rated by heat will be sufficient for about 1,000 cu. ft. of space, provided the
place is quite tight; or four or five sheets of the paper are usually enough.
Upon lighting, the paper smolders, giving off the nicotine vapor. The
length of time necessary for nicotine treatment varies with different
insects, but is generally begun in the evening, continued all night, and
the place opened and aired the next morning.

Sulfur. — The value of sulfur as a fumigant is probably due both to its
combination on burning with the oxygen of the air, eliminating this and
suffocating the insect, and to the formation in this way of a poisonous gas.
It is prepared by burning powdered sulfur in the place to be fumigated,
and is used for household pests and also in greenhouses between crops.
It cannot be safely used with living plants. From 1 to 2 lb. of sulfur per
1,000 cu. ft. of space is the usual quantity used. Polished metal surfaces
in the place to be. fumigated will become tarnished by the gas, and these
should be removed, as well as colored goods which are bleached by it.
Metal can be protected by covering it with vaseline.

The general practice is to place a large iron kettle on bricks to keep
it off the floor, which in that place should be covered for a distance of
several feet with something which will not be injured or burned if the
sulfur spatters over. In the kettle place the sulfur and add to it a little

INSECTICIDES AND FUNGICIDES : FUMIGATION

57

denatured alcohol to insure burning: then light the sulfur and keep the
place tightly closed for 24 to 48 hr.; then air thoroughly.

Hydrocyanic -acid Gas (HCN). — This is one of the most powerful and
dangerous gases known, and persons having had no training in its use are
advised not to try it. It is produced by the addition of sodium or potas¬
sium cyanid to sulfuric acid which has been diluted with water. Formerly,
potassium cyanid was used almost entirely but now the sodium cyanid has
taken its place. Care should be taken that the cyanid is of good quality
and (at least for use with plants) contains no chlorine. If potassium
cyanid is used it should contain 38 per cent of cyanogen : if sodium cyanid,
51 to 52 per cent. The sulfuric acid should have a specific gravity of 1.83
and be free of any nitric acid.

Hydrocyanic-acid gas can be used to advantage in the following ways:

(a) For household and storehouse pests and for fumigating bales of
imported cotton.

( h ) For greenhouse insects.

(c) For insects on dormant nursery stock.

( d ) For insects on citrus trees.

For the first class, an ounce of sodium cyanid for every 100 cu. ft. of
space is used, and at least 2 hr. of fumigation is necessary.

For greenhouse insects the dose is )4 1° M oz. of sodium cyanid for
every 1,000 cu. ft., with a fumigation period of % to 1 hr. This treatment,
at a temperature of about 65°F. and a low percentage of atmospheric
moisture, should be given only after dark. Some of the more delicate
varieties of plants may be somewhat injured by this, but in all probability
much less than by the continued attacks of the insects. The plants
should be dry (not watered recently) at the time of treatment.

Dormant nursery stock should be treated with % to 1 oz. of sodium
cyanid for every 100 cu. ft., fo'i* 1 hr. The stock should not be wet nor
very closely packed.

For the fumigation of citrus trees during their dormant or most
nearly dormant season (October to January) % to 1)4 oz. of sodium cya¬
nid should be used for every 100 cu. ft. of space for a period of % to 1 hr.
The value of good citrus trees is such that gas-tight tents are made and
used for fumigating them.

In using potassium cyanid, one-fourth more should be taken as the
dose than indicated above.

Before treating any place to be fumigated, determine the number of
cubic feet in the place and weigh out the proper amount of cyanid. Tak¬
ing this quantity as the unit from which to determine the amounts of
sulfuric acid and water for this dose, measure out 1)4 times as much of
the acid in fluid ounces and twice as much water, also in fluid ounces.
Thus if the space to be fumigated calls for 4% oz. (by weight) of the
cyanid, 6% fl. oz. of the acid, and 9 fl. oz. of water will constitute the

58

APPLIED ENTOMOLOGY

dose. With potassium cyanid the proportions of the materials differ
somewhat from this, being 1 part of the cyanid, 1 part of the acid and
3 parts of water.

Granite-ware dishes, without flaws exposing the metal, are excellent
containers for this work. They should be considerably larger than are
needed to hold the dose, and for large areas it is often desirable to divide
this among several containers. First, place the proper amount of water
in the container; then add the acid slowly to avoid spattering and the
production of too much heat; lastly, drop in the cyanid, which it is desir¬
able to have loosely wrapped up in tissue paper in order to gain a mo¬
ment’s time in getting out before the gas begins to be given off freely.

Great care must be taken to leave the place instantly after adding
the cyanid to the acid and water, and at the end of the fumigation period
there should be a thorough airing for at least a quarter of an hour before
entering. If there are windows, these should be opened from the outside
only, and under no circumstances should the operator enter too soon.

CHAPTER X

THE RELATIONSHIPS OF INSECTS

Classification may be defined as the orderly arrangement of different
objects into groups. Any articles can be classified in one way or another:
chairs for example, can be brought into groups according to the kinds of
wood of which they are made; or whether they are upholstered or not;
or according to their price, and any of these might be equally useful.
With living things, however, the problem becomes one of a “natural”
as opposed to an “artificial” classification.

It is now the general belief that the first animals were extremely
simple in structure, and that in the course of generations (and centuries)
variation in their descendants led to the production of different forms,
and finally to all the multitudes of kinds now in existence. This devel¬
opment has often been pictured as a tree, the trunk representing the
original animals, which, varying as individuals of the same kind always
do, began after a time to show several distinct lines along which the
variation took place. This would be represented in the tree by the lowest
branching of the trunk. Each main limb under the influence of the same
conditions would fork in its turn, perhaps into two, perhaps more, and
this process repeated again and again would finally produce the ter¬
minal twigs — the present animals. Thus each twig would represent all
the individuals of the same kind; i.e., a single species; those nearest it
the other species most closely related to it; and those on another part
of the tree, though species and also related, would only be distantly so,
and of course, quite different.

A natural classification of animals therefore, is an attempt to express
the actual relationships of the animals, placing nearest each other those
most closely related. To do this, the total of their differences and re¬
semblances must be taken into account. Classification based on a single
character then, is almost always unreliable. The division of insects into
three main groups based on their metamorphosis, is an example of this,
for while it is entirely correct as a statement of facts, a classification
using this character would bring near together many insects which in
reality are only distantly related.

The largest limb of the animal tree represents the original insects,
not because they were so numerous at first, but because they now form
such a large part of animal life. This limb is usually called a Class,
while the still more comprehensive groups considered in Chapter I are
called Phyla. These are the main divisions of the tree. In this, case
the Hexapoda is the name given to the insect class.

From all the evidence available, the original insects were at least

59

60

APPLIED ENTOMOLOGY

comparatively small, wingless, and with practically no metamorphosis.
After a time many of their descendants began to develop wings, and a
fork of the Class was produced, one branch (or Subclass), the Apterygota,
apparently retaining much of its former character, while the other sub¬
class became the Pterygota or winged insects. These have increased
greatly in abundance, and their variations have resulted in the produc¬
tion of many branches passing outward toward the twigs, named in
sequence, Orders, Families, Genera and Species. Intermediate branch¬
ings between these often also need recognition and are called Suborders,

Mecopfera-.
Hyrmnoptera \

Homopl'era-

Hzmipfc

Anoplura--.

MalIophaya-->
Corrodeniia -■

Hexapod a

Phzrycjoia -•

Apterygota

Diptem.

Siphonapiera

Lgoidoptera
Trichoptera

Neuroptera

i Streps! ptera
Coleoptera

Derma pie ra

Ernbiidina
Pkcophra
Odonaia
Dphemerida

Thysanura

Collembo/a

Fig. 34. — Diagram suggesting possible relations of the orders of insects to each other,
expressed in a tree-like way: the Hexapod limb.

Superfamilies, etc., as may be necessary. The twigs each represent a
single species, but here we may recognize subspecies, varieties, races, etc.,
among which the individuals which together constitute the species, are
distributed.

In any consideration of the different groups of insects one must
necessarily follow after another through the book, and when four groups
for example, are equally near relatives, the first and fourth treated may
thereby appear more distant than is really the case.

Between the fork of the insect limb which produced the Apterygota
and the Pterygota, and the twigs representing the species, the actual

THE RELATIONSHIPS OF INSECTS

61

divisions of the branches are more or less uncertain. The species in
general, group themselves quite easily into different genera and these
into families; but while these last can in most cases be definitely placed
in their orders, their correct relation to each other is often debatable.
The relation of the orders to each other is far from settled, and while
some are evidently more closely allied than others, within certain limits
one order could follow another in almost any sequence without any serious
loss to the expression of relationships. Where orders appear to be closely
allied to each other, this will be indicated in connection with their
consideration.

With the relations between the orders and also the families within
the orders, still uncertain in many cases, a tree showing these must of
necessity express only the views of the individual who drew it. Such a
tree carried to the species would be entirely too large for these pages
(there are about 80 families of beetles, and many of the other orders have
large numbers also), but one carried to the orders is given here (Fig. 34)
to illustrate the general idea of a tree-like classification.

Expressed in tabular form, the classification followed in this book
is given below.

Class Subclass Order Suborder Common Name, or Examples

Apterygota / Thysanura . Silver fish, etc.

\ Collembola . Snow fleas, etc.

Hexapoda

Ephemerida . May-flies

Odonata . Dragon-flies

Plecoptera . Stone flies

Embiidina . (No common name nor

examples)

Orthoptera . Roaches, grasshoppers,

crickets, etc.

Isoptera . Termites or White ants

Dermaptera . Earwigs

^ , , / Rhynchophora . . . Snout beetles

Coleoptera < „ . ,

( Coleoptera vera . . I rue beetles

Strepsiptera . Stylopids

Thysanoptera . Thrips

Ptervgota ( Corrodentia . Book lice; Psocids

Mallophaga . Bird lice (biting)

Anoplura . Sucking lice

Hemiptera . True Bugs

Homoptera . Scales, plant lice, leaf hop¬

pers, etc.

Neuroptera . Corydalis, aphis lions, ant

lions, etc.

Trichoptera . Caddis flies

T . , ( Heterocera . Moths

Lepidopteraj jjhopa]ocera Butterflies

Mecoptera . Scorpion flies

Diptera . Flies

Siphonaptera . Fleas

Hymenoptera . Saw flies, ichneumon flies,

ants, wasps, bees, etc.

CHAPTER XI

THE APTERYGOTA

These are all relatively small insects, some being nearly microscopic
in size, while the largest are seldom more than an inch in length. They
are all land animals though a few live near the ocean and are occasion¬
ally found in tide pools. They are widely distributed over the earth,
some living in arctic conditions while others occur in the tropics, but
nearly all at least, require a somewhat humid atmosphere.

In this group the mouth parts seem to be typically of the chewing
type. In many cases they are as much exposed as in most insects, but
in some they appear to have been drawn into the head so that when not
in use they are almost entirely concealed. Under such conditions they
are often so slender as to be no longer of value for chewing, and are
possibly used for rasping and sucking food.

Some Apterygota have traces of abdominal legs ("vestigial legs”).
Spine-like appendages, attached to the hinder margins of some of the
abdominal segments beneath and called styli, may also occur. A
ventral tube present in some Apterygota on the underside of the first
abdominal segment may be simply a small projection partially divided
into two, or it may be highly developed into two slender but delicate
tubes which can be extended to a considerable distance. Its use is not
known.

Bringing together these facts, the Apterygota may be characterized
as:

Wingless insects having the mouth parts either exposed and of the chewing
type, or drawn into a cavity within the head where they are sometimes so
slender as to be of no value for chewing but could possibly be used for sucking.
In those with exposed mouth parts, more then one pair of styli is present on
the back margins of the hinder abdominal segments: in those with mouth
parts drawn into the head, styli, a ventral tube or traces of abdominal legs
are present.

Very few of the Apterygota are of any importance from an economic
standpoint, but they are of much interest, being .the simplest insects
known and throwing some light upon the subject of the ancestry of the
insect group.

Two subdivisions, the orders Thysanura and Collembola, are generally
recognized in the Apterygota. The Thysanura have styli present,
while in the Collembola they are absent. Cerci, which are segmented,

62

THE APTERYGOTA

63

antenna-like projections backward from the end of the abdomen, occur
in the Thysanura. Here they are two in number, rather long and con¬
sisting of many segments, except in a few cases where they have been
transformed into a pair of good sized, unsegmented forceps. In the
Collembola, cerci are either entirely absent or very small and consist
of only one segment.

THE THYSANURA

The Thysanura average much larger than the Collembola. They arc
characterized as:

Apterygota with styli on the underside of the abdomen, and with usually
long, many-segmented cerci at the end of the body, except in a few species
adhere these have become a pair of forceps.

Only one Thysanuran is of particular eco¬
nomic importance in the United States; the
Silver Fish or “Slicker” (Fig. 35).

The Silver Fish ( Lepisma saccharina L.). —

This little household pest is found both in
Europe and this country. It is silvery gray in
color, usually less than half an inch long, and
very active and hard to catch. Besides the two
long cerci at the hinder end of the body it has a
similar “caudal filament” giving the insect the
appearance of having three “tails.” It prefers
dark places and feeds on book bindings,
starched clothing, or anything containing starch,
and often loosens wall paper by feeding on the
starch used to paste it to the wall.

It may be controlled by placing on pieces of
card, starch paste made as follows: Flour 1
pint; Arsenic \2 t° M oz.; water enough to make a thin paste after
boiling. Spread this on the cards and place near where the insects arc
found, for them to feed upon. Do not place the cards where young
children can get at them. The Silver Fish prefers moist to dry places,
so clothing should not be stored where it is damp. Sometimes Insect
Powder dusted in the haunts of this pest is helpful.

THE COLLEMBOLA

The Collembola are usually very small insects, and being dark colored,
in most cases are not often noticed. Most of this group have a “spring”
attached near the hinder end of the body beneath. This consists of a
single piece to which a pair of others are joined and the whole is carried
pointing forward when not in use (Fig. 36). When the spring is suddenly
pressed against the ground, the entire body of the insect is thrown into the
air and a peculiar hopping or leaping motion results.

F ig. 35. — S i 1 ve r Fish
( Lepisma saccharina L.)
about twice natural size.
( After 14 ih Rept. Minn.
State Entomologist.)

64

APPLIED ENTOMOLOGY

The Collembola may be characterized as:

Apterygota without styli on the underside of the abdomen: cerci either
absent or very small and consisting of only one segment. Usually much
smaller than Thysanura and most of them with a ventral “spring.”

Fig. 36.— Springtail (Papirius fuscus Lucas) showing forked “spring” projecting forward
toward the head beneath the body. Greatly enlarged. From, Lubbock.)

The most familiar members of this order are probably the Snow
Fleas, which are sometimes seen in enormous numbers on snow, where
their dark color and their hopping movements make them noticeable
(Fig. 37). Some of the group often become a nuisance by gathering

Fig. 37. — Snow Flea ( Achorutes nivicola Fitch) greatly enlarged. Real length 2 inch

{From Folsom.)

in maple-sap buckets on trees being tapped. Some also, feed on the leaves
of plants making tiny holes, which though of themselves unimportant be¬
ing small, still afford the spores of fungous diseases excellent opportunities
for entrance to the plant tissues. In cases where work of this nature by
Collembola is sufficient to warrant it, spraying the leaves as soon as the
injury appears, with arsenate of lead, standard formula, is effective.

CHAPTER XII

THE PTERYGOTA. THE EPHEMERIDA

The group Pterygota includes practically all our common insects
and is the main branch of the class Hexapoda, the Apterygota though
of equal rank, being a mere twig in size, in comparison.

As a whole the Pterygota are characterized by the presence of wings,
though as already indicated, many of them for one reason or another
have lost these structures.

Almost all characters present in insects may be found in this section
without referring to the Apterygota: practically all the pests and all the
beneficial forms belong here; and their differences are so great that 22
orders have been established as subdivisions for them.

The earliest writers on insects did not regard these differences as of
great importance, and called the groups families or gave them even lower
rank. More recent workers, however, have regarded them as of greater
significance, some students of the subject being inclined to recognize more,
rather than fewer orders, and it is not at all unlikely that time will finally
bring a general acceptance of 26 or 28 such groups instead of the first seven
established by Linne, or the 22 here treated.

THE EPHEMERIDA

The Ephemerida, May-flies or shad-flies as they are often called
(Fig. 38), are insects of medium or small size. The adults have delicate
bodies and gauzy, fragile wings, the latter usually with many cross- veins.
The fore wings are much larger than the hind ones, which in some cases
are absent, and the former are in general, rather strongly triangular in
outline. When at rest they are held vertically above the body. At
the end of the abdomen two or three long threads, each composed of
many segments and often called caudal filaments, are usually present,
the lateral ones being cerci corresponding to those in the Thysanura.

The mouth parts of the adult May-fly are of the chewing type, but
so poorly developed that it is doubtful if they are ever made use of.
In some cases they are even rudimentary. The reproductive organs
differ from those in all the other groups, the ducts being not united on the
middle line below, but opening separately to the outside — apparently
the retention of a very primitive condition. The early stages are passed
in the water, the nymphs breathing — at least after the first few molts —
by tracheal gills. These are delicate, usually wing-like in form, and are

65

5

66

APPLIED ENTOMOLOGY

outgrowths of the body wall. Into them pass tracheal trunks which
branch again and again so that only their own walls and those of the gill
itself separate the air in the tracheae from that in the water outside, and
so thin are these layers that the oxygen in the water can pass through
them into the tracheae, and carbonic acid gas pass out.

These insects add to their list of peculiarities also, the fact that after
becoming full grown and being able to fly, they molt once more, even a
thin layer over the final wings being shed.

Fig. 38. — Adult May-fly ( Hexagenia variabilis Eaton) showing the long cerei. Natural

size. ( From Folsom.)

From these statements the group may be characterized thus:

Insects having as adults delicate bodies and usually four wings, the
front pair much larger than the others ( which are sometimes absent), and
generally with many cross-veins: end of the abdomen with two or three long,
caudal filaments composed of many segments: reproductive organs with two
openings to the exterior: mouth parts of the chewing type but practically
rudimentary : nymphs living in water and with an incomplete metamor¬
phosis, the final molt coming after the wings have become fully developed.

May-flies are most abundant near streams and lakes, as their nymphs
live in the water. The fully mature nymphs leave the water, usually
in greatest numbers about sunset, and suddenly molting, extend their
wings and fly off, but as above stated usually molt again within a few
hours. As their flight generally begins about dusk and as they are
strongly attracted to lights, they are often seen in multitudes around
street lights during the evenings.

THE PTERYGOTA. THE EPHEMERJ DA

07

The adults live only a few hours — not more than a day or two at
most— but during this time the eggs are dropped into the water. The
nymphs which hatch from them feed, probably mainly on vegetable
matter at the bottom, though some are doubtless partly carnivorous.
They live for one, two or three years, according to the species concerned
(some have two generations each year), feeding, and molting with unusual
frequency for insects (Lubbock observed 21 molts in one species), until
they are full-grown. During this time the mouth parts are well developed
and of the chewing type, but in the adult they become practically useless.

These insects are of no economic importance except perhaps to a
very slight degree as scavengers in the water, feeding on matter that
might otherwise decay and become objectionable, but their value for
this is probably small at best. They are fed upon as larv® and to
some extent as adults, by fish and some carnivorous insects of other
groups, and for this reason also may be rated as slightly beneficial.
At present about 500 kinds are known, but the group has not been very
thoroughly studied. Many fossil Ephemerids have been found, which
suggests that the insects are possibly less abundant now than was once
the case.

CHAPTER XIII

THE ODONATA

The Odonata are such large and noticeable insects that they have
received many common names, such as dragon-flies, snake-doctors,
devil’s darning needles, snake-feeders, etc. They are most plentiful
near water, as in this they spend their early lives, though the larger
and more powerful members of the group are frequently seen flying high
in the air and at some distance from their more usual habitat.

The dragon-flies have rafher long, slender bodies, the abdomen being
less shortened by the fusion and telescoping of its segments than in
most insects. The head is large, generally rather spherical, though con¬
cave behind, and a great part of its surface is occupied by two very large
compound eyes, each of which in some species, contains more than
30,000 facets. As these insects are carnivorous and capture their prey
as it is flying, the advantage of large eyes which are also because of the
curvature of the surface of the head, capable of seeing in almost every
direction, is evident. There are also three ocelli. The antennae are
short and not very noticeable.

The mouth parts, which are of the chewing type, are large and well
developed. The food appears to be captured by the legs and held by
them while it is being eaten.

Four wings are present, all of about equal size, though the hinder
pair are somewhat larger except in the section known as the Damsel-
flies. The main veins are stout and are connected by many cross-veins.
Near the middle of the costa of each wing is a slight notch called the
nodus, at which point there is a particularly stout cross-vein. When at
rest the wings are held either nearly vertical over the body (damsel-flies)
or extended laterally, much as in flight. The metamorphosis is by pro¬
gressive changes at times of molting, and though the nymph can hardly
be said to ever greatly resemble the adult, development may be con¬
sidered as being by an incomplete metamorphosis.

The Odonata may then be characterized as:

Insects which as adults usually have long, slender bodies, large heads a?id
large eyes: wings four, membranous, the hinder pair as large or larger than
the front pair, and each has near the middle of its front margin a notch,
somewhat resembling a joint, called the nodus: mouth parts for chewing and
well developed. Metamorphosis incomplete.

There are two groups of dragon-flies. In one the insect is slender,
the two pairs of wings are of about equal size, and when not in use are

68

THE 0 DON AT A

G9

held almost vertically above the body (Fig. 39). These insects are often
called damsel-flies. In the other group the body is stouter and propor-

Fig. 39. — Damsel-fly ( Lestes uncata Kirby) showing position of wings when at rest. ( After
Needham , N. Y. State Mus. Bull. 68.)

Fig. 40. — Dragon-fly (Anax junius Dru.). Natural size. (Original.)

tionally shorter, and the wings when at rest extend out horizontally at
the sides of the body (Fig. 40).

70

APPLIED ENTOMOLOGY

The bodies of dragon-flies are often brilliantly colored, and in some
cases covered with a “bloom,” giving them a whitish appearance (Fig.
41). The adults feed on practically almost any flying insects smaller
than themselves which they may capture during their flight. Flies and

Fig. 41. — Dragon-fly ( Plathemis lydia Dru.) showing "bloom’’ on abdomen. About

natural size. (Original.)

mosquitoes form a favorite food, and the attempt has been made to
“tame” dragon-flies and keep them in houses on this account, but with¬
out success. They are very voracious, one specimen having been known
to consume 40 house-flies in less than two hours.

Many dragon-flies fly very swiftly either in direct lines or making
sudden changes of direction while hunting their prey, and are perhaps

Fig. 42. — Nymph of a Dragon-fly with mask extended forward. Enlarged one-third.

(Original.)

unequalled in this regard by any other insects. They also mate in the
air. The eggs are laid either in the water, attached to water plants, or
in the stems of plants under water. In the latter case they are laid singly
but otherwise they are usually in clusters containing either a small or a
large number of eggs.

The eggs may hatch after a few days, or if laid in the fall, may not
produce nymphs until the following spring. The young nymphs stay

THE ODONATA

71

at the bottom of the water and are carnivorous, feeding on larger and
larger animals as they grow, individuals of the largest species attacking
small fish in some cases, though the bulk of their food is undoubtedly
the aquatic larvae of insects. They lie on the bottom waiting for their
prey to come within reach, and when it is near enough they thrust out
the under-lip (labium) and seize it (Fig. 42). This labium has been
remarkably developed from its usual form, being drawn out into two long
pieces with a pair of jaws or claws at the end. When not extended the
piece connected at one end with the head is bent backward under the
body, while the second piece, hinged to the other end of the first, extends
forward so that its front end with the jaws lies near the front of the head,
which it somewhat conceals, and this has led to calling the structure a
“mask.” When this is extended forward it reaches out more than twice
the length of the head, thus enabling the nymph to capture animals which
are not very close to it.

Breathing in the nymphs of the damsel-flies appears to be, in part at
least, by means of long and rather large, tracheal gills at the end of the
abdomen, which are also used for swimming. In the other section of
the Order, the gills are found in the rectum, into which water is drawn,
bathing the gills there, after which it is expelled, and if this is done quickly
the recoil carries the nymph forward, thus providing one means of
locomotion.

Molts are frequent, and when full-grown the nymph crawls out of
the water and molts for the last time, whereupon the wings grow to full
size and the adult insect is produced. Some dragon-flies have two
generations a year or possibly even more, while in other cases more than
a year is necessary to a generation, but one each season is the usual
condition.

Despite tradition and their bad reputation, dragon-flies are in no
way injurious to man, not stinging — they have nothing to sting with —
nor biting to such an extent as to cause the slightest pain, their jaws
being too weak to even break the skin. They are beneficial insects
both as young and adults, so much of their food consists of injurious
insects such as flies, mosquitoes, etc., while the injury they cause by
feeding on fish is usually so slight as to be negligible.

Dragon-flies are sun-loving animals, concealing themselves during
dark, cloudy weather Between 5,000 and 10,000 kinds are known, and
the greatest number of these occur in the warmer regions. Fossil dragon¬
flies or insects resembling them are numerous, and some of them were
very large, one measuring more than two feet from wing-tip to wing-tip.

CHAPTER XIV

THE PLECOPTERA

The most usual common name for the Plecoptera is the Stone-flies.
They range from small to good-sized insects whose bodies are quite long,
flattened and with rather parallel sides. The wings are nearly always
well developed and with many cross-veins, though in a few cases they are
very small and in some species the cross-veins are few. Considering
only the more usual condition, the fore wings extend well behind the
end of the body when closed and have a considerably smaller area than
the hind wings which are so broad that when they are at rest upon the
upper side of the body they must be folded lengthwise into plaits to
reduce them to the necessary width (Fig. 43).

Fig. 43. — Adult Plecopteran ( Pteronarcys regalis Newm.). Slightly reduced. ( From

Folsom.)

The antennae are long and composed of many segments. In most
members of the group a pair of cerci is present at the end of the abdomen.
The mouth parts are of the chewing type but are generally so weakly
developed as to be practically useless. The larvae live in water and do
not differ greatly in appearance from the adults.

The group may be described as follows:

Insects which as adults have four membranous wings, usually longer
than the body, and generally with many cross-veins. Hind wings larger
than the front ones and when at rest folded lengthwise and lying, covered by
the front pair, on the abdomen. Antennce long: a pair of caudal cerci
usually present: mouth parts for chewing but generally poorly developed.
Metamorphosis incomplete.

72

THE PLECOPTERA

73

Adult stone-flies are most numerous near streams and particularly
those with a rapid current. The eggs which are often several thousand
in number, are laid in the water and the nymphs locate on the underside
of stones. Some breathe through the surface of the body. Tracheal
gills, when present, are not leaf-like as in the May-flies but are tufts of
numerous short, thread-like structures containing tracheae, a tuft or
bundle just behind each leg, on the underside, and also on the first two
abdominal segments. When fully grown the nymphs leave the water
and molt for the last time on land. They feed on small insects, probably
largely May-fly nymphs, and possibly on vegetable matter (diatoms)
and are themselves a favorite food for fish.

Some species of stone-flies appear in enormous numbers just as the
ice is breaking up in the streams, in the northern United States, and others
are found on the snow even earlier in the season, on warm days. In
general the group is without economic importance, but a few kinds of
adults have recently been observed injuring the buds and foliage of fruit
trees as these first develop, in the northwest, and in these species the
mouth parts are much more strongly developed than in the others.
Only 2,000 to 3,000 species are known.

CHAPTER XV

THE EMBIIDINA

This is a small group of insects, only about 60 species having been
described. They live in warm climates either under stones or on plants
in crevices of the bark or elsewhere, spinning silken tunnels in which to
live. The largest species known is less than an inch long (Fig. 44).

The wings are generally (always?) present in the males and absent
in the females. The tunnels appear to be formed at least partly for
protection, but perhaps also to aid in preserving moisture, for when dry

/

Fig. 44. — Emhia major Inims, about 1 fa times natural size. {Reduced from Imms. Trans.

Linn. Soc. Lond. 1913.)

weather comes on they are carried deeper into the soil in the ground-
inhabiting forms. The silk appears to be produced by glands located
in the tarsi of the fore legs — something unparalleled elsewhere among
insects. The mouth parts are of the chewing type.

The food of these insects is probably vegetable matter, but the injury
they do to plants, as thus far reported, is not great. Even where they
are most abundant they are seldom seen except by those looking for
them. A few fossil specimens belonging to this group have been found
preserved in amber. The Embiids appear to be more closely related to
the Plecoptera than to any of the other orders of insects.

74

CHAPTER XVI

THE ORTHOPTERA

The Orthoptera is a large group of insects containing over 10,000
species. Many of them are very large and striking in appearance and
common names have been given to different families in the order, but
none to it as a whole.

The insects of this order are so diverse in structure, appearance and
habits that it is difficult to give distinctive characters, but they all
have well-developed chewing mouth parts. The majority of them have
four wings, the front pair being slightly thicker than the others, somewhat
leathery in texture, and overlapping more or less when folded. The
hind wings are almost always larger and fold in plaits. In many of the
group, however, the wings are lacking or very small, in which case it is
difficult to determine whether the insect is an adult or a nymph, without,
or with only partially developed wings.

In some of the families the hind legs are much developed and the
insects have the power of jumping: in others this is not the case and
walking and running are their methods of locomotion on the ground.
On this basis the Order has often been divided into two sections, Cursoria
or running Orthoptera, and Saltatoria or leaping Orthoptera.

The Orthoptera may be defined, despite the difficulties above indi¬
cated, as:

Insects which when adult have mouth parts for chewing; usually four
wings, the front pair thicker than the others; the hind pair larger and folded
in plaits when at rest. A pair of cerci is always present. Metamorphosis
incomplete.

Many students of the group are of the opinion that the insects
included in this order should really be placed in two or three, but at
present such a separation seems hardly advisable. Most of the families are
quite distinct. The group is frequently divided into eight or ten families,
but for the purposes of this book, six will be considered. These are:

( Blattidae, Roaches.

Cursoria ! Mantidse, Mantids.

I Phasmidae, Walking Sticks.

( Acrididae, Locusts and Short-horned Grasshoppers.

Saltatoria \ Tettigoniidaj, Long-horned Grasshoppers and Katydids.

^ Gryllidae, Crickets.

75

76

APPLIED ENTOMOLOGY

Family Blattidae (The Roaches)

These insects are known by a variety of common names such as
roaches, cockroaches, water-bugs, and black-beetles. The group is
primarily one living in warm countries with many kinds living in houses,
and many more, some of them several inches in length, occurring wild.
In more northern climates only a few are wild and four are household
pests; these last when adult ranging from less than an inch to nearly
two inches in length. In the north the wild species are found under
logs and stones and never enter houses. They are pale brown and the
wdnged adults are an inch or slightly more in length.

Roaches are generally brown or dark colored, though some are
green. They are broad and flattened, with the head bent under the body
so that the mouth opens backward and the eyes look downward. The
antennae are long, slender and of many segments. Wings are usually
developed in the adults and the hinder pair fold once. The mouth
parts are strong and the legs are long, and bear many spines. Roaches
are active at night, hiding in dark places such as cracks and crevices
during daylight, and can run rapidly.

Fig. 45. — Egg case of American Roach: a, side; b, end view. Both considerably enlarged.

(Modified from U. S. D. A. Farm. Bull. 658.)

The household pests of this group consume foods and food materials
freely; gnaw woolen goods, leather, and anything which has paste
on it, and thus often injure book bindings; in fact they are practically
omnivorous. Besides eating, they leave a disagreeable “roachy” odor
which spoils food where they have been. When abundant they become
very troublesome and vigorous measures must be taken for their control.
They lay their eggs in packets, the number per packet varying with the
species, and the outside case is horny in nature (Fig. 45). This case
may be carried around partly projecting from the body of the parent for
several days or even weeks. The young are active, feed freely and molt
several times, but it is doubtful if there is more than one generation a
year, at least in the northern United States.

House Roaches

The German Roach ( Blatella germanica L.). — This insect, often
called the Croton bug, came from Europe and is generally the most
common of the house roaches in the eastern United States (Fig. 46).

THE ORTHOPTERA

77

Fig. 46. — German Roach or Croton Bug (Blatella germanica L.). c, egg case much enlarged
e, adult, natural size; /, adult carrying egg case. ( From U. S. D. A. Farm. Bull. 658.)

Fig. 47. — American Roach ( Periplaneta americana L.) adults: a, from above; b, from
beneath, about natural size. (Modified, from U. S. D. A. Farm. Bull. 658.)

Fig. 48. Fig. 49.

Fig. 48. — Australian Roach ( Periplaneta australasice Fab.). Adult, about two-thirds
natural size. (Reduced from U. S. D. A. Farm. Bull. 658.)

Fig. 49. — Oriental Roach (Blatta orientalis L.) adults about two-thirds natural size;
O, female; b, male. ( Reduced from U. S. D. A. Farm. Bull. 658.)

78

APPLIED ENTOMOLOGY

The adult is from one-half to three-fourths of an inch long, pale brown
with two darker brown stripes. It is very active and increases in
numbers very rapidly.

The American Roach (. Periplaneta americana L.). — This is the largest
of the house roaches, being from one and one-fourth to one and one-half
inches long when adult. It is brown, darker than the German roach,
and has a more or less definite yellow band around the margin of the
pronotum (Fig. 47). It is a native of the warmer parts of this country
but has spread north and is now abundant everywhere except in the
most northerly states.

The Australian Roach ( Periplaneta australasice Fab.). — Somewhat
smaller and apparently broader than the last, and with the yellow
band around the prothorax brighter, and a yellow streak on the costa
of the fore wing extending part way toward the tip (Fig. 48). It is
particularly common in the Southern States.

The Oriental Roach ( Blatta orientalis L.). — This insect is the “black-
beetle” of Europe. It is almost black and the wings in the adult male
are considerably shorter than the body, while in the female they are
hardly more than stubs. It is a stout-bodied insect, quite generally
present in the eastern, southern and central United States as far west
as the great plains, and is the most common species in Europe (Fig. 49).

Other kinds of roaches are occasionally found in the Northern States
brought there in bunches of bananas or with other southern fruits, but
they do not appear to be able to live long in the colder climates.

Control.— Various materials are more or less effective as roach killers,
but the best of these is commercial sodium fluorid. It may be mixed with
flour or some other inert substance, but nothing is gained by this except
a reduction of the cost of treatment and the killing may not be as rapid.
The powder is thoroughly dusted where the roaches occur, particularly
in their hiding places, using a dust gun or blower. The insects which
by crawling or in other ways get the dust on their antennae or legs, clean
these parts by drawing them between their mouth parts so that the
powder enters the mouth and probably acts through the alimentary
canal.

Family Mantidae (The Mantids)

The Mantids are usually quite large insects with bodies much longer
than wide, and a broad head which moves very freely upon the thorax.
The prothorax, with few exceptions, is very long, and bears legs adapted
for grasping the prey and which are well provided with spines, the in¬
sects walking on the other four. In nearly all members of the group
the wings are well developed, the hinder pair larger and folding in
plaits when at rest with the other pair on the back of the abdomen.
They are often called Rear-horses, Devil-horses, Soothsayers, Praying
Mantids or Mule Killers.

THE ORTHOPTERA

79

The Manticls arc carnivorous, feeding on flies and other insects and
are therefore beneficial. Fifteen to twenty kinds occur in the United
States, particularly in the south, but the group is mainly found in tropical
countries where it reaches its greatest development and includes some
remarkable forms.

Mantid eggs are laid in cases composed of a thick material which
quickly dries. They are usually laid in the fall and hatch the following
spring. Some of the cases are very noticeable, being an inch or more
long. They are usually attached to plant stems (see Fig. 51).

Fig. 50.

Fig. 51.

Fig. 50. — Common American Mantis ( Stagornantis Carolina L.) waiting for its prey.
Slightly reduced. {Original.)

Fig. 51. — Egg case of common American Mantis, natural size. {Original.)

The most common Mantis ( Stagornantis Carolina L., Fig. 50) is found
as far north as southern New Jersey, Pennsylvania and Ohio. It is about
two and one-half inches long when adult, green or brown, or a mixture
of the two colors, and is found not only on plants but also often on
houses, sheds or in other places where it may obtain its prey. It locates
in some spot, then raising its prothorax and head somewhat, with its
fore legs partly extended, quietly waits until an unwary insect comes
within its reach. When this happens, a quick motion of its fore legs and
the prey is seized, the spines aiding in holding the insect, which is then fed
upon.

In 1897 a Mantid from China ( Paratenodera sinensis Sauss.) was dis¬
covered near Philadelphia where it appears to have successfully estab¬
lished itself. It is much larger than the common native Mantis, being
about four inches long. In 1899 the common European Mantis ( Mantis
religiosa L.) was found near Rochester, N. Y., where it appears to be
quite common. It much resembles our native form but is slightly larger
(Figs. 52 and 53).

80

APPLIED ENTOMOLOGY

As these insects are beneficial, attempts have been made to establish
them in other places, but thus far they do not seem able to withstand
severe winters, and in the case of the last named species it has until now

Fig. 52. Fig. 53.

Fig. 52. — European Mantis ( Mantis religiosa L.), natural size, with wings spread.
{Original.)

Fig. 53. — Egg case of European Mantis, natural size. {Original.)

apparently been unable to live north of Ontario, and colonies placed in
New England have died out.

Family Phasmidae (The Walking-Sticks)

The Phasmids are generally called “ walking-sticks. ” Their bodies
are usually long and stick-like, due largely to their very long and slender

Pig. 54. — Common Walking-stick {Diapheromera femorata Say) natural size. {Original.)

meso- and metathoracic segments. Their legs and antennae are also
generally long, and the 15 to 20 kinds found in the United States

THE ORTHOPTERA

81

are wingless, or with only wing stubs, which adds to their stick-like
appearance. They are brown or green in color and thus much re¬
semble the twigs on which they rest, or the larger leaf veins. Only
one species ( Diapheromera femorata Say) is abundant except in the more'
southern states, but this is quite generally present (Tig. 54).

Walking-sticks feed on foliage and when abundant may entirely
strip many acres of forest trees of their leaves, though this does not
often happen. Their eggs are laid in the fall, being dropped singly,
wherever the insects happen to be, and falling to the ground remain
there until the following spring, or in some cases until the second spring,
before hatching. Though not laid a
number together in a case as in the last
two families, each egg has a case or
capsule of its own.

Where forest areas are attacked, no
entirely satisfactory method of control
is known. In the case of a few trees or
plants easily accessible, spraying with a
stomach poison is sufficient to prevent
farther injury.

This group is mainly a tropical one,

over 600 kinds being known, very variable

in size and appearance. One species has

a body nine inches or more in length,

and with its front legs extended forward

and its hinder ones backward — a position

it often assumes — may measure sixteen

inches Or even more, while its body has Fig. 55.— A Tropical Leaf-insect

a diameter of less than one-quarter of (Pulchnphyiiium scythe Gray) about
... . half natural size. {Original.)

an inch. In the tropical forms wings are

often present, and in some cases colored and marked to resemble leaves.
This resemblance is increased in Pulchriphyllium scythe Gray (Fig. 55),
found in the East Indies, by leaf-like expansions of the femora and tibiae
and of the body itself.

The insects belonging to the three families of this order, treated thus
far, are all walkers or runners (Cursoria). Those now to be considered
are leaping forms (Saltatoria), the hind legs being longer than the others
and provided with powerful muscles. Their heads are generally strongly
hypognathous, the mouth being directed downward and in some cases
even a little backward. Sounds sometimes called musical are produced
by most members of these families.

Family Acrididae (The Grasshoppers)

The insects belonging in this group are commonly called grasshoppers.

A few kinds when adult migrate, often in such enormous numbers as to
6

82

APPLIED ENTOMOLOGY

look like clouds in the sky. These migrating species are sometimes
spoken of as locusts.

Grasshoppers are feeders on grass and vegetation in general and
are injurious, the amount of injury they cause varying with their-
abundance. Their antennae, shorter than the body, and their tarsi,
consisting of only three segments, quickly distinguish them from the
related family Tettigoniidae. The pronotum is extended backward
somewhat, and down on the sides of the prothorax almost to the base
of the fore legs. In the female there is a short, stout ovipositor com¬
posed of four parts, and the rather narrow fore wings, usually somewhat
leathery in texture, cover the large, delicate hinder pair when these,
folded in plaits, are at rest above and along the sides of the body.

Most grasshoppers lay their eggs in the ground, usually in the fall,
and these hatch the following spring. The female works its ovipositor
into the soil a short distance, then pushes apart its four pieces and
deposits its eggs in a cluster containing from twenty-five to perhaps

Fig. 57

Fig. 56,

Fig. 56. — Two-striped Grasshopper ( Melanoplus bivittatus Say) laying eggs. ( Reduced
from U. S. D. A. Farm. Bull. 747.)

Fig. 57. — Sac, or “Egg-pod” of Grasshopper eggs in the ground. About natural
size. {Reduced from U. S. D. A. Farm. Bull. 747.)

five times that number of eggs, covered by a fluid which hardens and forms
a sort of protecting case (Figs. 56 and 57). The young on hatching,
work their way out of the ground and feed, molting several times and
becoming adult after 2 or 3 months.

Only a few of the kinds of grasshoppers found in the United States
are sufficiently migratory in their nature to deserve the name “locust.”
During the period between I860 and 1880, however, and to some extent
since, inhabitants of the states west of the Mississippi River have at
times suffered the entire, or almost entire loss of their crops by the
ravages of swarms of the Rocky Mountain locust ( Melanoplus spretus
Thom.) which, breeding in immense numbers on the eastern slopes of
the Rocky Mountains, upon maturity migrated eastward for food, and
stripped everything where they alighted. Settlement of these breeding
grounds, and cultivation, destroying the eggs, has largely put an end to
these migratory flights, but occasionally grasshoppers occur in destruc-

THE ORTHOPTERA

83

tivo abundance, not only in the West but in all parts of the country
wherever they become so plenty as to lay large numbers of eggs in ground
not cultivated, such as pastures. Under such conditions, a sudden,
more or less local outbreak of these insects may take place in the spring,
the damage being caused in these cases, at first by the feeding of the
nymphs, and later, if nothing is done, by the adults.

Aside from plowing, harrowing or disking land in which grasshoppers
breed, before the eggs hatch in the spring, the most successful method
of control when they appear in sufficient abundance to make treatment
necessary, is the use of a poisoned bait. There are various formulas for
this, but there is no marked difference in the results in most cases.

One in general use is: wheat bran, 25 lb.; Paris green or white arsenic,

1 lb.; oranges or lemons, 6 fruits finely chopped; low-grade molasses,

2 qt. Mix the bran and poison well, dry; then add the chopped fruit
and its juice; finally add the molasses and stir thoroughly. Enough
water — 2 or 3 gal. — should be added to this so that each flake of the bran
is sufficiently moist to have some of the poison adhere to it, and also
take up the flavor of the fruit and molasses, yet not enough to make
the flakes stick and prevent Sowing broadcast. This amount of material
should be sufficient to spread over two or three acres. In the Eastern
States and wherever the air is moist, the best results are obtained by
spreading the bait very early in the morning. In arid or semiarid
regions, 3 or 4 gal. of water may be needed in the mixture, which should
be distributed toward night.

A form of poisoned bait, known as the modified Griddle Mixture,
substitutes a half barrel of fresh horse droppings for the bran and
omits the molasses. The only advantage with this is that it can be used
where bran is too expensive or hard to obtain.

Fig. 58. F;g. 59.

Fig. 58. — Red-legged Grasshopper ( Melanoplus femur-rubrum De G.) about natural
size. {Reduced from U. S. D. A. Farm. Bull. 747 )

Fig. 59. — California Devastating Grasshopper {M elanoplus devastator Scudd.) about
natural size. {Reduced from U. S. D. A. Farm. Bull. 747.)

There are many kinds of grasshoppers in the United States. Among the
more abundant and therefore injurious species, may be mentioned the red-legged
grasshopper {Melanoplus femur-rubrum De G., Fig. 58), about an inch long, its
hind tibiae bright red; the California devastating grasshopper ( Melanoplus
devastator Scudd., Fig. 59), a little smaller, found in the Western States; the
differential grasshopper {Melanoplus differ entialis Thom.), about an inch and a

84

APPLIED ENTOMOLOGY

half long, present nearly everywhere, but rare in the East; the two-striped
grasshopper ( Melanoplus bivittatus Say) about the size of the last, with two
yellow stripes along its back, generally distributed except in the South Atlantic
States (Fig. 60); the lesser migratory grasshopper ( Melanoplus atlanis Riley)
about an inch long, found nearly everywhere in the. United States and frequently

Fig. 60.

Fig. 61.

Fig. 60. — Two-striped Grasshopper ( Melanoplus bivittatus Say) about natural size.
{Reduced from U. S. D. A. Farm. Bull. 747.)

Fig. 61. — Lesser Migratory Grasshopper (4 Iclanoplus atlanis Riley) about natural
size. (Reduced from U. S. D. *4. Farm. Bull. /47.)

seriously abundant west of the Mississippi River (Fig. 61); and the clear-winged
grasshopper ( Camnula pellucida Scudd.) which though small is often very injurious.
It is found in all the northern United States and has its hind wings clear and
almost colorless, while its fore wings are spotted with brown. All of these
species attack various cereal and forage crops.

Fig. 62. — Florida Lubber Grasshopper ( Dictyophorus reticulatus Thunb.) about natural
size. ( From U. S. D. A. Farm. Bull. 747.)

In the Southern and Western States are large, short-wTinged grasshoppers
which are very stout, and from their appearance and clumsy movements are
called “lubber grasshoppers” (Fig. 62). They attack grass, alfalfa and other
crops.

The Carolina grasshopper ( Dissosteira Carolina L., Fig. 63), one and a half
inches or more in length, is gray or brown, varying somewhat with the color of
the ground where it lives. It is most noticeable along roads and when startled
into flight its black hind wings with yellow margins, and the crackling sound
often produced at such times are sufficient to attract attention. It is found
throughout the entire United States,

THE ORTHOPTERA

85

In one section including the smallest grasshoppers, generally called “grouse
locusts,” some of which are less than half an inch in length, the pronotum is
extended back to, or even beyond the end of the abdomen and the fore wings
are reduced to mere stubs. Two common species are shown in Fig. 64.

The hind wings of grasshoppers are often brightly colored, yellow,
red, or black. The legs also often show bright colors.

Fig. 63. — Carolina Grasshopper ( Dissostcira Carolina Say) natural size. (Original.)

The sounds produced by grasshoppers are made in one or the other
of two ways. In some species the hind legs are drawn up and down
across the fore wings, ridges on the inner face of the femur scratching
against a heavy vein on the wing and giving a rasping sound. In others
the sound is produced while flying. Here the front edge of the hind wing

Fig. 64. — Two types of “Grouse Locusts,” natural size. (Original.)

is struck against the under surface of the fore wing, making a short,
sharp sound, which, quickly repeated, gives a kind of “ crackling.”
Apparently the organs of hearing are located on each side of the body
just above the base of the hind leg. Each is a rather large, smooth disk,
suggestive of an ear drum membrane, connected by nerve fibers with a
small ganglion which in turn connects with the main nervous system.

Family Tettigoniidse (The Green Grasshoppers and Katydids)

A part of the insects of this family are called green grasshoppers,
long-horned grasshoppers, or meadow grasshoppers, while others are
the katydids. Their tarsi consist of four segments. Most of them are
green in color, and all have antennae longer than their bodies. Some of
the katydids have broad fore wings and these live among trees and
shrubs, feeding on the leaves and even on the more tender twigs (Fig. 65).

86

APPLIED ENTOMOLOGY

Others have narrow fore wings and appear to prefer bushes or tall weeds
and grass as their abiding places (Fig. 66). The meadow grasshoppers
resemble the narrow-winged katydids but average smaller and are most

Fig. 65. — Broad-winged Katydid ( Amblycoryphci rotundifoiia Scudd.), natural size.

0 Original .)

abundant in fields and pastures, particularly where the grass is thick and
tall. In most members of the group the ovipositor is long or at least
large enough to be quite noticeable.

Fig. 66. — Narrow-winged Katydid ( Scudderia curvicauda De G.), slightly enlarged.

(Original.)

Some of the Tettigoniids are wingless and come out only at night,
hiding under logs, stones or in dark places during the day. They are of
various shades of brown or gray, and the species found in different parts
of the country vary much in appearance (Fig. 67). They are called
“wingless grasshoppers,” “camel crickets,” “shield-backed grasshop-.

THE ORTHOPTERA

87

pors,” “Jerusalem crickets,” etc., according to their kind and the local
usage.

Sound in this family is produced by the males. The base of the
fore wing is modified, not necessarily in the same way in all the species,
but in such a manner that rubbing these wings together will produce a
sound. The organ of hearing is a small, oval membrane located near

Fig. 67. — “ Wingless Grasshopper,” natural size. (Original.)

the base of the tibia on each side of the front leg. Inside the membrane
is a hollow space or resonance chamber, and a nerve supply. The sounds
made by these insects are produced chiefly toward evening and at night,
though in dense woods they may sometimes be heard earlier in the day.

The members of this group are rarely serious pests, though katydids
have been known to injure orange groves and presumably some forest

Fig. G8. — ‘‘Western Cricket” (Anabrus purpurascens Uhl.), slightly enlarged. ( After

Gillette.)

trees suffer more than is generally realized, when these insects are abun¬
dant. One exception to this general unimportance of the family is met
with in the case of the wingless species known as the “western cricket”
(Anabrus purpurascens Uhl., Fig. 68), which in some of the Western
States may be a serious crop pest.

88

APPLIED ENTOMOLOGY

Family Gryllidae (The Crickets)

The crickets are familiar insects, often seen walking or leaping over
the ground.

In this family the wings are frequently reduced or absent, but when
present the front pair are so bent that one part lies fiat over the back
while the other lies against the side of the body when not in use. The
antennse are in most cases, longer than the body. A convenient group¬
ing of these insects is into the field crickets, the mole crickets and the
tree crickets.

Fig. 69. — Common Black Cricket ( Gryllus abbreviatus Serv.), natural size. {Original.)

The sounds are produced by the wings of the males, which are rubbed
over each other. On one wing is a strong vein which bears cross ridges,
while on the other is a thickened area. These two parts (termed file and
scraper by Comstock) when rubbed together cause the sound. Ears in
crickets are located as in the last family, on the fore legs, but the two on
the same leg differ somewhat in appearance.

The common field crickets (Fig. 69) are black or brown, and a long
ovipositor is present in the females. They are rather indiscriminate
feeders, consuming either vegetable or animal materials, and may even
be cannibals. In houses they will eat foods but are rarely abundant
enough to become pests.

The mole crickets are larger and stouter than the common field
crickets, and because of their habit of burrowing in the ground are less
often seen (Fig. 70). They are brown in color and their fore legs are
broad and flat, forming most effective digging organs. The eyes are
much reduced and the hind legs not being used for leaping, are not so
greatly developed as in the other crickets. They prefer rather moist

THE ORTHOPTERA

89

Fig. 70. — Common Mole Cricket ( Gryllotalpa borealis Burm.), about natural size.

{Original.)

Fig. 72.

Fig. 71. — Adult Male Tree Cricket ( (Ecanthus niveus De G.), somewhat enlarged.
{Reduced from N. Y. Agr. Exp. Sta. Tech. Bull. 42.)

Fig. 72. — Female Tree Cricket ovipositing in a twig. Enlarged about one-half.
{Reduced from N. Y. Agr. Exp. Sta. Tech. Bull. 42.)

b a

Fig. 73. — Raspberry canes showing: a, row of egg punctures along the cane, inducing
cracking open; b, cane split open to show the depth of the punctures. Natural size.
{Original.)

90

APPLIED ENTOMOLOGY

land in which to make their burrows, and feed on plant roots, earth worms
and insect larvse. The “Changa” (Scapteriscus vicinus Scudd.) of Porto
Rico attacks the roots of various crops in that island, causing much
injury, and has recently been discovered along the sea coast of some
of the Southern States where it attacks cotton and may become a serious
pest.

The tree crickets differ greatly in appearance from the field and
mole crickets, being slender, greenish white and only about half to three-
quarters of an inch in length (Fig. 71). They occur on trees and bushes
and attract attention from July till frost by their shrill, steadily repeated
note or song, beginning as it grows dark and continued through the
night, the rapidity of the note being so closely related to the temperature
that by timing the number of repetitions per minute a close approxima¬
tion to the thermometer reading can be obtained.

The tree crickets are rather serious pests as during the fall the females
make long rows of punctures in the twigs of trees and in berry canes
(Fig. 72), laying their eggs in these punctures which usually are nearly
as deep as the diameter of the twig or cane (Fig. 73). The general
result is the drying and splitting open of the portion of the plant attacked,
causing its death, besides providing an opportunity for the spores of
fungous diseases to enter and attack the plant. .Control of these insects
is at present limited to cutting off and destroying the injured parts of the
plant, with their contained eggs, before these hatch in the spring.

A few species of crickets live a semiparasitic life in ants’ nests and in
consequence are so much modified as to show little resemblance to the
common forms.

CHAPTER XVII

THE ISOPTERA

These insects are commonly called White Ants or Termites, the
former name being used because though not nearly related to ants,
they live in colonies and in many of their ways resemble these insects.

The White Ants, as their name suggests, are whitish in color (the
winged adults may be brown or blackish). The group is essentially a
tropical one but some of them are found as far north as Canada. The

Fig. 74. — Castes of a Termite colony: o, queen; b, male; c, worker; d, soldier. ( After
Jordan and Kellogg , Evolution and Animal Life, l). Appleton and Co.)

tropical species differ so markedly in many of their ways from the north¬
ern ones that separate descriptions almost seem necessary. In all,
however, there is a colonial life and a division of the insects into several
groups or “castes.”

A colony normally consists of one or more males or “kings;” one or
sometimes several females or “queens” and a variable but generally
large number of other individuals, nearly always at least, of two castes,
known as workers and soldiers (Fig. 74). These may be individuals of
either sex which have not developed to reproductive maturity. During
a short period of their lives the kings and queens have fully-developed
wings, four in number, long, narrow and quite similar in appearance,

91

92

APPLIED ENTOMOLOGY

which when at rest are laid flat upon the back. Near the base of each
wing is a line marking where it will easily break off. The part between
this point and the body is horny, while the remainder is at most only
somewhat leathery. At the end of the abdomen is a pair of short cerci.
Development of the young is by an incomplete metamorphosis.

The group may accordingly be characterized as:

Insects living in colonies and of several castes, of which only the kings
and queens ever have wings. These are four in number, long, more or less
leathery, narrow, similar, laid flat on the back when not in use, and easily
broken off near their bases. The bodies of the insects are soft, and usually
whitish in color. The abdomen has a pair of cerci at its hinder end. Mouth
parts for chewing. The metamorphosis is incomplete.

The food of Termites is mainly dead wood, though living trees and
other plants sometimes suffer from their attacks. Their nests in the
tropics are made of earth, wood
which has been chewed up, and
their excrement. They are often
prominent objects, sometimes twenty

Fig. 75.

Fig. 75. — Adult male of a tropical Termite ( Termes spinosus Latr.) about half natural
size. ( After Desneux.)

Fig. 76. — Laying queen of a tropical Termite ( Termes gilvus Hag.). Reduced nearly
one-half. ( From Desneux.)

feet or more in height, and seem to vary in form to some extent ac¬
cording to the species.

Termites “swarm” at some seasons, enormous numbers of winged
kings (Fig. 75) and queens leaving their nest at about the same time and
flying off. After alighting the wings are broken off and each pair of
individuals turns its attention to the establishment of a new colony.
In the tropical species which form large nests and have thousands of
individuals in a colony, the abdomen of the queen gradually becomes
distended by the developing eggs until this part of the body may become
several inches long and an inch or more in diameter, so that the insect is
entirely helpless and unable to move (Fig. 76). The workers which are
generally blind, provide for the queen, carry away the eggs, feed and
care for the young, construct the nest, and indeed do all the work of the
colony. The soldiers are generally regarded as a caste produced for the

Fig. 76.

THE I SOFT ERA

93

protection of the colony, but numerous observations which show the
workers to be better fighters, throw doubt upon the real duties of this
caste.

Other castes besides those already mentioned have been discovered
in different species of Termites, at least 15 having been recognized, though
not for any one species. In addition to the royal pair, workers and
soldiers, however, a caste consisting of individuals generally called
complementary kings and queens or neoteinic members of the colony
is generally present, at least in the older colonies. This caste is capable
of reproduction, though less abundantly so than the true queen, and
appears to be produced to continue the colony after her death.

The most generally common species of Termite in the United States
( Reticulitermes flavipes Kol.) except perhaps in the far South and on the
Pacific Coast, does not appear to form large colonies (see Fig. 74). Its
nests occur under logs and in them, in fence posts, timbers of buildings
or other structures, or in tunnels in the ground, though here usually in
near proximity to wood. Centering here they go out through tunnels,
always protected from the light, mining in woodwork, honeycombing
it and leaving only a thin film on the surface to conceal them and shut
out the light. If necessary to reach the wood they desire, they may
construct small covered passages over the surface of stone, brick or
similar materials, through which they pass. They will also attack
books and papers, pasteboard, leather, etc., if stored in dark and moist
places. In some cases they attack trees, infesting roots and the heart-
wood near the base. Citrus trees in the South are often seriously in¬
jured by them. Field crops are also affected, the roots being fed upon,
and plants in gardens and greenhouses are often attacked, the termites
sometimes coming up to the benches through covered tubes, in the latter
location, and working first in the wooden bench sides, and then passing
to the plants themselves. True queens have seldom been found in the
nests of this species.

Control. — To check the ravages of these insects in buildings, bridges
and other structures, all infested wood should be removed. Founda¬
tions should be of stone, brick or concrete, and as far as possible all
timbers should be exposed to light and not be so placed as to become moist.
As these insects must have moisture where they are, dryness is an effective
protection. Where posts must be set in the ground they should be dipped
in coal-tar creosote before setting. In general, ventilation and dryness
should be secured whenever possible, as the best protection against the
ravages of these insects.

The Termites are not a large group, probably numbering less than two
thousand species, but the size of their nests in the tropics attracts atten¬
tion, and their habits and colonial life are of much interest. They appear
to be most closely related to the Orthoptera. Fossil species are quite

numerous.

94

APPLIED ENTOMOLOGY

About 1913 a group of insects was discovered, living in Ceylon, Java,
Africa and Costa Rica,- which seemed to differ so greatly from those
already known as to justify placing them in a new order. Those first
found were minute, wingless, with only vestiges of eyes at most, and a
thorax as long as the abdomen. Cerci are present. The insects aver¬
age about a twelfth of an inch in length, with legs similar in form and
used for running. The tarsus consists of only two segments and the
mandibles are well-developed, the mouth parts being of the chewing
type. More recent discoveries of these insects in Florida and Texas
show that the adult females may have well-developed eyes; wings, at
least in some cases, which they shed like the Termites, and that while the
head resembles that of the Plecoptera the hinder end of the body resem¬
bles that of the Termites. It is also known that these insects are social
and generally occur near Termites, though not usually mingled with
them. They will probably prove to be rather nearly related to the
Isoptera.

The order Zoraptera has been established to include these insects,
but so little is as vet known about them that they have not been treated
in a separate chapter in this book.

CHAPTER XVIII

THE DERMAPTERA

The insects belonging in this group are commonly called Earwigs,
because of a mistaken belief that they crawl into the ears of sleeping
persons. They are most abundant in warm climates, very few being
found in the more northern states. Both winged and wingless species
are known, the wings always shorter than the body and the front pair
tough, leathery and shorter than the hinder pair. The latter are very
broad, nearly half-moon shaped, with veins radiating from a point behind
the costa and about one-third the distance from the base to the apex.
These wings first fold in plaits like a fan, then twice across to reduce
their length and thus bring them under the fore wings, the forceps aiding
in this. At the end of the abdomen is a pair of prominent, horny cerei,
shaped like forceps, differing in form in the two sexes. The mouth parts
are well developed and of the chewing type. The order may be char¬
acterized as:

Insects which when adult are usually rather long and, narrow in form;
with chewing mouth parts and a pair of forceps-like cerci at the end of the
abdomen. Wings may be absent or present: in the latter case the front
'wings are leathery and shorter than the others which are broad and fold, in
plaits from a center , and in addition fold crosswise. The metamorphosis
is incomplete.

Earwigs are not generally of great importance as pests in North
America, though in the South and on the Pacific Coast, as they generally
feed on fruits, blossoms and other vegetable matter, they may occasion¬
ally cause some injury. This appears to be more frequently the case in
Europe than in this country.

They hide in crevices, among leaves and in the ground in the day time,
coming out at night to feed. In the northern states the most common
species is the Little Earwig (Labia minor L.), brownish in color and only
about a quarter of an inch long. It is sometimes attracted to lights at
night. A much larger, dark-brown, wingless species ( Anisolabis mari-
tima Bon.), a native of Europe has now reached this country and is
found on the sea beaches of the Eastern United States, under seaweed
near high-water mark, probably feeding chiefly on decomposing vege¬
table matter (Fig. 77).

In 1911 the common European Earwig ( Forficula auricularia L.),
which is about three-quarters of an inch in length when adult, was found

95

96

APPLIED ENTOMOLOGY

to have established itself at Newport, R. I., and another colony of this
species was discovered at Seattle, Wash, in 1915 (Fig. 78). Both of these
colonies are increasing and spreading rapidly. The adults lay their
eggs in the ground in the fall and the adult females winter there also.

a b

Fig. 77. — Adults of a Wingless Earwig ( Anisolabis mnritima Bon.), natural size: a, male;

b, female. ( Original .)

The nymphs feed on green plant shoots, injuring garden plants and flowers
during the spring, and later in the season turn their attention to blossoms,
eating the stamens and bases of the petals. The adults too, feed on
these and also on dead flies, larvse, and even dead or dying individuals

a b

Fig. 7S. — Males (a) and females (b) of the European Earwig ( Forficula auricularia L.),
about twice natural size. ( From U. S. D. A. Bull. 566.)

of their own kind. Their actual injuries however, are far less serious than
the annoyance caused by their presence in residences, where they crawl
over everything at night and hide under chair cushions, dishes, in folds
of clothing and in all crevices in and about the houses during the day.

THE DERMAPTERA

97

Control. — During the spring months the nymphs may be destroyed
by the use of poisoned bread bait, using 16 lb. of stale bread and 1 lb. of
Paris green or arsenic. Grind the bread fine and thoroughly mix it with
the poison; then add water enough to make a mixture which will run
through the fingers and which, spread broadcast, will scatter in small
particles. Spread this during the evening over lawns or gardens where
the insects occur. It may need to be repeated once or twice. After
the first of July when the earwigs have taken to feeding on blossoms,
the best treatment thus far found is to spray the plants at night with
the following contact insecticide:

Soft potash soap . 30 oz.

Water . 96 oz.

Nicotine sulfate 40 per cent . 20 teaspoonfuls

Dissolve the soap in some of the water by heating, then add the rest
of the water and the nicotine sulfate, making about a gallon of stock
solution. For use, mix 1 part of this with 22 parts of water. The spray
should be a fine mist and be thoroughly applied, to be effective.

In Europe this earwig is not a serious pest, perhaps being kept in
check by natural enemies not present in this country.

The Dermaptera as a whole cannot be considered as a group of great
economic importance. They have sometimes been regarded as a family
of the Orthoptera and sometimes as a separate order akin to the latter,
but recent studies seem to indicate a closer relationship to the Coleoptera
or beetles. Probably not over 500 species of the group are known.

7

CHAPTER XIX

THE COLEOPTERA

The Coleoptera or beetles is the largest group of insects and members
of it are familiar to everyone. Over 175,000 kinds are already known,
and more are discovered every year. Beetles usually have wings, though
in some cases they are very small and never used. The front pair are
hard and horny and are called elytra. They are not used in flight but
when closed lie flat on the back, covering and protecting the hind wings
and the rather soft external skeleton of the upper side of the abdomen.

Fiu. 79. — Water Beetle with wings spread.

(From Folsom .)

In some groups they do not reach the end of the body, and in those in¬
sects the unprotected portion of the abdomen is generally of its usual
thickness. The hind wings are usually quite large and fold in an irregular
peculiar way to reduce their size and bring them under the elytra when
they are not in use (Fig. 79).

The external skeleton of the beetles is usually harder and thicker
than in most of the other groups. The mouth parts are for chewing,
both as larvae and adults, and the jaws are often very powerful. The
early stages are entirely unlike the adult condition, the members of this
group undergoing a complete metamorphosis.

98

THE COLEOPTERA

99

The distinctive characters of the group are:

Insects which as adults' nearly always have four wings, the front pair
entirely thickened and horny; the hind pair membranous: mouth parts for
chewing: body usually rather stout. Metamorphosis complete.

There is a great diversity in the structure of the antennae in different
beetles, and also in the form of the legs and number of tarsal segments.
The arrangement of the skeletal plates around the articulation of the
fore coxae to the body is also variable and of importance in classification.

Eggs of the Coleoptera are laid in many kinds of places — on leaves,
in branches, in decaying matter, water, etc. The larvae which hatch
are usually called “grubs” except when they bore in wood. Then, as
with larvae of any order found under such conditions, they are termed
“borers.” They usually have the three pairs of legs which become those
of the adult, though these are sometimes wanting. Some feed upon other
animals, some on leaves or wood, some on carrion, and others on various
substances. After full larval growth has been attained they pupate.
The pupal shell or skeleton generally covers the surface of the body
closely, but the wings and legs though lying close to it are covered sepa¬
rately as projecting appendages and not ensheathed by the shell enclosing
the body proper. Such a pupa case is called a pupa libera, or free pupa.
In some Coleoptera this condition does not obtain, the pupa shell en¬
closing wings, limbs and body with no projecting appendage sheaths,
and such a case is called a pupa obtecta (see Fig. 33).

The beetles are generally divided as a matter of convenience into the
true Coleoptera (Coleoptera genuina or Coleoptera vera) and the Snout
Beetles (Rhynchophora), though it is at least doubtful if the latter is a
natural group. The insects in this section are easily recognized, in most
cases, by having the front of the head prolonged into a snout which may
be long and slender — in some cases even longer than the body — or short
and stout, being sometimes so short as to be hardly noticeable. The
antennse arise from the sides of the snout and in most cases have a bend
like an elbow near the middle. The mouth parts are at the end of the
snout, but the labrum and both pairs of palpi are absent. The insects
of this group are even more firm bodied than the other Coleoptera.

The true beetles (Coleoptera vera) have no snout. The mouth parts
are all present and as a group its members average larger than the
Rhynchophora: indeed the largest bodied insects known belong here.

THE TRUE COLEOPTERA (Coleoptera vera)

This is by far the larger section of the beetles, more than 75 of the
80 odd families belonging here. They vary greatly in structure, habits
and food. Many of the families are of little or no economic importance
and have few members, while others include a very large number of
species, many of wnich are very destructive.

100

APPLIED ENTOMOLOGY

Family Lampyridae (Fire flies, etc.)- — In several ways the insects
belonging here appear to be among the simplest of the beetles (Fig. 80).
Their bodies are quite soft as compared with the others; the abdomen has
been little reduced, seven or eight segments being perceptible, and the
larvse are quite simple and feed on small insects and other animals such as
snails, either living or dead.

Only a few members of the group are often noticed except by ento¬
mologists, but those which attract attention are familiar by the light they

produce at night, which has given them the
names “fire flies,” “lightning bugs,” etc. The
light is produced by specialized areas of the
body, frequently at least on the underside of
the abdomen near its tip. The light itself is
not persistent but comes in flashes and is dis-
^ , , tinctly yellow in most cases. It is believed to

Common Lampyrid Beetles, be produced by the oxidation of granules 111 the
.bout natural size, outer layer of the luminous organ, the oxygen

being supplied by the tracheae, and under
control of the nervous system. In some species the adult female is
wingless so that its light appears as it crawls on the ground, and such
individuals are often called “glow-worms.”

Other insects and animals also have luminous organs, but the lights
they produce are probably less frequently seen than those made by Lam-
pyrids, these being widely distributed and very abundant insects.

Fig. 81. — Common Ground Beetle Fig. 82. — European Calosoma Beetle

( Harpalus caliginosus Fab.), natural ( Calosoma sycophanta L.) and its larva, natural

size. {Original.) size. (Original.)

Family Carabidae (Ground-beetles). — These insects are active, running quickly
over the ground, and the group is a large one containing many different species,
over 1,200 of which are found in the United States (Fig. 81). They feed mainly
at night, hiding by day, and the majority are dark colored or black, though a few
have bright colors. They are predaceous, both as larvse and adults in most
cases, though a few have been known to depart from their usual habits and feed on
berries and seeds. One species ( Calosoma sycophanta L.) has been brought to this
country from Europe as it feeds to quite an extent on the caterpillars of the Gypsy

THE COLEOPTERA

101

Moth, even climbing trees in search of its prey, and it is now fairly common in
most of the New England States (Fig. 82). .Asa whole, the group is distinctly a
beneficial one, feeding on injurious insects both above ground and as these enter
the ground to pupate.

Family Cicindelidas (Tiger beetles). — The active flight and bright colors
of many of the tiger beetles, though most of them are small insects, only about
half an inch long, make the members of this family quite noticeable (Fig. 83).
They are sun- loving forms, most common along roadsides and in sandy places.
When flushed they fly quickly a few yards, then alight and often turn, facing the
intruder as though watching his movements. Both they and their larvse feed on
other insects, the larva living in a burrow in the ground and placing itself at the
mouth of the burrow ready to grasp any unwary insect which may come near.
The elytra of the adult are usually metallic brown with light-colored marks sug¬
gestive of musical characters or perhaps hieroglyphics, though in some cases bright
green, purple, or other colors dominate. In the West the largest insect belonging
to this family ( Amblychila cylindriformis Say) does its hunting at night, as is also
the case with certain related forms of the Pacific Coast.

Fig. 83.- — Tiger Beetle {Cicindela), slightly Fig. 84. — Dytiscid Beetle {Dgtiscus verlicalis
enlarged. {Original.) Say), natural size. {Original.)

Family Dytiscidae (Carnivorous diving-beetles). — Members of this family are
present in almost every quiet stream and pond. They are oval, rather flat
beetles, usually black, and good swimmers, the hinder pair of legs being broad and
somewhat oar-like and heavily fringed with hairs (Fig. 84). The antennae are
thread-like. Whenever they need air, they float up to the surface of the water
and allow the hinder end of the body to project a little out of the water. Then,
lifting the elytra slightly, the air enters the space under them and is retained
there aided by hairs present. The insect can now stay under water until this air
supply has been exhausted. The larvae, often called “ water- tigers, ” they are such
voracious creatures, feed, like the adults, on various water insects and other
animals, even attacking small fish. Some of this family may be at least an inch
and a half long.

Family Gyrinidae (Whirligig-beetles). — These insects swim on the surface
of quiet water, generally in groups, and go around and around in a “whirligig”
sort of fashion. They are usually bluish-black, oval in form, and the compound

102

APPLIED ENTOMOLOGY

eyes are so divided that one part of each is directed upward and the other down¬
ward (Fig. 85). They feed on small insects which come within their reach. The
larvse, living in the water, breathe by abdominal tracheal gills, and are also
carnivorous. The group does not include many species, but their habit of
swimming in companies, and their peculiar “gyrating” over the surface attracts
attention, nearly everybody having noticed them on this account.

Family Hydrophilidae (Water-scavenger beetles). — The water-scavenger
beetles occur in the same types of stream and pond as the carnivorous diving
beetles, which they greatly resemble (Fig. 86). The outline, however, is usually
a little more elongately oval;., the antennae are club-shaped, and in addition to
other structural differences, they obtain air by raising the head slightly above

Fig. 85. Fig. 8G. Fig. 87.

Fig. 85. — Gyrinid or Whirligig Beetle (Dineutes) , natural size. ( Original .)

Fig. 86. — Water-scavenger Beetle ( Hydrous triangularis Say), natural size. {Original.)
Fig. 87. — Rove-beetle ( Staphylinus vulpinus Nordm.), slightly enlarged. {Original.)

the surface and collecting a film of it over the under surface of the body, where
it is retained by a close coating (pubescence) of fine hairs. They feed on decay¬
ing animal and plant material for the most part, though sometimes taking to
living plants and insects. Some species may be about two inches in length.
They are of little economic importance.

Family Staphylinidae (Rove-beetles). — This large family in some regards is
suggestive of the fire flies as the body of the insect in this group is not as hard
and firm as in most beetles and seven or eight abdominal segments are present
(Fig. 87). In other ways, however, it differs greatly from the Lampyrids, the
body being slender for its length, and the elytra short, not nearly covering the
top of the abdomen, the segments of which are very movable. The insects run
rapidly, often lifting up the end of the abdomen in a menacing way. Most of
the thousand or more species found in this country are small, the larger kinds
seldom being more than an inch long. They are land forms, feeding on decay¬
ing vegetable and animal materials near which, or under stones and wood,
they are found. They must be considered as beneficial insects, acting as scav¬
engers.

THE COLEOPTERA

103

Family Silphidae (Carrion-beetles). — Most of the members of this family
are of good size, ranging from half an inch to three times that length. Two
rather distinct types of insect are common in the group, one ( Silpha , Fig. 88)
having a broad, rather flat body and with the sides of the pro thorax very thin.
These insects average less than an inch in length and the elytra are usually
black. In the other type ( Nccrophorus , Fig. 89) the insect is larger, stout, with
a body more cylindrical, and the elytra generally have dull red markings and
are frequently shorter than the abdomen. Both types feed on dead animals in
most cases, and their larvae have the same food, so that the group may therefore
be regarded as beneficial. It is not a very large family, in the United States
at least.

Fig. 8 8. — Carrion-beetle ( Silpha
americana L.), about natural size.
(Original.)

Fig. 89. — Carrion-beetle ( Necrophorus
marginatus Fab.), slightly enlarged.
(Original.)

Family Dermestidae (Dermestids). — These insects are small, the largest
common species in this country being only about one-third of an inch long. Most
of them are rather short, thick-set beetles, covered with very small scales which
give them a gray or brown color, with occasional black, white or red scaly areas
in some cases, producing spots or bands of these colors. They feed on decaying
substances,, but those most important as pests attack wool, furs, feathers and
meat, cheese and fats. In some cases the adults feed on pollen and only the larvae
are destructive.

The Larder Beetle ( Dermestes lardarius L.). — This common insect is fre¬
quently found in pantries on foods, particularly of a fatty nature. The adult
(Fig. 90) is dark brown, with a pale-yellowish band across the elytra near their
bases, in which are a few black dots. The larva (Fig. 91) is longer and more
slender than the adult, with numerous, rather long, black hairs; is brown in
color, and attacks ham, cheese, beeswax, feathers, and almost any material oily
or fatty in its nature.

Control. — Little can be done in the way of controlling this pest, except by
cleanliness and close watch of all fatty substances kept in stock, removing and
destroying the insects whenever they are discovered. Tightly closed receptacles,
giving no opportunity for the insects to enter, should be used in which to
keep such substances.

104

APPLIED ENTOMOLOGY

The Buffalo Carpet Beetle (Anthrenus scrophularice L.). — The adult of this
insect is a tiny beetle about three-sixteenths of an inch long, mottled black and
white, with a red line having three pairs of side branches or lobes, down the middle
of its back (Fig. 92). It is a household pest in the northeastern states and as
far west as Iowa and Kansas. In Europe, of which country it is a native, it
does not appear to be of much importance. The beetles appear in the fall and
may continue to be found in heated houses all winter. The eggs are laid on
woolen cloth or clothes, carpets, rugs, furs, feathers or silk, all of these being
animal products, and the small hairy larvse feed on the materials named. After
pupation has been completed, the adults appear and are often noticed on windows.
In the spring months, probably after laying their eggs, the beetles appear out-
of-doors and feed on the pollen of various blossoms, the Spiraea being a favorite.

Fig. 92.

Fig. 91.

Fig. 90.

Fig. 90. — Adult Larder Beetle ( Dermestes lardarius L.) four times natural size. ( From
Herrick's Insects Injurious to the Household. By Permission of the Macmillan Company ,
Publishers.)

Fig. 91. — Larva of the Larder Beetle, three times natural size. ( From Herrick’s
Insects Injurious to the Household. By Permission of the Macmillan Company, Publishers.)

Fig. 92. — Adult Buffalo Carpet Beetle ( Anthrenus scrophularice L.), nine times natural
size. ( From Herrick's Insects Injurious to the Household. By Permission of the Macmillan
Company, Publishers.)

Whether there is more than one generation a season has not been definitely
settled. Many of the larvse breed in floor cracks under carpets and rugs, on the
woolen debris there.

A somewhat similar, closely related beetle, the Black Carpet Beetle ( Attagenus
piceus Oliv.), also of European origin, and dull black in color (Fig. 93), is likewise
an enemy to the same general class of materials as the Buffalo Carpet Beetle.
It appears to be a pest farther south than the last-named insect. The larva
(Fig. 94) is longer and more slender than that of the Buffalo Carpet Beetle, reddish-
brown, and with a tuft of long hairs at the end of its body.

Control of Carpet Beetles. — These insects are repelled by the odors of various
substances, and clothing, furs, feathers, etc., when put away, can be protected
from their attacks by placing them in tight bags or boxes, together with the repel¬
lent. Naphthaline (“moth balls”) is the most effective for this purpose, and

THE COLEOPTERA

105

the oil in cedar wood is also of value, hence the use of cedar chests for storage
purposes, these giving some protection as long as their odor lasts. Camphor also
is a fair repellent. But with all these materials the tendency is to use too little,
and in such cases the insects are not driven off. Then too, if the food of these pests
be put away with either eggs or larvae present, the repellent will not prevent the
larvae from feeding. The best practice therefore, is to fumigate all material
likely to be attacked, before packing it away, placing it in a tight box and treating
it with Carbon disulfid for 24 hr. Then add a liberal supply of moth balls and
close tightly. The fumingation will destroy these pests in any stage in which

Fig. 93. Fig. 94.

Fig. 93. — Adult Black Carpet Beetle ( Atfagenvs piceus Oliv.), enlarged nine times.
( From Herrick's Insects Injurious to the Household. By Permission of the Macmillan
Company , Publishers.)

Fig. 94.- — Larva of the Black Carpet Beetle, five times natural size. ( From
Herrick's Insects Injurious to the Household. By Permission of the Macmillan Company,
Publishers.)

they may be present, while the naphthaline will keep out adults which might
otherwise enter thereafter. Fumigation of a room or an entire house if necessary,
with Hydrocyanic acid gas, or sulfur, is also a good treatment, though if the latter
substance be used its effect upon metals, and on colors in clothes and wallpapers
should be remembered. Carpets may be steam-cleaned, this killing the pest in all
stages, and cold storage for furs and feathers at least, if the temperature be kept
below 40°F. will prevent injury, though not necessarily killing any of the insects
which may be present. As some of the larvae may be in floor cracks when carpets
and rugs are infested, these should be treated with kerosene or gasoline. Woolen
clothing kept in closets during the warmer seasons of the year should be frequently
brushed out and aired in the sunlight.

Family Buprestidae (Flat-headed Borers). — This group of beetles
contains many forms which injure trees by boring in their trunks.
Others attack berry canes which often show swellings as a result. A
few are leaf miners or gall makers. The adults are generally stout,
robust beetles with heads set into the thorax, rather flat backs, and in
general dark colored but with a metallic luster, though a few are bright

106

APPLIED ENTOMOLOGY

green or other colors. The larvae which bore in trees, are white except
for a small, yellowish head, arid have a large, flattened prothorax and no
legs. Some of these insects attack pines; others, different forest trees,
burrowing at first just under the bark in the sap-wood and later in the
heart-wood. The average life history requires about a year for its com¬
pletion, but if the tree be vigorous the larva is liable either to die or be
delayed in its development. The adults are fond of the sun and fly
freely in the daytime. They are often found on flowers. Several hun¬
dred species are known in this country, all of them injurious, the damage
they do being largely dependent upon the importance of the tree or
plant they attack.

The Flat-headed Apple-tree Borer (Chrysobothris femorata Fab.). — 1
This is probably the most injurious of the Buprestids. It attacks more
than' 30 kinds of trees and shrubs, generally selecting individuals which
are not in a healthy condition or are otherwise favorable for their larva? .

Fig. 95. — Adult Flat-headed Apple-tree Borer ( Chrysobothris femorata Fab.), enlarged
3J4 times. ( From U. S. D. A. Farm. Bull. 1005.)

The beetle (Fig. 95) is about half an inch long, rather broad, dark brown,
faintly marked with bands and indefinite spots of gray, and having a
brassy metallic reflection at certain angles. The underside is bronze,
and under the wings the abdomen is a metallic greenish-blue. It occurs
almost everywhere in the United States and in Southern Canada, and
is a serious enemy of fruit trees.

The beetles appear soon after apple-blossom time and live for several
weeks. They frequent the sunny side of the trunks and limbs of trees.
Here the eggs are laid in fine cracks or under small scales of the bark.
They hatch in from 2 to 3 weeks and the tiny larva (Fig. 96) bores into
the inner bark, feeding on this and on the sap-wood and grows rapidly

THE COLEOPTERA

107

unless the tree Is vigorous, in which case such an outpouring of sap may
occur at the wound as to kill (drown?) it or drive it into the outer layers
of bark where it may live for a time, later working back into the sap-wood
if the flow becomes small enough to permit it. If the larva can feed in
the sap-wood it will grow to full size, about an inch long, by fall, at this
time burrowing into the wood to form a pupal cavity in which the winter
is spent, pupation itself taking place there the following spring and con¬
tinuing several (three to four) weeks, after which the adult beetle escapes.

Fig. 96. — Flat-headed Apple-tree Borers ( larvce ) of various sizes. Natural size. ( From
U. S. D. A. Farm. Bull. 1065.)

Control. — Vigorous, healthy trees are not generally liable to attack,
and cultural methods which will insure this condition are important.
Trees headed low will shade their trunks and the sun-loving beetles will
go to those exposed to sunlight. Shading trunks exposed to the sunlight,
by boards cutting off this light, is a protection, as are also poles set in
the orchard and covered with sticky material to catch and hold the beetles
visiting them in search of places to lay their eggs. Wrappings of burlap
or paper extending from the ground to the limbs will prevent egg-laying,
but should be removed when this period is past. Birds and insect enemies
aid in controlling this pest.

Family Elateridae (Snapping beetles; click-beetles; skip-jacks). —
These insects somewhat resemble the Buprestids when adult but are
usually more slender, with their sides more nearly parallel, and the
economic species also lack a metallic reflection. The hinder corners of
the pronotum are elongated forming sharp points in the majority of the
group, and the insects are usually some shade of brown or black, though
the pronotum and elytra sometimes differ in color and the latter are
spotted in some cases, mottled black and white in our largest common
species, and some have rather bright colors or markings (Figs. 97 and 98).
When these insects fall on their backs they are able to throw themselves

108

APPLIED ENTOMOLOGY

into the air by a sudden snap of the body for the purpose of getting onto
their feet as they alight again, and if this fails at first the snapping is
repeated. The larvse (Figs. 97 and 98), commonly called wireworms,
are nearly all slender, yellow or brown, with very hard shells, often glis¬
tening, one sub-family where they are soft-bodied and white forming a
notable exception to this. The outline of the hinder end is often made
use of in distinguishing the
different kinds of wireworms.

Their food habits have a wide
range: some feed on decaying
wood under bark or elsewhere;
others on fungi ; several groups
are carnivorous, and still
others feed on roots or seeds
in the ground.

Fiq. 97. Fig. 98.

Fig. 97. — Wheat Wireworm ( Agrioles mancus Say): a, adult, enlarged about five
times; b, full-grown larva (Wireworm), enlarged about three times; c, side view of last
segment of larva. ( From U. S. D. A. Bull. 156.)

Fig. 98. — Corn and Cotton Wireworm ( Horistonotus uhleri Horn): a, adult, enlarged
about ten times; b, full-grown larva (Wireworm), enlarged over four times. ( From U. S.
D. A. Bull. 156.)

One of the largest insects of this family found in the United States
is the Eyed Elater ( Alaus oculatus L.), which is about an inch and a half
long; the elytra black, finely marked with white dots; and with a pair of
large, oval, velvety-black spots rimmed with white on the pronotum
(Fig. 99). The larvse of this insect feed on insects in decaying wood,
often that of the apple, but are of little economic importance.

THE COLEOPTERA

100

In the South and also in the West Indies and Mexico are species
of Elaterids ( Pyrophorus spp.) which have an oval, yellowish spot near
each hinder corner of the pronotum (Fig. 100), and also an area on the
underside of the abdomen close to, and partially concealed by the meta-
thorax, which are luminous, producing an intermittent, greenish-yellow,
quite brilliant light, making the insects very noticeable at night. They
are beneficial, the larvse feeding on white grubs.

The injurious members of this family are those wireworms which feed
on seeds and the roots of plants, and there are many kinds which have

this habit. Some attack wheat; others
corn, and still others feed on cotton,
grass, potatoes, sugar-beets and other
crops, doing much damage. Some are
most abundant in heavy soils containing

Fig. 100.

Fig. 99. — Adult Eyed Elater ( Alaus oculatus L.), about natural size. ( From Linville
and Kelly, General Zoology, Ginn and Company, Publishers.)

Fig. 100. — A Luminous Elaterid ( Pyrophorus sp.) showing luminous spots on sides
of pronotum. Natural size. {Original.)

much vegetable matter, while others prefer high, sandy land. So many
species of wire-worms are injurious and so unlike are their habits in
different parts of the country that each kind seems to require treatment
especially adapted to it.

Control. — Some general factors in control may, however, be suggested.
When wireworms are abundant in low, poorly drained land, drainage
will be of much assistance. When they attack grass roots in great
numbers, it is desirable in cultivating such places to substitute field peas,
buckwheat, or some crop not closely related to grass, for the first crop, if
possible, even though this does violence to the general ideas of crop
rotation. When sod land is to be planted, plowing it in July and cultivat¬
ing often and deeply the rest of the summer will destroy many of the
insects. In the South and in arid regions, however, the insects go deeply

Fig. 99.

110

APPLIED ENTOMOLOGY

into the ground during hot or dry weather, beyond reach by cultivation.
In such cases planting early in the season and forcing the plants ahead by
fertilizers and frequent cultivation are helpful. As the underground
feeding period of these insects is from 3 to 6 years, proper treatment
for a single season will at best give only partial relief, and to obtain the
most successful control the special habits of the particular species
concerned should be ascertained, and control measures to correspond
be adopted. Various methods for the protection of planted seed have
been tried but the results have not agreed in all cases and further
studies along this line are needed.

The Elateridae is one of the most important groups of beetles from an
economic standpoint, and injurious species occur practically everywhere
in the United States. Several hundred kinds are known in this country.

Family Scarabaeidae (Lamellicorn beetles). — This is a very large
and important family of beetles, containing many pests. The antennae

in this group have several of the terminal segments
large, flattened, and broader on one side, movable
but generally carried close together. The insects
are stout and rather short in most cases, and
the elytra usually do not cover the entire
abdomen.

Based on their habits, two sections of the
family can be distinguished: the scavengers
which both as larvae and adults feed on decaying
matter; and the leaf chafers which as adults
generally consume leaves or flowers, and whose
larvae occur in the ground feeding on roots, or
in decaying wood.

The' Scavengers, though they may be con¬
sidered as beneficial, are not of great importance, but some species
because of their peculiar habits have attracted attention for centuries.
The habit referred to is that shown by some of the so-called “Tumble-
bugs” in connection with egg laying. A pair of these beetles will to¬
gether form a little dung into a ball which they then begin to roll over
the ground, often for a long distance. Finally they bury it in the
ground after an egg has been laid upon it, thus providing partially
decomposed food for the larva. The Sacred beetle or Scarabseus of
the Egyptians was one of the insects of this group (Fig. 101) and has
been preserved in their drawings and carvings as a symbolic record
of their beliefs. The leaf chafers form the larger part of the family.
Among them are a number of serious pests.

The June Bugs or May Beetles ( Phyllophaga and other genera). —
This is a group of beetles quite similar both in appearance and habits.
The adults are generally dark brown and rather glossy above, from half

Fig. 101. — Egyptian
carving of a Secarabaeus.
{Original.)

THE COLEOPTERA

111

an inch to an inch long, and very stout (Fig. 102). They appear
during the spring months, earlier in the South than in the North,
Hying at night and are attracted by lights, to which they hy in a clumsy,
erratic way. They feed at night on the leaves of various trees, often
entirely stripping them. Different kinds of June bugs appear to prefer
different kinds of trees for their food. Some species seem to select the
oak, others the ash, still others the pine. Small birches have been
completely stripped of their foliage in a single night. In the South two
species appear to prefer the longleaf pine and whatever the species,
large areas of timber may be defoliated when the beetles are abundant,
though this seldom appears to be the case in New England. On the
Pacific Coast too, though June bugs occur, they do not seem to be as
important as in the interior of the country, particularly in the Mississippi
Valley and as far north as the Great Lakes.

Fig. 102. Fig. 103.

Fig. 102. — Adult “June Bugs,” • female and male, natural size. ( From U. S. D. A.
Farm. Bull. 940.)

Fig. 103. — Full-grown larva ( white grub) of “June Bug,” natural size. {Original.)

The eggs of the June bugs are laid in the ground and hatch in a few
weeks into tiny “white grubs” with brown heads and legs, and soft,
white bodies which increase in size toward the hinder end. The grub
(Fig. 103) as usually found when dug up is curled through the greater part
of a circle and this, is very characteristic, only a few other beetle larvae
(and those belong in the same family) greatly resembling it. The grubs
feed during the summer on decaying vegetation and living plants close to
the surface of the ground but on the approach of cold weather go deeper
into the ground to pass the winter. The following spring they come up
near the surface again and now feed on the plant roots, causing in this,
their second season, the largest injury. In the fall of the second season
they again go deep into the ground to pass the winter, coming up the
third spring to feed on plant roots until June or July, when they go down
a little, though not usually much if any below where they may be reached
by deep plowing. Here they transform to pupae which become adult

112

APPLIED ENTOMOLOGY

after a month or two, but the beetles remain in these underground pupal
cells until the next (fourth) spring, when they emerge. The length of a
generation as thus outlined therefore is 3 years, but the progeny of any
given beetle appearing one spring will appear the spring of the fourth year
following, i.e., a generation requires 3 years but is present in parts of 4
calendar years.

This life history holds for most of the injurious species of June bugs
in the Central States, through the country east of the Rocky Mountains.
In the North, however, the life history in some cases at least, requires 4
years, while in the Southern States 2 years appears to be the normal period.
Some appear every year though, indicating the existence of three broods
in those regions where the 3-year life-history exists, but the size of these
broods is markedly different. Though undoubtedly subject to factors
which may increase or decrease the size of these broods as years pass, the
most abundant and destructive one at present is that in which the beetles
appeared in 1917 and 1920, and which will reappear at 3-year intervals
hereafter, the greatest destruction being caused by the grubs the following
year. The second brood, the beetles of which appeared in 1918, was not
of sufficient size to attract much attention by their injuries in 1919 and
probably will not be important in 1922, while the third brood with the
beetles in 1919 and their injuries in 1920 was of importance in only a few
areas. How soon favoring conditions may lead to one of these last-named
broods becoming large enough to be important, or unfavorable factors
reduce the importance of the first-mentioned one, cannot be predicted.

Though white grubs have many natural enemies, including numerous
mammals, birds and insects, and also several diseases, both bacterial and
fungous, they are not sufficient checks to prevent considerable injury.

Control.— Pasturing hogs in fields considerably infested by white
grubs is a good practice, the hogs feeding on other insects they find in the
ground, as well. Poultry can be made use of in the same way, but this is
most effective when the ground is being cultivated. Rotation of crops
is also of value if used intelligently. Corn and clover are crops in which
the beetles will not lay eggs freely. Grain fields have many eggs laid in
them, but if followed by clover the grubs will do little damage. Fall
plowing before the grubs go down to pass the winter will destroy many of
them. This should be done as late before t he grubs start down as possible.
The spring after beetles were abundant the year before, many small grubs
should be found in cultivating. In this case seed with small grain or
clover. If large grubs are abundant either in the fall or the following
spring, plant late if possible, as the grubs finish feeding before July in
most cases; or plow as soon after July 15 as possible, to break up and
destroy the pupae. Where beetles are stripping foliage, spraying with a
stomach poison, standard, or a little above standard strength, is a good
treatment where conditions are such as to make it practicable.

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113

In general the treatment can be based on the year the beetles are
abundant. Sod land broken up that year should be plowed before Octo¬
ber and should not be in corn or potatoes, but in clover, small grain or
buckwheat the next year, if the farm practice of that region will permit.
The following year delay planting till as late as possible. Pasture every
season with hogs in the fall as soon as the crop is out.

The Rose Chafer (M acrodadylus subspinosus Fab.). — This insect occurs all
over the Eastern United States as far south as Virginia and Tennessee and west to
Colorado, being particularly abundant and destructive in sandy localities. The
adult beetle is about a third of an inch long, rather stout, though less so in pro-

Fig. 104. — Rose Chafer (M acrodadylus subspinosus Fab.): a, adult beetle; b, larva
(grub) ; e, pupa; /, injury to leaves and blossoms of grape with beetles at work. Fine lines
beside a, b, and e, show the true length: /, somewhat reduced. (From U. S. D. A. Farm.
Bull. 721.)

portion to its length than are the June bugs, dull yellow, with pale, red legs which
are long and slender. It appears about the time roses begin to bloom, i.e., in
May in the South, and in June in the more northern part of its range, and attacks
a large number of plants. It seems originally to have been a rose feeder: later
it became a serious pest of the grape and is now destructive to many fruit and
shade trees and shrubs, and even to garden fruits and vegetables when abundant,
eating blossoms, leaves and any fruit which may be available during its adult
condition (Fig. 104).

The eggs, about thirty in number, are laid a little below the surface of the
ground, sandy land being apparently somewhat preferred, and these hatch in
2 to 3 weeks into tiny white grubs somewhat resembling those of the June bugs.

114

APPLIED ENTOMOLOGY

These grubs feed on plant roots, particularly those of grass, until quite late in the
fall, then work down in the ground to below the frost line, where each forms a
small earthen cell in which to winter. In the spring pupation takes place and
from 2 to 4 weeks later the adult beetle is produced and digs its way to the surface.
An adult individual lives about 3 weeks.

Control. — Stomach poisons will kill the adults in time but they work too
slowly to save the plants, which are seriously injured before the beetles die.
In any case, these could hardly be used on flowers as they would at least mar their
appearance. On grapes and other fruits, arsenate of lead, using 5 lb. of the paste
in 50 gal. of water or Bordeaux mixture (better), applied very thoroughly as soon
as the beetles appear, or just before the blossoms open in the case of the grape,
has given fair results, though a second treatment just after the blossoms fall is
sometimes needed.' With stone-fruit trees the self-boiled lime-sulfur wash should
be used instead of the Bordeaux.

Hand picking, though tedious, .is effective with plants growing low enough to
make this method of control practicable, but must be repeated every day to get
those which fly to the plants from elsewhere, or emerge from the ground later.
Bagging the clusters of grapes is often practiced where this plan seems worth
while. Harrowing the breeding grounds of the insect to a depth of three or four
inches, during the time they are pupae, i.e., the latter part of May for the central
part of their range, destroys many of the pupae which appear to be very easily
killed by any disturbance while in this stage. The difficulty with this is to locate
the areas where they are breeding most abundantly. Light, sandy ground will
generally prove to be the place for such treatment.

This insect seems to have a poisonous effect when eaten by small chickens,
many dying within a day or two after feeding on Rose Chafers.

On the Pacific Coast several species of ILoplia seem to play much the same
role as the Rose Chafer does in the East. Their life history does not appear to
have been worked out but probably does not differ greatly from that of the Rose
Chafer, and the treatments are practically the same. The beetles of all the
species range from about one-quarter to one-half an inch in length and are light
brown, grayish, mottled, or black with brown, orange-yellow or olive, either in
spots or entirely concealing the black. Grape, rose, greasewood, blackberry, etc.,
are the chief food plants.

The Green Japanese Beetle ( Popillia japonica Newst.) has recently been
discovered in New Jersey. The beetles attack the foliage of many kinds of
plants including fruit trees, small fruits, garden crops and ornamental trees and
shrubs: the larvae feed on the roots of plants and on decaying vegetable matter.
The beetle is about half an inch long and somewhat resembles several of our native
forms. If, in spite of vigorous measures now being taken to eradicate it, this
insect should become widely distributed, it will undoubtedly become a serious
pest as it already is in Japan.

Many other Scarabseids are occasionally injuriously abundant in
different parts of the country but can hardly be considered as of nation¬
wide importance. The largest beetles found in the United States also
belong here and are called rhinoceros beetles. One species, Dynastes

THE COLEOPTERA

115

iityrus L. (Fig. 105), about two and one-half inches long, is greenish-gray
with black spots on the elytra. The male has a long horn on the head,
projecting forward and upward, and another projecting forward from the
pronotum. The female has only a small tubercle on the head. It occurs
in the Southern States. In another species found in the West the pro-
thoracic horn is much longer.

Fig. 105. — Rhinoceros Beetle ( Dynastes tityrus L.), about natural size. {Original.)

Family Chrysomelidae (Leaf beetles). — This is the largest family of
beetles but its members are small, not often being over half an inch long.
Most of them are leaf feeders, though the larvae of a few are worm-like
and attack underground stems or roots. Many are serious pests, and
though almost none are found throughout the entire country, allied species
working in similar ways, occur.

In the group as a whole, yellowish elytra with black lines or spots
seems to be the prevailing color pattern, though of course, with many
exceptions. Together with the next two families, from which other
characters separate this one, the third segment of the tarsus is generally
broad, being drawn out into a lobe on each side, and is covered beneath
with minute, closely set hairs (pubescent). The antennae are at most,
of only average length.

The Colorado Potato Beetle (Leptinotarsa decimlineata Say). —
This well-known insect was discovered about 1823 by Long’s exploring
expedition to the Rocky Mountains, in the region of the upper Missouri
River. Its food there was the Buffalo-bur ( Solarium rostratum Dunal)
and the insect was apparently not remarkably abundant, and certainly
of no economic importance, nor did it become so until civilization, and
with this the potato, reached that territory. Then a new and satis¬
factory food plant, abundant enough to provide all the insects with food
became available and the potato beetle increased in numbers and began
to spread to the East. At first its rate of spread was only about 50
miles a year but after crossing the Mississippi River this became more
rapid and it reached the Atlantic Coast about 1874. Since then it has
spread both northward and southward until it is now found practically

116

APPLIED ENTOMOLOGY

everywhere east of the Rocky Mountains where the potato is grown and
it has also reached the Pacific Coast. It does not apparently thrive
in the hot climate of the more southerly States.

The adult beetle (Fig. 106b) is somewhat less than half an inch long
and about two-thirds this width, its back rather high and rounded. It
is clay-yellow and has 10 longitudinal black lines on its elytra. The head
has a black spot above, and the pronotum has a number of irregular spots.
Winter is spent as the adult in the ground but the insects come out quite
early in the spring. As soon as the potatoes are up, they begin to feed
and soon lay their eggs, placing these on the under surface of the leaves

in small clusters, an individual laying 500
or more in all. They are small, yellow
eggs which hatch in from 4 days to a week
or more, according to the temperature.
The grubs or “slugs” as they are often
called (Fig. 106a) are dull brick-red, soft
and with fat bodies. They feed for from
2 to 3 weeks, then go into the ground
where they pupate for a week or two, after
which the adults emerge and lay eggs for a
second generation, the adults of which ap¬
pear early in the fall. This second gen¬
eration of beetles feeds for a time, then in
September or October enters the ground to pass the winter.

As the eggs of this insect are not all laid at one time, different ages
and different stages even, may be found together in the same field. And
as the adults feed in the spring during their egg-laying period, as do the
two generations of adults produced during the season, in addition to the
two generations of grubs which also consume the leaves, the plants are
being attacked much of the time.

While the potato appears to be the preferred food of this insect, other
members of the nightshade family are sometimes attacked, particularly
the tomato and eggplant.

Control. — This pest is easily controlled by spraying with either
of the stomach poisons and as the potato is quite resistant to poisons, the
strength of the mixture can with safety be somewhat increased above
that of the standard formula. The chief difficulty in control is that as
the beetles attack the rapidly-growing plant as soon as it appears above
ground, the spray should be applied then, while a week later a large
amount of new growth which has no poison on it will have developed,
upon which the insects can feed. To avoid this, spraying during the
period of rapid growth needs to be done more frequently than is the case
with most plants. Two or three treatments, however, will generally be
sufficient, and a combination with Bordeaux mixture is advantageous
where arsenate of lead is the stomach poison used.

a b

Fig. 106. — Colorado Potato
Beetle ( Leptinotarsa decimlineata
Say), slightly enlarged: a, full-
grown larva (Grub); adult Beetle.
(From Berlese, After U. S. Bur.
Eut. Cire. 87.)

THE COLEOPTERA

117

On small areas, Paris green dry, mixed with 10 to 20 parts of some
inert material, dusted over the plants, preferably while the dew is on
them, is a fair treatment, and this poison as a spray can also be used.
Arsenate of lead is at present the preferred poison for this pest, however.

Various birds, skunks, snakes and toads feed on the Colorado Potato
Beetle to some extent, and it also has numerous insect enemies.

The history of the development of the Colorado Potato Beetle, from
an unimportant, even probably a rather uncommon insect, feeding upon
a plant of no value to man, into one of the most abundant and widely
distributed of our pests, attacking and seriously injuring an important
crop, is a suggestive one. In a division of the insects of the United
States into those which are injurious as regards man and his various
interests; those which are beneficial, and those which are of little or no
economic importance either way, we shall find that the last group is by
no means a small one. How many species in this group are there which
are potential pests? It is true that the making available of a new food
plant to which the Colorado Potato Beetle could turn, was probably the
chief factor in this particular case, but any insect which for some reason
changes from an unimportant food plant to a crop plant may at once
become a pest. Thus another Chrysomelid only a little smaller than the
Colorado Potato Beetle and closely related to it, the Three-spotted Do-
ryphora (Doryphora clivicollis Kirby), which feeds on milkweed, is now of
practically no importance. But if it should change its food to some
valuable crop plant it would at once become an important addition to
the list of insect foes man has to combat. Several such cases are al¬
ready known. How many others may appear as the changing conditions
which always accompany an increasing population and the consequent
changes in plant population take place, no one can predict. Some species
of plants once common are rapidly disappearing. As they go, will the
insects feeding on them go too, or will they be able to find another food
plant, and will this one be of value to man? The appearance of new
pests in such ways may come at any time, and the fact that an insect is
not now a pest should not lead to its being ignored, for it may have great
potential importance. The Murky Ground Beetle ( Harpalus caliginosus
Fab.) is now mainly a carnivorous beetle, but sometimes, though rarely,
attacks the strawberry. If it should turn to this latter plant entirely
for its food, another important pest would be added to our list and lost
from among our friends.

Such facts call for as complete a knowledge as possible of the life
and habits of all insects whether now beneficial or only of no economic
importance, in order that we may have the knowledge of them and
their ways which is necessary in case they should become injurious.

118

APPLIED ENTOMOLOGY

The Striped Cucumber Beetle ( Diabrotica vittata Fab.). — The com¬
mon Cucumber beetle is found everywhere in this country (of which it is a
native) east of the Rocky Mountains. It is a small beetle about a fifth of
an inch long, with a black head, yellow pronotum and three black stripes
along its yellow elytra (Fig. 107). The insect passes the winter as the
adult beetle in protected places, probably among dense weed growth.
It leaves its winter quarters early in the spring, before any of its culti¬
vated food plants are available, and feeds on blossoms of various kinds
until cucumbers, squashes and the other cucurbits which are its favorite
food plants are available. It then attacks these and may also seriously
injure peas, beans, apples, and later in the season, corn. It lays its
eggs either singly or in clusters, in the ground
near the stems and roots of the cucurbits, often
in crevices of the soil, the total number of eggs
per beetle varying from a few hundred to over a
thousand. The eggs hatch in a week or two, ac¬
cording to the temperature at that time, and the
grubs feed on the stems and roots. They are tiny,
white, slender, and resemble maggots more than
the usual forms of beetle larvae, and when full
grown, after 2 to 5 or more weeks, according to the
temperature, are only about three-tenths of an
inch long. They then soon change to pupae, still
in the ground, in which stage they remain for
about a week before the beetles emerge. The life
cycle therefore varies in length according to the
temperature, it being perhaps not over 4 weeks in
the South and 8 in the more northern States. This gives time for
several generations each season, and though in the North there is
apparently but one, this number increases farther south until in Texas
there may be four.

The destruction caused by these insects when they are abundant is
often very great. Their first attacks come just when the young plants
are struggling to establish themselves and the feeding of the adult
beetles is often sufficient to kill them. Later in the season the beetles
continue feeding on the leaves and stems, reducing the vigor of the plant
and its productiveness, and they may also feed on the outer surface of
the fruit, making it more or less unsalable. They also frequently enter
greenhouses and attack cucurbits there. The larvae affect the vitality
of the plant by attacking the underground stems and roots but are less
injurious than the adults.

The beetles are also injurious by carrying the “bacterial wilt”
disease and “cucurbit mosaic” disease, not only from plant to plant,
but also from one season to the next. As these diseases are serious ones.

Fig. 107. — Adult
Striped Cucumber Beetle
( Diabrotica vittata Fab.)
enlarged about six times
(see hair line for true
length). {From U. S.
D. A. Farm. Bull. 1038.)

THE COLEOPTERA

119

often destroying plants, this adds to the importance of the insect as a
pest.

On the Pacific Coast is a slightly larger species known as the Western
Striped Cucumber beetle ( Diabrotica trivittata Mannerh.) which has much
the same habits as the eastern form. In the more southerly portion of
this region the adults are more or less active during the cold months.
There appear to be at least two generations a year, and the methods given
below for the control of the eastern species also apply for this one.

Control. — This is a difficult insect to control, particularly where large
areas are planted to any of the cucurbits and small garden methods will
not pay. Protective methods, practicable in gardens, enable the plants
to get well started, after which they are able to grow and produce the crop
to quite an extent, despite the insect. Screening the plants before they
come up, using fine-mesh wire or thin cheese-cloth stretched over a
frame, works well for this purpose, provided the edge of the frame fits
tightly into the earth everywhere, so that the beetles cannot burrow un¬
der it. Sometimes an excess of seed is planted with the idea of giving
the insects enough food so that few or none of the plants will be too thickly
infested to be able to live, and the poorest ones can be thinned out later.
Gathering all but a few of the plants as soon as the crop has been har¬
vested, and burning them will leave the others for the beetles to gather
on. These can then be sprayed with a strong stomach poison or a strong
contact insecticide. Early cucurbits such as gourds, can be planted near
later cucumbers and will act as trap plants, attracting the beetles.

Spraying with a stomach poison, either alone or with Bordeaux
mixture, is a good treatment if both sides of the leaves and the stems are
well covered. Arsenate of lead 6 lb. of paste in 50 gal. of water seems
generally to give the best results. The addition of 3 lb. of soap to each 50
gal. of spray makes the latter adhere better to the plant. Arsenate of
lime gives fair results. Dusting the plants with the dry poison mixed
with air-slaked lime or plaster, at the rate of 1 lb. of the poison to any¬
where from 25 to 50 lb. of the inert material, sometimes works well.
Its weakness as a treatment is mainly that it is difficult to get it onto the
under side of the leaves and have it stay there.

Whatever spray material is used, give the first treatment as soon as
the plants show above ground and repeat two or three times at about
weekly intervals, or oftener if rain makes it necessary.

Several other minor remedies such as dusting the plants while the
ground is moist, with tobacco dust, lime, or a mixture of the two; and
hastening the growth and increasing the vigor of the plants by fertilizers
and frequent cultivation, have some merit. If any or all the above-sug¬
gested treatments have been used, however, some of the insects will
generally be present, none of these methods giving absolute freedom from
the pest.

120

APPLIED ENTOMOLOGY

The Corn -root Worms. — -There are several species of the genus Diabrotica
which as larvse appear to make a specialty of feeding either upon the base of the
stem or the roots of corn.

The Southern Corn-root worm or Twelve-spotted Cucumber beetle ( Diabrot¬
ica duodecimpunctata Oliv.) is found practically everywhere in the United States
east of the Rocky Mountains, but is usually a serious pest only from Maryland
to Florida and as far west as southern Ohio, Indiana and Illinois, Alabama,
Louisiana and Texas. The insect generally winters as the adult beetle (Fig. 108)
under rubbish or in other protected places, except in the far South where it is

Fig. 108.

Fig. 109.

Fig. 10S.- — Adult Southern Corn-root Worm ( Diabrotica duodecimpunctata Oliv.),
enlarged about eight times. ( From U. S. D. A. Farm. Bull. 950.)

Fig. 109. — Grub of Southern Corn-root Worm and its burrow in corn. Much en¬
larged. ( From U. S. D. A. Farm. Bull. 950.)

more or less active during this period. In spring it lays its eggs just below ground,
on or near the young corn plants, and the tiny grubs which hatch, attack the corn,
feeding on the roots and drilling into the stem just above them, boring out the
crown and killing the bud (Fig. 109). From this habit the insect is often called
the “budworm” or “drillworm.” Small plants injured in this way break off
at the crowns when pulled, and larger ones become dwarfed and yellowish.
Other plants such as wheat, millet, alfalfa, etc., are also attacked by the larvae.
The adult beetle is about a quarter of an inch long, yellowish-green with black
head and legs and twelve black spots on its back. It feeds on squashes, cucum¬
bers and many other plants. There appear to be two generations each year in the
North and three in the South, but most of the injury is caused by the first genera¬
tion. Burning over waste places where there is rubbish, during the cold months
or on cold days will destroy many of the beetles which are seeking protection

THE COLEOPTERA

121

there. A careful crop rotation, never planting corn twice in succession on the
same land is also of value. Cotton, not being attacked by this pest is a safe crop
to follow corn and a legume is desirable in the rotation. The insect is most
serious in wet seasons and on low land. Corn is often more thickly planted on
low places on this account, to increase the chance of getting a stand. Fertiliza¬
tion and cultivation increase the vigor and resistance of the plants to attack.
In the far South corn planted during April is more likely to be injured than that
planted before this time or after the tenth of May.

The Western Corn-root worm ( Diabrotica longicornis Say) occurs from
Nova Scotia to the Gulf of Mexico and west to Minnesota, Nebaska and New
Mexico, but is most injurious from Ohio
to Tennessee and from South Dakota
through Nebraska, Iowa and Missouri.

The winter is spent in the egg in the
ground and the grubs (Fig. 110) hatch
in the spring and attack the corn roots
(Fig. Ill) but never the stem. After
feeding until full-grown they pupate in the ground
emerge in July and August and lay their eggs,
one generation a year. The adult beetles (Fig. 112) are about one-fifth
of an inch long and, except for their black eyes, are entirely greenish or
yellowish-green. They feed on the pollen and silk of corn and on the

Fig. 110. — Grub of Western Corn-root
worm ( Diabrotica longicornis Say), much
enlarged. ( From U. S. D. A. Bull. 8.)

and the adult beetles
There is therefore, but

Fig. 111. — Work of Western Corn-root worm in corn roots. ( From U. S. D. A.

Bull. 8.)

Fig. 112. — Adult Western Corn-root worm, enlarged. Hair line at right shows
real length. {From U. S. D. A. Bull. 8.)

blossoms and leaves of other plants, in August and September and if abundant
then in a corn field, one may be certain that that field will be well stocked with
eggs and therefore that corn should not be planted there again the following
spring Corn attacked by the grubs at first produces shortened ears with kernels
lacking at the tips: later it fails to produce the ears, and dwarfing of the plants

122

APPLIED ENTOMOLOGY

occurs. Rotation of crops has proved a successful control for this insect in
practically every case where it has been tried.

Another species ( Diabrotica vergifera Lee.) having similar habits and similarly
controlled, is often destructively abundant in Colorado.

On the Pacific Coast a different species, the Western Twelve-spotted Cucum¬
ber Beetle or Flower Beetle ( Diabrotica soror Lee.), appears to have the same gen¬
eral habits as its eastern relatives, but observations thus far indicate that the
grubs are injurious mainly to alfalfa, beet, pea and peanut roots, while the adults
do much damage to many plant leaves, buds and flowers. The winter appears
to be spent in the adult stage and the eggs are laid from March to May in
different latitudes. There are probably two generations each year. The adult
is one-fifth to one-fourth of an inch long. The head, antennae, legs and body are
black; the pronotum and elytra green or yellowish, the latter with twelve black
spots often partly fused. Control thus far has been directed mainly against the
beetles, spraying plants on which they are feeding with arsenate of lead (neutral)
at the standard formula, using either water or Bordeaux mixture.

a be

Fig. 113. — Adult Flea Beetles: a, Spinach Flea Beetle, enlarged nearly five times;
b, Potato Flea Beetle, enlarged about seven times; c, Egg-plant Flea Beetle, enlarged about
seven times. ( From U. S. D. A. Bulletins.)

Flea Beetles. — Many tiny beetles belonging in the Chrysomelidae
are known as Flea beetles because when disturbed they hop away like
fleas. The economic forms vary in size from about a fifth to a fifteenth
of an inch in length (Fig. 113). Most of them are blackish or steel-
blue, though some have portions of the body yellow, whitish, red or
other colors. The hind femora are very large, enabling the insects to make
vigorous leaps. The adults feed on the leaves, eating tiny holes, while in
most cases the larvae are root feeders, generally on the same plants which
their adults attack, though in some cases they also attack the leaves.
Many attack garden crops such as the potato, turnip, beet, spinach,
rhubarb and radish, while other species feed on the strawberry, grape,
tobacco, hop, clover, apple, Virginia creeper, wallow, alder, etc. In most
cases there are two generations a year, the first appearing early in the
season and the second in mid-summer or early fall, though some species
have but one generation and some have several.

Control. — These insects which are often serious pests, appear to be
repelled by Bordeaux mixture, but it is better to combine this with

THE COLEOPTERA

123

arsenate of lead, standard formula. Dusting with Paris green and land
plaster may also be used with some success as a control method. Where
the larvae mine in the leaves, as certain species do to some extent, treat¬
ment must be directed toward the destruction of the adults which indeed,
should be the case with all the species. Where plants are started in seed
beds and are attacked there, screening the beds with cheese-cloth is
practicable. When plants from seed beds are set out they may be pro¬
tected by dipping them in 1 lb. of arsenate of lead paste in 10 gal. of
water before setting them.

It is believed that the Cucumber Flea-beetle like the Three-lined
Cucumber Beetle may inoculate plants with the cucurbit wilt already
referred to. Certainly the tiny holes made in the leaves by their feeding
provide excellent places for the spores of fungi to establish themselves
and produce disease.

The Common Asparagus Beetle ( Crioceris asparagi L.). — This insect
reached this country from Europe about 1856 and is now present in the
Eastern States as far south as North Carolina and westward to the Mis¬
sissippi River. Farther west it has been reported from several scattered
localities, including California, and it may be assumed that it will in
time become generally distributed.

Fig. 114. — Common Asparagus beetle ( Crioceris asparagi L.) : a, Adult; b. Egg; c,
larva, just hatched; d, full-grown larva. Greatly enlarged: hair lines beside a and b show
real length. ( From U. S. D. A. Farm. Bull. 837.)

The adult beetle (Fig. 114) is a little less than a quarter of an inch
long. It is dark blue or bluish black, with a red thorax, and its elytra
are dark blue and yellow, the former present as a band along the middle,
with two lateral extensions toward the sides into the yellow, while the
outer border is reddish. The distribution and amount of the blue and
yellow varies considerably according to the locality, the blue often so
encroaching on the yellow as to leave only six spots of the latter color.

The insect winters in the beetle stage in any protected place it can
find, and as the asparagus plants begin to come up in spring, leaves its
winter quarters to feed and lay its eggs (Fig. 115a). The beetles at this

124

APPLIED ENTOMOLOGY

time feed on the stems and when abundant do considerable harm. The
eggs are laid on the stems, singly, attached by one end, are dark brown
in color, and hatch in from 3 to 8 days according to the temperature.
The grubs (Fig. 1 14c?) , often called “slugs” are gray with black heads.
They feed from 10 days to 2 weeks, gnawing the stems and thus aid the
beetles in making these unfit for sale. Then they enter the ground and
pupate for about a week which is followed by the emergence of the adults.
The life cycle therefore is from about 4 weeks during hot weather to 6 or

7 weeks in spring or fall. There are
at least two generations in the North
and probably three or four in the
South each year.

The later generations feed on
the leafy growth and in the case of
young plants may seriously weaken
them. Eggs when abundant on the
stems cut for market are objection¬
able, and a black fluid poured out by
the grubs when disturbed, often stains
the stems also. Fortunately, exces¬
sive heat appears to kill many of the
grubs, and the alternation of severe
cold with much warmer periods in
winter, has a similar effect on hiber¬
nating adults. Several parasites and
other enemies also reduce the numbers
of this pest.

Control. — Fresh air-slaked lime
dusted over the plants while these
are wet with dew is an excellent con¬
trol measure for small areas. Fowls
feed freely on the insects and are therefore of value when allowed to run
through the asparagus beds. For larger areas a frequent practice is to
keep the plants as closely cut as possible, leaving a few stems here and
there as traps on which the beetles can lay their eggs. These plants
should be cut once a week and destroyed, others being then allowed to
grow to take their places. Where cutting is not being done, spraying
with arsenate of lead a little stronger than the standard formula is a
very satisfactory treatment, the number of treatments required being
generally not more than two or three at most during an entire summer.

The Twelve-spotted Asparagus Beetle ( Crioceris duodecimpunctata L.). —
This insect arrived in this country from Europe about 1881 and was first dis¬
covered near Baltimore, Md. Though beginning its work here more than 20
years later than the other species, it has already nearly everywhere overtaken the
latter and is now widely distributed.

Fig. 115. — Eggs, larvae and adults of
Common Asparagus Beetle on the plant.
Natural size. ( From U. S. D. A. Farm.
Bull. 837.)

THE COLEOPTERA

125

The adult beetle (Fig. 116) is slightly larger and broader in proportion to
its length than the Common Asparagus Beetle. It is orange-red or brick-red
above except for twelve black dots on the elytra. The life history and habits
do not seem to differ much from those of the other species except in the follow¬
ing features. The beetle appears to depend upon flight rather than upon dodg¬
ing around the stems to escape its enemies: the egg is not attached by one
end but by a side, to the plant; the larva feeds inside the berries and is orange
to yellowish in color. The hibernating insects feed on the young plants like the
other species but the beetles of later generations feed on the berries. Control is

similar to that for the Common Asparagus Beetle
except that dusting with air-slaked lime will not
reach the larvae.

The Grape-root Worm ( Fidia viticida Walsh).
• — The Grape-root Worm appears to be a native

Fig. 116.

Fig. 117.

Fig. 116. — Adult Twelve-spotted Asparagus Beetle ( Crioceris duodecimpunctata
L.) nearly six times natural size. ( From U. S. D. A. Farm. Bull. 837.)

Fig. 117. — Adult Grape-root Worm ( Fidia viticida Walsh), about natural size, and
its work on a grape leaf. ( Modified from Cornell Exp. Sta. Bull. 208.)

of this country and is found from New York to North Carolina (and
Florida?) and west to Dakota, Missouri and Texas. There is also a California
record for it but it appears to be largely replaced there, by the California
Grape-root worm ( Bromius obscurus L.). The insect passes the winter as
the nearly- or full-grown larva, a number of inches deep in the ground, but in
spring it comes nearer the surface and feeds on the roots of the grape until full
grown. Pupation usually occurs two or three inches below the surface and the
adult beetles begin to emerge about the time blossoming of the grape ends, most
of them appearing during a period of 4 or 5 weeks. The beetles (Fig. 117) are
brown, covered with whitish hairs ; are rather stout, about a quarter of an inch
long and have long legs. They feed on the grape leaves, making irregular holes,
often so connected as to form narrow, crooked slits. The eggs are laid, several
hundred in all, placed in clusters of about 30 or 40, mainly under loose strips
of bark. These hatch in about 10 days and the tiny grubs drop to the ground
and work down to the roots consuming the smaller ones entirely and burrowing
in the larger ones, until winter, when they are full grown or nearly so.

When these insects are abundant the grape vines may be killed in a year or
two but the usual result of their presence is to so check the growth of the plants
that little or no crop is obtained. The grape-raising territory of western New
York, Pennsylvania and Ohio appears to suffer most from the attacks of this pest.

126

APPLIED ENTOMOLOGY

Control. — The adult beetles can be killed by spraying the leaves with arsenate
of lead using 3 or 4 lb. of the paste in 50 gal. of Bordeaux mixture, just before
or as soon as the first signs of feeding appear, and again after 10 days. Great
care must be taken, however, to do this work thoroughly, as the beetles avoid
sprayed foliage. The beetles may also be jarred off the vines, particularly on
warm days, onto sticky boards, fly paper, or sheets or some other type of catcher
placed beneath the plants, whence they can be gathered and destroyed. The
pupae are located within a few inches of the top of the ground and are mostly
within two or three feet of the vine. In this state of their existence they are easily
destroyed by any thorough breaking up of the soil where they are, and this is
taken advantage of by throwing up the earth on each side of the vines in the fall
to form a ridge. Most of the larvae work up into this to pupate, the following
spring, and while the insects are in the pupa stage there this ridge should be hoed
away by a horse-hoe and by hand, or by the latter alone for small areas. Later
cultivation will reach some of those escaping the first treatment which in the
grape belt named is usually about the middle of June.

The Californian species is a little smaller than the one just described, and jet-
black or brown. Its habits and methods for controlling it are about the same as
with the eastern pest.

The Elm Leaf Beetle ( Galerucella luteola Muls.). — This European insect
appears to have reached this country at Baltimore about 1834 and has now spread
through most of the New England and Middle Atlantic States and westward
nearly to the Mississippi River, though not everywhere present within these
limits.

The adult beetle (Fig. 118) is about a quarter of an inch long, dull yellow in
color, with black spots on the head and pronotum, a black band near the outside
of each elytron, and a short streak at the base of each, nearer the middle. The
beetles winter over in protected places and in the spring the dull yellow has
changed to an olive-green (Fig. 118). They fly to the elm trees when the foliage
develops, and feed, eating irregular holes in the leaves and from time to time lay¬
ing yellow eggs on the underside of the leaves, usually about 25 in number and
nearly always in two rows, side by side (Fig. 118). The eggs hatch after about a
week and the tiny yellow and black grubs feed for about 3 weeks, working on the
under surface and leaving the upper epidermis of the leaf unbroken. When full-
grown (Fig. 118) and about half an inch long they crawl down the tree to the
trunk and pupate for from 1 to over 3 weeks according to the temperature, either in
crevices of the bark on the lower part of the trunk or on the ground near the foot
of the tree (Fig. 118). In the more northerly states the larvae feed during June.
Farther south they begin in May and a second generation feeds during the late
summer or early fall. The European elms are most severely injured by this
insect but other species often suffer greatly.

Control. — -Spraying the trees about the time the eggs are laid, i.e., soon after
the leaves are fully grown, with arsenate of lead is the usual method of control.
The strength of the material should be increased above the standard to 5 lb. of the
paste, to obtain good results, and it should be kept in mind that as the grubs do
not feed on nor reach the upper surface of the leaves, the spray should be directed
as far as possible onto the under surfaces.

THE COLEOPTERA

127

Fig. 1 18. — The Elm Leaf Beetle ( Galerucella luteola Muls.) : 1, egg cluster; la, single egg
greatly enlarged; 2, recently hatched larva (grub); 3, full-grown larva; 4, pupa; 5,
beetles after wintering over; 6, freshly emerged beetles; 7, under surface of leaf showing
grubs, their work and a few holes eaten by adult beetles; 8, leaf nearly skeletonized by the
larvae; 9, leaf eaten by adults. Hair lines by Figs. 1 to 6 show natural size: 7, 8 and 9
natural size. ( From. Bull. 332 Ohio Agr. Exp. Sta. After Felt.)

128

APPLIED ENTOMOLOGY

Destroying the descending larvae and the pupae on the lower part of the trunk
and on the ground, with a strong kerosene emulsion spray is an auxiliary treat¬
ment, but as these individuals have completed their feeding, this affects only the-
abundance of the next generation. Power sprayers are a necessity for spraying
tall trees in the way here described.

Fig. 119. — Tortoise
Beetle ( Dcloyala clavata
Fab.) about times

natural size. {Original.)

The Tortoise Beetles are interesting members of the Chrysomelidse
(Fig. 119) because of their resemblance in form to tortoises and inmost
cases, on account of their golden color, which is
lost after death. Some species attack the sweet
potato but are not usually serious pests. They are
small insects, usually not over a quarter of an inch
long, nearly as wide, and often with black mark¬
ings. If they become injuriously abundant, spray¬
ing the leaves on which the larvse feed, with arsenate
of lead will control them.

Family Bruchidae (Pea and Bean Weevils). — In
this group of small beetles the head is extended
downward into a broad but short snout. The
elytra are shorter than the body leaving the hinder
end of the abdomen exposed above. The larvae feed in the seeds of
leguminous plants such as peas and beans, and frequently cause a great
amount of damage. Several kinds are abundant in the United States,
the pea weevil and the common bean weevil being perhaps the most
important.

The Pea Weevil ( Bruchus pisorum L.). — This pest of field and garden
peas winters as the adult beetle (Fig. 120a) either in peas or in protected
places, and after the pea pods
begin to form, lays its eggs on
them. It is about one-fifth of
an inch long, brownish, with
black and white spots. The
larvse (Fig. 1206) bore their way
into the peas, the holes they
make either closing up or being
too small to be noticed, and feed
on the contents of the pea until
full-grown. They then pupate
(Fig. 120c) and upon the pro¬
duction of the adult, those in the South leave the peas, while in the
North they remain in them over winter. Only one weevil usually feeds
in a pea and the insect cannot reproduce in dried peas. There is there¬
fore only one generation a year except where spring and fall crops of peas
are grown.

b a < C

Fig. 120.- — Pea Weevil ( Bruchus pisorum L.):
a, adult beetle; b, larva (grub); c, pupa.
Greatly enlarged. ( From U. S. D. A. Farm.
Bull. 983.)

THE COLEOPTERA

129

The Common Bean Weevil ( Bruchus obtectus Say). — This insect is
now found in nearly all parts of the world. The beetle is smaller than
the Pea Weevil and is brownish-gray in color, its elytra slightly mottled
(Fig. 1 21). The beetle lays its eggs on or in the pods of the beans growing
in the field, either in holes made, or in cracks caused by the pods splitting.
In the case of shelled beans the eggs are placed on the beans themselves.
The larvae gnaw their way to and into the beans, and unlike the Pea Weevil,
a number may enter the same seed and feed upon its substance. Devel¬
opment from the egg to the adult occurs within the bean and the adult
finally escapes through a circular hole it has cut in the skin after having
spent from 3 weeks to nearly 3 months there, according to the tempera¬
ture where the beans are kept. When infested
beans gathered in the field are brought in, their
infestation may not be apparent, but after
being kept a while, the adult beetles will escape

Fig. 121. Fig. 122.

Fig. 121. — Adult Common Bean Weevil ( Bruchus obtectus Say), greatly enlarged:
hair line at right shows real length. ( From U. S. D. A. Farm. Bull. 983.)

Fig. 122. — Work of Bean Weevils, natural size. {Original.)

and lay their eggs for another generation which will develop in the same
seeds if these are kept where it is fairly warm (Fig. 122), and thus by
spring there may be practically no beans left to plant. Six generations
may be produced in a year in the South and if the beans are kept where
it is warm during the colder months, as many may occur in northern
localities, though in the field it is doubtful if there are more than one
or two.

Another species, the Cowpea Weevil ( Bruchus chinensis L.) which feeds
on the cowpea, and other peas, and beans, is more abundant in the South, and a
fourth, the Four-spotted Bean or Cowpea Weevil ( Bruchus quadrimaculatus Fab.)
has a wide distribution, probably wherever cowpeas are grown. Both of these
species breed generation after generation in stored cowpeas, and in warm
temperatures there may be a number of generations each year.

The Broad Bean Weevil ( Bruchus rufimanus Boh.) in its life and habits more
nearly resembles the Pea Weevil than the other species above considered. It is
injurious in Europe and Northern Africa and has now established itself in Cali¬
fornia. The beetles resemble the Pea Weevil but seem to prefer broad beans or
horse beans. They appear in the fields in March and lay numbers of eggs on the
bean pods and the grubs on hatching make their way to the young beans, several

9

130

APPLIED ENTOMOLOGY

often entering one bean. Feeding is completed by early August and the adults
are produced later in the fall. They generally winter in the beans but do not
breed in dried beans, there being therefore only one generation a year.

Injuries. — The damage caused by the attacks of pea and bean weevils
is of two kinds: injury by consuming the bulk of the seed and leaving the
remainder unfit for food; and injury by so reducing the stored material
or the germ itself that the seed cannot germinate and grow.

Control of Pea and Bean Weevils. — The original attacks of these in¬
sects are upon growing plants out-of-doors. Here no. control seems pos¬
sible. When the crop is gathered, however, treatment can easily be
given by shelling at once, placing the seed in gas-tight receptacles, and
fumigating it with carbon disulfid, using this at the rate of at least 8 or
10 lb. for every 1,000 cu. ft. of space in the container, and continuing the
treatment for at least 1 — better 2 — days. The disulfid may be poured di¬
rectly onto the top of the seeds. For best results this should be done in a
place where the temperature is at least 75°F. Then the seed should be
packed in weevil-tight boxes, but it would be wise to examine it again
after a time and if living weevils are still present, give it another treat¬
ment. Where the seed is not to be used for food, packing it in air-slaked
lime at the rate of 1 part by weight of lime to 2 or 3 parts by weight of
seed has proved satisfactory. Even where use as food is intended, this
method can be used if the seed is thoroughly washed before cooking.
Cold storage below 34°F. will prevent development of the insects. Heat
will destroy the weevils and if seed is raised to 131°F. and kept at that
temperature for an hour, this will kill all the weevils present. Appar¬
ently, treatment in this way and for this length of time will not prevent
germination. None of these methods will prevent reinfestation if the
seeds are afterwards exposed to attack by insects from outside, where
the temperature is such that they are active. In general then, give the
first treatment immediately after gathering, and store in tight containers
and preferably in a cold place.

The shorter seasons and cold winters of the North give the pea and
bean weevils less opportunity to increase through a number of generations
than in the South, and many of the adults are killed by the cold. North¬
ern climates for these reasons are therefore better for the extensive pro¬
duction of seeds of these plants.

Family Cerambycidae (Round-headed Borers or Longicorn Beetles). —
The insects of this family are for the most part of fair size, a number being
several inches in length. Their antennae are usually long — sometimes
longer than the body — and the beetles are frequently bright-colored and
strikingly marked (Fig. 123).

The larvae are chiefly wood-borers, living in burrows in the trunks or
roots of trees, or the pith of plant stems, and are termed round-headed

THE COLEOPTERA

131

borers because the thoracic segments are circular in outline and the
tunnels they produce are therefore also of this shape. The larvae them¬
selves are soft, whitish or yellowish grubs, with strong jaws, and most of
them have no legs. The eggs are usually laid on the bark of the tree and
the larvae live on the wood they tunnel out, for a varying period, usually
2 or 3 years, and pupate in the tunnels just beneath the bark,
through which the emerging beetle finally gnaws its way and escapes.

Fig. 123. — Cerambycid (Monohammus) , natural size, showing long antennae. {Original.)

Some species cut the stem in which they live, nearly through, and when
it breaks off, fall with it to the ground, thus pruning the tree. Those
which tunnel in the heart-wood of timber trees often greatly reduce the
value of the timber by their holes. Some species attack sound wood and
apparently vigorous trees, while others seem to prefer trees already un¬
healthy, for their food. The family is a large one and contains many
forms injurious to shade and forest trees.

The Round-headed Apple-tree Borer ( Saperda Candida Fab.). — This
serious enemy of the apple tree is found practically everywhere in the
eastern United States except in the extreme South, and westward into
Minnesota, Iowa, New Mexico and Texas. It also attacks the service
tree, pear, quince, thorns, mountain ash, and a few other Rosace®. The
adult beetle (Fig. 124) is a little less than an inch long, pale brown above,
with a pair of white stripes extending backward from the head across
the pronotum and along the elytra to their tips at the hinder end of the
body. Beneath, it is silvery white. It appears during the late spring
and summer months and lays its eggs singly here and there in small slits
it cuts in the bark near the base of the tree, laying about 15 to 30 in all.
On hatching, 2 to 3 weeks later, the larva burrows through the bark to
the sap-wood, and there makes broad, rather shallow galleries just under
the bark and in general working downward. The bark over these gal¬
leries frequently dries and cracks, or the borer makes holes in it, letting

132

APPLIED ENTOMOLOGY

out the borings and castings, often called “sawdust” which shows the
location of the burrows. After hibernating during the winter the borer
(Fig. 124) resumes its work the following spring, still feeding on the sap-
wood, and if the tree is small or if several borers are present, girdling may
result. After a second winter in hibernation the borer turns its atten¬
tion to the heart-wood, boring into this, and finally as it approaches full
growth, working its way out toward the surface, being now about three-
quarters of an inch long. After a third winter of rest the larva pupates
in its tunnel in the spring, having previously carried the tunnel out to the
bark, and the adult beetle emerges after about 3 weeks. One generation

Fig. 124.— Round-headed Apple-tree Borer ( Saperda Candida Fab.): back and side
views of adult beetle on bark and exit hole; full-grown larvse (borers). ( After Rumsey
and Brooks.)

accordingly requires 3 years in which to complete its life history but
this comes in parts of 4 calendar years. In the southern part of its
range this is shortened to 2 years and in intermediate regions some may
require 2, and some 3 years.

Small trees suffer most severely by the attacks of this pest, a single
borer often entirely girdling a tree: larger ones are weakened and become
unhealthy and if strongly infested may also be killed.

Control. — Various methods of control have some value. “Worming”
the trees, i.e., cutting out the young borers early in the fall is a good
practice if it is thoroughly done and if the cutting is carried on carefully.
Litter should be carefully scraped away from the trunk to expose any
sawdust present, and from this the burrows can be located and the dead
bark cut out and the borer killed, either in place under the bark or by
running a flexible wire into its burrow if it has gone deeper into the tree.
In cases where the borer cannot be reached by the wire, a little carbon

THE COLEOPTERA

133

disulfid on cotton placed in the burrow, the opening then being closed
with mud, will serve the same purpose. Worming should be done in
early fall; the work should be thorough, and host trees of every kind
within several hundred feet of the orchard should be worked at the
same time for the beetles do not usually fly far and if the immediate
neighborhood is cleared of them, reinfestation from a distance does not
occur very frequently.

Thick paints are sometimes used as repellents. These are applied
beginning a few inches below ground, the earth being removed for the
purpose, and extending about a foot up the trunk, just before the egg-
laying period begins. The paint should be thick and be thoroughly
applied and should be pure white lead in raw linseed oil, as other materials
have been known to injure the trees.

Protectors, such as newspaper wrappings (several layers thick),
building paper, cloth, wire netting, etc., may be used, being placed around
the trunks before egg-laying begins. In all cases, however, these must
enter the ground at the bottom and be tightly fitted around the trunk
at the top and be without holes or cracks through which the beetle can
crawl. Asphalt.um has given fair results in some cases, but appears to
be liable to injure the tree.

As the beetle feeds somewhat on twigs and leaves, the usual sprayings
with a stomach poison for other apple pests are liable to kill some of the
beetles also. Woodpeckers feed freely on the borers.

Family Coccinellidae (Lady Beetles, Lady Bugs or Lady Birds). —
The lady beetles are nearly all carnivorous, feeding both as larvse and
adults on scale insects, plant lice and other important pests. They are
generally small beetles, nearly circular or oval in outline, strongly convex,
often resembling in size and form a split pea. Their colors are usually
black and red or reddish-yellow, sometimes the spots or markings being
black on a red ground, sometimes the reverse. In a number of species
the beetle is entirely black (Figs. 125 and 126).

The larvse (Fig. 126) are active and crawl around over leaves, twigs,
etc., searching for their food. They are dark colored, but frequently
have a few spots of yellow or blue on the side of the body, and their
general appearance has suggested to some persons, a resemblance to
alligators.

The family is quite a large one, and its species are abundant and well
distributed over this country. Among the more useful or noticeable of
the family is the Two-spotted Lady beetle ( Adalia bipunctata L.), one of
the smaller species averaging about a sixth of an inch in length (Fig. 1255).
The head is black, sometimes with two yellow spots; the pronotum black
with yellow side margins, and the elytra are red with a black dot in the
center of each. This insect frequently winters in houses and may be found
on the windows in spring trying to escape. It is often mistaken for some

134

APPLIED ENTOMOLOGY

injurious household pest on this account. This species feeds mainly on
plant lice, but to some extent also on the pear psylla. Another species of
about the same size is known as the Twice-stabbed Lady beetle ( Chilo -
corus bivulnerus Muls.). Here the head and pronotum are black, as are
also the elytra, except for a red spot in the center of each, thus just
reversing the elytral color pattern of the last described species. It feeds
on scale insects and also on plant lice and the Colorado Potato Beetle.

a b c d

Fig. 125. — Examples of Lady Beetles: a, Twice-stabbed Lady Beetle ( Chilocorus
bivulnerus Muls.): b, Two-spotted Lady Beetle ( Adalia bipunctata L.) ; c, Nine-spotted
LadyBeetle (Coccinella novem.nntata Hbst.) : d , Spotted Lady Beetle ( Coleomegilla fuscilab.ris
Muls.): all about twice natural size. ( From Conn. Apr. Exp. Sta. Bull. 181.)

Other common species are the Nine-spotted Lady beetle ( Coccinella 9 -notata
Herbst.) with nine black spots on its red elytra; the Fifteen-spotted Lady beetle
(Analis 15 -punctata Oliv.), the largest species in the Northeastern States, which
has 15 black spots on its red elytra; the Pitiful Lady beetle ( Pentilia misclla Lee.),
a very tiny black species which feeds on scale insects and aphids, and the Spotted
Lady beetle (Coleomegilla f uscilabris Muls.) about a fifth of an inch long, usually
bright pink with black spots and with its body rather oval in outline, somewhat
pointed behind. This species feeds on many kinds of plant lice and other small
insects and tends to hibernate in clusters, often several hundred together, under
leaves at the bases of treetrunks.

c

b d a

Fig. 126. — Different stages of the Nine-spotted Lady Beetle: a, adult; b, larva; c, pupa;
d, eggs. All much enlarged. {Modified from Palmer, Ann. Ent. Soc. Am., vii, 1914.)

The Convergent. Lady beetle ( Hippodamia convergens Guer.) is about
a quarter of an inch long, with two converging yellow marks on the
pronotum and six black spots on each elytron. This widely distributed
species has been found feeding on a number of kinds of plant lice and in
addition, on asparagus beetle larvse, eggs of the Colorado Potato beetle
and of the Grape-root worm, red spiders, the Bean Thrips, Alfalfa Weevil
and Chinch Bug. On the Pacific Coast it gathers in enormous numbers

THE COLEOPTERA

135

in the high mountains to hibernate and while thus collected in quantities
they are gathered and in spring distiibuted through the truck-growing
regions to attack the plant lice, about 30,000 being regarded as enough to
protect the plants growing on 10 acres. Several tons are often collected
for distribution for this purpose. It takes nearly 1,500 of these beetles
to weigh an ounce.

Because of their efficiency as feeders on insect pests, a number of kinds
have been introduced into this country to attack the special insects of
their native lands which have reached the United States and have become
pests here. Among these are the Vedalia ( Novius cardinalis Muls.)
(See Fig. 216), imported from Australia to attack the Cottony-cushion or
Fluted Scale; the Mealy-bug Destroyer ( Cryptolcemus montrouzieri Mills.),
brought also from Australia to attack several kinds of Mealy-bugs found
in California; the Steel-blue Lady beetle ( Orcus chalybeus Boisd.) which
feeds on a number of kinds of Armored Scales; and the Black Lady beetle
(Rhizobius ventralis Erichs.) which is an active enemy of the Black Scale
( Saissetia olece Bern.); besides numerous other species. Many of these
imported forms have done valiant work in their attacks upon their
ancient foes in the country to which both have come, but in some cases
this attempt to aid nature in the control of insect pests has been less
successful, and it is evident that the success of each experiment of this
kind can rarely be determined beforehand. (See Cottony Cushion Scale,
Chapter XXVI).

Family Tenebrionidae (Darkling Beetles). — This rather large family of beetles
contains many forms found on the ground and superficially resembling the Cara-
bidse. They are usually rather slow of movement, however, feed on vegetable
instead of animal food, and while their fore and middle
tarsi are each composed of five segments as in the Carabids,
their hind tarsi each have only four. They are particularly
abundant in the Southwest and West, though a number
are present practically everywhere.

The Yellow Meal-Worm ( Tenebrio molitor L.) about
three-quarters of an inch long (Fig. 127), is often found
around stores of grain, in pantries, stables etc., and its larva
which closely resembles a wireworm, feeds upon meal and
similar materials. It is often raised as food for cage birds.

Where abundant, a thorough cleaning out of infested places,
followed by sprinkling air-slaked lime around, or fumigation
of the infested material with Carbon disulfid, is all that is
necessary.

Family Meloidae (Blister Beetles). — The insects of this family also
have but four segments to each hind tarsus. The body is quite cylin¬
drical and rather soft, and the head joins the thorax by a distinct neck
(Fig. 128). Many of the members of this family contain a substance

Fig. 127. — Yellow
Meal-worm ( Tenebrio
molitor L.) , about
natural size. ( Orig¬
inal .)

136

APPLIED ENTOMOLOGY

called cantharidin, which when applied to the skin, produces blisters.
The bodies of these species, powdered, are used in medicine under the
name “ cantharides ” or “Spanish flies,” for blistering purposes.

A dozen or twenty kinds of Blister beetles, averaging from half
an inch to over an inch in length are more or less serious pests as adults,
feeding during the summer or fall on foliage and blossoms, various vege-

a be

Fig. 128. — Adult Blister Beetles: a, Black Blister Beetle ( Epicauta pennsylvanica
Be G.); b, Ash-gray Blister Beetle ( Macrobasis unicolor Kby.) ; c, Striped Blister Beetle
( Epicauta vittala Fab.); all about natural size. ( Modified from U. S. D. A. Bulletins.)

tables and ornamental plants being attacked. Vegetable crops are
sometimes seriously affected. The larvae on the other hand, feed on the
eggs of various species of grasshoppers and are therefore beneficial.
The adults are not easily controlled as they are rather resistant to arseni¬
cal poisons, and as they fly freely, it is difficult to reach them with contact
insecticides. In cases where stomach poisons can be applied, arsenate

of lead, taking about 4 lb. (if the
paste be used) to 50 gal. of wrater,
has proved the best treatment.
Where this cannot be done, hand¬
picking, and screening valuable
plants with netting, may be
resorted to.

RHYNCHOPHORA (Snout Beetles)
The snout beetles are included
in several families. Some are
called curculios, weevils, and bill-
bugs, and those of one family, the
larvse of which work in the bark
and wood of trees, are called Engraver beetles and also bark boieis.
Over twenty-five thousand species of Rhynchophora are known (Fig. 129).

Except for this last named family, most snout beetles feed on fruits,
nuts, etc., though a few attack stems and leaves. The white, nearly
always footless larvse, also feed for the most part on such materials, and
a number are very destructive and therefore important pests.

Fig. 129. — Examples of adult Snout
Beetles showing differences in the develop¬
ment of the snout. About twice natural
size. ( Original .)

THE COLEOPTERA

137

The Plum Curculio ( Conotrachelus nenuphar Herbst). — This insect
is a native of the United States and formerly fed upon the wild plum and
thorn fruits, but now also attacks cultivated plums, prunes, cherries,
nectarines, apricots, apples and peaches. It is found practically every¬
where east of the Rocky Mountains, though in
the western portion of this area it seems to be of
less importance than elsewhere. The adult beetle
(Figs. 130 and 131) is small, being only about a

Fig. 130. Fig. 131.

Fig. 130. — Adult Plum Curculio ( Conotrachelus nenuphar Hhst.), view from above.
About five times natural size. ( Modified from U . S. D. A. Bur. Ent. Bull. 103.)

Fig. 131.- — Side view of adult Plum Curculio showing humps on the back. Enlarged
about five times. {Modified from U. S. D. A. Bur. Ent. Bull. 103.)

fifth of an inch long, dark colored as a whole but mottled with gray
and brown. Its elytra are rough and on each is a black, shining hump
a little behind the middle.

This pest spends the winter, or the colder months in the South, hiding
in any protected place it can find, particularly in the woods, in stone
walls or under leaves. It appears
about the time the plum buds open in
spring and feeds more or less on the
developing leaves. When the fruit
begins to develop, the beetles turn
their attention to it, feeding by cutting
a circular hole through the skin and
consuming the flesh beneath to a
depth about equal to the length of
the snout of the insect. They also
begin now to lay their eggs in the
young plums, cutting a hole in the
skin and then running the snout ob¬
liquely into the flesh beneath. In
this cavity the egg is placed and it is
then pushed farther in by the snout.

The beetle next cuts a crescent-shaped
slit through the skin close to the
egg (Fig. 132) and carries this down through the flesh beneath the egg
which thus comes to lie in a sort of flap which wilts and remains soft, and
the crushing of the egg by the growth of firm tissue there is prevented.

Fig. 132. — Egg puncture and feeding
puncture of Plum Curculio in young
plums. ( From U. S. D. A. Farm. Bull.
908.)

138

APPLIED ENTOMOLOGY

Several hundred eggs are laid in this way and the “spot and crescent”
marks of the insect on small plums are familiar to plum growers. The
fruit often pours out gum at these places, probably in an attempt to
repair the injury.

The eggs hatch in a week or less and the tiny whitish grub bores
through the flesh, and in stone fruits passes to the stone, around which it
feeds for about two weeks or until full-grown. It then leaves the fruit,
and as this in most cases has fallen before this time because of the injury,
the larva finds itself on escaping, on the ground. Into this it now burrows
an inch or two and pupates. About a month later the adult beetle
emerges, comes to the surface of the ground and attacks fruit for food, egg-
laying rarely if ever taking place at this season, and when cold weather
comes on it locates in some protected place for the winter. There is
accordingly, but one generation a season.

Fig. 133. — Apple showing injury by Plum Curculio in fall. ( Modified from III. Agr. Exp.

Sta. Bull. 98.)

This insect, both by its feeding and egg-laying punctures, affects
the value of the fruit not entirely destroyed, not only in appearance but
by the opportunity these cuts afford for the entrance of the spores of
disease-producing fungi, and the destruction in the United States which
it causes has been estimated at over eight million dollars annually.
While the insect rarely succeeds in developing in the apple, the punctures
cause dropping of the fruit or its malformation, and the production of
hard, woody places in the pulp. In the fall its feeding holes in apples
also cause much injury (Fig. 133).

Control. — No one method nor even all the methods of control taken
together will give entire freedom from this pest. A combination of

THE COLEOPTERA

139

treatments, however, will accomplish considerable in this line. The
usual measures taken are as follows:

(1) Remove all opportunities for the successful wintering of the
adults, as far as possible. Rubbish, stone walls, and trash of all sorts
should be removed. Plum orchards near woodland are poorly located
from this standpoint. (2) The curculio prefers shade in which to work,
and larvae even inside fallen fruit are unable to survive any long exposure
to direct sunlight. The trees therefore should be so pruned as to let the
sunlight through all parts, and fallen fruit should be exposed to the sun
by proper treatment of the ground under the tree. (3) Fowls and hogs
will eat many of the larvae in the fallen fruit and larvae or pupae in the
ground, and should be allowed to run under the trees; or thorough, shallow
cultivation under the trees should be given from the time the larvae begin to
leave the fruit until at least 6 weeks later, to destroy the insects there.

(4) Spraying with arsenate of lead either alone or combined with the
self-boiled lime-sulfur has been fairly successful if the applications be
thorough and at the right times. For plums spraying with 2)4 lb. of
lead arsenate paste (134 lb. of the powder) in 50 gal. of water or lime-
sulfur as soon after the blossoms fall as leaves begin to develop, and the
treatment repeated 8 or 10 days later has proved the best method.
Cherries can be treated in the same way. With peaches, 2 lb. of the
arsenate in 50 gal. of water, to which the milk of lime obtained by slaking
2 lb. of quick lime has been added, is sprayed as soon as the “shucks”
are beginning to shed from the blossoms. About 3 weeks later a spray
of 2 lb. of the arsenate in 50 gal. of the self-boiled lime-sulfur is made. A
third treatment about a month before the fruit begins to ripen, using the
lime-sulfur only, is also often given. • For apples the precautions neces¬
sary in spraying stone fruits with arsenate of lead need not be taken.
Here the treatments commonly given for the Codling Moth (see Chapter
XXIX) are also effective at those times for the Curculio, though later
similar applications may also be necessary if the insects are abundant.

(5) Where only a few stone-fruit trees are involved, jarring them early
in the morning, after spreading white cloth under them, is a good treat¬
ment. The beetles at that time of day are sluggish and drop onto the
cloth when the tree is given a sudden blow, and they can then be gathered
and destroyed. This should be begun as soon as the blossoms have all
fallen and continued until the beetles no longer appear.

The Plum Gouger ( Coccotorus scutellaris Lee.). — This plum pest like the last,
is a native of this country and is found from New York west to the Rocky Moun¬
tains and south to Texas. It appears to be destructive, however, mainly west of
the Mississippi River. The adult (Fig. 134) is somewhat larger than the Plum
Curculio. The head and thorax are dull yellow and the elytra are lead-gray in
color, and the surface is without any humps or other irregularities. In many
regards the habits of the Gouger are like those of the Plum Curculio, but it leaves

140

APPLIED ENTOMOLOGY

its winter quarters earlier than the last named insect and feeds for a time on the
opening buds and leaves, gouging holes in the blossoms (Fig. 1346) and thus caus¬
ing them to drop off. Feeding holes and egg punctures in the young plums
(Fig. 134c) are holes into the flesh in some of which the eggs are placed, but many
more holes are made than eggs deposited. The grubs work their way to and into
the stone or pit and feed on the flesh (seed) within until full grown. Each then
gnaws a hole through the stone, after which it pupates inside the stone, the adult
appearing in late August and September. There appears to be but one insect in
a fruit.

a b c

Fig. 134. — Plum Gouger ( Coccotorus scutellaris Lee.) : a, adult beetle about three
times natural size; b, plum blossoms attacked at their bases by the beetle; c, young plums
punctured by the beetle. ( Modified from Minn. Agr. Exp. Sta. Bull. 66.)

Plums attacked by the Plum Gouger do not drop, but mature on the tree, but
such plums are worthless for market because of the injured spots and because of
the deformed fruit produced.

Control. — Picking off the injured plums before the beetles emerge in the fall
has been recommended as a method of control for this insect, and jarring in spring
has also been advised, though the beetles do not drop as freely as in the case of the
Plum Curculio. It is possible that spraying with arsenate of lead as for the
Curculio, making the first application as soon as the buds are open enough to
provide any surface for the poison to adhere to, may prove of some value.

The Cotton Boll Weevil ( Anthonomus grandis Boh.). — This is at the
present time the most serious insect pest of cotton which we have.
Recent estimates place the destruction by the boll weevil at about 400,000
bales per year, which at average prices for the cotton not thus destroyed
would be many millions of dollars. Diversification of crops has come
into practice, however, where the cotton crop has suffered, so that in a
number of the affected States the total value of all crops after the appear¬
ance of the weevil, has been greater than before. In some cases then,
the loss to cotton has been more than made up by turning to other crops,
but the reduction in the amount of cotton needed for use in the world is
important.

The cotton boll weevil is a native of tropical America, whence it
spread northward through Mexico, and about 1892 entered Texas. Since •
that time it has extended its area of infestation, reaching the Atlantic

THE COLEOPTERA

141

Coast in Georgia in 1916 and in time it will probably be present everywhere
in the cotton belt, except perhaps in the more arid portions and in places
where it can find little protection during cold weather.

The adult boll weevil (Fig. 135) varies considerably in size but aver¬
ages about a quarter of an inch in length. When it first emerges from
the pupa it is light brown, but it soon becomes gray or almost black.
It winters as the adult, hiding under rubbish, in cracks in the ground, in
Spanish moss growing on the trees, or in fact in any protected place,
though those which winter in the cotton fields appear to be least protected
and hence least liable to survive, while those in wooded areas winter more
successfully.

a be

Fig. 135. — Cotton Boll Weevil ( Anthonomus grandis Boh.); a, side view of adult
beetle enlarged about six times; b, larva (grub); c, pupa; both much enlarged. (From
Sanderson: Insects Injurious to Farm , Garden and Orchard.)

In spring the beetles leave their winter quarters, the time generally
varying from March to the last of June. “ In the spring and throughout
the fruiting season of cotton the eggs are deposited by the female weevils
in cavities formed by eating into the fruit of the plant. An egg hatches
under normal conditions in about three days, and the grub immediately
begins to feed. In from 7 to 12 days the larva or grub passes into its
pupa stage, corresponding to the cocoon of butterflies and moths. This
stage lasts from 3 to 5 days. Then the adult issues, and in about 5 days
begins the production of another generation. Climatic conditions cause
considerable variation in the duration of the stages, but on an average
it requires from 2 to 3 weeks for the weevil to develop from the egg to
the adult. Males and females are produced in about equal numbers.
The males feed upon the squares and bolls without moving until the food
begins to deteriorate. The females refrain from depositing in squares
visited by other females. This applies throughout most of the season,
but late in the fall, when all the fruit has become infested, several eggs
may be placed in a single square or boll. As many as 15 larvae have been
found in a boll. The squares are greatly preferred as food and as places

142

APPLIED ENTOMOLOGY

for depositing eggs. As long as a large supply of squares is present, the
bolls are not damaged to any serious extent. The bolls, therefore, have
a fair chance to develop as long as squares are being formed.” (Marlatt,
Farmers’ Bulletin 848, U. S. D. A., 1917).

The^e insects are extremely prolific. It has been calculated that from
a single pair of the beetles in spring there might be 12,755,100 progeny by
the end of the season, but many factors prevent this from actually being
the case. Infested squares soon drop off the plant and on the ground
generally become so heated as to kill the larvse in them. Parasites and
other enemies, particularly ants, attack the insect, and other minor
factors are of some value. All of these combined, however, only prevent
a bad condition from becoming worse, and control measures must be
resorted to.

Control. — There are several control measures which seem to give par¬
tially satisfactory results. One of these is to destroy all infested plants in
the fall, particularly in the southern part of the area where the weevil is
found. This kills great numbers of adults about ready to hibernate, many
more still in early stages in the plants, leaves no food for those escaping,
and prevents the production of the latest beetles, thus reducing the num¬
ber to hibernate. It also permits fall or winter plowing which is good
farm practice in cotton growing. Generally this destruction of the plants
should occur in October, even though a little cotton is lost in this way.
The destruction of any hibernating weevils wherever possible is advan¬
tageous. Crop rotation is also desirable, as many of the weevils winter
near the cotton fields and do not fly far in the spring. Any methods
which will hasten crop production, such as fertilizers, the use of
early maturing varieties and early planting, are desirable. Dusting
the young plants with arsenate of lead or arsenate of lime blown
directly onto them has frequently given good results. The use of all
these methods together gives considerable relief from the attacks of this
pest, and the problem how far to go in carrying them out is largely one of
their cost as compared with the value of the cotton which will be saved by
the treatments. Hand picking of the weevils and of infested squares has
not generally proved successful. As the insect has thus far been known to
feed only on cotton and the wild cotton of Arizona (where it probably
does not yet occur), the danger of its increasing on other food plants does
not at present seem to exist.

The White Pine Weevil ( Pissodes strobi Peck). — This native enemy of the
pine occurs practically wherever the white pine is found, viz., from New Bruns¬
wick and Canada west to Minnesota, and south to North Carolina. It also
attacks our other native pines and the spruces somewhat.

The adults (Fig. 136) pass the winter in protected places, possibly in the
ground, and in spring gather on the terminal shoots (leaders) of the pines, generally
on the trunk leader in preference to those of the branches. Here, near the tip,

THE COLEOPTERA

143

they feed on the bark and soon cut tiny holes in it, placing their eggs in the holes.
The borers which hatch from these eggs tunnel downward through the leader
(Fig. 137) and by August have finished feeding and pupate in the tunnels. After
transformation to the beetle has been completed, these escape to the outside by
making round holes through the stems they are in. Later they hibernate for the
winter.

The adult beetle is about a quarter of an inch long, reddish-brown or some¬
what darker, with a white spot on each elytron not far from its outer end, which
when the elytra are at rest brings these spots
not far from the end of the body. There
are also several irregular areas on the elytra
somewhat lighter than the ground color.

Control. — Spraying the leaders before the
beetles gather on them in the spring, with
arsenate of lead, using one pound more than
the standard formula for the paste, is one
method of control. Collecting the beetles
after they have begun to gather on the
leaders is also practiced, jarring them off into

Fig. 136. Fig. 137.

Fig. 136. Adult hite Pine tVeevil ( Pissodes strobi Peck), enlarged nearly three
times. ( After Fell: N. Y . State Mas. Mem. 8.)

Fig. 137.— Work of White Pine Weevil in terminal twigs of pine. ( After Felt: N. Y.
State Mus. Mem. 8.)

a net held beneath, as they generally drop instead of flying when disturbed
then. This treatment should be repeated several times at 4 or 5-day intervals.
It can hardly be done except on small trees.

The injury caused by these insects aside from their feeding, is the killing of the
leader which stunts the growth of the tree. Usually a side branch grows up to
replace the lost leader and makes the tree deformed, or when two do this, a fork
is produced. In either case the value of the tree either for timber or as an orna¬
ment is largely lost. The work of the weevil is most serious and also most
frequent on young trees, making its injuries more serious on this account.

The Alfalfa Weevil ( Phytonomus posticus Gyll.). — This European insect was
discovered in this country about 1904 and is now found in parts of Utah, Idaho
and Wyoming, and is gradually spreading. The adult (Fig. 138) is a snout
beetle only about three-sixteenths of an inch long, brown when fresh but almost

144

APPLIED ENTOMOLOGY

black after a time. It winters as the adult close to the ground or in crevices
there, and in some cases under rubbish, and in severe winters many are killed by
the cold. As soon as warm days come the weevils become active and lay eggs
in the dry alfalfa stems, before the regular laying season, and the larvae from these
eggs attack the young plants, often causing serious injury. The weevils also feed
on the plants quite freely at this season. After a few weeks the true egg-laying
period begins and the adults now puncture the living alfalfa stems and lay their
eggs in them, this process usually being finished by the tenth of June, though a
few eggs are laid much later. The eggs hatch in about ten days and the larva;
(Fig. 139) consume the alfalfa leaves, those from the ones laid early beginning to

Fig. 138. Fig. 139. Fig. 140.

Fig. 138. — Adult Alfalfa Weevil ( Phytonomus posticus Gyll.) much enlarged. ( From
U. S. D. A. Bur. Ent. Bull. 112.)

Fig. 139. — Side view of larva of Alfalfa Weevil, greatly enlarged. ( From U. S. D. A.
Bur. Ent. Bull. 112.

Fig. 140. — Cocoon of the Alfalfa Weevil, greatly enlarged. ( From U. S. D. A.
Bur. Ent. Bull. 112.)

feed in May, while later individuals are feeding until into July or even August,
with some stragglers later. The larval period varies greatly, but an average
length of time in this stage would be perhaps a month. When full-grown the
larva goes to some protected place such as a dry, curled leaf or dead vegetation
near the ground and spins a cocoon (Fig. 140) in the form of a loose network, in
which it pupates. This stage lasts about 10 days before the appearance of the
beetle. In late summer these beetles begin to look for winter shelter and in this
search may spread some distance. In spring a somewhat similar flight in search
of food, also increases their spread. This insect feeds on various species of clover
in addition to alfalfa, and as it seems to be persistently spreading, it must be
considered a menace to nearly all parts of the country.

Control. — The most serious injury to the crop is that caused by the spring
feeding before the first cutting, and this also delays the production of the second
crop. Any treatment of the field, such as disking it with a harrow, which will
hasten growth at that time will be a gain. Spraying these fields with arsenate of
lead, 1 lb. of the paste in 50 gal. of water, appears to reach many of the insects
and be quite effective. Pasturing during the spring months, dividing the fields
so that each piece may be grazed close about once every 2 weeks, and continuing
this until most of the eggs of the weevil have been laid, has also given good
results, as has cutting and feeding the crop before the eggs hatch. Spraying

TIIE COLEOPTERA

145

the stubble after the first cutting, or treating such fields by going over them once
or twice with a disk or spring-tooth harrow, followed by dragging with a brush
drag, to give a dust mulch, will protect the second crop but is probably less valu¬
able than the earlier spring methods.

The Potato Stalk Weevil ( Trichobaris trinotata Say). — This pest of the potato
is widely distributed over the United States east of the Rocky Mountains except
in the more northerly States. It has also been reported from California. The
beetle is gray with a black head and three black spots at the base of the elytra and
is about a fifth of an inch long. It winters in the old potato stalks and when the
young potato plants are large enough it makes small holes in the stalks and
sometimes in the branches, in which the eggs are deposited: The eggs hatch in
a week or 10 days and the grubs burrow downward toward the roots and after
reaching them turn upward again, enlarging the burrows. This tunnelling
weakens the stalks and causes the plant to wilt and die. Pupation takes place in
the stalks, usually near the ground, and the adults are produced in from 1 to 2
weeks, but generally do not leave the stalks until the
following spring. A number of individuals may be present
in a single stalk. Other food plants are Jamestown weed,
horse nettle, eggplant and other plants of the family
Solanaceae.

Control. — Where the plants have wilted and dying leaves,
and an examination of the stem shows borers to be present,
pulling up and burning infested stalks is desirable. Prac¬
tically the same result may be obtained by collecting and
burning all the stalks as soon as the crop has been dug, thus
destroying the weevils in them. The . destruction of all
weeds around, which are liable to be infested by the insects,
this work being done after the egg-laying season is over, is
also desirable.

The Sweet Potato Weevil (Cylas forrnicarius Fab.). —

This is a tropical insect which was first reported in the
United States about 1875. It now occurs in the most
southerly States from Georgia to Texas, attacking the
sweet potato. The adult (Fig. 141) unlike the other snout
beetles here considered, is very slender, about a quarter of an inch long, with
a black head, reddish prothorax and legs, and dark blue elytra. The prothorax
is strongly narrowed, forming a noticeable “waist” for the insect.

The eggs of this pest are laid singly in small holes eaten in the stem or any
exposed potato. They hatch in a few days and the grubs in the stems burrow
through them down to the potato, then tunnel irregularly about, becoming full-
grown in 2 or 3 weeks. The grub now forms a cavity and in this it pupates for
about a week and then a few days later eats its way out and may leave the potato,
or may remain there and lay eggs for another generation in the same potato
in which it itself developed, and this process may continue until the entire
potato is destroyed. As long as food is available, one generation after another is
thus produced, but when no more can be found the adult insects live along for a
considerable time without feeding, attacking the plants and laying their eggs in
them whenever more appear. Adult beetles feed on the leaves and stems somewhat.

Fig. 141— Adult
Sweet Potato Weevil
( Cylas forrnicarius
Fab.) enlarged over
five times. (From
U. S. D. A. Farm,.
Bull. 856.)

146

APPLIED ENTOMOLOGY

As soon as tunnels in the potato are formed, the tissues around them change
color and decay soon follows, so that an attack quickly ruins the value of the
crop.

Control. — Sweet potatoes found infested ever so slightly should immediately
be destroyed, either by feeding to stock or in some other way. If any area
becomes infested no sweet potatoes should be planted there for several years,
and as it is probable that the insect can also breed in the wild morning glory, all
plants of this species should also be destroyed as far as possible within the area.
Spraying the plants with arsenate of lead or other stomach poison, applied as soon
as the beetles appear has recently given encouraging results. Following sprays
at about ten-day intervals may be given if necessary.

Family Ipidse (formerly Scolytidse) (Bark beetles or Engraver beetles).
The members of this family are borers and nearly all attack the inner
bark or wood of trees. They are small insects, from one twenty-fifth
to two-fifths of an inch long,
brownish or blackish in color,
and usually with cylindrical
bodies (Fig. 142). In habits
they form two chief groups. In
the so-called Ambrosia-beetles
the tunnels extend through the
wood and the young develop
there: in the True Bark-beetles
the tunnels are formed either in
the inner bark or between this
and the wood. The adult in

Fig. 142. Fig. 143.

Fig. 142. — Adult Bark Beetles, greatly enlarged. ( Modified From Felt: AT. Y. Stale
Mus. Mem. 8.)

Fig. 143. — Work of Bark Beetles on inside of bark, slightly reduced. {Original.)

either case cuts a tunnel slightly larger than itself in to the inner bark
or through this, but the Ambrosia-beetles continue it on, into the
wood. The Bark-beetles having arrived at the desired depth, turn and
excavate one or more channels between the bark and the wood, which
become the egg tunnels. Along the sides of these the eggs are deposited,
either singly in little hollows, several together in larger excavations, or

THE COLEOPTERA

147

many in grooves of the tunnel. The larvae, on hatching, excavate tun¬
nels for themselves, leading away from the egg tunnel (Fig. 143) and
becoming larger with the growth of the larvae. Pupation is at the end
of the larval tunnel in a somewhat wider portion and after transforma¬
tion the adult bores its way to the outside. In the case of the Ambrosia-
beetles a fungus used as food by the insects, grows on the walls of the
tunnels and generally turns these walls black.

Destruction by these insects is mainly of forest and shade trees. As
nearly all the bark-beetles appear to prefer dying bark in which to live,
the refuse of cutting operations, commonly termed “ slash,” will provide
much of this, and most of the insects will work there. When slash comes
to an end, however, by operations ceasing in that area, the increased
abundance of the insects due to abundant slash often forces them for
lack of other material, to turn to the healthy trees, themselves changing
thereby from “secondary” to “primary” foes. Slash should therefore
be destroyed before beetles in it can develop to the adult condition. Fire
in forests produces many dead and weakened trees also, frequently lead¬
ing to insect attacks, and epidemics, either local or quite widespread,
may thus result. Many trees when the beetles bore into them, pour
out their sap or resin, and some of the insects may easily be
drowned in this. If attacked by multitudes, however, the supply of
sap becomes so reduced that the insects coming later can accomplish
their purpose.

Removing “beetle trees” before the adults escape, and either remov¬
ing and burning the bark, floating the logs, or sawing the same winter and
burning the slabs and trimmings, are some of the measures used for the
protection of our forests against these insects.

One species of Ipid, the Clover Root-borer, tunnels in the main
roots of clover. Several other species attack fruit trees, usually those
not healthy.

The Fruit-tree Bark-beetle or Shot-hole Borer ( Eccoptogaster rugu-
losus Ratz.). — This European fruit-tree pest has now been in the United
States about 50 years and is present nearly everywhere east of and in
many localities west of the Mississippi River, and has been reported from
California. It breeds in most of the cultivated deciduous fruit trees
as well as in several kinds of wild ones. The beetle (Fig. 144) is about
a tenth of an inch long, almost black, except the tips of the elytra and the
legs, which are dull red.

In the spring the beetles enter the trees and dig out egg channels one or
two inches long, about parallel to the grain of the wood, partly in this,
partly in the inner bark. Flere, in little niches or hollows along the sides,
the eggs are laid. These hatch in a few days and the grubs burrow,
first directly away from the egg channel, then turning in various directions,
extend these larval tunnel sseveral inches, and pupate at their ends.

148

APPLIED ENTOMOLOGY

When the beetles have been formed there, they bore out to the surface of
the tree (Fig. 145) and soon begin to tunnel in again, to lay eggs for a
second generation which in the North becomes adult before winter,
thus giving two generations a year. In the South with its longer warm

d

Fig. 144. — Fruit-tree Bark-Beetle ( Eccoptogaster rugulosus Ratz.) ; a, Adult Beetle; b,
side view of same; c, pupa; d, larva. Hair lines show true length. ( From, U. S. D. A.
Farm. Bull. 763.)

season, three or perhaps four generations may be produced each year,
the adult beetle in some cases at least, wintering in the tree, while in
others this season may be passed in the egg stage.

Healthy trees are not often attacked except when the beetles become
so abundant that a sufficient supply of weak or dying ones is not available.

Fig.

145. — Exit holes of the Fruit-tree Bark-Beetle in bark of a young tree, about natural
size. ( From U. S. D. A. Farm. Bull. 763.)

In healthy trees the flow of gum sometimes prevents the development of
larvfe but in time this becomes less and the insects then have a weakened
tree to attack. Trunk, branches and twigs are perhaps equally liable to
be injured. The burrows extending in all directions, partly in the outer

THE COLEOPTERA

149

surface of the wood, partly in the inner bark, destroy the cambium or
growing layer, often entirely girdling the twig, branch or trunk as the
case may be, and causing its death.

Control. — This must largely be accomplished by measures to keep
the trees as vigorous and healthy as possible. Any injured, broken
or otherwise affected limbs should be removed or so treated if possible,
as to restore them, and close watch of trees outside the orchard, liable to
infestation, should also be given. Infested trees which are still pouring
out gum can sometimes be saved by cutting back strongly and then culti¬
vating and fertilizing freely. In some cases a thick coat of whitewash
mixed with a little table salt can be applied as a repellent for the beetles.
This treatment sometimes needs to be applied three times — once in
spring, again in midsummer, and once again in the fall. Washes of soap
and carbolic acid have occasionally been used with some success, and it is
claimed that the larvae can be killed in their burrows by using a carbo-
lineum spray material. This is made by dissolving 3 lb. of naphtha
soap in 3 gal. of hot water; adding a gallon of carbolineum, stirring
thoroughly and then diluting for use at the rate of 1 part of this to 4
of water.

These methods should work equally well for any of the barkbettles
where the bark is no thicker than at the places where these insects
attack the fruit trees.

CHAPTER XX

THE STREPSIPTERA

These tiny insects are seldom seen except by entomologists, and
their parasitic habits aid in their concealment. For a long time opinions
were divided as to where they belonged, some regarding them as a
family of aberrant Coleoptera, while others considered them as forming
an order. Recent studies seem to confirm the latter view and the
group is now generally rated as a separate order, though its closest
relations are probably with the beetles.

The Strepsiptera, from the meaning of this name, may be called the
Twisted-wing Parasites, though the words stylops and stylopid are fre¬
quently used in referring to them. The males on reaching the adult
condition (Fig. 146), become free and can fly. The females on the other

Fig. 146.- — Male Strepsipteron ( Xenos vesparum Rossi), rather more than six times natural

size. ( After Pierce.)

hand, remain partly within the bodies of their host insects and are worm¬
like or grub-like (Fig. 147) in appearance. The males are very small,
soft-bodied animals, ranging from about one to perhaps four twenty-
fifths of an inch in length. The eyes are more or less stalked and the
antennae have one or more segments elongated on one side. The mouth
parts are greatly modified but appear to be of the chewing type, though
the adult does not feed. On the mesothorax is a pair of tiny clubs, some¬
times rather flattened, which represent the front pair of wings. The
metathorax forms nearly half the entire length of the body. It bears a
pair of well developed wings which are broad and fold lengthwise when at
rest. The abdomen is composed of ten segments. The females are
soft and resemble a rather long sack bearing traces of segmentation, and
at one end a constriction, beyond which is a sort of knob, believed to be a

150

THE STREPSIPTERA

151

combination of the head and thorax; a cephalothorax in fact. This
portion of the body is pushed out between two of the body segments of
the host during the latter part of the metamorphosis, thus becoming
external (Fig. 147) and the body of the host is distorted in this way.

The members of this order may be characterized as follows:

Tiny insects which from the first larval instar to the adult, are internal
parasites in other insects. The male adult has stalked eyes, mouth parts of
the chewing type, but little or not at all developed; antennae with one or more
segments prolonged laterally; pro- and mesothorax small, the latter with a
pair of small clubs corresponding to the fore wings of most insects; meta¬
thorax long, forming at least half the length of the body and bearing a pair of

Fig. 147.— Female Strepsipteron, top and side views and a Stylopized Wasp: a, end
of the parasite projecting between the abdominal segments of the Wasp. All greatly
enlarged. ( After Leuckart’ s W andtafeln.)

broad wings which fold longitudinally . The female adult is worm-like,
without feet, and located within the body of its host except for a cephalothorax
which protrudes between two abdominal plates of the latter. It is enclosed
by its pupa skin. Metamorphosis complete.

These insects, often called “stylops,” are parasitic only in some
Orthoptera, Homoptera, Hemiptera and Hymenoptera, as far as known,
and at the present time only Gryllotalpa in the Orthoptera and Chryso-
coris in the Hemiptera are known as hosts in those groups. Most of the
parasitism is of leaf-hoppers, wasps and the solitary bees, and these
are so disabled by the removal of their body fluids by the parasites that
“stylopized” individuals are unable to reproduce and are greatly lacking
in vitality. Their bodies are often distorted also and other changes are
produced.

152

APPLIED ENTOMOLOGY

The eggs of the st.ylops appear to hatch within the body of the mother
and the young escape by passing from the body out into the space between
this and the pupa case of the parent in which it remains, and then through
an opening in this at the cephalothorax, thus reaching the open air.
They are now on the body of the parental host and this insect may carry
them to its nest, where if it is a colonial form, the stylops may find young
to attack there. It is generally probable though, that they leave the
parental host at some place (possibly a blossom) where other insects of
the host species will be liable to visit. Transferring onto such individuals
as chance may permit, the stylopids finally arrive where larvae of the
proper species are available, and at once attack them. Thus far they
have been active little six-legged larvae, but after burrowing into the
body of their host larvae they change greatly, becoming worm-like and
legless. The males finally enter a pupa stage, after which the adults
escape, but the females remain throughout the rest of their life in the
bodies of their hosts.

Where stylopids are abundant and attack injurious species of insects,
such as are most at least of the Homoptera, the stylopized individuals,
being unable to reproduce, become of lessened importance and their
parasites must be considered as beneficial. Most of the Hymenoptera
they attack, however, are beneficial and parasitism in such cases can
hardly be considered helpful to man. The group is not sufficiently
abundant though, to be an important factor under ordinary conditions,
as only about a hundred species are known, but these are widely dis¬
tributed over the globe.

CHAPTER XXI

THE THYSANOPTERA

The Thysanoptera— sometimes called Physapoda— are very small
insects, peculiar in many ways. The common name for members of
this group is Thrips, unchanged in spelling whether one or many are

referred to.

As a whole these insects appear to have some affinities with the hemip-
teroid groups (Anoplura, Hemiptera and Homoptera) yet to be consid¬
ered, but are generally looked upon as forming an order by themselves,
though in some regards they seem to have certain relations to the Cor-

rodentia and Mallophaga. It is not improbable that they form a group
originating not far from the common trunk of all
the above-named orders.

Thrips vary from one-fiftieth to one-third
of an inch or more in length. Their mouth
parts (Fig. 148) form in part a short, stout cone
attached far back on the underside of the head,
composed of the labrum, a portion of the maxillae,
and the labium. Within this cone are three
bristles consisting of the lobes of the maxillae and
one mandible, the other not being developed.

The animals are sucking insects. Four wings
are usually present, rather long and narrow, with
few veins, and fringed behind and generally in
front also, with slender hairs, longer than the
breadth of the wing itself. When at rest the

wings lie flat on the top of the abdomen. In some cases they are greatly
reduced in size or may even be wanting entirely. The tarsi aie com¬
posed either of one or two segments, usually the latter: at the tip is a
bladder-like portion which can be drawn into the segment or pushed
out. The abdomen consists of ten segments, the last either conical or

Fig. 148. — Side view of
the head and prothorax of
a Thrips to show the mouth
parts. (From U. S. D. A.
Bur. Ent. Bull. 68 Part 2.)

tubular in form.

Summarizing these facts, the adult Thysanoptera may be described as:

Small insects with cjreatly modified mouth parts forming a cone attached
to the hack part of the head beneath and used for sucking. Wings four,
generally present, long, narrow, with few veins, and fringed behind ( usually
in front also ) with long hairs. Tarsi of one or two segments, the tip with a
bladder-like swelling capable of being drawn into the tarsus. Abdomen of
ten segments, the last either conical or tubular. Metamorphosis incomplete
but approaching completeness.

153

154

APPLIED ENTOMOLOGY

Thrips feed on plant juices, puncturing the tissues and extracting
the sap, leaving white marks or streaks where the cells without their
juices have dried. They attack stems, leaves and blossoms, in the last
case often blighting them and preventing the setting of fruit. On leaves
of plants the under surface appears in most cases to be the preferred
place of attack and the insects do not move about much. With grasses
and cereals the stems as well as the leaves suffer, thus checking the growth
of the top, and in some cases the kernels of growing grain are also fed
upon. Some species live under loose bark and a few have been reported
as feeding upon other insects. In many cases the injury caused by these
insects is very serious.

In one section (Suborder Terebrantia) the female has an ovipositor
with which she saws slits in the epidermis of plants, placing an egg in
each slit. In the other section (Suborder Tubulifera) there is no ovi¬
positor and the eggs are laid upon the surface of the food material. The
larvae considerably resemble the adult. After from two to four molts
they leave their food to find some more protected place and there molt
again, at which time wing stubs appear and other changes can be seen.
Another molt and now the insect becomes quiet unless disturbed, not
feeding, and marked changes become evident, bringing it more nearly
like the adult, and the completion of these changes is followed by a molt
which produces the adult itself. This is more than a typical incomplete
metamorphosis, yet not entirely comparable with a complete one. It
may be regarded therefore as intermediate between the two.

In some cases parthenogenesis, i.e., the production of the next gener¬
ation by unfertilized females, occurs. This is perhaps to some extent
determined by weather conditions, in this group. Parthenogenesis is
frequently present here and there among insects and will be considered
more fully elsewhere. Driving rains are very destructive to all kinds of
Thrips. Lady beetles and other insects of several species feed freely
upon them.

The Wheat or Strawberry Thrips ( Frankliniella tritici Fitch). — This
is probably the most widely distributed species of the group in this
country. It feeds on wheat, strawberry, apple and many other plants and
where the blossom is attacked as in the case of the strawberry, it is blighted,
preventing the formation of the fruit and producing the stunted struc¬
tures known as “buttons,” instead. Leaves attacked often curl and be¬
come malformed, the particular parts injured soon turning brown and
dying. In California it is a particular pest of alfalfa.

The adult is about a twentieth of an inch long, yellowish in color. In
the warmer parts of the South it is more or less active at all seasons of
the year, but in the North it winters in protected places, many probably,
like other species, in grass fields close to the ground.

The life history in the South requires about 12 days but is probably

THE T II YS A NOP TER A

155

longer in the cooler temperatures of the northern states, and several genera¬
tions are produced in a season.

Control. — In general, spraying with nicotine sulfate 40 per cent,
standard formula, or with kerosene emulsion, 1 part in 4 parts of water,
is a good treatment. Success with these materials, however, depends
largely upon the thoroughness of the application and the number which
are killed. A favorite formula in California consists of 1 34 gal. of com¬
mercial lime-sulfur, and 3^ fl. oz. of nicotine sulfate 40 per cent in 50
gal. of water, applied as a spray. Where the adults are wintering in grass
fields and it is practicable, burning these over will
destroy many.

The Onion Thrips ( Thrips taoaci Linde.;. — This
pest is present practically everywhere in Europe
and the United States, having first been noticed
here about 1872 (Fig. 149). The adult is about a
twenty-fifth of an inch long, rather light yellow,
but turning brown as it becomes older. It feeds
on a great variety of plants but being the species
which is particularly injurious to growing onions,
is generally known as the Onion Thrips. The onion
leaves are whitened by the removal of their juices,
and soon begin to bend sharply downward, and
later they may curl or twist and even die, an area
much affected in a field being noticeably pale
colored and the plants stunted, while the bulbs
make little growth.

Winter in the North is spent as the adult in
protected situations such as in dead grass close to
the ground or in rubbish left on the field. In
spring the young onion plants are attacked soon
after they come up, first in the bud, later on the leaves, in which the eggs
are laid. The life cycle from egg to adult is influenced by the tempera¬
ture, varying from a little less than 3 weeks to over a month, and in
the most southerly states the generations overlap so that practically all
stages may be found at the same time. Sometimes in the North this
insect becomes a greenhouse pest on roses, carnations, cucumbers and
tomatoes, though the Green-house Thrips ( Heliothrips hcemorrhoidalis
Bouche) is most often responsible for this injury.

Control. — Any methods of farming which will reduce the oppor¬
tunities for this insect to pass the winter successfully, are of value. The
destruction of all refuse on the field after the crop has been gathered:
fall plowing of such fields, and burning over grass lands adjacent to them,
at the proper time in the spring, are all beneficial. Cultivation and fertili¬
zation to push the crop ahead early to “keep it ahead of the thrips” is

i — _ _ _ j

Fig. 14Q. — Nymph
of the Onion Thrips
(Thrips tabaci Linde.),
greatly enlarged.
( From Britton: Third
Rept. Conn. State
Entomologist.)

156

APPLIED ENTOMOLOGY

also helpful. Spraying the plants with nicotine sulfate 40 per cent,
% pint., 4 lb. more or less of soap, and 50 gal. of water is a fairly
effective treatment. Fish-oil soap is better than laundry soap when
obtainable, and the amount to use is determined by spraying a leaf with
the mixture. If the spray gathers together into larger drops, leaving
parts of the leaves dry, more soap is needed, for its use is mainly as a
“spreader” over the leaf surface. This treatment should be repeated
every 8 or 10 days as long as the Thrips are present in any abundance,
until within a month of harvesting. Use a fine, misty spray with con-
derable pump pressure. Only thorough spraying will give effective
results.

The Pear Thrips ( Tceniothrips inconsequens Uzel). — This insect was
first discovered in the United States in the central part of California,

Fig. 150. — Adult Pear Thrips ( T ceniothrips inconsequens Uzel), greatly enlarged. ( From

U. S. D. A. Bull. 173.)

attacking deciduous fruit trees, particularly pears, prunes and cherries,
blighting the blossoms by the abstraction of their sap. Later it was found
in British Columbia, in the Hudson River Valley in New York, and still
later in Pennsylvania, Maryland, and in England. Recently it has been
learned that the insect was first discovered in Bohemia, feeding in
blossoms.

The destruction caused by this pest in California has been very great
some years. The crop of prunes in the Santa Clara Valley alone has
been estimated as having been reduced in the 7 years, 1905 to 1911,
141,000,000 lb. The injury is caused by the feeding of the young and
adults on leaves, buds, flowers and fruit, -and by laying eggs in the leaves
and fruit stems and also in the small fruit.

THE THYSANOPTERA

157

The dark brown — almost black — adults (Fig. 150) appear early in
spring, coming out of the ground about the time the fruit buds are swelling
and opening, and as soon as these have opened slightly the insects work
their way into them and feed on the most delicate parts. The eggs are
laid mainly in the young leaf and fruit stems and young fruit and hatch
on an average after about 8 days. The nymphs (Fig. 151) feed on the
leaves and young fruit forming a sort of “ scab ” on the surface of the latter,
and remain on the tree for 2 or 3 weeks, though from the first young to
appear to the last young to disappear, may be
more than 2 months. When through feeding
they fall to the ground, which they enter for a
varying distance, and there, after from 2 to 5 or
6 months, they transform to the last stage before
the adult, having previously molted once under¬
ground. Late in the fall or winter the final
molt produces the adults which remain in the
ground till early spring.

This remarkable life history, quite unlike
anything known for any other Thysanoptera,
permits but one generation a year, with active
injury during only a rather short period in the
spring.

Control. — These insects can be destroyed by
spraying with Nicotine sulfate 40 per cent used
at the rate of 1 part to 800 parts of water, stand¬
ard formula. Success with this treatment, how¬
ever, is entirely dependent upon the thoroughness
of the application. The first treatment should
at once follow the discovery of the Thrips upon
the swelling buds and should be repeated at least
every 2 or 3 days until the buds are open or
the Thrips have become very few. No spraying
should be done from the time the blossoms open

until the petals fall. Then, if Thrips are abundant on the remains of
the blossoms, another treatment should be given.

The Citrus Thrips ( Scirtothrips citri Moult.) is a rather serious pest
in California and Arizona. It feeds upon the tender stems, leaves and fruit
of citrus trees, and occasionally also attacks the grape, apricot and other
plants. With seedling plants the leaves and buds are injured and
growth is checked. The fruit is injured by scars and scabs caused by the
feeding, and greatly reduced in value, and some drops to the ground.

The adult is one of the smallest of the Thysanoptera, varying from
one-fiftieth to one-twentieth of an inch in length, and is orange-yellow in
color. The young appear in April and May and gather on the leaves

Fig. 151. — Nymph of
Pear Thrips, greatly en¬
larged. ( From U. S. D A.
Bur. Ent. Bull. 68, Part 1.)

158

APPLIED ENTOMOLOGY

and fruit where they remain until the midsummer hardening of these
parts leads most of them to leave for various other food plants, until
August and September when they return to the citrus trees again and
lay their eggs in the leaves and stems of the plant. These winter over
and hatch the following spring. Following the production of adults
from the hatching and development of these eggs, there may be six to
eight generations during the season and all stages may be present at
once on a tree as late as December, though these die with colder weather,
leaving only the eggs to hatch in the spring. The last stage before the
adult, during which the insect is quiet, is passed in crevices of the trunks
or in rubbish under the trees, but not in the ground.

Control. — Spraying, either with lime-sulfur wash using 1 part (if of
a density of 33°Be.) in 50 parts of water, or with more water than this if
the wash reads higher; or with Nicotine sulfate 40 per cent, at the rate
of 1 part in 800 parts of water, have given excellent results. The first
application should be made as soon as four-fifths or more of the blossoms
have fallen, and a second 10 days to 2 weeks later. If these two treat¬
ments have been well-timed and thorough, the third can be delayed until
about 3 weeks after the second. A fourth treatment late in August or
early in September, if the returning insects are very abundant on new
shoots, will aid much in checking their increase. In all treatments the
application should be very thorough and with a pressure of at least 1251b.
Particular attention should be given at the second application to
completely drenching the fruit and any tender leaves.

In addition to the species of Thrips given separate consideration
above, nu nerous other species are frequently of some importance.
Among these the Grass Thrips which sucks the sap from the stems of the
lighter grasses, turning them white and killing them, thus causing “silver
top” as it is called; the Greenhouse Thrips which attacks tomatoes,
cucumbers and many other plants in greenhouses in the North and out-
of-doors in the South, and the Camphor Thrips which is a serious pest
of the Camphor tree in Florida, are perhaps the most important.

CHAPTER XXII

THE CORRODENTIA

Most of the Corrodentia are very small, even tiny insects, though
a few giants of the group found in South America have a wing-spread of
about an inch. Some of the group are wingless and are most often
noticed as small, whitish, gray or brown specks running over the leaves
of old books. These are generally called Book-lice. The winged forms
(frequently called Psocids, though this name really applies to the entire
group) when adult are somewhat larger and
are found on tree trunks, weathered fences
and other places where lichens grow, and
furnish them with their food. In general
the members of the group eat animal or
vegetable refuse, mould, fungi and similar
materials. Several hundred kinds are
known.

The body in the Corrodentia though
quite soft, is well developed, but the pro¬
thorax is small and concealed in some cases
between the head and the mesothorax. In
others it is distinct, but as the meso- and
metathorax are grown together in those
cases, only two of the three thoracic seg¬
ments are evident. The antennae are rather
long and slender, and the mouth parts are
for chewing but considerably different in
some details from the typical structure.

The wings when present are four in
number, with very noticeable veins, few of which are cross-veins. When
at rest the hinder margins of the wings of the opposite sides are brought
together over the back of the insect with their upper surfaces sloping
down at the sides, thus assuming the position of a steep house roof.
They are often more or less dusky or mottled. The tarsi consist of only
two or three segments. Ocelli may be present in the adults but not in
the nymphs. These are quite similar to the adults otherwise, and develop
through a series of molts into the adult condition.

The group may be characterized as follows:

Small, soft-bodied insects with or without wings when adult. In those
having wings there are two pairs, with prominent veins: when at rest they

159

160

APPLIED ENTOMOLOGY

are held at a sharp angle over the body, hinder margins uppermost. An¬
tennae long and slender. Tarsi of two or three segments. Ocelli sometimes
present in the adult condition. Metamorphosis incomplete.

This little order contains few species of much economic importance.
The wingless forms — book-lice (Fig. 152)— found in buildings, eat the
paste and paper of old books and are also found in birds’ nests where
they find in feathers and other organic debris their food. The winged
forms, frequently called Psocids, are found in various places, but perhaps
most frequently on the trunks of trees, generally in clusters and often in
various stages of their development. They have the power of producing
silk and sometimes the clusters appear to be covered, at least partly, by
a web of this.

Fig. 153.— Adult Psocids: a, side view showing position of wings at rest; b, Psocid
(Psociis lineatus ) with wings spread. Both greatly enlarged. ( From Sanderson and
Jackson, Elementary Entmology: a, after Kellogg: b, after J. B. Smith.)

Some of the book-lice are claimed to be able to make a ticking sound
something like that of a watch, and this sound is often called the “death
watch.” Such a sound is certainly produced by a small beetle, and the
possibility of the book-lice also being able to make it has been questioned.
The weight of evidence thus far, however, seems to favor this possibility.
It is heard chiefly in old houses at night or when everything is quiet, as
a faint, rapidly repeated tick-tick-tick, and is in all probability, the call
of an insect to its mate.

The winged Corrodentia (Psocids, Fig. 153) are not known to be of
any economic importance. Where the wingless forms (book-lice) be¬
come extremely abundant in buildings, relief may be obtained by a
thorough cleaning of the infested places. Light and air, particularly
dry air, are unfavorable to them, and heating a room to quite a high
temperature for a few hours and the exposure of all the furniture to
sunlight for a time on a bright day will generally free the place from these
insects. All stages except the egg appear to die at the beginning of
winter.

CHAPTER XXIII

THE MALLOPHAGA

The Mallophaga are generally called bird-lice but as they feed by biting
off particles of feathers, hairs and scales of the skin, from the animals on
which they live, the name biting-lice would be better as it would dis¬
tinguish them more accurately from a large number of very similar
insects found in many cases on the same animals, which feed by sucking
the blood of their hosts, and which are called sucking-lice.

Fig. 154. — Samples of Mallophaga or Biting Liee, greatly enlarged: hair lines show
actual length. ( After Kellogg.)

The bird-lice or biting-lice (Fig. 154) are very small insects ranging
from about one-twenty-fifth to one-tenth of an inch in length, rather
whitish in color, much flattened and with an external shell which is
unusually hard for such small insects. They are wingless and are rarely
found off the bodies of the birds and mammals on which they live.
Development from the egg is gradual, through a series of molts which
finally produces the adult.

The group may be described thus:

Small, wingless insects, usually with a large head; mouth parts for
biting. Body quite hard, flattened. Parasitic on the bodies of birds and
some mammals. Metamorphosis incomplete.

About fifteen hundred kinds of Mallophaga are known, most of them
living on birds, where they feed on feathers and skin scales. On mam¬
mals, hairs replace the feathers as their food. When abundant, bare
areas on the bodies of birds appear where the feathers have been eaten or

161

n

162

APPLIED ENTOMOLOGY

have dropped out as a result of the feeding of these insects. Birds nor¬
mally dust themselves, working the dust in among their feathers, where
it is claimed it gets into the spiracles of the lice and suffocates them.
Apparently the greatest injury to the fowls does not come from the feeding
on the feathers and scales, but from the irritation produced by the
scratching of the skin caused by the tarsal claws of the parasites as
they move about, and this must be quite severe, for birds considerably
infested become dull and act sick, and are certainly less able to resist
disease than usual.

The eggs of the lice are attached separately to the feathers or hairs
of the host, and hatch into nymphs, which on the whole considerably
resemble their adults. They feed, molt, grow and become adult in a
few weeks.

Fig. 155. — Female Chicken Body Louse ( Menopon biserialum Piag.), greatly enlarged.

( From U. S. D. A. Farm.. Bull. 801.)

Though these insects are widely distributed on many kinds of birds
and on a number of mammals, they are of importance from an economic
standpoint mainly on the domesticated birds such as chickens, turkeys,
geese, ducks and pigeons, though occasionally dogs, cattle and horses
become infested.

Seven different kinds of biting-lice are fairly common on domestic
fowls. Of these, some prefer the head for their location, others the body
(Fig. 155), etc., though not found exclusively in those locations. Four
kinds are often present on turkeys and quite a number occur on geese
and ducks. Pigeons and guinea fowls have several species.

THE MALLOPHAGA

163

Control of Lice on Poultry. — Various methods of control for poultry
lice are in use, but in most cases at least, the best one is the use of sodium
fluorid, dry or dissolved in water. Either the commercial or the chemi¬
cally pure grade can be used but the commercial is somewhat easier to
work with, particularly for dusting the fowls.

The first step in treatment is to shut up all the fowls. Then each
bird is taken and while being held either by the wings or legs with one
hand, pinches of the powder are placed in among the feathers, “one on the
head, one on the neck, two on the back, one on the breast, one below the
vent, one on the tail, one on each thigh, and one scattered on the under¬
side of each wing when spread.” For young birds dusting rather than
dipping is advisable.

If dipping is preferred for the older birds, use warm water in a tub,
measuring the water put into the tub and adding from to 1 oz. of
the commercial fluorid (or % oz. of the chemically pure fluorid) to each
gallon of water. Dip the birds in this, holding the wings over the back
with one hand and ruffling the feathers with the other, below the surface
of the water. Then duck the head of the bird once or twice, take it out
of the water, let it drain for a moment and then let it go. After a little
experience, three-quarters of a minute per bird will be an ample amount
of time for this treatment.

The water in the tub will be reduced in quantity of course, by use,
and more, having the proper amount of fluorid dissolved in it should be
at hand to add from time to time.

Whether the sodium fluorid treatment, which has only recently been
discovered, will give satisfaction for the treatment of biting lice on mam¬
mals cannot be stated. Heretofore, washing an infested animal with
kerosene emulsion has been advised.

Boxes of road dust, available in poultry houses during the winter
months for the birds to dust themselves in, are desirable. Formerly
used to actually aid the birds in freeing themselves of lice, they now act
as indicators that lice are present and that treatment should be given

CHAPTER XXIV

THE ANOPLURA

These insects are the sucking lice which attack mammals, and mam¬
mals only. They are small, wingless insects from about one twenty-fifth
to one-fourth of an inch in length, and with mouth parts for sucking. The
head is usually rather pointed in front and is often joined to the thorax
by a distinct neck which permits its free movement. The distinction
between thorax and abdomen is less evident, the constriction there being
practically non-existent. The legs, which join the thorax well out on its
sides, are constructed for climbing and grasping, and each ends in a
single claw, so placed with reference to the rest of the leg that it can
tightly grasp a hair, the claw on one side and the tibia on the other.
The eyes are rudimentary or absent in some cases.

The group may be defined as:

Small, wingless insects with sucking mouth parts, feeding on the blood
of mammals. Eyes present or absent. Tarsi each with one claw. Meta¬
morphosis incomplete.

Fig. 156. — Samples of Anoplura or Sucking Lice, greatly enlarged. ( After Dalla Torre.)

Anoplura (Fig. 156) occur on man, monkeys, domestic animals, rats,
mice, rabbits, squirrels, the elephant, etc., and one genus is found on the
seal. The mouth consists of a flexible proboscis which may be drawn
in or pushed out, turning inside out as it goes and exposing some chiti-
nous hooks which attach themselves to the skin of the host. Lodged
in the head are two long, slender, sharp-pointed structures called stabbers,
one, possibly both, apparently double in nature but more or less fused,
and so placed as to form a canal between them through which saliva may

164

THE ANOPLURA

165

be injected into the wound they make. These stabbers are forced
through the skin within the area encircled by the proboscis, saliva is
forced into the wound and after a few moments feeding begins, the blood
of the host being pumped into the body of the louse.

Eggs or “ nits” are laid singly, attached to the hairs of the host or in
some species, to the fibres of the clothing. They hatch in from 1 to 2
weeks, according to the species and the temperature, but when the
latter remains low, as where the eggs do not feel the effects of the warmth
of the host, they will not hatch (at least with the lice infesting man).
The nymph stage probably requires 8 to 10 days, though practically
nothing is known of the development except with the lice attacking
man. Several hundred eggs are usually laid by each female during a
period of nearly a month, so that a heavy infestation becomes possible
in quite a brief time.

The Anoplura is a small group of insects, probably only about a
hundred species being known. They were formerly considered degener¬
ate Hemiptera, but with the division of the
old Order Hemiptera into separate orders — the
Hemiptera in a more restricted sense and the
Homoptera — it has seemed more logical to regard
the Anoplura as also an Order, most closely re¬
lated to these, but still sufficiently different to
entitle it to ordinal rank.

The Human Body Louse ( Pediculus humanus
L.).— This pest (Fig. 157), which during the
European war also received the common name
“cootie,” is now generally regarded as being of
two races, the head louse (formerly called Pedi¬
culus capitis) which is found chiefly on the head,
and the body louse (formerly Pedicidus vestimenti
or P. corporis ) found mainly on the clothing,
rather than different species, but the races differ
somewhat because of different conditions under
which they live. This insect under ordinary conditions of cleanliness
can be easily controlled, but in camp life finds an opportunity to increase,
often almost without possibility of being checked.

Under ordinary conditions a simple treatment for the race living on
the head is to wash thoroughly with tincture of larkspur, which can be
obtained of a druggist, and repeat this two or three times at intervals of
about a week. For the race living on the body, treatment is somewhat
different, as the pests are largely on the clothing, reaching across from this
to the skin to feed. Here boiling all clothing which can be so treated,
dry heating the rest to 130°F. for ^ hr. and taking a hot bath will usu¬
ally be sufficient.

Fig. 157. — Human Body
Louse ( Pediculus humanus
L.) about eight times
natural size. ( From
Bei lese.)

166

APPLIED ENTOMOLOGY

Rather recently it has been discovered that the lice of man are con¬
cerned in the transmission of Relapsing fever, Trench fever, and that
terrible disease Typhus fever. It does not at present seem that the
causal agents of the first two of these are actually transferred to man
by the feeding of the infested lice, but rather that these agents are present
in their bodies and feces, and that by scratching parts irritated, fluids from
crushed lice or the feces get rubbed into the irritated areas, are able to
enter the body, reach the blood and begin the disease. This also
appears to be true in the case of Typhus fever, but here inoculation by the
feeding of the lice also seems probable. In some cases where scratching
does not occur but where Relapsing or Trench fever nevertheless develops,
it is probable that the feces get into the feeding wounds and in that way
cause the disease.

The Crab Louse ( Phthirus pubis L.). — This louse is quite different
in appearance from the last, being smaller, shorter, broader, and with

its legs projecting outwardly near together
(Fig. 158). The fore legs are slender but
the others are stout and each has a powerful
serrated claw which shuts against a pro¬
jection of the preceding segment of the leg
in such a way as to give a very firm grip
on a hair. This insect is found primarily
on the hairy parts of the body except the
head, but in exceptional cases it may be
found there also. It holds onto the hairs
while feeding and in moving about always
holds tightly to hairs on one side until it
has obtained a grasp on others on the
other side. This gives it a sideways move¬
ment which is responsible for its common name. Its life history is
much the same as in the other species.

Washing thoroughly with tincture of larkspur as for the head louse
is usually an effective treatment. An ointment made of 4 parts of crude
naphthaline mixed with 1 part of soft soap rubbed on the undercloth¬
ing in the infested region has also been found to be a very successful

Fig. 158. — Human Crab Louse
( Phthirus pubis L.) about twelve
times natural size. ( From Bcrlese.)

treatment.

Lice on Domestic Animals. — These are sometimes serious in their
attacks, weakening the animal greatly if they are abundant. In the
treatment of these pests it should be borne in mind that poisonous
materials cannot be used because of the danger coming from the animals’
licking themselves. Various substances have been used for live stock,
such as 15 per cent kerosene emulsion scrubbed on the skin; washing
with potassium sulfid, using from 2 to 4 oz. per gallon of water according
to the size and vigor of the animal; the application of a mixture of sulfur

THE ANOPLURA

167

1 part, lard 4 parts, rubbed over the body, or washing with dilute car¬
bolic acid using 1 part of the acid in 30 parts of water. The most usual
treatment for cattle lice, however, is by the use of stavesacre (Delphin¬
ium) seeds. Four ounces of these seeds and 1 oz. of white hellebore are
boiled in a gallon of water until only 2 qt. remain. This is then applied
with a brush to the animals. It may need to be repeated if more lice
appear, showing that eggs or some of the lice escaped the first application.
Raw linseed oil, applied with a brush has recently been recommended as
an alternative treatment, the material for one animal costing about five
cents.

The relation of insects to disease as has been brought out above,
where lice serve to convey the germs or parasites causing illness to man,
is one of the newer subjects in Entomology but one which has been shown
to be of great importance. Medical Entomology is already a large field
upon which much has been written, and yet one about which little is
probably known in comparison with its actual size.

CHAPTER XXV

THE HEMIPTERA

The Hemiptera is a large group containing many insects which are
always injuriously active, and many more which occasionally become so.
They vary greatly in size, some being minute while others may attain
a length of four or five inches. They are most numerous in species in
the warmer portions of the globe, but an abundance of individuals in
colder regions results in making them extremely common everywhere.

Most Hemiptera have the dorsal surface of the body rather flattened,
though there are many exceptions to this statement, and the wings when
not in use rest upon this surface. The wings are nearly always present,
four in number, and the basal half, or sometimes more, of the front
pair is thickened and horny, resembling the elytra of beetles. The outer
end, however, is membranous and veins traverse this portion, so that the
fore wings are appropriately called hemielytra. The membranous part
of one wing largely overlaps that of the other when they are at rest. In a
few families the difference in the texture of the two portions is not very
perceptible but in most cases it is plainly evident. The hinder wings are
entirely membranous and when not in use are concealed beneath the
others.

The body of the Hemipteron with few exceptions, shows no constric¬
tion at the junction of thorax and abdomen and is usually widest at the
hinder end of the prothorax. The attachments of the wings behind
this do not occupy anywhere near all of the width of the body, and
directly behind the pronotum, between the wings, the space is taken
up by a rather large, usually quite triangular plate called the scutellum.
In some families this becomes greatly enlarged, covering more or less
of the dorsal surface of the body from the pronotum back, and in such
cases the wings in closing slip under this so that little besides their costas
show.

Hemiptera are sucking insects (Fig. 159), obtaining their food by
piercing the surfaces of plants or animals and drawing into their own
bodies the sap or blood. The mouth parts in the group have been identi¬
fied with those of chewing insects, but they have been greatly modified to
form a beak or rostrum which is attached to the front of the underside
of the head. The details of structure of the rostrum differ in different
Hemiptera but agree in general plan (Fig. 160). The outside of the

168

THE IIEMIPTERA

1G9

rostrum is a sheath which appears in the main to be derived from the
labium or hinder lip of the chewing insect, being much elongated, and
its sides rolled forward to meet or almost meet in front, forming a
tube. The front part of this tube, however, near the head, seems not to
be formed by the labium, leaving open a somewhat triangular place
and the labrum or front lip appears to have grown downward to more or
less completely close up this portion of the sheath. Within the tube

Fig. 159.

Fig. 159. — Side view of a Squash Bug (Anasa tristis De G.) showing the rostrum,
and its attachment to the front of the head. Some of the mouth parts usually within the
sheath have been pulled out and show in front of it. Rather more than twice natural size.
(Original.)

Fig. 160. — Diagram of a cross-section of rostrum of a Squash Bug: la, labium; md,
mandible; mx, maxilla; Sa, tube carrying saliva to the wound; su, tube through which the
food is drawn into the body. ( Modified from Tower, Am. Ent. Soc. Am. VI, 1913.)

thus formed lie the mandibles and maxillae which have become trans¬
formed into long and slender bristles with pointed tips. The surfaces
of the maxillae which face each other have so changed their outline as to
form two gutters or troughs and when the maxillae are pressed together
as is the case in the living insect, each gutter of one side coincides with the
corresponding one of the other to form two tubes, half of each being
contributed by each maxilla. The more anterior of the tubes is for suck¬
ing the nourishment obtained, into the bug, while the other is for inject¬
ing saliva into the wound. The mandibles lie beside the maxillae and
seem to function chiefly as piercing organs.

In feeding, the tip of the rostrum is brought into contact with the sur¬
face of the object to be fed upon and the tips of the mandibles and maxillae
are then driven into it until sap or blood as the case may be, is reached.
Then saliva is forced into the wound and this seems to be irritating or
even poisonous in its nature and its presence in the wound causes (in
animals at least) an increased flow of the body fluids to that point.
Assured thus of a sufficient supply of food, sucking it into the body of
the insect is then begun.

The eggs of Hemiptera are laid under greatly differing conditions.
Some are inserted in twigs or stems; others are laid either singly or in

170

APPLIED ENTOMOLOGY

clusters on leaves, twigs or in other places. The eggs themselves vary
much in appearance, some being provided with circlets of spines, some
with long filaments and some being smooth but of unusual form or color.
They hatch into nymphs (Fig. 161) more or less closely resembling the
adult, which stage they reach by a series of molts, changing with each
molt.

The Order Hemiptera may be characterized as:

Insects which when adult nearly always have four wings, the front pair
in most cases partly horny, partly membranous: with a plate located between
the bases of the wings, usually triangular in outline, in some cases covering
more or less of the abdomen above: mouth parts for sucking, and attached to
the front end of the underside of the head. Metamorphosis incomplete.

Fig. 161.— Metamorphosis of the Squash Bug (Anasa tristis De G.) : adult and nymphs
of different ages, all twice natural size. ( From. Folsom.)

Hemiptera occur under almost every conceivable condition of life.
Some live in water, coming to the surface only to obtain air: some are
found on the surface of the water and some are found on the ocean hun¬
dreds of miles from land. Most of the group are terrestrial, however, and
in many cases are widely distributed. Probably fifteen thousand species
are already known but the group has been little studied as compared
with some of the more attractively colored and marked orders. Those
living in water are at least for the most part, feeders on insects and other
animals small enough for them to capture: those which live on the surface
are also predaceous, while of the land forms some consume other insects
but probably the larger number are plant feeders. The Hemiptera are
the true bugs, the general use of the term “bug” as applied to all insects
being incorrect.

THE HEMIPTERA

171

Family Pentatomidae. — This group consists of land forms, many of
them producing a disagreeable odor which has resulted in applying to
these insects the common name “stink bugs” (Fig. 162). Most of them
suck the sap from various plants, leaving behind the odor so often
noticeable on berries. Others are carnivorous, attacking caterpillars and
sucking their juices. Many of them are minor pests and potentially
important ones, and their fair size — often half an inch or more in length-
together with considerable width, giving them a broad surface, makes
them fairly familiar objects.

Fig. 162. Fig. 163. Fig. 164.

Fig. 162. — Pentatomid Bug (Euschistus) , natural size. (Original.)

Fig. 163. — Adult Harlequin Bug ( Murgantia hislrionica Hahn.), slightly enlarged
(Original.)

Fig. 164. — Eggs of Harlequin Bug, slightly enlarged. (Modified from Essig. Inj.
and Benef. Ins. Cal.)

The Harlequin Bug ( Murgantia hislrionica Hahn).— This pest,
native to Mexico and Central America, has gradually spread northward,
feeding on cabbage, kale, mustard, turnip, radish and other cruciferous
plants, and its present northern limits are now in New Jersey and Long
Island, Ohio, Indiana, Wisconsin, Iowa, Nebraska, Colorado, Arizona,
Nevada and Washington, though the insect rarely does much injury so
far north.

The adults (Fig. 163) are about half an inch long, black or dark blue
with bright red or orange marks, the brilliancy of the colors making the
insects very noticeable and resulting in the common names “calico-
back,” “terrapin-bug” and perhaps “fire-bug” as well. They winter in
the adult stage under rubbish or wherever they can find protection,
though in the far South they are more or less active nearly all the time
and there the nymphs are also present then.

Farther north the bugs become active during the early spring and
attack various wild cruciferous plants and lay their eggs (Fig. 164).
These are usually placed in clusters of about 12, in two rows, and are
somewhat barrel-shaped, white, with two black rings around each, and a
third ring on the upper end, being both very noticeable and distinctive.
They hatch in from 3 to 11 days according to the temperature and the
nymphs suck the sap from the plants for 1 to 2 months, again according

172

APPLIED ENTOMOLOGY

to the temperature, before becoming adult. When cabbage, cauliflower,
kale, turnip, radish, etc., become available, the bugs go to these and there¬
after devote their attention to these plants until late in the fall when
various other kinds, such as egg plant, asparagus, tomato, beans, beets,
etc., may be attacked.

Control. — Insecticides which do not injure the plants the bugs are on,
are not usually effective against this pest and preventive methods have
thus far given the best results. Planting a very early crop of kale,
mustard or rape, to which the bugs when they first become active in
spring may be attracted, is a good practice, for the insects seem to prefer
these to the other plants. Here the bugs may be killed by spraying with
kerosene, collected in nets and destroyed, or may be burned with a torch.
The few that may escape this treatment can be picked by hand wherever
found, but if the trapping method above is followed, few usually escape.

Clean culture is also helpful. As soon as the crops are gathered all
the stalks and leaves of the plants on which the Harlequin bug feeds
should be gathered and destroyed, both to leave them no food and to
remove possible places where they might winter. Rubbish which might
provide wintering quarters should also be carefully removed. Recent
tests with contact insecticides show some possibility that control by
these materials may be obtained, but this subject has not yet been suffi¬
ciently investigated to warrant definite recommendations.

Family Cydnidae. — The bugs of this family are usually of little eco¬
nomic importance. Some of them are interesting, however, as in them the
scutellum, usually quite small, becomes greatly enlarged, covering nearly
all of the thorax and abdomen behind the pronotum. In one genus the
insects are nearly circular in outline, very convex, having much the form
of lady beetles, and are generally glistening black, in a few cases with a
narrow line of white. These are often called “negro-bugs” and one
species feeds on small fruits and leaves a disagreeable odor.

Family Coreidae. — Many of the members of this large family are of
considerable size for bugs, some being over an inch long, but their bodies
are much more narrow in proportion to their length than in the Penta-
tomidse. Some of the southern species have broad, flat expansions of the
tibiae, giving them a curious appearance. The insects of this group suck
plant juices and a number are frequently more or less injurious to various
plants.

The Squash Bug ( Anasa tristis De G.). — The Squash Bug is common
almost everywhere in the United States feeding on squash and pumpkin
and sometimes on cucumber and melon plants (see Fig. 161). The adult
is a dark brown bug, very finely mottled with gray or lighter brown in
many cases, about three-quarters of an inch long. It winters as the
adult under rubbish or in other protected places, and appears in spring,
ready for its food plants when these come up. When the leaves of the

THE HEMIPTERA

173

plants develop the bugs lay their eggs on their under surface in clusters
which vary greatly in the number of eggs composing them. The eggs
themselves kre oval in outline, very convex, and being resin-brown in
color are very conspicuous against the green background of the leaf.
In a cluster the eggs are not usually so laid that they touch, but somewhat
spaced apart in most cases. At intervals before and during the egg-
laying period the adults feed on the plants and when they are very abun¬
dant may seriously injure or in some cases even kill them.

The eggs hatch on an average in about 10 days and the tiny nymphs,
green and reddish in color, begin to suck the sap from the under side of the
leaves, at first together, but scattering later. The reddish color of the
nymph quickly changes to black and the green gradually becomes more
of a gray. Feeding and molting five times results in the production of
the adult after a period of from 4 to 5 weeks from the time the eggs
hatch, and in the North the adults feed on the plants until fall; then
go into winter quarters. In the South the longer seasons which permit
an earlier start in the spring and the higher temperature which causes
the eggs to hatch more quickly, permit the production, in some cases at
least, of two generations each season.

The injury to the plants caused by the spring feeding of the adult is
continued by the sucking of the young. Where these are plenty, growth
is checked and the crop reduced. If the plants are killed by frost before
the nymphs are mature, they often attack the fruits in order to obtain
the nourishment they need to become adult.

Control. — Contact insecticides are not effective for the adult Squash
bug, which has an unusually thick shell. The usual methods for cont rol are
the removal as far as possible of all rubbish and places where the insects
can obtain protection during the winter; stimulation of growth of the
plants by fertilizers and cultivation; protection of the young plants by
fine netting until they are so well started that they can thrive despite the
bugs; traps of bark or shingles placed close to the plants, under which the
bugs gather at night and whence they can be gathered and destroyed
early in the morning (this can be begun even before the plants are up) ;
egg-masses being easily seen can be quickly found and crushed; and while
the nymphs are small, spraying with Nicotine sulfate 40 per cent, 1 part
in 400 of water will destroy them. The difficulty in reaching the nymphs
on the under side of the leaves with the spray, can in part be obviated
by attaching the nozzle of the spray pump to a piece of tubing connecting
at its other end with the hose, and bent in a loop so as to give an upward
spray.

In the South one or two very closely allied species also attack the
squashes and cucurbits and may be controlled in the same ways.

Family Pyrrhocoridae. — The insects of this family superficially re¬
semble the Coreids and are of medium size. Only one is of any economic

174

APPLIED ENTOMOLOGY

importance in the United States, and that in only a few of the Southern
States though it is also injurious in some of the West India Islands.
The Cotton Stainer ( Dysdercus suturellus H.-S.) as it is called (Fig. 165),
feeds on cotton, and occasionally the egg plant and orange among culti¬
vated crops. On oranges it attacks the fruit about the time it is ripen¬
ing, puncturing the skin and thus hastening decay. On cotton the insect
punctures the partly developed bolls and if the attack is severe these
may be destroyed. If not, the fiber is more or less stained, apparently
from the punctures in the seeds, reducing the value of the cotton
anywhere from 5 to 50 per cent. As the bugs develop in colonies and
remain close together for some time and in their early stages are red, they

Fig. 165. — The Cotton Stainer ( Dysdercus suturellus H.-S.): a, nymph; b, adult.

Enlarged about three times. ( From U. S. D. A. Farm. Bull. 890.)

are easily located and knocked off into dishes containing kerosene. In
fall and spring they are attracted to baits, either of cottonseed or sugar
cane, where they can be killed with kerosene. The bugs also feed and
breed freely on Hibiscus and the Spanish Cocklebur, and the destruction
of these plants near cotton fields will prevent their breeding there and
spreading in larger numbers to the cotton.

Family Lygaeidae. — There are many kinds of insects in this family
but nearly all are small, being in most cases less than a third of an inch
long. A number occasionally injure various plants, and one — the
Chinch Bug — is one of the worst half-dozen pests in the United States.

The Chinch Bug ( Blissus leucopterus Say). — This little bug, less than
a quarter of an inch long, feeds on all the grasses and cereal crops. It is
apparently a native of tropical America which has migrated northward,

THE HEMIPTERA

175

up the Atlantic Coast, the Mississippi Valley and the Pacific Coast, and
is now found everywhere south of the St. Lawrence River and the Great
Lakes and also in southern Ontario, Minnesota, Manitoba, the Dakotas
and along the eastern slope of the Rocky Mountains to Texas. It has
also been found in Arizona, California and Washington. It is not a
serious pest usually in the northeastern states and many of the others,
but in the Mississippi Valley it often destroys crops valued at a hundred
million dollars, in one season.

The adult bug (Fig. 166) is a tiny insect seemingly incapable of causing
so much injury, but its enormous numbers make up for its small size.

a b c

Fig. 166. — Different stages of the Chinch Bug ( Blissus leucopterus Say): a, nymph
in first instar; b, fourth instar nymph; c, adult. All enlarged about nine times. ( Modified
from III. Agr. Exp. Sta. Bull. 95.)

Its body is black or dark gray, with white and therefore conspicuous
wings, each having a single black spot. There are two forms of adult,
however, one with long, full-sized wings; the other with short wings
only partially covering the top of the abdomen. The former occurs in
the Mississippi Valley while the latter is met with, together with the long¬
winged form, in the Atlantic States and to some extent inland from there
along the more southern of the Great Lakes to Illinois.

The long-winged form passes the winter as the adult in grass tufts,
under fallen leaves or in other places giving it protection. Corn shocks
left out over winter often harbor enormous numbers. In spring the bugs
leave their winter quarters and fly to the grain fields. Here they lay
their eggs, several hundred in number, on the ground at the base of the
plants or on the roots just below the surface, this process lasting about a
month. The average length of the egg stage is about 2 weeks and the
young which hatch, suck the sap from the plants for about 40 days before
becoming adult. The nymphs are yellow with an orange tinge about
in the middle of the abdomen. This soon spreads over the greater part

176

APPLIED ENTOMOLOGY

of the body. In later stages the red becomes vermilion, with a pale band
across the front of the abdomen, the head and prothorax dusky and
before becoming adult the red becomes quite dark.

Development, at least for the individuals coming from the later eggs,
is not complete before harvesting time, and to finish their growth they
are obliged to migrate and find more food. They accordingly march in
armies, often travelling some little distance on foot, and many which
have already become adults, able to fly, march with them. In new feeding
grounds development is completed and the eggs for a second generation
are laid. This generation appears to feed more particularly on corn,
kafir corn, millet and other, similar crops, and its members become
adult before winter, and go into hiding until the following spring.

With the short-winged form, hibernation at a distance from its food
plant is impossible because of its inability to fly. This form therefore
winters in grass-land and begins its work there in the spring. It is a
question whether there is more than one generation a year for this form.
Migrations when they occur, are of course on foot, and corn is no more
liable to be attacked than timothy or any other grass crop.

The Chinch Bug is particularly affected by weather conditions,
dry weather being favorable, and wet seasons unfavorable. Dry weather
appears to induce migration, and a succession of several dry years
favors a large increase in their numbers and consequently of the injury
they cause. Rains during the hatching periods of the eggs are very
destructive to the insect, and the suppression of a Chinch Bug attack,
anticipated because of the great abundance of the wintering bugs, by
heavy rains at the right time in the spring is one reason why these pests
are not even more serious than is the case.

A fungus ( Sporotrichwn globuliferum Speg.) generally called the
“Chinch-bug Fungus” frequently attacks this insect, particularly during
periods of wet, cool, cloudy weather, and then kills enormous numbers
of them. In dry seasons it seems to have little effect, and attempts
to control the Chinch Bug by placing individuals inoculated with the
fungus in infested fields, while successful from the experimental stand¬
point, have on the whole, hardly produced the results hoped for. It
is most valuable in seasons which are dry during the egg-hatching period
but wet thereafter.

In seasons then, when rains occur during the egg-hatching periods
of the bugs, these and the fungus present will usually prevent serious
outbreaks. In dry seasons, and particularly where there are several in
succession, artificial methods of control must be resorted to.

Control. — Numerous methods of control have been tested, with vary¬
ing degrees of success. Destruction of the adult bugs while wintering,
has proved to be an efficient treatment when conditions are such as to
make it reasonably complete. Burning over fields where the bugs are

THE IIEMIPTERA

177

hidden in the grass has destroyed from about 50 to 75 per cent of them
in cases where counts of the bugs could be made, including as well, how¬
ever, areas covered with weeds, fallen leaves and other rubbish. The
difficulty with this treatment is to get weather conditions such that the
burning can be well done and without injury to the grass. Where
thickets, hedges and other excellent hibernating places which cannot be
burned out are plenty, this treatment, while of value for the bugs in the
areas where this method can be used, will of course fail to reach those in
the other locations and thus leave many to appear in the spring.

Where Chinch Bugs leave one field for another, an old practice
has been to plow a furrow across their line of march and dig an occasional
hole in the furrow into which the bugs, diverted from their first direction
of march, might fall and be destroyed with oil or other material. Bands
of tar or of road oil across their line of march have also been used with
some success, the difficulty with this plan being in most cases that the
band must be placed on firm, hard ground or it will soak in and need
frequent renewal, besides forming (with some materials) a surface film
on which the bugs can cross.

Crude creosote similarly applied, has recently been found to work
well. Though it soaks into the ground it appears to repel by its odor,
and the bugs reaching the band turn away from it. Renewal is necessary
only when the odor becomes so slight that it no longer acts as a repellent.
In 1914 the average cost for material of maintaining a mile of this band
during the migrating period of the bugs was only $16.50 at the then
prevailing price of the creosote.

When the Chinch Bugs are entering fields (usually corn) at this
season, spraying the plants with kerosene emulsion, Nicotine sulfate
40 per cent and soap solutions has been tested. The former is liable
to injure the plants if great care is not given to its application, but the
tobacco extracts have proved satisfactory. Soap alone, used at the
rate of 3 oz. per gallon of water has given excellent results, and while
the Nicotine sulfate, using Y^ fl. oz. in 1 gal. of water in which Y oz.
of soap has been dissolved, may be the most effective, soap alone is
likely to prove very satisfactory and is less costly. As the bugs enter
corn fields from elsewhere, the spray need be applied only to the outer
rows if the invasion is observed in time.

The advice has also been given to cease planting corn in years
when the Chinch Bugs are liable to be abundant, raising instead
cowpeas, buckwheat, stock beets or soy beans, on which the bugs do
not feed.

In the case of the short-winged form there is little migration, and
plowing and the rotation of crops where the insects appear, seems to be
about the only treatment available, and probably all that will
be necessary.

12

178

APPLIED ENTOMOLOGY

That insects like other animals suffer from the attacks of various
diseases, is perhaps not generally realized. Yet the list of these diseases
is not a small one and our knowledge of them is still extremely limited.
Some of them are caused by bacteria and are just as truly germ diseases
as are those from which man suffers. Others are caused by parasitic
plants which in one way or another enter the body of the insect and grow,
consuming the nourishment they find there and finally kill the animal,
usually making its body hard and firm, or “mummifying” it. A third
type of disease is that known as the “wilt disease,” in which neither
bacteria nor fungi have been discovered, where the insect “wilts” after a
time, becomes soft, and gradually decays. The producing cause of this
class of diseases is still unknown, but they are infectious, spreading from
one individual to another, and where the insects are abundant and
weather conditions are favorable they cause a high mortality.

Attempts have been made to utilize diseases for the control of insect
pests. The Chinch Bug has been the subject of one of the most thorough
of these experiments, the fungus already referred to having been cul¬
tivated for the purpose. It was found that by the use of appropriate
methods, cultures of the fungus obtained in the fall could be grown
during the winter, and bugs inoculated with it in the spring could be sent
out to fields where the insects were abundant, and liberated there to
spread the disease. To some extent this was a success, but it was soon
found that if the inoculated bugs were set free during dry weather the
disease failed to spread rapidly enough to prevent great injury, while if
the weather was wet the fungus was in most cases already present and
the addition of more diseased bugs at best only hastened its spread
somewhat. As a business proposition then, the artificial cultivation
and distribution of the fungus has been given up.

In the case of a bacterial disease of grasshoppers which has at times
been observed greatly to reduce the numbers of this insect, somewhat
similar results have been obtained. In a few instances some degree
of success has been secured by spreading the germs, but here the factor
of cannibalism seems to enter into the problem. With species of grass¬
hoppers which feed considerably on dead or dying individuals, there is
some probability of successful treatment in this way, but such species
are not numerous, and there also appears to be more or less immunity
to the germ in some species.

The whole problem of control by disease appears to hinge on satis¬
factory answers to three questions: Can the disease be cultivated so
that a supply can be obtained and continued? Can it be introduced
successfully into regions where it is needed but not present? Will the
disease establish itself there and become effective?

The answers to the first two of these questions are liable to be affirma¬
tive ones, though this is not always the case. The third is the most

THE II EMITTER A

179

difficult to determine. It may be that the disease is not already present
where it is desired to introduce it because conditions there are such that
it will not thrive. Fungous diseases at least are influenced to a very
large degree by the weather, most of them thriving best in warm, moist
weather and if these conditions are not present they will amount to little.

At the present time it would appear that the success of artificially
introducing diseases to control insect attacks is so dependent upon
weather conditions that man can do little more than supply the disease
and trust that the needed kind of weather may follow. Unfortunately
the very conditions under which injurious abundance of the insect takes
place, appears in too many instances to be those distinctly unfavorable
to the spread of the disease.

Family Tingididae. — The insects (Fig. 107) of this family are delicate
little bugs, usually having the pronotum broadly expanded and, with the

L.

Fig. 167. — Example of a Tingidid Bug (Gargaphia solani Heid.), enlarged about ten times
{From, U. S. D. .4. Farm. Bull. 856.)

hemielytra, covered with reticulated marks, giving them something the
appearance of a bit of lace and this has been responsible for their com¬
mon name — lace-bugs. They are rarely more than an eighth of an inch
long, usually whitish in color, and suck the sap from various plants,
being generally found on the under side of the leaves. Their eggs are
placed on the leaves, generally at the tops of small, brown, rather conical
projections produced by the bugs, and which somewhat resemble places

180

APPLIED ENTOMOLOGY

where fungi project from the leaf surface. Several species are occasion¬
ally rather injurious.

Family Miridae. — This family until recently was called the Capsidse.
It contains a very large number of species, perhaps more than any other
family of bugs, all small, and all feeding on plant juices. Some feed on
grass; others on succulent stems; some make a specialty, at least at cer¬
tain seasons, of sucking the sap from leaf and flower buds, distorting
them or even preventing their development. Sometimes they are
present in great numbers and do much injury. Fruit is attacked by some
species, while it is small and rapidly growing, and such attacks produce
“dimples” or small depressed areas, or they may even deform and thus
greatly reduce the value of the fruit. Many secondary and potential
pests belong in this family.

Some of the adults are bright red; others red and black, yellow and
black or other colors. In those feeding on grass, grayish-yellow or
greenish-yellow is a frequent color. In many cases
it seems that this is in some way connected with the
color of their food, as for example, some species
found on the stems of the red dogwood are them¬
selves largely red, though in other cases it is difficult
to discover any such correspondence of color between
the insect and its food plant.

The Meadow Plant-bug ( Miris dolobratus L.). —
This is apparently a species introduced from Europe
about a hundred years ago and now found over the
eastern United States and as far west and south as
Minnesota and Kentucky. It attacks cultivated
grasses and is often extremely abundant. The adult
(Fig. 168) is a rather slender bug about two-fifths
of an inch long, with quite narrow wings. It is
yellowish-gray with darker markings and has long, black

Fig. 168. — Meadow
Plant-bug ( M iris
dolobratus L.), nearly
twice natural size.
{Original.)

gray or
antennae.

The eggs are laid in late summer and fall in grass stems, for the most
part below the cutting level. They hatch the following spring and
the nymphs feed on the sap of the plant stems for a little over a month
before becoming adult. Many of the adults have short wings, a similar
condition to that found in the chinch bug, but here the two forms mingle
everywhere, though the short-wingecl individuals may make up as much
as 90 per cent of the total number.

Control. — Wintering in the egg stage in grass stems suggests the
possibility of destroying many of the insects by burning over grass fields
and particularly places where the grass was not cut, during the winter
season. Early and close cutting of the fields might leave the insects
little to feed on. Fall pasturing of the fields and the cultivation of sod

THE HEMIPTERA

181

land found heavily infested may be of assistance, but so far, little or
nothing has been done to combat this pest.

The Tarnished Plant-bug ( Lygus pratensis L.). — The Tarnished Plant-
bug is widely distributed, both in Europe and this country. It is about
a quarter of an inch long (Fig. 169), shorter and broader in proportion than
the Meadow Plant-bug, and varies greatly in its coloration. The general
color, however, is brown, variegated with shades of yellowish and brown¬
ish and with black spots in some places.

This pest feeds on over 50 different kinds of plants which are
of value to man. The adults attack apple, pear, peach, and in fact all
fruit tree buds, destroying or at least
seriously injuring them: small fruits
are often stunted or “buttoned” by
them: flower buds of such plants as
the chrysanthemum, dahlia, peony
and aster are punctured and de¬
stroyed or malformed: potato leaves
are often injured, causing tip-burn,
and beets, particularly sugar beets,
have their leaves curled and injured.

Corn, wheat, oats and other grain
and grass crops are also injured by
this omnivorous feeder. With young
peach trees in nurseries it causes the
trouble called “stop-back” by killing the terminal buds, and it is a
carrier of the fire-blight of the pear, conveying the bacteria causing this
disease from infected to healthy trees. It is therefore a serious pest.

The insect passes the winter as the adult and possibly as the nearly
full-grown nymph also, in protected places, and appears with the first
warm spring days and attacks the buds of fruit trees and other plants.
Its eggs are inserted in leaf veins and stems, flowers and similar places,
and they hatch in about 10 days. The nymphs feed on the juices of the
plants and become adult in from 3 weeks to a month. There is therefore,
time for several generations in a season, though the actual number of these
does not appear to have been worked out and probably varies somewhat
according to the length of the season in different parts of the country.

Control. — No effective method of control has as yet been discovered
for this pest, though many have been tried. Spraying the plants infested,
with kerosene emulsion, Nicotine sulfate or soaps, early in the morning
has been found to kill some of them. Shields covered with sticky fly¬
paper, placed beside and over the plants which are then jarred, captures
some: the destruction of all wild plants such as asters and goldenrod on
which they feed and breed has been advocated; and growing plants under
cheese-cloth; driving the insects down the wind, and other methods have
been suggested, but no really efficient control is yet known.

Fig. 169.- — Tarnished PI ant- bug
C Lygus pratensis L.) : a, adult; b , nearly
full-grown nymph. Nearly four times
natural size. ( From U. S. D. A. Farm.
Bull. 856.)

182

APPLIED ENTOMOLOGY

Family Phymatidae. — The Ambush-bugs (Fig. 170) as members of
this family are called are carnivorous bugs which usually hide in blossoms
to capture insects visiting there. They are rather short and stout,
generally less than half an inch long, and have colors so combined on t heir
bodies as to render them very inconspicuous in the flowers. Their prey is
generally any insect they can grasp with their stout fore legs, whether
it be injurious or otherwise.

Fig. 170. Fig. 171.

Fig. 170. — Ambush-bug ( Phymata erosa woljffii Stab): a, from above; b, from the side,
showing the grasping front leg. Enlarged: true length shown by hair line. ( Modified
from Sanderson and Jackson, Elementary Entomology, after Riley, U. S. D. A.)

Fig. 171. — Reduviid Bug, about natural size. {Original.)

Family Reduviidae. — This large family consists of carnivorous insects
some of which are small while others are considerably more than an inch
long (Fig. 171). Though generally feeding on the blood of other insects
they may occasionally attack man and in such cases produce rather
painful wounds. One species, most common in the Southern States,
often enters houses and feeds upon the bedbug, and from this habit has
been called the Masked Bedbug Hunter, the mask referring to dust which
adheres to its rather sticky body before it becomes adult. Another
species in the West and South is occasionally found in beds where it
imitates the habits of the true bedbug. A similar but different species
occurs in California.

The group as a whole, preying as its members do upon other insects
almost entirely, must be regarded as a beneficial one. The family is
most abundant in the warmer climates.

Family Cimicidae. — The Cimicidse is a very small group but well
known through one of its members, the Bedbug. All of the insects
belonging here are small, rather oval in outline, very flat, and rather
reddish in color. Birds, poultry and bats are attacked by species similar
to but smaller than the Bedbug and some of these under unusual condi¬
tions, may enter houses and attack man.

The Bedbug ( Cimex lectularius L.). — This universally distributed
and well-known pest (Fig. 172) appears to have originated in Asia and
has now spread wherever man is found. It is a small, flat insect, reddish-
brown in color, about a fifth of an inch long when adult, and wingless,

THE HEMIPTERA

183

only tiny stubs of wings remaining to show that it has been derived
from winged ancestors. It produces a very noticeable odor.

It is a nocturnal animal, hiding during the day in any cracks and
crevices it may find, either in the bedstead, behind loose wall paper or
elsewhere. In these places it lays its eggs, probably about 200 in num¬
ber, these hatching in from a week to a much longer period dependent
upon the temperature. The nymphs are yellowish-white at first, turning
brown gradually with increasing age. Nymphal life varies greatly in its
length, being affected by the temperature
and food supply, but when these are favor¬
able, about 7 weeks is required to produce the
adult bug. Under less favoring circumstances
the nymphs may remain unchanged but alive,
for a long period. The number of genera¬
tions in a year may therefore differ greatly
under different conditions but in warmed
houses there are probably at least four.

Where human blood is not obtainable for
food, that of mice, rats or other animals
where available, may be taken instead, and
living bedbugs in empty houses may perhaps
be accounted for in this way. Without food,
however, death within a year is a practical
certainty.

The “bite” of the bedbug is quite poison¬
ous to some persons but not to others and in

some cases a sort of immunity is obtained by individuals continuously
exposed to attacks.

Bedbugs are known to be carriers of contagious diseases of man, such
as the African relapsing, fever, Kala-azar, plague, and possibly leprosy
also, but of course the insect must first become itself infected with the
causal agent of the disease which is very rarely the case, at least in
the United States. It does not appear to transmit the diseases except
as the agents of them by accident get on the mouth parts of the insect.

Control. — Where sulfur can be burned in a room, using a pound lor
each 1,000 cu. ft. of space for 24 hr. the fumes will destroy all stages of the
bedbug if t he room is reasonably tight. A thorough treatment ol all places

Fig. 172. — Adult female
Bedbug ( Cimex lectularius L.)
gorged with blood. Greatly
enlarged. ( From U. S. D. A.
Farm. Bull. 754.)

where the insects can hide and lay their eggs, with gasoline, benzine or
kerosene is also successful if the material penetrates all parts of the cracks.
Corrosive sublimate at least as strong as a 6 per cent water solution, can
be used in the same way. Heating a room or house to from 120 to 130CT .
in summer for an hour or even less has proved effective, as has a tempera¬
ture below 32°F. continued for 3 or 4 weeks. Persons obliged to stop at
infested places can usually obtain protection by dusting insect powder
(Pyrethrum) bet ween the sheets of the bed.

184

APPLIED ENTOMOLOGY

Family Gerridse. — These insects, the Water Skaters or Water Striders
(Fig. 173) as they are commonly called, are often noticed during the
summer, skating over the surface of quiet pools of water. Their bodies
are slender in most cases, less than half an inch long, usually black or
brown, and their long, slender legs project some distance from the body.
A few are shorter and broader bodied. They feed on any small insects
they are able to capture and winter
either under sticks or stones under
water, or in mud near the edge, under
leaves and rubbish. A few live on
the surface of the ocean in warm
climates. They are interesting insects
to watch but are of little if any
economic importance.

Family Notonectidae. — The Back-
swimmers (Fig. 174) as they are
termed, live in fresh water. They

Fig. 173. Fig. 174.

Fig. 173. — Water Skater ( Gerris conformis Uhl.) about natural size. {Original.)

Fig. 174. — Notonectids and Corixid: A, Notonectid at the surface of the water
showing under surface; A', swimming showing upper surface; B, Corixid swimming.
Somewhat enlarged. {From. Linville and Kelly , Text-book in General Zoology.)

are small, rarely more than half an inch in length and generally black
and cream-colored. The back has sloping sides something like the
bottom of a boat and they swim on their backs, propelling themselves
by their long legs which are fringed with hairs. They occasionally
come to the surface for air, a supply of which they carry down with
them under their wings and between the fine hairs covering the under
side of the body. They are carnivorous, feeding on other small insects
but are of little importance.

Family Corixidae. — Living in the same places and with similar habits
to the Back-swimmers are small, greenish and blackish mottled insects,
rather oval in outline with heads somewhat flattened in front, and known
as Water-boatmen (Fig. 174B). They have long, fringed, oar-like legs
but do not swim on their backs and in some way are able to remain under
water without coming up for air for a much longer time than the back-

THE HEMIPTERA

185

swimmers. Like the latter group they often leave the water and fly at
night and are frequently attracted to lights.

Family Nepidae. — The water-scorpions as these insects are called,
live in fresh-water ponds and pools. Two types of form are included,

Fig. 176.

Fig. 175. — Water-scorpion (Ranatra americana Montd.) about natural size. ( Original .)
Fig. 176. — Giant Water- bug ( Lethocerus americanus Leidy), natural size. (Original.)

one having a long, slender body and long legs (Fig. 175), the front pair of
which, unusually long, are constructed for grasping their prey which
consists of small insects. In the other type the body is short, rather broad,
and flat. In both a long tube consisting of two pieces which can be pressed
together to form the tube, joins the hinder end of the
body and while the insect is an inch under water in .
some cases, this tube is pointed upward until its tip
is out of water and through it the insect obtains air.

The slender forms lying quiet on the bottom of pools
resemble dead twigs and thus obtain the concealment
needed to enable them to get within reach of their
food.

Family Belostomidas. — These insects are gen¬
erally termed the giant water-bugs. Some of them
are the largest members of the Hemiptera, being
two, three or more inches long, broad, flat and brown
in color (Fig. 176). They live in fresh water and
feed on insects and even small fish and are thus
sometimes injurious in the production of food fishes. They fly by
night and are frequently attracted to electric lights, which has led to
the larger species being sometimes called “electric-light bugs.” In some
of the smaller species (Fig. 177) the eggs are laid on the back of the male
who is thus obliged to carry them around until they hatch.

Fig. 177 . — M a 1 e
Belostomid ( Belostoma
flumineum Say) carry¬
ing eggs on its back.
Natural size. (Orig¬
inal.)

CHAPTER XXVI

THE HOMOPTERA

The Homoptera is a large group containing insects of many forms,
often showing little resemblance to one another. They suck sap from
plants through a beak, apparently very similar in structure to that al¬
ready described for the Hemiptera, but it is attached, not to the front but
to the hinder part of the under surface of the head which is very closely
joined to the prothorax so that the beak frequently appears to arise
between the front legs. In some instances where the adults do not feed,
this structure is lacking. The wings are often absent but when present
are usually held, while at rest, sloping over the body like a house roof.
They are of the same thickness and usually, though not always, trans¬
parent. In this group (except the male scale insects) the metamorphosis
is incomplete. These facts may be summarized as follows:

The Homoptera are sucking insects with the beak ( when present ) arising
from the back part of the under side of the head which is very closely joined
to the prothorax. The wings ( frequently absent ) are of uniform thickness
throughout and when not in use are held sloping over the body. The meta¬
morphosis ( except in male scale insects) is incomplete.

Few groups of insects show as great differences in their members as are
found here. The cicadas, often two or three inches in length and with a
wing spread of four inches or more, are among the giants of the order,
while some of the white flies and scale insects are hardly more than
just visible to the eye. Most of the group move about freely, though
some locate in one place soon after they hatch and remain there
the rest of their lives. In one section the insect produces a protec¬
tive scale which covers it, and beneath this, degeneration of some
parts of the body occurs.

Many Homoptera secrete a sweet, sticky fluid called honey-dew,
often in such quantities when the insects are in abundance, that in falling
it makes a noise like fine rain. Striking on leaves, fruit or bark, it adheres
and dries, and a blackish fungus grows in it, giving to such places a sooty
appearance. This secretion appears to be produced most abundantly by
the soft scales, white flies, plant lice, jumping plant lice and some of
the tree hoppers. Ants and honey bees feed on the honey-dew and
frequently visit the insects producing it, for this food.

Nine families of Homoptera are generally recognized, but four of

1S6

TIIE HOMOPTERA

187

these may, for convenience, be combined here. The six to be considered
therefore are:

Order Homoptera

Cicadas (Cicadidse).

Leaf Hoppers and Tree Hoppers (four families).
Jumping Plant Lice (Chermidae).

Plant Lice (Aphididae).

White Flies (Aleyrodidae).

Scale Insects (Coccidae).

Family Cicadidae (The Cicadas). — Most of the members of this family
are rather large insects, with bodies often two or three inches or even
more in length and quite stout as well. Their wings are correspondingly
large, and in some species have a spread of more than six inches. Though
usually transparent and with prominent veins they sometimes have
pigmented areas of various colors.

The adults place their eggs in slits they make with their ovipositors
in twigs. On hatching the nymphs drop to the ground and make their
way to the roots where they feed on the sap. Metamorphosis is more
nearly a complete one than in the other families of Homoptera (except
the scales), the nymph having but little resemblance to the adult, and the
last two nymphal stages are rather transitional in appearance between the
two.

The adult males have vocal organs located on the under side of the
basal segments of the abdomen and covered by extensions backward of
the metathorax. The sound produced is often so loud, especially when
the insects are abundant, as to be very noticeable and even unpleasant.
No auditory organ has as yet been discovered with certainty, in either

sex.

Cicadas are particularly inhabitants of warm countries, though some
species are abundant quite far from these regions. In North America
they occur in Canada and probably in
all the States farther south, and are
found as far north as England in the
Old World. They are often wrongly
called locusts.

The Periodical Cicada or Seventeen-
year Locust ( Tibicina septendecim Say).

— This remarkable insect is a native of
North America. It is found from Mass¬
achusetts to Northern Florida and west
to Wisconsin, Iowa, Kansas, Oklahoma
and Texas, but is much less important near its northern limits than near
the center of its range.

The adult (Fig. 178) is about an inch long, with a stout, black body,
orange eyes, legs and wing veins. The wings when at rest extend consicl-

Fig. 178. — Adult Periodical Cicada
{Tibicina septendecim L.), natural size.
{Original.)

188

APPLIED ENTOMOLOGY

erably behind the body. In the far South it appears early in May while
near its northern limits it may be as late as early June. The insects are
usually in evidence for 5 or 6 weeks and are particularly noticeable in and
near wooded areas. They suck the sap from various trees but do little
injury in this way. The females lay their eggs in the smaller twigs of
trees, shrubs and even in herbaceous plants, the oak and hickory, and in
the case of fruit trees the apple seeming to be preferred for this purpose,
though more than 75 kinds are attacked. The eggs are placed in slits
made in rows by the ovipositor and a twig thus punctured is liable to
break off either entirely or in part. The eggs hatch in 6 or 7 weeks and
the nymphs drop to the ground and burrow to the roots where they feed
until the seventeenth spring from the one when they entered the ground,
most of them being between six and eighteen inches below the surface.

During the seventeenth spring the nymphs burrow upward, nearly to
the surface of the ground but do not usually come out until ready for the
final molt producing the adult. In some cases, however, upon reaching
the surface they construct earthen cones or chimneys sometimes six or eight
inches high, within which the burrow is continued. It is supposed that
these are constructed where the cicadas are in moist places and these
structures will bring the insects out above the moisture, or that a shallow
soil enables them to reach the surface before the normal time, or unusu¬
ally warm conditions hasten their start, and on their arrival they are
not ready for their final molt. Recent work indicates that length of
day is a factor. Probably the last word on this subject has not yet
been said.

Arrived at the surface of the ground and ready to molt for the last
time the nymphs crawl out of their burrows, the greater number of them
in the afternoon and evening, and make their way to any objects such as
a tree, stick or anything at hand, and on these molt for the last time and
become the adults which are ready for flight the next morning.

In the course of nearly 17 years of underground feeding it is only natu¬
ral that some finding an abundant food supply should be able to gain a
little time and appear during the sixteenth year as “forerunners” of the
main brood, and that others with scanty food should be delayed until the
eighteenth season. These are few in number, however. In the South
is a race with a 13-year life, the origin of which as related to the other
race is not as yet explained.

Though a cicada’s life is (except for the race just mentioned) 17
years, they occur in one place or another every year, showing that in
some way in the past these insects have diverged so that there are now
17 broods. Some places are so unfortunate as to have several of these
broods but though the cicada may appear there every 4 or 5 years, the
descendants of any one of these will not be found until 17 years have
elapsed.

THE HOMOPTERA

189

Some of the broods are more abundant and widely distributed than
others. Four are of sufficient importance to be mentioned. These are
Brood II, due in 1928 from Connecticut into North Carolina and at a few
scattered points to the west; the insects are quite abundant: Brood VI,
due in 1933, widely scattered over the country but not very abundant :
Brood X, due in 1936 from New York to Georgia and west to Michigan
and Illinois and at scattered points elsewhere, this being the most abun¬
dant brood: and Brood XIV, due in 1923, from Massachusetts to Georgia
and west to Illinois; also an abundant brood. The important thirteen-
year broods are: XIX, due in 1924, from Iowa to Louisiana and eastward
to the Carolinas and Virginia, the largest of these broods : and Brood XXIII,
due 1928, from Missouri, Illinois and Indiana down the Mississippi Valley
with scattered colonies here and there to the east as far as Georgia.
This is also a large brood.

Numerous enemies of the Periodical Cicada are known, many of them
being parasites. Some birds feed on them and a fungus causes disease
of the adults. Various mammals feed on them as they are coming out of
the ground.

Control. — In forests nothing can be done to control these insects,
but when they appear in sufficient numbers in parks and orchards to
make treatment desirable, certain methods for preventing injury or for
the destruction of the insects are feasible. In some cases collection
of the adults by hand has paid. In others, spraying the tree-trunks
and other objects on which they rest while molting after leaving the
ground, aiming to hit as many of the insects as possible, and using a
strong kerosene emulsion for the spray material has proved quite effec¬
tive, for where the cicadas are not killed they are crippled by the action of
the particles of the spray which strike them. This treatment, however, to
be successful must be repeated every evening about sunset or very early
in the morning before the insects begin to fly, as long as they continue
to come out of the ground. .

In the case of fruit trees anywhere, pruning is not advisable the spring
cicadas are due in that locality, until after the eggs are laid. Then,
pruning and burning the punctured twigs before the eggs hatch is desirable.
In some cases young trees suffer so severely that it is not advisable to
set out nursery stock the year before cicadas are due. Apple “whips”
however, can usually be safely planted the same spring that the cicadas
come, being generally too small to suffer much by the attacks of these
insects. Hogs allowed to run under trees known to have cicadas at
their roots will kill many of these pests as they come to the surface to
become adult in May and June of their seventeenth year.

Various species of cicadas are common in nearly all parts of the United
States. In the East the Dog-day Harvest-flies ( Tibicen linnei Sm. &
Grsb., and others) are often noticeable (Fig. 179), singing in the trees

190

APPLIED ENTOMOLOGY

during late July and August. Most of these species are somewhat larger
than the Periodical Cicada and generally black and olive-green, with a
white powder or “bloom” on the under side of the body. They are
supposed to have about a 2-year life history and as individuals occur
every year, two distinct broods. A few of these species greatly resemble
the Seventeen-year Cicada in color but are smaller, and as they appear
more than a month after the latter have disappeared, no confusion should
lead to the belief that the Seventeen-year Cicada has appeared at that
season.

Fig. 179. Fig. 180.

Fig. 179. — Adult Dog-day Cicada ( Tibicen linnei Sm. and Grsb.), natural size.
{Original.)

Fig. 180. — Tree-hoppers showing remarkable forms of the pronotum. Enlarged
about twice. {Original.)

Leafhoppers and Treehoppers. — The four or more families included
under this heading contain a large number of kinds of insects, many of
which are extremely numerous. Among them are the lantern-flies of South
America arid the candle-flies of China and India which are quite large insects,
a number of which at least are luminous. Some of the insects here in¬
cluded are highly colored and some secrete quantities of wax which is often
used for candles and other purposes.

In one of the families — the Treehoppers — the pronotum is largely and often
remarkably developed, sometimes giving these insects a very grotesque appear¬
ance. In this country, however, such forms are not usual, the development of
this section of the body being mainly in the line of horns or humps and the
enlargement of this plate in width or height and in its extension backward until it
covers most or all of the body (Fig. 180). The Treehoppers of the United States
are all small insects, less than half an inch long, and as they sit on twigs their
peculiar forms seem to give them resemblances to buds, swellings or other charac¬
ters, which suggests that their odd outlines may be for resemblance to these
structures and thus secure the protection from their enemies which this would
give.

In general the Treehoppers puncture the twigs of plants and are injurious,
though only a few kinds are ever so abundant and attack plants of such impor¬
tance as to need consideration.

Among these the most common is the Buffalo Treehopper ( Ceresa bubalus
Fab., Fig. 181) found practically everywhere in the United States except perhaps

THE HOMOPTERA

191

in the most southerly portions, which injures the twigs of fruit trees by its egg
punctures made in the fall. Two rows of punctures are made', nearly parallel to
each other, the two rather resembling parenthesis marks,
and in each a number of eggs is laid which hatch the follow¬
ing spring. Injury caused by the feeding of the nymphs and
adults is slight, and in fact most of the young feed mainly
on weeds, but the egg punctures (Fig. 182) cause distorted
growth and weaken the twig. Spraying with a fairly strong
contact insecticide to destroy the nymphs wherever these
are found, and the destruction of all weeds like burdock,
thistles, etc., near the fruit trees appear to be the only
methods of control, and the former is rarely practicable.

The Leaf hoppers (Fig. 183) are extremely abun¬
dant insects and some of them must do much injury
to the grass crop as it has been estimated that there
are frequently as many as one to two millions of them per acre. Most
of them are very small.

Some leafhoppers have one generation a year, others more, and

different species appear to hibernate in
different stages. In addition to various
grasses, grain, alfalfa, clover, sugar beets,
grape, and rose, the apple, elm, willow
and other trees have their juices ex¬
tracted by the feeding of these insects.

A group of tiny leafhoppers known as
froghoppers or spittle insects (See Fig. 183)
is also included here. They are common on
grasses and other herbaceous plants and also
on some trees such as the pine, etc. The
nymphs produce a fluid and liberate air in
this in such a way as to form a sort of froth or “spittle” in which they
live. They are very abundant in the northern states practically across
the entire continent, and one species, the Grass-feeding Froghopper
( Philcemis lineatus L.) is often so common as to wet the shoes of a person who
walks through the grass in June. The nymphs suck the sap from the grass stems,
withering and turning white the upper parts of the stems and the blossoms, much
as does the grass thrips. Burning over old grass fields where these insects are
most abundant, in early spring will destroy many of these insects in their winter
quarters close to the ground.

The Apple Leafhoppers ( Empoasca mali Le B. and others), tiny insects
about a twelfth of an inch long, attack over fifty different kinds of
plants being generally most abundant on the apple, Norway maple,
and some kinds of oaks among the list of trees, and on alfalfa, clover,
potato and beets. They appear to occur in almost every part of the
United States and in some sections of Canada. The adults are
generally pale green with white markings on the pronotum. Other
similar insects are often present along with these species, but treatment
for all would be identical,

Fig. 183.- — Three kinds of Leaf¬
hoppers enlarged about twice. The
left hand figure is of a “spittle in¬
sect.” ( Original .)

Fig. 181. — Adult
Buffalo Tree-hopper;
view from above.
Enlarged about
twice. {Original.)

192

APPLIED ENTOMOLOGY

The apple leafhoppers winter as the adults under rubbish and in spring
after mating the eggs are laid in the veins of the leaves. Some observers
claim that at least a part of the nymphs in spring hatch from eggs laid
in apple bark in the fall. The eggs hatch in about a week and the nymphs
feed for about 3 weeks, and the adults of these nymphs lay eggs for
another generation. In the middle Atlantic States there are three
generations each year, but this number may be reduced near the northern
limits of their range or increased farther south.

Fig. 182. — Twigs showing injuries caused by the Buffalo Tree-hopper in laying its eggs.

About natural size. ( From Britton , Fifteenth Kept. Conn. Agr. Exp. Sta. 1915.)

The injury caused by these insects appears to be a curling and check¬
ing of the growth of the leaves in some cases, particularly those near the
tips of the shoots in the case of young apple trees. Older trees suffer
less than nursery stock.

Control. — Spraying thoroughly with nicotine sulfate 40 per cent,
1 part in 1,400 or 1,500 parts of water, with the addition of soap, is a
successful treatment to use for these insects if applied soon after the
nymphs appear in the spring, or at least before the leaves have curled.
Good results have also been obtained by dipping nursery stock in a

THE HOMOPTERA

193

solution of whale-oil soap 1 lb. in 8 gal. of water, or dissolving a bar of
common laundry soap in 6 to 8 gal. of water for the purpose.

The Rose Leafhopper (E?npoa rosce L.). — This European insect is now
present practically everywhere in the United States and is also found
in Nova Scotia, Ontario and British Columbia. It is a general feeder
and will probably attack most plants of the family Rosace®, but appears
to be particularly injurious to the rose and apple. The adult is almost
as large as the apple leafhopper and is creamy white to light yellow. It
lays its eggs during the fall in the bark of rose bushes, apple trees, berry
canes and other plants and there they remain until spring, when they
hatch. The nymphs suck the sap from the under side of the leaves of
the plants, producing a mottled appearance, and as the injury increases
the leaves may turn yellow and dry up, but they do not curl. There
are two generations of this insect a year, the eggs for the second genera¬
tion being laid in July. Most of the wintering eggs are deposited in rose
stems.

Control. — This insect is rarely of importance as an apple pest but
rose bushes often suffer by the loss of sap and the impossibility of their
injured leaves performing their proper functions. Spraying infested
plants with nicotine sulfate as for the apple leafhoppers, as soon as the
nymphs are observed, is usually sufficient to prevent further injury.

Many other leafhoppers are at times serious pests. The beet leaf¬
hopper in the Western States in addition to its injury to the plants by
feeding, transmits a “curly leaf disease” and the grape leafhopper is
sometimes so abundant that grape leaves in vineyards are turned brown
and much injured. The six-spotted leafhopper attacks some grains and
grasses, and other species generally of slight importance, at times assume
prominence. In general, nicotine sulfate prepared as indicated above,
is an effective control material for these insects wherever conditions
permit its use.

Family Chermidae. — The Jumping Plant-lice as the members of this family
are usually called, are very small insects which feed on various plants but are
rarely abundant enough to become of economic importance. One exception
to this occurs and a consideration of that species will also give something of a
general idea of the insects of the group as a whole.

The Pear Psylla ( Psyllia pyricola Forst.). — The Pear Psylla is a European
pear pest which seems to have reached this country about 1832 and is now
present everywhere in the eastern United States at least as far south as Virginia
and west to the Mississippi River, and has also been reported (perhaps errone¬
ously) from California. Where it is abundant it is very injurious, seriously
checking the growth of the tree, so that many of the leaves turn yellow and drop
off, as does much of the young fruit, while the entire vitality of the tree is reduced
and it makes little or no growth.

The adult (Fig. 184) is about a tenth of an inch long, the body black with
reddish markings, and long antenn® are present. Except for this last feature

13

194

APPLIED ENTOMOLOGY

it greatly resembles a tiny cicada. The insects pass the winter as adults hiding
in crevices of the bark or similar protected places and in spring lay their eggs
on the twigs, and particularly around the bases of the buds. These eggs hatch
in from 2 to 3 weeks according to the temperature. The nymphs (Fig.
185) suck the sap from the axils of the leaves and fruit stems and if abundant
gather around the bases of leaves and fruit stems and spread to the under surface
of the leaves themselves. They move about but little and secrete large amounts
of honey-dew, sometimes so much when they are very numerous, as to cover
the leaves and branches. They are broadly oval, flat creatures, yellowish at
first but blackish with reddish marks later and with bright red eyes. They
become adult in about a month and lay their eggs, this time on the under side
of the leaves or on the leaf petioles. These eggs hatch in a week to 10 days and
adults are produced in about a month. There are three or four generations a
year in New England and more in the South.

Fig. 185'.

Fig. 184.

Fig. 184. — Adult Pear Psylla ( Psyllia pyricola Forst.) about ten times natural size.
( From Britton , Third Rept. Ent. Conn. Agr. Exp. Sta. 1903, after Slingerland.)

Fig. 185. — Nymph of Pear Psylla, greatly enlarged. ( From Britton, Third Rept. Ent.
Conn. Agr. Exp. Sta. 1903, after Slingerland.)

Control. — Methods for checking the injuries caused by these insects center
around their control in winter and early spring. Most of the adults winter
under the loose bark of the trees or in tufts of grass and rubbish near the trees.
Scraping off all loose bark and removal of the rubbish, followed during any
warm days in November or December by a thorough spraying of these places
with nicotine sulfate, standard formula, will kill large numbers. It should not
be cold enough for the spray to freeze on the trees. In spring, just as the clusters
of blossom buds begin to separate from each other, but before the blossoms
open, the lime-sulfur wash diluted at the rate of 1 part of the wash to 8 or 9
parts of water will kill the eggs and any newly-hatched nymphs. The fruit
spurs and the under sides of the twigs should receive particular attention with
this treatment.

Family Aphididse (Plant Lice or Aphids). — This is one of the most
important groups of insects from an economic standpoint, as all its mem¬
bers are injurious, often very abundant, and a species usually doing little
harm may at any time become a serious pest.

THE HOMOPTERA

195

Aphids arc tiny, soft bodied insects, the largest being less than a third
of an inch long, generally with long legs and antennae, and are of various
colors, green, black, various shades of red and brown, white and gray
being the most usual ones. Some are more or less completely concealed
(Fig. 186) beneath long, white waxy threads, giving them a “woolly”

1 iu. 1SG. Alder twig covered by woolly plant lice, the “wool” entirely concealing their
bodies. Somewhat enlarged. ( Original .)

appeal ance, others have a sort of dust or “bloom” like that on a plum,
coating their bodies; but the majority (Fig. 187) are without any covering.
Many species of aphids have a pair of tubes called cornicles, projecting
upward from the top of the abdomen. These were formerly believed to

I io. 187. Portion of leaf showing plant lice clustered together. Somewhat enlarged.

{Original.)

be the exit ducts through which honey dew, abundantly produced by the
insects, escapes, but it is now known that this substance is expelled
through the anus, often in such quantities that when the insects are abun¬
dant it forms a sort of fine rain which can be heard falling on the leaves

196

A PPL1ED EN TOMOLOG Y

and ground. This fluid which is sweet and sticky is eagerly fed upon by
ants. Falling on twigs and leaves it dries there and a fungus grows in it
turning it black, and plants where aphids have been abundant often show
this by their black appearance. Some plant lice produce galls within
which they live for at least a part of their lives but most of them are not
thus enclosed, living on leaves, twigs, succulent plant stems or roots.

Though there are great variations in the life histories of different
aphids, certain general facts hold for most of the group. In general, eggs
are laid in the fall, on a food plant of the species concerned, and these
hatch the following spring. The nymphs soon become full-grown and are
known as “stem-mothers” and without fertilization (there are no males)
produce eggs, or in most cases living young which like the stem-mother
are all females and on reaching maturity produce young in a similar way.
The production of young without fertilization of the parent is not uncom¬
mon in insects and is called parthenogenesis or agamic reproduction. In
this case the production of these young alive rather than from deposited
eggs introduces the additional fact that these insects are also viviparous
except in (generally) one generation. The number of young produced by
each parent varies but will perhaps average about ten, a few being born
every few days, and the number of generations is variable but is also likely
to be about 10, though the first born young in each generation, being a
week or two older than the last born young, will gain enough time during
the season to produce more generations than the others. In fact, in
some species a range from 8 to 21 generations for late and early born
individuals has been observed, and an average number of 28 young pro¬
duced per parent, so that the figures given above may be regarded as
conservative. But even with this moderate estimate, allowing only 10
young to a generation and 10 generations a season, the total product from
a single egg hatching in the spring and itself counted as the first generation,
would be 1,111,111,111, and this would be far below the actual number in
most cases, were it not for the enormous destruction of these insects by
their enemies and by unfavorable weather conditions.

In many species instead of 10 young being produced per female as an
average, the number is likely to be nearer a hundred, and in those species
which also have more than 10 generations the total number of individuals
which would theoretically be produced in a season “would be sufficient to
completely cover the entire world with a continuous layer of plant
lice.”

With such a marvelous reproductive power as this it becomes evident
that despite natural checks to their increase, plants infested are liable
after a few weeks to be entirely unable to provide food for the hordes of
plant lice upon them. Accordingly we find that in most of the genera¬
tions winged individuals may be produced so that they can migrate to
other plants. Winged and wingless forms may therefore be found at

THE HOMOPTERA

107

almost any time during the summer, and a wide distribution of the insect
is obtained in this way.

When cold weather approaches in the fall a generation appears, con¬
sisting of both sexes, and the females of this generation lay fertilized
eggs which winter over and hatch the following spring. In some cases
this does not happen until the second fall and in a few species at least,
sexual individuals have not been discovered and may occur only at long
intervals, if at all.

Many aphids do not feed entirely on one kind of plant but spend a
part of the year on one species, and the rest on another. One of the
species which is injurious to the apple remains on this tree from fall until
May or June when it migrates to grain and spends the summer months
there. Another species, living on the elm during the fall, winter and
spring, passes to the apple for its summer residence, and a long list of
aphids having alternating food plants is now known.

Plant lice suck the sap from plants and often produce curling or mal¬
formation and even wilting of the leaves, frequently accompanied by
discoloration. Root-attacking forms produce knots and deformities
affecting the health of the plant, and young fruit becomes hard at the
attacked spots and remains small. The punctures aphids make often
enable the spores of fungi and bacteria causing plant diseases to enter the
plants, and they may even transfer these from one plant to another.
Among the diseases transferred thus are an oat blight, fire blight of the
pear and cucurbit wilt. Indirectly by the honey dew in which spores can
live for several days, it is probable that the diseases can also be widely
distributed through the agency of other insects which visit and feed on
honey-dew. In general a year when plant lice are abundant over a
large part of the country is certain to result in great injury to plants of all
kinds affected by these insects.

Ants not only gather the honey dew the Aphids produce, but in some
cases the relation is closer, particularly with root feeding species. The
eggs of the corn-root louse for example, are gathered by ants in the fall
and kept in their underground chambers during the winter. In the spring
the ants place the insects on the roots of certain weeds but after the corn
has begun to grow well, they transfer them to the corn roots where they
visit them during the summer to collect honey dew. (See page 203.)

Plant lice have many enemies which destroy great numbers of them.
They are also affected by the weather, cloudy, wet periods being favor¬
able, though driving rains destroy many.

In general the best control of plant lice is obtained by the use of
nicotine sulfate 40 per cent used at a dilution of from 1 to 800 to 1 to
1,000 parts of water. Where this cannot be obtained, kerosene emulsion
or fish-oil soap solutions rank next as control.

198

APPLIED ENTOMOLOGY

The Apple Aphids. — There are three species of plant lice which attack
the apple more or less generally throughout the United States, and a
fourth is injurious in some parts of the country. In addition, a woolly
species feeding both on the twigs and roots is of importance and will be
treated later.

The three species referred to are the Green Apple Aphis ( Aphis pomi
DeG.), the Rosy Apple Aphis ( Anuraphis roseus Bak. and Turn.) and
the Apple Grain Aphis ( Rhopalosiphum prunifoliee Fitch), the latter until
recently believed to be the same as a European species and generally
known therefore, as the European Grain Aphis. All three lay their eggs
in the fall on the twigs of the apple. In the spring the eggs of the Apple
Grain Aphis hatch a week or 10 days before those of the other two. The
young of all three kinds feed on the buds and become stem mothers which
when full-grown, differ in appearance.

Fig. 188.

Fig. 188.— Green Apple Aphis ( Aphis pomi De G.), stem mother, about eight times
natural size. {Modified from Cornell Agr. Exp. Sta. Mem. 24.)

Fig. 189. — Rosy Apple Aphis ( Anuraphis roseus Bak. and Turn.), stem mother, greatly
enlarged. {Modified from Cornell Agr. Exp. Sta. Mem. 24.)

The Green Apple Aphis stem mother (Fig. 188) has a uniformly green
body, brown head and long, dark cornicles: the Rosy Apple Aphis stem
mother (Fig. 189) is greenish but blended with purplish brown, and the
cornicles are long, slender and dark; the body in this case is so dark as
to be often described as blue: the Apple Grain Aphis stem mothers
(Fig. 190) are yellowish-green, with a broad darker green stripe along the
middle above, from which several side branches pass off, and with rather
short, stout, yellowish cornicles.

As the leaves develop the lice feed on them and in the case of the
Rosy Apple Aphis produce much curling. This is usually less pronounced
with the Green Apple Aphis and does not occur with the Apple Grain
Aphis.

After a generation or two on the apple, winged forms (Fig. 191) begin
to appear and these migrate to summer food plants, except with the Green
Apple Aphis which remains an apple feeder throughout the year. The

Fig. 189.

TIIE II OM OPT ERA

199

Rosy Apple Aphis migrates to species of plantain, particularly the nar¬
row-leaved plantain and it is noticeable that the spread of this plant
louse over the country has closely followed that of this introduced weed.
The Apple Grain Aphis migrates to small grains such as wheat and oats.
On these summer food plants generation after generation is produced
but in the fall a migration back to the apple occurs and here a sexual
generation appears and eggs are laid which hatch the following spring.
In some cases the Apple Grain Aphis may winter over close to the ground
on the grain, not returning to the apple. The winged form of the Rosy
Apple Aphis during the summer months has a pinkish or reddish body
which has led to its being given its common name.

In the middle West the Clover Aphis ( Aphis bakeri Cowan) has a
similar life history to those just outlined, but during the summer lives on
clovers.

Fig. 190. Fig. 191.

Fig. 190. — Apple Grain Aphis ( Rhopalosiphum prunifolice Fitch), stem mother, greatly
enlarged. (Modified from Cornell Apr. Exp. Sta. Mem. 24.)

Fig. 191. — Winged Migrant of Green Apple Aphis, greatly enlarged. ( Modified from
Cornell Apr. Exp. Sta. Mem. 24.)

The chief injury to the apple caused by these insects is that their
feeding on the buds checks their growth. The leaves are also curled and
growth is reduced.

Control of Apple Plant Lice. — Destruction of the winter eggs by
sprays has not thus far been very successful. The best control known
at present is to very thoroughly spray the trees just as the buds are
beginning to open and the eggs hatch, with the standard formula of
nicotine sulfate 40 per cent. If an application of lime-sulfur is desired
the nicotine sulfate can be added to that, provided the soap be left out.
A second application about 2 weeks later, is sometimes desirable. In case
nicotine sulfate cannot be obtained, kerosene emulsion, 1 part to 9
of water, or fish-oil soap, 1 lb. in 5 to 7 gal. of water may be used instead.

The Woolly Apple Aphis ( Eriosoma lanigera Hausm.). — This European
pest has been in the United States for many years and is widely dis-

200

APPLIED ENTOMOLOGY

tributed. The adult is a small insect more or less completely covered by
white, cottony or woolly threads of wax which practically conceal the
louse beneath. Recent studies have shown that in most cases at least,
the winter is spent in the egg stage in crevices in the bark of the elm.
The eggs hatch in spring and the young lice pass to the buds and attack
the leaves when these develop, causing them to become deformed, curled
and clustered together forming “rosettes.” Several generations partici¬
pate in this work.

During the later spring months winged migrants are produced and
these pass to the apple, hawthorn and a few other related trees where

they locate on the under side of the leaves
and produce young which crawl to thin
places, wounds or water shoots and there
locate and reproduce during the summer and
fall (Fig. 192) until cold weather comes on,
when migrating forms are produced which
return to the elm where the eggs are laid.

This life history is complicated by the
fact that during the summer some of the
plant lice migrate from the branches of the
apple tree to its roots and feed there, pro¬
ducing knots and swellings which interfere
with the nutrition of the plant, and if suffi¬
ciently abundant may cause its death. These
lice are believed to remain on the roots the
year around, generation after generation, but
with their ranks recruited from time to time
by migrants from the aerial members. Some
of the latter also, are believed to remain on
the apple all winter as hibernating nymphs.

The amount of injury to the apple caused
by this insect above ground is not very great
except perhaps on nursery trees. Woolly spots
at scars and wounds on the branches, notice¬
able chiefly in the fall, are not abundant enough to affect the trees
much, usually. The root form, however, is sometimes quite injurious,
particularly south of the latitude of Washington, and young orchards
may suffer severely.

Control. — The waxy “woolly” threads covering the bodies of these
insects make control more difficult by spraying than would otherwise
be the case, as the threads repel the spray. Nicotine sulfate 40 per cent,
standard formula, or kerosene emulsion 1 part to 9 of water, driven with
much force are about the only treatments for the aerial forms which have
given much success. It is evident that elms growing near apple trees

Fig. 192. — Apple twig show¬
ing Woolly Apple Aphis
( Eriosoma lanigera Hausm.)
and swellings of the twig pro¬
duced by their attacks. About
twice natural size. {Original.)

THE HOMOPTERA

201

directly favor the successful migration of this pest, and as far as possible
therefore, no elms should be allowed to grow near apple orchards.

For the root form, when sufficiently injurious to make it pay, removing
the earth to a depth of six or eight inches over the root area and pouring
kerosene emulsion or nicotine sulfate diluted as above, over this exposed
surface, using enough to thoroughly wet the ground, has given good
results.

Nursery stock affected can be dipped in the lime-sulfur wash or
in these materials, when dug either for transplanting or sale, and as
the Northern Spy seems to be rather free from this pest, using trees
grown on stocks of that variety is desirable.

The Grape Phylloxera {Phylloxera vitifolice Fitch). — This aphid is a native
of America and attacks the grape. Native American vines, however, are resis¬
tant to its work to a considerable degree, so that injury to them is not serious.

Fig. 193. — Under surface of Grape ieaf showing galls produced by the Grape Phylloxera
(Phylloxera vitifolice Fitch). Somewhat reduced from natural size. (From Riley, U. S.
D. A.)

The European grape (Vitis vinifera) on the other hand, is very susceptible to
its attacks and when the Phylloxera reached Europe about 1860, it became very
destructive, causing the loss of over two million acres of vineyards before any
successful checks to the insect were discovered. In this country it reached
California where the European grape is also grown, about 1874 and has been the
cause of great injury there also.

The insect lays its eggs, one per female, on old wood of the grape in the fall,
and these eggs hatch the following spring into tiny lice which locate on the upper
surface of the young leaves and begin to suck the sap. 1 his causes the leaf to
become depressed at each place where a louse is at work, so that galls (hig. 193)
projecting from the under surface are soon produced, in which the insects live.
Upon becoming full-grown these lice lay eggs in the galls and the young which
hatch from them pass to other parts of the leaves and produce galls of their

202

APPLIED ENTOMOLOGY

own. This process continues through the summer but in the fall the young
desert the leaves (Fig. 194) and work down to the roots and rest until the follow-

Fig. 194. — Grape Phylloxera: a , galls on grape roots; b, galls enlarged, showing the
insects; c, Phylloxera from a root gall: b and c enlarged. ( From Sanderson, Insects Injuri¬
ous to Farm, Garden and Orchard-, after Marlatt, U. S. D. A.)

Fig. 195. — Grape root showing galls caused by Phylloxera. ( From Berlese.)

ing spring. Then they attack the roots, forming swellings (Fig. 195) which on
young rootlets stop their growth, and on the larger ones cause decay which spreads
around the root and kills it beyond that point.

THE HOMOPTERA

203

During the latter part of this second season some winged forms (Fig. 194)
are produced and these make their way up to the surface of the ground and
migrate to other vines where they lay eggs. These produce both male and
female plant lice and each female lays a single fertilized egg which winters over.

This 2 -year life and the production of leaf galls is not always necessary to
the continued existence of the insect however. The root form generally goes on,
brood after brood, particularly on the European grape, without the formation
of leaf galls, and while young from the leaves may probably pass to the roots
at any time during the summer, the migration of root forms to the leaves is
unknown. Apparently then, the life history just outlined applies to American
varieties of the vine, but in the case of the European species, while the lice may
pass to the roots they do not usually, at least, seem to migrate in the reverse
direction, the insects coming from fertilized eggs passing directly to the roots.
Root forms may spread to other plants through the soil.

Control.— Four methods of control have been made use of for this pest, viz.,
the injection of Carbon disulfid into the soil close to the roots; flooding the vine¬
yard with water; planting in very sandy soils; and the selection of resistant
varieties. The first of these has given fair results where the soil is loose, deep and
rich, but is most successful in cooler locations, and here the insect is least abun¬
dant. It is also rather expensive and has therefore largely been replaced by other
treatments.

Submersion of the ground under water is a better method, but obviously
cannot be made use of in most cases. The vineyard must be kept covered with
at least six inches of water in order to drown the lice and unfortunately the best
time to do this is during the summer when the vines are most liable to be injured
by this treatment. The time chosen therefore, is after the vines have stopped
active growth but before the lice have become dormant. In California this is
generally some time in October. Flooding then should last from a week to
10 days: later in the season it must be extended and in the winter months 35
to 40 days of treatment is necessary.

Planting in sandy soil is, for some reason not understood, a protection of the
vines against Phylloxera, particularly where it contains a high percentage of
siliceous sand. It is not always possible to locate vineyards on such soil however.

The selection of resistant varieties of the grape is now the favored method of
control. With such varieties the insects when present on the roots do not in¬
crease rapidly and the diseased tissue of the swellings on the roots does not go
deeper than the bark, leaving the roots proper quite healthy. At the present
time the grafting of vinifera varieties on resistant stalks which preserves the
resistant properties of the roots while producing the vinifera quality of grapes
so much desired, seems to give the best results in vineyards, though the proper
combination of different varieties of the two calls for a detailed knowledge of
the subject in actual practice.

The Corn Root Aphis (Aphis maidi-radicis Forbes). — This insect, though it
can hardly be regarded as universally distributed through the United States,
is both a serious pest of corn over a large area and because of its interesting rela¬
tion with ants, an interesting species. It appears to occur throughout the
eastern United States as far west as South Dakota and Colorado and south to
South Carolina, Louisiana and Texas, but its destructive work mainly covers the
territory from New Jersey to South Carolina and west to the Mississippi River.

204

APPLIED ENTOMOLOGY

The eggs of this aphid hatch early in spring and from 10 to 22 generations
(Figs. 196 and 197) are produced during the season. As cool fall weather
appears, a generation of sexual individuals (Fig. 198) appears and these lay
eggs which pass the winter. During this season they may be found in the
ground in nests of several kinds of ants but most
frequently in those of the little brown ant, Lasius niger
americanus. They are oval, black and glistening and
are sometimes found in small piles in the nests of the
ants. In cold weather the ants carry the eggs down
below the frost and on warm days bring them up to
warmer levels. In spring, when various weeds such as
smartweed, begin to grow, the ants tunnel along the
roots of these weeds and place the young lice as they
hatch, on them to feed. Later, when corn roots
become available the ants transfer the lice to them,
where they and their descendants feed during the rest
of the season. Winged migrants are produced after a
generation or two and these individuals spreading, are
taken to corn roots by ants which may find them. All
summer and fall the ants care for the lice, taking them
from one plant to another and collecting from them the
honey-dew upon which the ants feed. In the fall when
the eggs are laid these are gathered by the ants and
stored in their nests over winter.

Where the Corn Root Aphid is abundant it becomes a serious corn pest,
dwarfing the corn and turning the leaves yellow or reddish and sometimes destroy¬
ing the plants, particularly when weather conditions are also unfavorable.

Fig. 196. — Corn Root
Aphis ( Aphis maidi-
radicis Forbes) ; wingless,
viviparous female.
Greatly enlarged. ( From
U. S. D. A. Bur. Ent.
Bull. 85, Part VI.)

Fig. 197. — Winged, viviparous female of the Corn Root Aphis, greatly enlarged. ( From.
U. S. D. A. Bur. Ent. Bull. 85, Part VI.)

Control. — Rotation of crops is of much value as a control, for as the lice
cannot migrate until their second generation, corn planted on land where they
are not already present will get well started. Fertilization and frequent cultiva-

THE HOMOPTERA

205

tion to produce vigorous growth will aid in this. The worst injuries are usually
where corn is planted to follow corn and therefore where this pest is already
present in the field from the preceding year. Any method which will destroy
the nests of the ants which care for the lice will also be helpful, and deep plowing
and harrowing both in late fall and early spring has
proved of value for this purpose.

Some plant lice attack evergreens and pro¬
duce rather soft, fleshy galls, generally at the
bases of the outer shoots. These appear during
the spring months and are of full size by mid¬
summer. They then dry and crack open, showing-
little cavities occupied by the plant lice which now
leave the galls for other parts, either of the same or
some other kind of tree, according to the species
concerned. The gall formation interferes with the
growth of the tree by preventing wholly or in
part, the circulation of the sap in the shoot at the
base of which the gall is located, and this results,
by the death or checking of the growth, in trees which look thin rather
than dense, and in some cases they may become worthless as lawn
ornaments. In the East the spruce is often seriously injured in this way.

Many kinds of plant lice often become seriously abundant for periods
of 2 or 3 years, then disappear for a time. The Potato Plant louse, the
Pea louse, the Beet-root louse, Cherry plant lice and others have all been
destructive for a year or two at a time within the last decade, and similar
outbreaks of these or others may be expected any year. Wherever it is
possible, spraying thoroughly upon the first appearance of the lice, with

Fig. 199. — Aphid parasite ( Lysiphlebus iestaceipes Cress.) ovipositing in the body of a
Spring Grain Aphis. Greatly enlarged. ( From U. S. D. A. Bur. Ent. Bull. 110.)

nicotine sulfate, kerosene emulsion or fish-oil soap should be resorted to
as measures of relief. If for any reason this cannot be done and no special
method of control seems available, dependence must be placed upon
climatic influences and insect enemies to check these pests, and this will
occur within 2 or 3 years in nearly every case.

Among their many enemies is one group of tiny insects which makes a
specialty of attacking plant lice. An insect of this group will select a

Fig. 198. — Oviparous
female of the Corn Root
Aphis, greatly enlarged.
( From U . S. D. A. Bur.
Ent. Bull. 85, Part VI.)

206

APPLIED ENTOMOLOGY

louse (Fig. 199) and, facing it, will thrust its abdomen forward beneath
its body and drive its ovipositor into the louse. The young parasite
hatching from an egg thus deposited, will feed upon
the aphid whose body becomes distended and
generally changes color after a time and finally
dies adhering to the plant on which it was. When
the parasite has completed its development within
the body of the louse it escapes by cutting a
circular, lid-like opening through the skin (Fig. 200),
and lice attacked and killed in this way are often
very plentiful during and particularly toward the
end of a period of destructive abundance of these
insects (see page 344).

Family Aleyrodidse. — The adults of the insects
belonging in this family (Fig. 201) are very small
arid have four wings which are broadly rounded
and have a white dust covering them, which has
led to calling the group the White Flies. Occa¬
sionally the wings have dark spots or streaks. The
eyes are often constricted in the middle or even
divided into two parts. The body is generally
yellowish, though in some species it may be of
other colors.

The nymph on hatching, crawls around for a
short time before settling down* on a leaf, then in¬
serts its rostrum in the tissues and begins to feed.
After molting the insect becomes quiet, with its legs and antennae much
reduced, and thereafter does not move from its location until it becomes

Pig. 200. — Plant Lice
killed by parasites. Up¬
per figure shows the
circular piece of chitin
cut by the parasite in
escaping, but still at¬
tached. Lower figure
shows the parasite just
escaping. Much en¬
larged. ( From, U. S. D.
A. Bur. Ent. Bull. 110.)

Fig. 201. — Adult White Flies twice natural size. ( From Britton , Second Report Ent. Conn.

Agr. Exp. Sta. 1902.)

adult, and wax which may have been produced before the first molt,
now becomes more noticeable. This wax may take the form of a fringe

THE HOMOPTERA

207

around the sides and may more or less cover the body. The animal after
its third molt differs so from its former appearance that this stage is
often called a pupa, and as the following molt produces the adult there
is evidently quite a metamorphosis to justify the use of this term in the
group. Honey-dew is produced by these insects.

White Flies are essentially tropical though a few species live in the
northern United States. In greenhouses everywhere the Greenhouse
White Fly ( Aleyrodes vaporariorum Westw.) is too often a serious pest,
for it multiplies rapidly and the tiny nymphs (Fig. 202) are not generally
noticed in time to check their increase before the plants have suffered

Fig. 202. — Nymphs of the White Fly on underside of a leaf, enlarged twice. ( From.

Britton, Second Rcpt. Ent. Conn. Agr. Exp. Sta. 1902.)

greatly. When they are abundant, fumigation for 3 hr. at night, using
between ^5 and oz. of sodium cyanid to each 1,000 cu. ft. of space in
the greenhouse should kill all but the eggs and some of the pupae, and
repeating this treatment twice afterwards at intervals of 2 weeks should
destroy the others in the stages to which they will have then progressed.
If for any reason this treatment is not desirable, syringing the plants
with fish-oil soap using from 1 to 1^2 oz- Per gallon of water, giving
particular attention to the under surface of the leaves will give some relief.

I11 the Southern States and in California, white flies attack citrus fruits and
cause much injury. Several species are more or less concerned, the most impor¬
tant one being the Citrus White Fly ( Dialeurodes citri Ashm.). These insects
usually check the growth of the tree and fruit, reducing the yield and its size,
and also by the production of honey-dew, induce the growth in this of a fungus
called “sooty mould” which interferes with the ripening of the fruit and is also
believed to affect its flavor, besides making it look objectionable, so that fruit
partly covered with the mould must be cleaned before shipping. The reduction
of the vitality of the tree by these insects also favors the more active development
of other citrus insects and of diseases.

208

APPLIED ENTOMOLOGY

Certain fungi live on the white flies, however, and are of assistance in their
control, but as they need certain weather conditions for their best growth during
about 3 months, they can rarely accomplish more than a third of the amount
of control necessary.

Spraying with paraffin-oil emulsion prepared according to special directions
has proved to be a successful method of control for citrus white flies, and miscible
oil has also given good results. In either case the material as applied should
contain about 1 per cent of oil.

Family Coccidae (Scale Insects). — These are remarkable insects
having been much modified and changed in appearance from the more
ordinary forms. Without attempting an accurate classification, they
may be grouped under three heads: the armored scales, the soft scales,
and the mealy bugs.

The mealy bugs are the least degenerate of the three groups. In
them the females preserve their body segments, eyes, antennae and legs,
and can move about. They secrete a waxy material, usually as long
cottony threads or plates, more or less covering their bodies and some¬
times forming a large egg sac at the hinder end. In the female soft
scales the antennae and legs are not lost but they become reduced to
such an extent that though the adult can move about somewhat, it
seldom does so. Wax when secreted, is usually to form a sac at the hinder
end of the body enclosing the eggs, and the skeleton on the back of the
insect becomes very much thickened, forming a scale, often very convex,
strong and protective, though seemingly softer than in the armored
scales. In this last-named group the female loses antennae, eyes, and
legs, and secretes a waxy scale, with which the molted skins from the
body are felted together, forming generally a rather flat and very tough
scale. The metamorphosis in the females of all three groups is incom¬
plete. In some cases the females are fertilized before they have attained
full size and grow considerably afterwards.

The males develop much as do the females, at first, though not losing
any of their parts by degeneration. After reaching full size, however,
they pupate and emerge from the pupa as very tiny insects with only one
pair of wings and no mouth parts. Thus in the scale insects we have the
remarkable fact that while in the males there is a complete metamorpho¬
sis, in the females it is incomplete. Whether the former was the original
condition in the group, and the females through the degeneration con¬
nected with their mode of life have changed to an incomplete meta¬
morphosis, or whether this was the primitive condition and complete
metamorphosis has been developed in the males, is unknown, though the
other Homoptera all have an incomplete metamorphosis.

About 2,000 species of scale insects are known, attacking nearly all
kinds of trees and shrubs, and sometimes other plants as well. Many
have an almost incredible rapidity of increase, and when under favorable

THE HOMOPTERA

209

conditions, this results in the death of the plant they are on. A few are
beneficial to man. Thus the bodies of a scale feeding upon cactus, when
dried and prepared, furnish the dye known as Cochineal. Shellac is
obtained from the excretions produced by another scale, and China wax,
used as furniture polish, conies from a third species. Most scale insects,
however, are injurious and fail to compensate for the injury they cause by
producing anything of value.

Among so many serious pests, only a few can be considered in detail
here. Taking the armored scales first, these are the Oyster shell, the
Scurfy and the San Jose Scales, with brief reference to a few others.

Armored Scales

The Oyster-shell Scale ( Lepidosaphes ulmi L.). — This insect, native
to Europe, has been so long in this country that it is now very generally
distributed. It is chiefly an enemy of the apple, pear, poplar, willow,
ash and lilac, but is often found on other plants. It feeds on all parts
covered by bark, and the male scales are also often found on the leaves.

kt.

Fig. 203. — Female scales of the Oyster-shell Scale ( Lepidosaphes ulmi L.) on a twig, about
twice natural size. {Original.)

The full-grown female scale (Fig. 203) is about one-eighth of an inch
long and has much the form of an oyster shell, one end narrowly rounded,
the other rather more broadly so, and the shell as a whole usually bent
somewhat to one side. It is brown to gray in color, varying with age,
and to some extent, the plant it is on. During the winter examination
of the scale will show beneath it at the narrower end, the dead body of the
insect, and behind it from 15 to 100 tiny whitish eggs. These hatch the
following Ma}r or June, according to the advancement of the season, into
very small whitish nymphs or “crawling young,” which are extremely
delicate and with no scale. These young crawl out from beneath the
parent scale and wander about for a few hours or even a day or so, seeking
for places where they may settle: then each thrusts its beak through
the bark and begins feeding, and degeneration of eyes, antennae and
limbs, and the secretion of wax over the body begins. To this secretion

the molted skin is added at each molt, making a very tough, hard, cover-
14

210

APPLIED ENTOMOLOGY

ing scale. The insect beneath this becomes adult after a time and
following the laying of its eggs, dies. In the northern states the eggs are
laid in August or September, but in the middle states and farther south,
the earlier seasons permit hatching enough earlier in the season for the
adult condition to be reached and the eggs laid by midsummer, and these
eggs soon hatch and produce egg-laying adults before the following
winter. Thus, this insect though having but one generation each year
in the more northern states, has two from about the latitude of New
Jersey southward, except at such altitudes as to produce northern
conditions.

Many of the male crawling young go to the leaves to settle and the
scales they form are smaller and somewhat different in shape from those
of the females. Beneath them they attain their growth, then pupate,
still under their scales, and at the end of this process emerge as very
small two-winged adults without any mouths or mouth parts, having un¬
dergone a complete metamorphosis.

Control. — These insects are least protected while crawling young, and
as they are sucking forms, a contact insecticide should be applied
while they are moving about or at least before they have had time to
produce scales covering themselves. The usual treatment therefore is
to spray with 1 part of kerosene emulsion to 9 of water, or with Nicotine
sulfate 40 per cent, 1 part, water 800 to 1,000 parts, as soon as the young
appear. They are so small, however, that it is very difficult to reach
them all with the spray, and as all do not hatch at the same time, a
second application about 10 days after the first, is desirable. Winter
spraying with lime-sulfur wash is also a fairly good treatment. Where
neither of these methods proves effective (as is sometimes the case),
spraying in spring, shortly before the eggs hatch, with linseed oil emulsion,
has worked well. This is prepared as follows:

Raw linseed oil . 1 gal.

Hard soap . hj lb.

Water, to make . 10 gal.

Dissolve the soap in the water; add the oil and churn through a
pump as for kerosene emulsion until thoroughly mixed (it does not
thicken up like the latter) and spray.

The Scurfy Scale (Chionaspis furfura Fitch). — This insect is a native
of America and is usually less abundant in the more northern states than
elsewhere, attacking the apple, pear, mountain asn, currant, gooseberry,
hawthorn, Japanese quince and other plants. The full-grown female
scale (Fig. 204) is shorter and broader than the Oyster-shell scale,
and when perfect in outline, rather pear-shaped, and dirty white in color.
Its life and habits are much the same as those of the Oyster-shell scale,

THE HOMOPTERA

211

but the eggs are fewer in number and dark purple in color, as are also the
crawling young which usually hatch a few days later in the season than
the other species. Control methods are the same as for the Oyster-shell
scale.

Fig. 204. — Scurfy Scales ( Chionaspis furfura Fitch). Male scales at right, female
scales at left. Left hand figure greatly enlarged; the other two somewhat enlarged. (From
U. S. D. A. Farm. Bull. 723.)

The San Jose Scale ( Aspidiotus perniciosus Comst.). — This is one of
the most serious pests among the scale insects. Its original home was
probably China, but it appears to have reached California about 1870
and since then has spread practically all over this country. It has a
wide range of food plants, on many of which it thrives sufficiently to
quickly kill them. The plants which suffer most from its attacks are
the fruit trees and currants, the dog- woods, thorns, poplars, ornamental
cherries and plums, hardy roses, willows, lilacs and lindens; and even
maples and elms are sometimes attacked, the total list of plants upon
which it has been found numbering over a hundred. It feeds on all
parts of the plant above ground, even including the fruit.

The full-grown female scale (Fig. 205) is about the size of a pin head,
nearly circular in outline and rather flat, sloping gradually upward from

212

APPLIED ENTOMOLOGY

its edge to near the center where a slight circular depression surrounds
the raised center or “nipple” itself. It is brownish-gray in color when
adult, but in earlier stages may vary from this. The adult male scale
is somewhat smaller, more oval in outline, and with the nipple not cen¬
trally placed but nearer one end.

At the beginning of the winter season specimens of this scale of
practically all ages occur, but probably only those from about one-third
to one-half or two-thirds grown survive the winter. In the spring these

individuals resume their feeding on
the sap and after a time the males
appear. In the northern states
this condition is hardly reached
before the middle of May, but at
Washington, D. C. it conies early
in April, and farther south still
earlier. After mating, the females
continue to grow and about a
month later the first young appear.
These do not, in the San Jose
Scale, hatch from eggs laid by the
parent but the young are born
alive; i.e., this insect is viviparous.
These young are produced, a few
every day or two, and the parent
lives for a month or more, pro¬
ducing an average total of about

Fig. 205. — San Jose Scale ( Aspidiotus 400 young. These resemble the

pcmiciosus Comst.) : adult female scales crawling young of the scales already
enlarged about five times. ( From Houser, . , , .

Ohio Agr. Exp. Sta. Bull. 332.) considered, except that they are

lemon yellow in color, and they
crawl about and settle down to feed in the same way. The scale
now begins to appear, at first as white waxy threads over the back,
which soon mat together to form a pure white covering. As the
nymph beneath molts, the molted skins are added to this and variations
in color of the scale appear. Sometimes the scale of the partly grown
insect may show white, black and gray, varying in arrangement according
to the completeness with which the different parts have combined, but
before maturity it becomes a quite uniform grayish-brown. The young
become adult in a little over a month and then themselves begin to
produce young, and in the northern states there are usually at least
three generations in a season, while in the south there are four or even
more. The generations overlap, the earliest young produced by the
second generation for example, sometimes appearing before the last born
of the preceding one, which results in the almost constant presence of

THE HOMOPTERA

213

crawling young on an infested tree, from the time the first one appears
until reproduction is stopped by cold weather. Assuming the production
of four full generations in a season, equally divided between the sexes,
and with no loss in number from death by accident or other causes to
reduce the number produced, we have a total of 3,216,080,400 in individ¬
uals as the descendants during one season from a single pair. Fortu¬
nately, many never reach maturity, or an infested tree would often
be sucked dry before winter.

The San Jos6 Scale has a number of parasites which are sometimes
quite effective, destroying a large per cent of the scales in some localities,
but with such an enormous power of increase of the pest, even a high
degree of parasitism fails to give the relief needed. A few predaceous
insects are also known, which feed upon the
scale. Most noticeable among these is the
Twice-stabbed Lady Beetle ( Chilocorus bivulnerus
Mills.), a small black beetle (Fig. 206) with twro
red spots. It is nearly circular in outline, very
convex and is about one-eighth of an inch long.

A fungous disease also attacks the scale, par¬
ticularly in the South, but parasites, predaceous
foes and diseases together, generally fail to hold
it entirely in check.

A lady beetle closely resembling the Twice-
stabbed Lady Beetle is an enemy of the scale in
China, the native home of the pest, and this
insect has been brought to the United States
with the hope that, it might do effective work here, but thus far, for
various reasons, it has failed to accomplish much.

Control. — Spraying as for the Oyster-shell Scale is useless, for that
treatment is based upon the destruction of the delicate, crawling young,
by one or at most two applications. With the San Jose Scale, however,
the young do not all appear at about the same time, but are present
practically from May or June according to the latitude of the locality,
until winter. To use this method successfully therefore wrould require
spraying about every 2 weeks or so for a period of at least 5 months —
a treatment manifestly impracticable.

Stronger materials are therefore used, during the dormant season,
when the tree is least liable to injury by the spray, and when a more
thorough application can be made, the leaves having fallen. For this
purpose the lime-sulfur wash and miscible oils are generally used (see
Chapter VIII). At times injury to the trees has been observed following
the use of miscible oils, but on the other hand these materials spread
better over the tree than the lime-sulfur. Many persons now make a
practice of spraying every third winter with miscible oil, but using the
lime-sulfur at other times.

a b

Fig. 206. — Twice-stabbed
Lady Beetle { Chilocorus bi¬
vulnerus Muls.): a, adult; b,
larva enlarged: real length
shown by the hair lines.
(. From Sanderson and
Jackson, Elementary Ento¬
mology. after Riley.)

214

APPLIED ENTOMOLOGY

In some cases summer treatment may be desirable where the scale
is increasing rapidly, to preserve the tree until winter gives an oppor¬
tunity for the regular application. In such cases a greater dilution of the
lime-sulfur becomes necessary, and with' stone-fruit trees the self-boiled
material should be used.

Fumigation with Hydrocyanic acid gas is the most effective treatment
for the San Jose Scale, but the cost of the tents large enough to cover all
but the smallest trees is so great that this method is made use of only for
fumigating nursery stock after it has been dug, in houses built for that
purpose.

a b

Fig. 207. — Rose Scales ( Aulacaspis rosce Bouche): a, female scales; b, male scales.
Considerably enlarged. ( From Houser, Ohio Agr. Exp. Sta. Bull. 332.)

The Rose Scale ( Aulacaspis rosce Bouche). — Generally distributed in the
United States on raspberry, blackberry, dewberry, rose, pear and some other
plants. Female scales (Fig. 207) white with more or less yellow at margin;
nearly circular, about one-tenth of an inch in diameter. Male scales white, nar¬
row, very small. Plants thickly infested appear as though sprayed with white-

THE HOMOPTERA

215

wash. Winters in various stages, so all may be present at almost any time.
Two or three generations per year. Control by cutting out the worst infested
stems during the winter, and spraying with lime-sulfur as for San Jos6 Scale in
early spring. Whale-oil soap (1 lb. in 1 gal. water) may also be used.

The Pine-leaf Scale ( Ckionaspis pinifolioe Fitch). — Occurs generally in the
United States on leaves of pine, and sometimes other evergreens. Female scale
(Fig. 208) white, narrower than Scurfy Scale but varying to fit the width of the
leaf: male scale much smaller. When abundant, whole branches may appear

Fig. 208. — Pine-leaf Seale ( Ckionaspis pinifolioe Fiteh). Female scales on pine leaf, about
twice natural size. (Original.)

as though their leaves had been sprayed with whitewash. Two generations a
year, purplish crawling young appearing in the northern states about the middle
of May and the first of September, at which times spray with either kerosene
emulsion or the linseed oil emulsion as advised for the Oyster-shell Scale.

The Purple Scale ( Lepidosaphes beckii Newm.). — In the South and on the
Pacific Coast this insect is very injurious to citrus plants, even on the fruit of
which it is often seen. It greatly
resembles the Oyster-shell Scale in
appearance (Fig. 209) and size There
are three or four generations each
year. Control is usually by fumiga¬
tion with Hydrocyanic acid gas during
the colder months.

Fig. 209. Fig. 210.

Fig. 209. — Purple Scale ( Lepidosaphes beckii Newm.), about natural size. (Modified
from Cal. Agr. Exp. Sta. Bull. 226.)

Fig. 210. — Red Scale (Chrysomphalus aurantii Mask.) on a portion of a grape fruit.
About natural size. (From Cal. Agr. Exp. Sta. Bull. 214.)

The Red Scale (Chrysomphalus aurantii Mask.). — A serious pest of citrus
trees in California. The female scale resembles the San Jose Scale in outline,
but averages larger (Fig. 210) and the scale is transparent enough to allow the
red body (yellow in a variety) of the insect to show through. The male scales
are smaller and rather elongate. The life history is similar to that of the San

216

APPLIED ENTOMOLOGY

Jose Scale, the young being born alive during the summer months. Control on
citrus trees appears to be best obtained by fumigation with Hydrocyanic acid gas,
but with deciduous fruit trees the lime-sulfur wash may be used.

Occasionally the lenticels or breathing pores through the bark of
plant twigs resemble armored scales, particularly the more circular
ones. To determine in any case whether a debatable structure on bark
is a scale or only a lenticel, it may be scraped with the finger nail. If it
can be removed without breaking the bark (it may leave a whitish mark)

the object is a scale, but if the bark is neces¬
sarily torn or broken to get it off, it may be
assumed that it was a lenticel.

Soft Scales

As a group the soft scales are less injurious
than the armored scales. Their rate of in¬
crease is less, their covering less protective,
and their larger size renders them more cer-

Fig. 211. Fig. 212.

Fig. 211. — Tulip Tree Scale ( Eulecanium tidipiferce) Cook), about natural size.
{Original.)

Fig. 212. — Black Scale ( Saisettia oleae Bern.), about natural size. ( From Cal. Agr.
Exp. Eta. Bull. 223.)

tain to be reached by sprays. The largest one found in the United States
is the Tulip Tree Scale, the adult female scale being about one-third of an
inch in diameter (Fig. 211). An African soft scale is known which is
about an inch long.

The Black Scale ( Saissetia olece Bern.). — This scale is found in nearly all
parts of the world. It has a long list of food plants but is chiefly a pest on citrus
trees and the olive, oleander, apricot and prune. In the United States it is
therefore chiefly important in the South and West. The adult female scale is

THE II OM OPT ERA

217

from one-eighth to one-fourth of an inch in diameter and almost hemispherical in
form, black in color and with ridges forming an “II” on the back (Fig. 212).
The male scales are much smaller, long, narrow and flat. The eggs, from 50 to
3,000, are for the most part, laid in May, June and early July, and the adult
condition is reached early the next year, though variation from this is frequent.
The young scales attack the leaves generally, but
later pass to the twigs. The injury they cause by
removing the sap from the tree is increased by
the honey-dew they secrete, which falling in large
amounts on fruit and leaves, forms an excellent
material in which a sooty fungus grows, and
more or less cuts off light from the leaf surface,
thus affecting the growth, and may also clog the
stomata or breathing pores on the leaves, besides
causing the fruit to look objectionable and need
cleaning before its sale. Control of this pest is
by Hydrocyanic acid fumigation between Septem¬
ber 1st and January 1st. Several parasites and
enemies are known. One parasite, imported from
South Africa, has at times done excellent control
work, but has not been continuously effective.

The Terrapin Scale (Eulecanium nigrofasciatum
Perg.). — This is a native insect attacking various
shade and fruit trees. The scale of the female is
nearly hemispherical in form, about one-sixth of
an inch in diameter, reddish, mottled and streaked
with black (Fig. 213). This insect is viviparous,
the young appearing in June and July and be¬
coming adult the following spring. The young
spend a part of their life on the leaves before
migrating to the stems. Control, when necessary,
is by spraying just before the buds open in spring
with miscible oil, using 5 parts of this and 3 parts
of gasoline thoroughly emulsified, and 92 parts of
water. Fig. 213. — Terrapin Scale

The Cottony Maple Scale (Pulvinaria vitis L.).

This insect attacks maple, linden, and other (right hand figure), and some-
shade trees and plants. The scale of the adult what enlarged (left hand
female is rather flat, about one-fourth of an inch °h>°

in diameter, and by midsummer generally lifted

at one end from the twig it is on, by a projecting mass of cotton-like threads
which surround 2,000 to 3,000 eggs (Fig. 214). These soon hatch and the young
crawl to the leaves and cover themselves with a thin waxy coating. In fall they
migrate to the twigs for the winter and become adult the following spring. When
abundant the large, white, cotton-like masses make this a very noticeable insect.
Contro is by spraying with a miscible oil, 1 part, water 15 parts, just before the
buds open in the spring, or with kerosene emulsion, stock 1 part, water 3 parts.

218

APPLIED ENTOMOLOGY

The Hemispherical Scale ( Saissctia hernisyharica Targ.)- — This scale is
usually found in greenhouses and on house plants, such as ferns, palms, orna¬
mental asparagus, etc., and also out of doors in the South. It is very convex, but
rather oval than hemispherical, about one -eighth of an inch long, brown in color.
The partly grown young are very flat and with a notch at the hinder end. The
eggs are laid during about a 3-month period in late spring, thus resulting in the ap¬
pearance of young during a long time. Fumigation
as for the Black Scale, or dipping the plant in whale-
oil soap 1 lb., water 2 gal., and after an hour rinsing
the plant by dipping it in water, are fairly effective
treatments.

Mealy Bugs

Mealy Bugs move about more or less freely
during their life, as their limbs are not lost to
any extent by degeneration. Nor is a scale
present, the body being generally well covered
by long, waxy threads, though in some cases
waxy secretions forming plates connected with
the body are produced.

These insects are inhabitants of warm cli¬
mates and in the North are found only in green¬
houses and on house plants.

Fig. 215.

Fig. 214. — Cottony Maple Scale ( Pulvinaria vitis L.), about half natural size.
( Modified from. Felt, N. Y. State Mus. Mem. 8.)

Fig. 215. — Citrus Mealy Bug ( Pseudococcus citri Risso.), enlarged.

The Citrus Mealy Bug {Pseudococcus citri Risso). — This insect attacks many
plants and is a serious pest on citrus plants, feeding on the roots, stems, leaves
and fruit, gathering in large clusters on the last. It produces a large amount of
honey-dew, on which the sooty fungus already referred to grows. The adult
females, pale yellow in color and well covered by a th ck waxy secretion (Fig. 215),
are one-fourth of an inch long. The 300 to 500 eggs are laid in loose, white cotton-
like masses, chiefly during fall and winter, and young and adults move about
freely, the former becoming adult before the following summer. The cottony wax
covering the insects renders them particularly difficult to reach with sprays.
The best spray thus far found is a carbolic acid emulsion. To prepare this take
8 gal. of water and boil, adding 8 lb. of soap. After this has dissolved, add 1 lb.
crude carbolic acid and boil 15 to 20 min., which will give a thick, creamy emul¬
sion. To spray, dilute 1 gal. of this with 20 gal. of water. Spray between

THE HOMOPTERA

219

October and March. Hydrocyanic acid fumigation has also given satisfactory
results, especially with light doses frequently repeated. A number of natural
enemies are of some value against this insect.

The Long-tailed Mealy Bug ( Pseudococcus longispinus Targ.). — This is
often found in greenhouses attacking many kinds of plants. The bodies of adult
females vary from yellow to gray, and the young are born alive, there being
apparently several generations each year. Hydrocyanic acid fumigation seems
to be the most successful treatment for these insects. Nicotine sulfate may
also be used.

The Cottony Cushion Scale or Fluted Scale ( Icerya purchasi Mask.). —
This serious pest of citrus and many other plants, apparently reached
California from Australia about 1868 and by 1880 had spread all over
the citrus-growing regions of the State and was threatening the destruc¬
tion of the entire citrus fruit industry.

Fig. 216. — Cottony Cushion Seale ( Icerya purchasi Mask.) and its lady beetle enemy,
the Vedalia ( Novius cardinalis Muls.): a, larvae of the Vedalia feeding on a Seale; b, pupa
of the Vedalia; c, adult Vedalia; d, twig with the Scales and lady beetles, a, greatly
enlarged; real length of b and c shown by hair lines; d about natural size. ( From, Sanderson
and Jackson, Elementary Entmology: after Marlatt, U. S. D. A.)

Investigation showed that in Australia it had an enemy known as
the Vedalia ( Novius cardinalis Muls.), a lady beetle, and these were
finally brought to California and colonized in the orange groves, where
they attacked the scales so effectively that in the course of a few years
these were brought under control, and now only an occasional local
outbreak makes the scale of importance. When this happens, the in¬
troduction of the lady beetles to that region is soon sufficient to check
all injury. In later years the scale has appeared in Portugal, South
Africa and elsewhere, and when the introduction of the Vedalia into those
regions has successfully followed, the scale has soon become relatively
unimportant.

The female scale has a red, yellow or brown body. It lays its 400

220

APPLIED ENTOMOLOGY

to 1,000 eggs in a large cottony mass formed at the hinder end of the
body, the upper surface of the mass being grooved or fluted (Fig. 216).
There are several generations in a season.

Several of the scale insects treated in this chapter furnish good illustra¬
tions of the way in which nature works to preserve a balance in the
insect world. In the first place it should be noticed that our native
scales are often found with tiny circular holes in them showing where
parasites after having fed on the insect beneath, have made their escape.
Other scales, long in this country, such as the Oyster-shell Scale, now
have numerous parasites, some of which are also enemies of other kinds
of scales, and in fact may be considered as scale enemies in general, or at
least of most scales of the same section. New parasites also appear
from time to time as enemies of scales, such as a tiny insect, Prospaltella
perniciosi Tower, first discovered about 1912, which at times has done
remarkably good work against the San Jose Scale. But when a new
scale or other insect native elsewhere, establishes itself in this country,
one of the factors at least in its success here, must be that none of its
parasites in the locality whence it came, accompanied it in its transfer.
If under these circumstances, climatic and other conditions prove
satisfactory, we have a case of an insect set free from all restraint, to
work its destruction with no check, at least until some insect already
present shall select it as a new and satisfactory food. This was evidently
the case with Prospaltella and the San Jose Scale, already mentioned.
In the meantime, however, years of destruction may elapse before any
such check will appear, and the possibility of obtaining its special enemies
from its native country appears to offer much in the way of quick relief.
This “bug vs. bug” idea as it has been called, has a strong appeal to those
suffering losses from the attacks of a newly introduced pest, and it has
therefore been widely exploited.

Probably the first attempt to carry out this idea was the introduction
of the Vedalia for the Cottony Cushion Scale, and in this case an un¬
qualified success resulted. On the other hand, the attempt to establish
the Chinese Lady Beetle in this country to control the San Jose Scale
has thus far been a failure, and the introduction of the parasite Scutel-
listn cyanea Motsch. to work on the Black Scale cannot be regarded as
more than partially effective.

The danger of introducing along with the parasite, its own parasites
(secondary parasites) at such a time is great, and therefore this work
should be attempted only by those especially trained for it.

All in all, the “bug vs. bug” idea is one which, though always having
many possibilities of success, is also one which will often fail, and there¬
for cannot be relied upon as a certain panacea for troubles caused by
introduced pests.

CHAPTER XXVII

THE NEUROPTERA

The insects placed in this group, though quite similar in structure,
differ markedly in appearance in many cases. They vary much in size,
ranging from less than a quarter of an inch to several inches in length,
and their wings may be small or large.

The mouth parts are for chewing or biting, and most of the group
feed upon insects and other small animals. The wings are four in num¬
ber, well supplied with both longitudinal and (with a few exceptions)
cross-veins. The larvae in general are active, moving about in search
of their prey. A few though, live in the egg sacs of spiders, feeding on
the young spiders, and in one or two cases, fresh-water sponges appear
to be their food. There is a quiet pupa stage.

The group may be characterized as:

Insects which when adult have two pairs of wings usually large as com¬
pared with the body and with nwnerous longitudinal and (in most cases )
cross-veins. Mouth parts for chewing. Metamorphosis complete.

So far as is known, none of the Neuroptera are injurious insects and
some at least are decidedly beneficial. About half a dozen families are
usually recognized and some of these are here considered, either because
of their economic importance or because they are large and common
enough to frequently attract attention.

In the family Sialidae belongs the largest member of the order (Fig.
217) found in the United States. This is commonly called the Corydalis
or Hellgrammite ( Corydalis cornuta L.) which is quite common throughout
the country except in arid regions. The mandibles of the male are
nearly an inch long, slender and somewhat curved; those of the female
are short. The distance from tip to tip of the wings when these are
extended, may be over five inches, and the size of the insect and the long
jaws of the male have led to the mistaken belief that this really harmless
animal is dangerous. The egg are laid in large masses on objects which
hang over the water, into which the larvae enter on hatching, making
their way under stones where they feed for nearly 3 years on the nymphs
of May-flies and other insects. Here they are searched for by fishermen
to use as bait, and are usually called ‘'Dobsons.” When full-grown the
larva makes a cell under some stone close to the stream and pupates
for about a month, after which the adult escapes .

221

222

APPLIED ENTOMOLOGY

Smaller species, some with gray, black, or black wings spotted with
white, belong here. They are often. quite common around streams and
ponds during the summer months and are frequently called “Fish-flies.”

Fig. 217. — Adult Corydalis, about natural size and its larva. ( From Sanderson and
Jackson, Elementary Entmology; after Comstock.)

The members of the family Chrysopidae are of great economic im¬
portance as the larvae feed freely on injurious insects, particularly aphids,
and are so voracious, that they are often called Aphis-lions. The adults
(Fig. 218) are rather small, slender-bodied insects averaging less than an

Fig. 218. — Adult Lacewing (Chrysopa plorabunda Fitch), slightly reduced. [From Folsom.)

inch long, with long antennae and large, finely-veined, green wings, which
when not in use are carried sloping over the body. These adults are
sometimes called “Golden-eyes” because of their shining, golden-yellow
eyes, but perhaps more frequently “Lace-wings” from the delicacy and
beauty of these structures.

THE NEUROPTERA

223

The Lace-wings are found practically everywhere in this country
and are usually quite abundant. They lay their eggs on the stems,
branches, and leaves of plants, first constructing a slender but quite stiff
stalk of silk about half an inch long, to the end of which the egg itself is
attached (Fig. 219). These eggs are usually placed in groups and it is
believed that were the eggs not raised on stalks out of reach, the first
larva to hatch would at once proceed to eat the eggs as its first meal.

Fig. 219. — Eggs of a Lacewing, greatly enlarged. ( From Sanderson and Jackson,
Elementary Entmoloyy; after S. G. Hunter.)

These larvse are rather short, somewhat oval in outline, and have long
mandibles with which they grasp their prey. The lower side of each
mandible is grooved and the maxilla of the same side is so modified as to
fit into this groove and convert it into a tube. An insect attacked by an
Aphis-lion is seized by the tips of the jaws and its blood is drawn through
the tubes into the body of its captor.

Aphis-lions are often found in colonies of plant lice which have by their
feeding caused leaves to curl, and with an abundant food supply thus
provided, the insect is both protected by the leaf and insured of the food
it needs for its development.

When full-grown the Aphis-lion forms around its body a white, shin¬
ing, spherical silken cocoon in which it pupates. When this process is
complete the adult cuts out a circular piece of the cocoon, forming a hole
through which it escapes.

The importance of Lace-wings as friends of man is such that they
should be protected and not destroyed under the impression that being
among known pests they must also be for that reason injurious.

224

APPLIED ENTOMOLOGY

In the Western States are a few insects belonging to the Neuroptera, and
family Raphidiidae. They are small, less than an inch in length, but with an
unusually long prothorax (Fig. 220). The larvae feed on other insects and,
among others, on codling moth larvae. They occur chiefly under loose bark in
this stage, and while not as abundant as could be desired, do good work by attack¬
ing many injurious species. They have been introduced into Australia in the
hope that they may become effective enemies of the codling moth there.

Fig. 220.

Fig. 221.

Fig. 220. — Adult Raphidian ( Raphidia oblita Hagen), about twice natural size.
{Original.)

Fig. 221. — Adult Mantispa {M antispa brunnsa Say) showing grasping front legs.
Somewhat enlarged. {Original.)

Another family, the Mantispidae, though few in numbers, has its members
quite widely distributed. The Mantispas (Fig. 221) as they are called, like the
Raphidians, have a greatly elongated prothorax and their fore legs are also long
and adapted to grasping their prey. The adults are larger than the Raphidians,
being about an inch in length and with long wings. Though feeding on other
insects, most of which are likely to be injurious, the Mantispas are not numerous
enough to be of any great importance.

Fig. 222. — Adult Ant-lion about natural size. {Original.)
Fig. 223. — Larva of an Ant-lion, about twice natural size.

Fig. 223.
{Afier Meinert.)

The insects belonging to the Family Myrmeleonidae are generally
spoken of as the Ant-lions, though the name “Doodle-bug” is sometimes
applied to their larvae. They are widely distributed over the United
States, particularly in sandy places, but are most abundant in the South.

THE NEUROPTERA

225

Many kinds of the adults (Fig. 222) superficially greatly resemble the
“damsel-fly” section of the Dragon-flies (Odonata), their long, slender
bodies, large, gauzy wings and their general size causing the resemblance.
Their antennae, however, instead of being very small and not noticeable,
are of fair size and knobbed at the tip, which provides an easy way by
which to distinguish the two groups. Other characters and their life
history also prove that the resemblance is only superficial.

The larvae of the ant-lions (Fig. 223) greatly resemble those of the
lace-wings in general form and in the possession of long jaws grooved for
sucking the blood of their victims. They excavate little conical pits
in soft, dry, preferably sandy ground, an inch or two across and as deep
as possible for the sandy sides to hold. At the bottom of the pit thus dug
the young ant-lion buries itself except for its head, and waits for an
unwary insect to fall in. Sliding down the slope of loose earth the victim
literally falls into the jaws of the waiting enemy and is killed and de¬
voured. It has been stated that sometimes the insect on its way down
the side of the pit is able to check itself and start to climb out, and that
then the ant-lion shovels a load of sand onto the top of its flat head, with
its leg, and snaps the sand up the side of the pit, where falling, it sweeps
the prey down to the bottom within reach of the ant-lion!

The process of excavating the pit is also one of extreme interest.
The insect first traces out a circle of the desired size, loading its head with
sand from inside the circle and snapping it out, and on completing the
circle, repeats the process but in the reverse direction, and this is continued
until the pit has been completed. In doing this the larva always moves
backward.

After becoming full-grown the ant-lion larva forms a spherical cocoon
of sand and silk in the ground, within which it transforms to the adult.

The ant-lions, though feeding on other insects, are of little if any
economic importance as the forms they are most liable to capture are not
often probably, serious pests. Their habits and manner of life, how¬
ever, are so interesting that much attention has been given to them and
what has been published about them forms one of the most interesting
chapters of Entomology.

The Neuroptera, though widely distributed over the world, do not
constitute a large group. Less than two hundred kinds are known in
this country, and probably not more than a thousand kinds in all have
thus far been discovered. Fossil specimens of several of the families have
been recognized.

15

CHAPTER XXVIII

THE TRICHOPTERA

The Caddice (sometimes spelled Caddis) Flies, as the members of this
order are usually called, are rather soft-bodied insects ranging in size
from less than an eighth of an inch to an inch or more in length.

The wings, though much reduced in a few cases, are almost always
large and well developed, with numerous longitudinal, but few cross-veins.
They are membranous, the front pair somewhat leathery, and all are
more or less densely covered with hairs which in some species are rather
scale-like in form. The hind wings are usually broader than the front
pair and when not in use are sometimes folded lengthwise. The position
of all the wings when at rest is with their hinder margins together over the
back of the insect and. their costas down at the sides of the body, upper
faces sloping downward and outward like a house roof (Fig. 224).

The mouth parts of the adult are poorly developed though evidently
modified from the chewing type and it is probable that little if any food is
taken in this stage. The antennae are generally well developed, and in
some species they may be several times’ as long as the body. The legs
are quite long and slender.

The larvae (Fig. 225) somewhat resemble small caterpillars in form.
They are nearly all found in water, chiefly that of ponds or slow-running
streams, though a few inhabit rapid currents. The abdomen is soft, the
chitinous skin being delicate, and the larvae therefore construct cases of
various materials. as a protection for this portion of the body.

The Trichoptera may be defined as:

Insects which as adults have rather soft bodies: four membranous wings
with numerous longitudinal and few cross-veins, and more or less closely
covered by hairs, folded over the body like a house roof when at rest: mouth
parts rather rudimentary: antennae and legs quite long, the former sometimes
exceptionally so. Larvce living in cases, nearly always in the water. Meta¬
morphosis complete.

The adult Caddice-fly, though having well-developed wings, is not a
strong flier and these insects are therefore most frequently found near
water.

The eggs are, at least usually, laid in clusters in a mass of jelly, and
are probably dropped into the water. On hatching, the larvae begin the
construction of cases in which to live. The materials of which these are

226

THE TRICHOPTERA

227

made differ according to the species of Caddice-fly concerned and vary
greatly (Fig. 226). Some take pieces of leaves which have fallen into the
water; others select veins of the leaves and similar sized straws and put
them together cris-cross, something like the logs of a log house; some
species use the finest sand for this purpose;
others coarse gravel, and still others use a mix¬
ture of long and short pieces of plants so that
the ends of the longer ones extend some distance
behind the end of the case.

The case itself is usually straight but in some
species it may be curled, and resembles a small
snail-shell. Indeed this resemblance is so close
that in one instance at least, such a case was
actually described as that of a shell! The ma¬
terials, whatever they may be, are held together
by silk spun by the larva, coming from silk glands
within the body and poured out through an
opening close to the mouth. Within the case
the larva lives, crawling about by extending its

Fig. 224. — Caddice-flies: adult at rest, above; with wings spread, below. Larvae showing
three kinds of rases, crawling. ( From Linville and Kelly , General Zoology.)

head and thorax out of the front end so that its feet can be used, and
dragging the case along.

Some caddice-fly larvse make simpler houses than these. Such species
live in rapid water and there fasten a few tiny stones under rocks by their

228

APPLIED ENTOMOLOGY

silk, and between these spin a silken tube in which to live. Close to this
they spin more or less funnel-shaped webs, the mouth up-stream and so
arranged that tiny animals swept down by the current within the outer
limits of the funnel come within reach of the larva lying in its tube.
While the food of these larvae is carnivorous, in most of the species plant
materials are consumed.

The larvae, in most cases, breathe by tracheal gills which are slender
filaments, frequently grouped in clusters, and attached to the abdominal
segments. Other structures present in some species are also suspected of
being concerned with respiration.

Fig. 225. Fig. 226.

Fig. 225. — Caddice-fly larvae: larva with head and thorax extended out of its case,
above; larva removed from its case, below, showing tracheal gills. About twice natural
size. (Modified from Leuckart's Wandtafeln.)

Fig. 226. — Examples of different types of cases formed by Caddice-fly larvae. (From
Sanderson a?id Jackson, Elementary Entomology: after Furneaux.)

When full-grown the Caddice-worm forms a sort of lid or door grating
across the front opening of its case, though not complete enough to pre¬
vent water from entering and supplying the insect with the oxygen it
needs. After pupation in its case the adult swims to the surface and
grasps some object, from which it takes its flight. In some species it is
apparently the pupa which when ready to become the adult, comes
to the surface and passes its final molt there.

The Trichoptera is quite a large group of insects and representatives
of it are found in almost all parts of the world. Probably not many more
than a thousand species have been described, as they do not appear to be
of any economic importance unless their consumption of decaying vege¬
table matter in pools can be considered as desirable, but it is very likely
that there are from five to ten thousand kinds in existence. Their cases
have been found as fossils and adults have also been preserved in this way.

THE TRICHOPTERA

229

The Trichoptera are evidently closely related to the Lepidoptera in
many ways and are undoubtedly with the last-named order, divergent
descendants iiom common ancestors. Some Lepidoptera so closelv resem¬
ble Trichoptera in fact, that they have been placed in the latter group.
They also have many resemblances to the Neuroptera, but their connec¬
tion with this order is plainly more remote, and sufficient time has elapsed
since the divergence of the present Neuroptera and Trichoptera from their
common ancestors, to permit the development of many differences.

CHAPTER XXIX

THE LEPIDOPTERA

The Lepidoptera are the moths and butterflies, which form one of
the largest and most noticeable groups of insects. Its members are
found in all countries and their large size in many cases, their brilliant
colors and the habits of their larvae as well as the injuries they cause,
have attracted much attention.

The adults have four, large, membranous wings in most cases (a few
have lost their wings), more or less completely covered by overlapping
scales making the wings opaque where these are present. Colors of the

wings are due either to the presence of
pigments in the scales: to optical colors
caused by the surfaces of the scales break¬
ing up the light striking them; or by both
factors together.

The mouth parts of the adult are greatly
modified from those of chewing insects,
though enough remains to show that the
ancestors of the group must have fed by
chewing. The development of the parts
varies in different species, some of the
lower forms having as a whole, a much
closer resemblance to the condition in
chewing insects than is the case with most
of them. In one group, the mouth parts
are sufficiently of the mandibulate type to
enable the insects to feed on pollen.

In general a labrum or front lip is evi¬
dent, but the mandibles are practically lost.
The maxillae are extremely modified, a por¬
tion of each contributing its half to the formation of a proboscis or tongue
(Fig. 227). This is a flexible organ varying greatly in length, its two
halves so interlocking as to form a tube between them, through which,
when completely developed, fluids may be drawn into the mouth. The
degree of development of the proboscis differs greatly in different
Lepidoptera, and while it is functional in perhaps the majority of the
group it is only partly developed or even rudimentary and useless in
others. Such Lepidoptera evidently do not feed while adult.

230

Fig. 227. — Diagram of head of
a Lepidopterous insect, showing
the tongue. ( From a drawing by
M. F. Webster.)

THE LEPIDOPTERA

231

In some cases the maxillary palpus is developed: in others it is nearly
or wholly lacking. The labium or hinder lip is also practically absent
except for the labial palpi which are usually large, thickly covered by
hairs or scales, and project forward at the sides of the head, often
turning upward somewhat, and partially or wholly concealing the pro¬
boscis when this is coiled up under the head, the place where it is carried
when not in use.

The mouth parts of the larva (or caterpillar as it is usually called)
are entirely different. In this stage they are chewing structures, similar
to those of a grasshopper in a general way, and no special description is
needed. In the center of the end of the labium, however, is a slender
projection called the spinneret, which at its tip has the external opening
of the duct leading to the silk glands.

The antennae of adult Lepidoptera are usually quite long but vary
greatly in their form in different species. In the butterflies they are
slender but enlarged near the tip forming a club (Figs. 309 to 317), or
with this enlarged part bent into a sort of hook (Fig. 308). These forms
of antennae are almost never found in the moths, where they may be
simple and thread-like; with small hair-like projections at the side;
bristles in place of the hairs; clusters of the bristles; with tooth-like or
saw-like side projections; with long projections on one or both sides, in
the latter case giving the antennae a feather-like appearance; and other
forms also occur. (Compare Figs. 228 to 305).

The eyes are large, though in some cases partly concealed by hairs
or scales, which as a rule thickly clothe the entire body. Ocelli are also
sometimes present. On the top of the prothorax a pair of projections or
lobes often occurs, called patagiae, sometimes very large -and capable of
some movement ; in others, smaller or even reduced to mere traces. On
the large mesothorax is a somewhat similar pair of structures called the
tegulse which extend backward over the point where each fore wing
articulates with the body. The abdomen may be long or short, stout
or slender, connected with the thorax either by a broad or a rather
constricted attachment. The legs are quite long and slender.

Characters by which the members of this group may be distinguished
are:

Insects which as adults have ( with a few exceptions) four membranous
wings more or less completely covered by overlapping scales: mouth parts
for sucking. The larvae have chewing mouth parts. Metamorphosis
complete.

The Lepidoptera is such a large order that great differences in its
members are very common. The smallest ones are almost microscopic
while the largest one known may measure about a foot between the tips
of its expanded wings. The wings of each side, to obtain their greatest
efficiency, are more or less completely coordinated for flight by one

232

APPLIED ENTOMOLOGY

of three methods. In the butterflies and some of the moths, the basal
portion of the costal region of the hind wing is enlarged, forming a sort
of shoulder over which the hind margin of the fore wing lies, thus enabling
the two to a large extent, to function as a single wing. In most moths,
however, instead of a shoulder, a rather long, curved bristle or cluster of
bristles, called a frenulum, arises near the base of the hind wing and runs
forward and outward, passing under a small flap or through a tuft of
scales on the under side of the fore wing, so that as the two wings move in
flight, this frenulum slides backward and forward in its track under the
fore wing and holds the two together. A third type of connection, found
in only a few moths, is a small lobe near the base of the hind margin of
the fore wing, which extends backward toward the hind wing. This lobe
is called a jugum and is also probably more or less effective in producing
coordination in the use of the wings.

The number and arrangement of the wing veins is of great importance
in the Lepidoptera, much of the classification in this order being based
upon these structures. The main veins (see Fig. 20) are of course,
longitudinal, starting at the point of attachment of the wing to the body
and diverging toward its outer margin, some of them branching several
times. Cross-veins are very few, however, and consequently there are
only a few closed cells (see page 13), and some at least (perhaps all)
of these are produced by the fusion of branches of longitudinal veins,
rather than by true cross-veins.

Various ways of designating the veins and their branches have been
offered, but these are best comprehended in connection with laboratory
work on the insects themselves, and are therefore not given here.

The eggs of Lepidoptera vary greatly in form and also in color.
They may be elongate, spherical, flattened, scale-like, or of other forms,
and the shell or chorion may be smooth or sculptured with ridges and
reticulations. The eggs may be laid singly or in clusters and may or
may not be covered with hairs from the body of the parent moth, or
with a secretion which conceals them from view. They may hatch in
a few days or after longer periods, in some cases many months. The
adults have no ovipositor so the eggs are always laid on the surface
of the place of deposition, though if the abdomen of the insect be small,
this may be in a small crack or other opening.

The larvae produced by the hatching of the eggs are called cater¬
pillars and have no resemblance whatever to the adults they are to
become. They are usually rather worm-like animals, with a generally
recognizable head and a body consisting of a series of rather similar seg¬
ments, the first three of which correspond to the thorax of the adult and
almost always bear six legs. Some of the following segments will also
have legs but these are totally different in structure from the others and
are merely temporary in their nature, designed to support this portion of
the body.

THE LEPI DOPTERA

233

The internal structures of the caterpillar do not differ greatly in their
arrangement from those of an adult insect, except that the reproductive
organs are only slightly developed at this time, and in the presence
along each side of the body of a silk gland, large in those which will
later need large quantities of silk, but present in all. A duct from each
gland runs forward to the mouth where the two unite and open to the
exterior through the spinneret already referred to.

Most caterpillars feed on plants or vegetable material. Their work
is noticed chiefly by their stripping plants of their leaves, though some
bore in stems, roots, fruit, seeds or other parts. A few attack feathers,
silk, etc., but this is not the general habit. The larval stage may last
only a few days for some species but is generally a month or more, and
some feed during the fall, become quiet during the winter, and complete
their feeding the following spring.

A large majority of the caterpillars are termed naked, having only
a few tiny spines or hairs, not large enough to be noticeable. From
this condition every grade of density of covering occurs, to species entirely
covered by long, thickly placed hairs which give the animal a hairy or
“ woolly ” appearance. Some have large warts or horns on the thorax or a
sort of horn above, near the hinder end of the body.

Their colors also vary greatly, some being brightly colored while
others, green, either with or without white streaks, appear to seek con¬
cealment by their resemblance to the leaves on which they feed. Those
living in protected situations, such as in plant stalks, are nearly white:
cutworms which pass the day in the ground are dark as a rule, with
rather faint markings.

When the caterpillar has become full-grown it generally leaves the
place where it was feeding and in some satisfactory location, spins a
cocoon around itself, using for this purpose the silk produced by its
silk glands. In some species the cocoon is very complete, thick, tough,
and entirely conceals the larva within. On the other hand, there are
cocoons where only sufficient silk is used to attach the insect and hold it
in place; and between these extremes all degrees of cocoon construction
occur. Sometimes leaves, hairs from the body of the caterpillar, or dirt
when the insect enters the ground at this stage, are incorporated in the
cocoon.

Within the cocoon the caterpillar molts, leaving its cast-off skin at
one end. The result of this molt is a pupa, its form showing through
its new skin which is generally brown, the outlines of the adult body
and its appendages including the wings being evident, these last, however,
very small as there would be no room for the full-sized wings of the adult
within the cocoon. Internal changes and the completion of such external
ones as are necessary, now proceed until the adult insect has been entirely
formed, and is ready to escape. When this happens another molt re-

234

APPLIED ENTOMOLOGY

leases the insect from the brown outer pupa skin, and either before or
after this, an opening in the cocoon is made and the adult emerges.
It then crawls up on something and remains quiet for a while; its wings
being free to expand, increase rapidly till of their full size; the surplus
fluids in the body are expelled, and after an hour or two the insect is
ready for flight.

While for most Lepidoptera this outline of development is in general
correct, in the butterflies we find that cocoon making is limited to attach¬
ing the hinder end of the body by silk, to the object on which it is to
pupate, and the formation of a silken loop around its body to hold it up.
Such a pupa, producing a butterfly, is usually given the special name
“chrysalis.” (See Fig. 317/).

Besides the names “butterflies” (Rhopalocera), and “moths”
(Heterocera) used to distinguish different sections of the Lepidoptera,
we also have the terms “Microlepidoptera” or small moths, and “Macro-
lepidoptera” or large ones. These are wholly relative and rather indefi¬
nite, but are nevertheless convenient in spite of the fact that it would be
doubtful under which head to designate many species of the order.

The latest list of the insects of this order found in North America
places them in about 70 families, but there are more of these divi¬
sions in other parts of the world. Some of the families include many
species and insects of much economic importance, while others have
only a very few. Only the more important families, either in size or
because of the pests they contain, are included here.

Family Cossidae (Carpenter Moths). — The larvae of the moths belonging in
this family bore in trees and are sometimes quite injurious. There are several
native species, the most common being the Carpenter Worm or Goat Moth
(Prionoxystus robinice Peck) which lays its eggs in the crevices of the bark of
various trees. The larvae bore in the limbs injuring or killing them, and the
entire life history is believed to take 3 years. The adults which appear in June
and July are quite large, the wings of the female spreading about three, and those
of the male about two inches. The wings are mottled light and dark gray, except
the hind wings of the male which are yellow. The Leopard Moth ( Zeuzera
pyrina L.), a European pest belonging in this family, reached this country before
1879 and now occurs along the Atlantic Coast from New Hampshire to Delaware
and a rather short distance inland. The wings of the moths (Fig. 228) spread from
one to about two inches and are white with numerous black spots. The thorax
has seven black spots above. The moths appear from May till September and lay
their eggs on the bark, several hundred in all, but usually only a few at a place.
The caterpillars (Fig. 229) are liable to enter the small twigs, but may enter else¬
where, and bore through the wood. Small twigs are killed and larger ones weak¬
ened and in time may also be destroyed by this boring, and if the branch becomes
too small at any time for the larva, it will leave it for a larger one. Injured
limbs are often so weakened as to break off during storms. The borer feeds during
parts of three seasons, pupating in its burrow the third spring. It is more
abundant in and near cities and towns than in the open country

THE LEPI DOPTERA

235

The work of borers of this group is often evidenced by fine chips, excrement
or frass pushed out of the entrances to the tunnels; by wilted leaves; by tunnels

Fig. 228. — Adult female (left) and male (right) of the Leopard Moth ( Zeuzera pyrina L.)
about natural size. ( From Britton, Eleventh Rept . Ent. Conn . Ayr. Exp. Sta. 1911.)

Fig. 229. — Larva of Leopard Moth in its burrow. Natural size. ( From Britton, Eleventh
Rept. Ent. Conn. Ayr. Exp. Sta. 1911.)

in fallen branches, and by splits and breaks in the bark when the larvse work just
beneath it.

236

APPLIED ENTOMOLOGY

Control for the Leopard Moth and for Carpenter Moths in general is to locate
the entrance holes of the larvse and inject a little carbon disulfid into them, then
stopping the opening with putty, mud or wax. Thoroughly infested trees should
be cut and burned during the cold months, to destroy the caterpillars in them,
as such trees are doomed in any case.

Family Tineidae (Tineids). — -The insects belonging in this family
are all Microlepidoptera, the distance between the tips of their wings
when spread being generally much less than an inch. They are not
noticeable insects and only a few are of great importance. Three,
however, are serious household pests and cause much injury, being the
species commonly called Clothes Moths, all natives of Europe but for
many years now, present in this country.

The Case-making Clothes Moth ( Tinea pellionella L.). — This is the
most generally distributed of the three species and is the most common
one in the North. The moth flies at night and may frequently be seen in

Fig. 230. Fig. 231.

Fig. 230.- — -Adult of Case-making Clothes Moth ( Tinea pellionella L.) four times natural
size. ( From Herrick’s Insects Injurious to the Household. By Permission of the Macmillan
Company, Publishers.)

Fig. 231. — Case of the Case-making Clothes Moth, three times natural size. ( From
Herrick's Insects Injurious to the Household. By Permission of the Macmillan Company,
Publishers.)

infested houses flying about the rooms but not attracted to any light
there may be present. In fact, if during June, July or August any tiny
moth flies to the light in a room at night, that fact is of itself evidence that
the insect is not a clothes moth.

The adult (Fig. 230) is grayish-yellow with faint spots, its hind wings
more nearly a silvery gray. It spreads about half an inch. The eggs are
generally laid on woolen goods of any kind, furs or feathers. They
hatch in about 10 days and each larva constructs a case (Fig. 231) made of
particles of the materials on which it feeds, lined with silk, and with its
body in the case, crawls about, feeding as it goes. As it grows and the
case becomes too small, the caterpillar enlarges it and when full-grown
attaches it to some object and pupates in it, the moth emerging about
3 weeks later. In the North there usually seems to be but one generation
a year but in the South there are two and possibly more.

The Webbing Clothes Moth ( Tineola biselliella Hum.). — This species,
though found in the North, is most common in the South. The adult

THE LEPIDOPTERA

237

(Fig. 232) is of about the same size as that of the last-described species,
but its fore wings are uniformly yellowish. There are two generations
each year. The caterpillar feeds on the same materials as that of the
Case-making Clothes Moth and has also been known to eat cobwebs,
dried specimens of insects and beef meal. It does not form a case but
spins a sort of web of silk as it moves about. When ready to pupate
it forms a cocoon of silk to which particles of wool or whatever it has been
feeding on, are added.

Fig. 233.

Fig. 232.

Fig. 232. — Adult of the Webbing Clothes Moth ( Tineola biselliella Hum.), four times
natural size. ( From Herrick's Insects Injurious to the Household. By Permission of the.
M acmillan Company, Publishers.)

Fig. 233. — Adult of the Tapestry Moth ( Trichophaga tapetzella L.), three times natural
size. ( From Herrick's Insects Injurious to the Household. By Permission of the Macmillan
Company, Publishers.)

The Tapestry Moth ( Trichophaga tapetzella L.). — The Tapestry Moth
is not as common in this country as the other two clothes moths, and is
a larger insect (Fig. 233), spreading about three-quarters of an inch. It
seems to prefer to attack heavier and coarser cloths than the other species,
' as well as felts, skins, etc., and is found in carriage upholstering and similar
places, as often as in houses. The caterpillar tunnels in its food, lining
the galleries somewhat with silk, and in these galleries it also pupates.

Control for Clothes Moths. — All woolen goods, furs, feathers, rugs and
similar materials not in regular use during the summer should be care¬
fully aired in the sun as long as possible, and brushed, beaten or shaken
thoroughly before being put away in the spring. They should then be
placed in tight trunks, boxes or bags either of cloth or paper. After
being thus treated they should be safe for the summer, provided no
eggs nor larvae have escaped and are still present in the materials. But
a surer method is to thoroughly fumigate the articles when they are
packed away, using carbon disulfid. Thus an ordinary trunk filled with
such articles can be fumigated for from 24 to 48 hr., then opened and a
liberal supply of moth balls (naphthaline) or flake naphthaline be added
and the trunk finally closed.

Repellents are of some value to keep clothes moths away from
materials liable to injury, but their value is largely dependent upon the
amount used and on whether the insects are already present. It appears
that while clothes moths will not usually, at least, lay their eggs on
materials stored with an abundant supply of naphthaline, this substance

238

APPLIED ENTOMOLOGY

in any such amounts as are usually added will not keep eggs already
present from hatching, nor the larvae from feeding. Therefore, fumiga¬
tion first, to kill any of these insects which may be present in any stage,
followed by an abundant supply of naphthaline to keep them away
thereafter would seem to be the best method of procedure.

Other repellents often used are cedar-wood chests, sprigs or chips of
cedar, camphor, tarred paper, and tobacco. They are all repellents,
but apparently less effective than naphthaline. In the case of cedar it
is the oil present which gives the protection, and as this is volatile it is
lost after a time and then a cedar chest is of no more value for storage
than one of any other kind of wood.

Closets often become infested by clothes moths and even after taking
out and treating the clothing the moths may appear. It is probable
that in such cases the larvae find particles of wool or other edible materials
in the cracks of the floor or e]se where on which to live. In such cases the
free use of gasoline or kerosene on the walls and floors, paying particular
attention to all cracks, followed after a few hours by a thorough airing,
should give relief. If not, fumigation of the closet, being careful that
cracks around the doors or other openings are tightly sealed, will
exterminate the insects there.

Rugs and carpets infested should be thoroughly cleaned and can
then either be baked to 125°F.. fumigated as above, or sprayed with
benzine. Furniture attacked may be saturated with benzine or fumi¬
gated. Where an entire house is infested, no one place apparently
more than another, fumigating with hydrocyanic acid gas at the rate
of 1 oz. of sodium cyanicl to every 100 cu. ft. of space has given good
results.

Rugs, furs and woolens valuable enough to place in cold storage
may be protected during the summer by cold. It has been found that
exposing infested goods to very low temperatures for a few days, followed
by another short period in a fairly warm place, then returning them to the
cold room for a short time will kill the insects present, these being unable
to live through such severe temperature changes. After this the articles
can be stored during the rest of the season in a temperature of about 40°F.
with safety.

Family Eucosmidse. — In this family are a number of pests of fruit
trees and other plants. All of them are small moths, rarely spreading
over three-quarters of an inch. One of the worst pests of the apple — the
apple-worm or codling moth — belongs here.

The Codling-moth ( Laspeyresia pomonella L.). — This pest of apples,
pears and occasionally of other fruits is a native of Southeastern Europe
but is now found almost every where and is present in all the apple-growing
sections of this country.

THE LEPIDOPTERA

239

The adult moth (Fig. 234) has its fore-wings brown, crossed by irreg¬
ular gray and brown lines. It spreads about three-quarters of an inch
and is not often seen as it flies only at night and is not attracted by lights.

Winter is passed in the full-grown caterpillar stage in some protected
place, usually under a piece of bark of the tree where the insect fed (Fig.
235). Under the bark the caterpillar digs out
an oval cavity and lines it with silk in which to
winter. In the spring it pupates here and the
adult moth escapes a week or two after the
petals fall at the blossoming season in the

Fig. 234. Fig. 235.

Fig. 234. — Adult Codling Moth ( Laspeyresia pomonella L.), twice natural size.
{Original.)

Fig. 235. — Piece of bark showing Codling Moth cocoons and pupae on its under
surface. About one-third less than natural size. {Modified from Cornell Agr. Exp. Sta.
Bull. 142.)

spring. Tiny, white, flattened eggs, 50 to 75 in number, are now laid
singly on leaves, twigs or on the small fruit, but mainly on the leaves.
The eggs hatch in about a week and the little caterpillars feed for a short
time on the foliage, but soon leave this and crawl to the fruit, where from
60 to 80 per cent enter at the blossom end, often burrowing their way
through between the closed calyx lobes or sepals to reach the cup-shaped
cavity within. From the bottom of this cavity they tunnel into the fruit
to the core, in and around which they
feed until full-grown; a period of
nearly a month in most cases. The
other 20 to 40 per cent enter the fruit
at any point, but appear to prefer a
place where a leaf or some other
object lies against the fruit.

When its growth has been com¬
pleted the caterpillar (Fig. 236) is
about three-quarters of an inch long,

pinkish or whitish, with its head and a patch above, just behind the head,
and another at the hinder end of the body, brown. It now leaves the
fruit, generally burrowing out through the side and makes its way down
the tree until it finds some piece of bark loose enough to permit it to
gnaw its way under, and here it forms an oval cavity as already
described.

Fig. 236. — Full-grown larva of Codling
Moth, about twice natural size. {Modi¬
fied from Cornell Agr. Exp. Sta. Bull. 142.)

240

APPLIED ENTOMOLOGY

Over the greater part of the United States there are two generations
of the Codling-moth each year. Where this is the case the larva pupates
in this cavity for about 2 weeks before it escapes as an adult. Eggs are
now laid for the second generation and on hatching the larvae attack the
fruit, which is quite well grown by this time, entering it at any point and
showing no preference for the blossom end. The feeding of this genera¬
tion of caterpillars proceeds as with the spring generation, but in many
cases has not been completed when the fruit is gathered. In this way
a number of the larvae may be carried to the bins or barrels in which the
fruit is stored. Later, they leave the fruit and make their wintering
cases on the sides of the bins or elsewhere.

In the Northern States there is only a partial second generation,
most of the caterpillars feeding during late June and July, failing to
transform into moths that season, so that the work of the insects in fruit
during the fall is comparatively unimportant. From Southern New
England south, however, two complete generations are the rule and in the
more southern States with long growing seasons, there may be three gener¬
ations. In the West, even as far north as Washington, two generations
occur. Cold and drought have a considerable effect everywhere, how¬
ever, late springs reducing the number of moths which appear the same
season.

The injury caused by this insect places it among our most important
pests. Small apples attacked, drop in many cases, resulting in the entire
loss of some of the fruit early in the season. In years of an abundant
crop, this is of less importance, but in “off years” it is a serious matter.
Fruit infested which remains upon the tree is reduced in value and thus
another loss is produced. It has been estimated that a few years ago
the State of New York alone lost apples and pears forming a third of the
entire crop, which valued at SI. 50 per barrel, would amount to about
$3,000,000 per year.

Control. — There appear to be two chief ways by which the habits of
this insect aid in control measures. The number which enter the fruit
at its blossom end is large, and poison placed there for them to eat as they
bore their way through it into the apple, has proved effective. The fact
that the caterpillars feed for a time on the leaves before going to the fruit
also indicates a place for successful treatment.

Accordingly, spraying with arsenate of lead, standard formula, within
10 days after the petals fall, directing the spray so that as far as possible
it will fall into the cup surrounded by the calyx lobes (sepals) is the most
usual method of control. In applying this spray, however, it should be
remembered that in the case of the apple these calyx lobes which at first
stand widely open around the edges of the cup, soon draw together and
close up the cup mouth, after which no spray can be placed where it is of
use (Fig. 237). This closing comes about 10 days after the petals fall

THE LEPIDOPTERA

241

(Fig. 238) and thus limits the effective spray period to that time. For¬
tunately, different varieties of apples do not bloom at quite the same time,
so that spraying where large orchards are involved should begin with those

Fig. 237. — Apple blossoms in proper condition for receiving the calyx spray. Adult
Codling Moth, natural size, above. ( From Felt , 27th. Rept. N. Y. State Ent., 1911.)

trees which lose their petals first, taking the later-blooming varieties
afterwards. When the sepals close this helps to hold the poison in the
cup ready to be consumed whenever the caterpillars reach it. Where

Fig. 238. — Small apple showing calyx lobes practically closed. Too late for successful
spraying. ( Modified from Cornell Agr. Exp. Sta. Bull. 142.)

pears are to be sprayed, their treatment can be postponed until the work
on the apples has been completed, as in the pear the calyx lobes do not
16

242

APPLIED ENTOMOLOGY

close and the spray can be successfully applied more than 10 days after
the petals fall.

About 3 weeks after the petals have fallen, or perhaps a few days
later, a second spray of arsenate of lead, placed upon the leaves, poisons
these just before the young caterpillars of the Codling-moth hatch and
begin to feed. Many of these larvse will thus be poisoned before they
reach the fruit.

Another application of arsenate of lead 8 or 9 weeks after the petals
fall will poison the leaves just before the second generation of caterpillars
begins feeding, which seems to be the chief protection available against
these insects at this time.

Minor methods for reducing the numbers of this pest are also made use
of. Some of the caterpillars may escape death from feeding on the poi¬
soned leaves and in the first, as well as in the second generation, enter the
fruit through the side. These larvse cannot themselves be reached, but
the pupae or adults they become, if destroyed, will reduce the number of
the next generation. To accomplish this all loose bark on the trees is
removed about the first, of July (earlier in the South) and a loose band of
cloth or burlap is placed around the trunk. The larvse on leaving the
fruit, seek for a place in which to transform to adults, and finding no bark
under which to make their cocoons, crawl down the tree till they find the
band which provides the opportunity they desire, and under which they
therefore go. Turning over this band frequently during the summer and
fall and destroying the insects found under it will therefore eliminate
them from any further consideration.

Cleaning out bins, barrels and all other places where fruit has been
stored, early in the spring, destroying all the insects found there is also
a good practice and is a desirable treatment for the Codling moths
located in such places.

In spraying for the codling-moth there has been a considerable
difference of opinion as to the most successful method. Some western
workers have advised a rather coarse spray driven with great force, such
as by a pressure of 200 lb. or more at the pump, just after the petals
fall, claiming that, in this way the spray is driven to the bottom of the
cup and that later sprayings are unnecessary. Others, mainly in the
East, have advised a misty spray driven by a pressure of about 100 lb.,
and giving a second (and where there are two full generations a third)
spray. These opposing views may have an explanation in the different
conditions in apples at the calyx end during and after the closing of the
calyx lobes in different parts of the country, but in general a compromise
between the two methods, resulting in the use of a medium spray driven
with considerable force, followed by the other sprays as they may be
needed, seems to be the usual practice at the present time.

THE LEP1D0PTERA

243

Family ^geriidae (The Clear-winged Moths). — This family, some¬
times called the Sesiidse, includes a number of moths whose wings are
only partially covered by scales. They are not large insects, spreading
on an average, about an inch and are often brilliantly colored. They
fly during the day and particularly during its warmest portion, and are
very rapid in their flight. The larvae are whitish in color and are all
borers, either in stems, roots or under bark. They are therefore, all
injurious, their importance to man depending on the value of the plant
attacked.

The Peach Borer ( Synanthedon exitiosa Say). — This insect which is
a native of North America is a serious pest of the peach wherever these
trees occur east of the Rocky Mountains. West of this a very closely
related species, the Pacific Peach Borer ( Synanthedon opalescens Hy.
Edw.) has a similar life history, habits and control methods.

Fig. 239. — Adult Moths of the Peach Borer ( Synanthedon exitiosa Say), twice natural
size: a, male, 6, female. ( From, Britton, Ninth Rept. Ent. Conn. Agr. Exp. Sta. 1909: after
Beutenmuller.)

The adult insect (Fig. 239) is a little larger than the average, usually
spreading a little more than an inch. The male has a dark blue body
and its transparent wings are bordered with blue. In the female the
fore wings are entirely blue, the hind wings transparent and an orange
band crosses the blue body at about the middle of the abdomen. The
moths may often be noticed darting about in peach orchards during the
middle of the day, anywhere between early May and October (even
earlier in the Gulf States), but are most abundant during June and July
in the Southern States, and July and August in the North. The eggs,
several hundred in number, are laid singly or a few together on the trunk
of the tree near the ground, and the larvse on hatching bore into the
sap-wood close to the ground and feed in that region until winter, at
which time most of them are about one-third grown. In the spring they
resume their feeding (Fig. 240) and upon reaching full size work their
way to the surface and pupate, forming their cocoons of their excrement

244

APPLIED ENTOMOLOGY

and particles of bark, and lined with silk. These cocoons may be at the
openings of the burrows but are more frequently fastened to the bark
just about at the level of the ground. After 3 to 4 weeks in the pupa
stage, the transformation to the adult is completed and the pupa breaks

its way through the cocoon until it is
about halfway out. Then the pupa skin
splits and liberates the moth.

The injury caused by this insect when
it is abundant is often serious. The feeding
of the borers is in the cambium layer which
is tunneled through in an irregular way,
interfering with the growth of the trees,
and where these are small they are often
girdled. The weakened trees also become
more liable to injury and destruction by
bark borers and other insects.

Where the tunnels are formed, a flow of
sap results in the pouring out of gum and
this substance on the bark near the ground
is usually a good indication of the presence
of the borers.

Control. — Of the many methods which
have been tried, only two appear to have
given at all valuable results. These
are “worming” and “mounding.” Worm¬
ing is the removal of the borers late in the
fall and again in the spring, the date for
the spring treatment varying with the
locality but before the borers have com¬
pleted their feeding. A day or two before
this treatment the earth around the trunk
should be removed to a depth of several
inches, so that fresh gum and sawdust pro¬
duced thereafter by the borers, or below
the level of the ground, will show. With
these as guides where to work, the borers
can be located and removed with a sharp
knife, and a light, pointed wire, care being
taken to cut as little as possible and to
leave clean-cut edges. Then replace the earth. In the spring, following
the “worming,” mound up the earth six or eight inches high around
the trunk and leave it there until after the moths are done flying, but
remove it in time for the bark to harden before winter. This mounding
forces the moth to lay its eggs further up where the bark is tough

Fig. 240. — Larva of Peach Borer
Moth and its work on a young
peach tree. ( From U. S. D. A.
Farm. Bull. 90S.)

THE LEPIDOPTERA

245

and harder than at and below the ground level, and fewer of the borers
are able to penetrate it to the cambium layer.

Probably more kinds of materials have been tested for the control
of this insect than of any other, but it is still without an entirely satis¬
factory treatment, though Paradichlorobenzine pulverized to the fineness
of coarse salt, has given fair success recently. The ground close to the
tree is somewhat loosened, an inch or two deep; the material is then
evenly sprinkled around the trunk in a band an inch or two wide; then
two or three shovels of earth are placed over it and compacted with
the back of the shovel. Three-fourths of an ounce to an ounce of the
material is enough for trees 6 to 15 years old. It is not entirely safe
for use with younger trees. The base of a tree treated thus, should be
uncovered a month or so later and left exposed for a day or two before
recovering with the earth.

Fig. 241. — Squash-vine Borer ( Mellitia satyriniformis Hbn.) ; a, male moth; b, female,
wings folded; c, eggs on a piece of squash stem; d, full-grown larva in squash stem; e, pupa;
/, pupal case, found in the ground. All one-third larger than natural size. ( From U . S.
D. A. Farm. Bull. 856.)

The Squash-vine Borer (Melittia satyriniformis Hbn.). — This pest is
also a native of the New World, and is found from Canada southward to
Brazil and west practically to the Rocky Mountains. It attacks the
squash, pumpkin and occasionally the gourd, melon and cucumber, but
does not usually, at least, infest the last two plants when the others are
at hand. The adult moth (Fig. 241 a and b) is about the same size as,
but a little stouter than the Peach Borer. Its fore wings are a dark,
metallic green, its hind wings transparent, its abdomen orange and black
and its hind legs heavily fringed with long, black, orange and a few white
hairs, making these legs look very large. It appears about the time the
plants are large enough for egg-laying and feeding upon — in April or
May in the South; in June in the Middle Atlantic States and in July in
New England — and lays its eggs at first near the base of the plant on the

246

APPLIED ENTOMOLOGY

stem but later almost anywhere on it. About 200 eggs (Fig. 241c)
are laid singly, and these hatch in from 1 to 2 weeks. The larvae
now bore into the stem and feed, generally working toward the base of
the plant, making holes through it to the outside here and there, through
which some of the excrement is expelled. They become full-grown (Fig.
241d) in about 4 weeks and then go a few inches into the ground to
pupate, making dark-colored silken cocoons (Fig. 241/) mixed with dirt.
Some soon pupate (Fig. 241e) while others remain as larvae in their
cocoons until the following spring. After the pupal stage has been
completed the pupa works through the cocoon and to the surface of the
ground and the moth then emerges from its pupal skin.

In the South there are two generations a year of this insect: far¬
ther north there is a partial second generation, and in the northern
part of its range there is only one, winter in any case being passed in the
ground.

The injury caused by these insects when they are abundant is serious.
The burrows become wet and slimy, hastening decay and thus separating
much of the plant from its roots. The feeding also interferes with the
circulation of the sap to some extent. A sudden wilting of the leaves is
generally an indication of the presence of the borers, and coarse yellowish
excrement beneath the stems is also evidence of their activity. In some
cases entire fields of the plants have been killed by the work of this
pest.

Control. — Sprays tried thus far have proved ineffective. As the
winter is spent in the ground of the field where the insects fed, it is evi¬
dent that their food plants should not be planted 2 years in succession
on the same land. Light harrowing of infested fields in the fall to bring
up the cocoons and expose them to winter surface conditions, followed
by spring plowing to a depth of at least six inches has given good results.
Planting a few plants of very early varieties of summer squash as a trap
crop on which the insects may lay their eggs before the real crop is
available for them, followed by the destruction of the trap plants before
the larvse are full-grown is helpful. Covering the stems with earth to
induce the production of roots from the nodes along the stem will often
enable an attacked plant to continue to grow even after its connection
with its original roots has been destroyed. Finally, when borers are
found in the stems they may be cut out, using a sharp knife and splitting
the stem lengthwise where the borer is and removing it, then covering
the stem thus treated with moist earth to aid it in healing the wound.

Many other injurious insects belong in this family, among which the
Imported Currant Borer boring in currant stems and killing them; the
Blackberry Crown Borer which bores in the roots and crown of the black¬
berry and raspberry and has a 2-year life history; and the Maple Sesian
which bores in the trunks of maples, may be mentioned.

THE LEPIDOPTERA

247

Family Gelechiidae. — Some of the small insects which compose this
group are leaf-miners; others feed on buds and others skeletonize leaves
or attack plants in various ways. Many are injurious at times, the
amount of injury done depending on their abundance which varies from
year to year.

The Angoumois Grain Moth ( Sitotroga cerealella Oliv.). — This little
insect, a native of Europe where it was extremely injurious in the French
province of Angoumois, whence its name, has been known in the United
‘States since about 1730 and is widely distributed but is not often im¬
portant in the more northerly states,
oats and corn, both in the fields and
in storage, often destroying a large
part of the grain.

The adult moth (Fig. 242a) is
small, spreading about half an inch,
yellowish in color, slightly speckled
with black. Winter is spent as the
caterpillar in the grain wherever it
may be stored, and pupation occurs in
the spring, also in the grain, followed
by the emergence of the adult which
flies to the fields and lays its eggs,
about a hundred in all, in the young
grain heads. The eggs hatch in about a week and each tiny caterpillar
attacks a kernel, gnawing into it (Fig. 2426) and consuming its contents.
After about 3 weeks the larva becomes full-grown and pupates in the
kernel (Fig. 242c) where it fed, escaping a little later as the adult moth.
Eggs are now laid on grain ready to harvest and either in the harvested
grain or in corn after it has been husked and is therefore accessible to
the insects, there now follow later generations, until cold stops their
further development which is resumed the following spring.

Small grains and corn thus attacked are badly injured, not only by con¬
sumption of the contents of the kernels but also because of the presence
of the bodies of the insects themselves and of their excrement which
.gives a disagreeable taste to the flour, which lacks adhesiveness and
breaks up when stirred in water.

Control. — When this insect is present, destroy or feed all waste grain
and screenings and clean up all grain and refuse from places where grain
has been stored, in early spring. Good grain should be fumigated at this
time also, if the caterpillars are present. The purpose of this is to destroy
the insects before they pass to the growing food plants out of doors.
Threshing the grain soon after harvest, not keeping it in the mow long,
is also important. Fumigation of the threshed grain for 24 hr., with
Carbon disulfid, using 1 lb. for each 100 bu., if it is infested or heats,

The larva attacks wheat, barley,

a be

Fig. 242. — Angoumois Grain Moth
( Sitotroga cerealella Oliv.) : a, adult
moth, about twice natural size; b, larva
in a grain of wheat; c, pupa in another
grain, b and c about three times
natural size. ( Modified from Sander.)

248

APPLIED ENTOMOLOGY'

which is due to infestation, is an important control which should not be
omitted. If the insect is present the sooner fumigation is given the
sooner the loss by feeding will be stopped.

Family Pterophoridae.— The insects of this family, though rather small, are of
much interest, the wings being cleft for a part of the distance in from the outer
margin toward the base (Fig. 243). In most cases the fore wing is divided into
two such parts and the hind wing into three. A single species found in this
country and placed in a separate family (Orneodidae, Fig. 244), has each of its
wings divided into six parts.

1'

V;'-Tr

Fig. 243.

Fig. 244.

Fig. 243. — Adult Pterophorid Moth showing the cleft wings, nearly twice natural size.
(Original.)

Fig. 244. — Orneodid Moth showing the cleft wings. Twice natural size. (Original.)

Most of the Pterophoridae are not of great economic importance. One species,
however, causes some injury to the grape by webbing together the leaves, usually
the terminal ones, and feeding within the web. As this frequently involves a
cluster of buds which may also be fed upon, the crop may be somewhat reduced
in this way. The only control known is to remove the webs by hand and crush
the little caterpillars.

Fig. 245. — Adult Mediterranean Flour Moth (Ephestia kuhniella Zell.), three times
natural size. (From Herrick’s Insects Injurious to the Household. By Permission of the
Macmillan Company. Publishers.)

Fatnily Pyralidae. — This is a large family but most of the moths belonging here
are small. The members of the group have very varied habits. Some fold or roll
leaves; some bore in plant stems; some feed on stored cereals or dried fruit; one or
two feed on wax and are pests in bee hives; others attack foliage, grass or vari¬
ous materials. Many are injurious but few can be rated as serious pests over
the entire country.

THE LEPTDOPTERA

249

The little white or brown and white moths which are so numerous in grass
fields during the summer months, belong here. On alighting on a grass stalk
they place their bodies parallel to the stems and fold their wings closely about
them. Their larvte feed on grass and are sometimes quite injurious, corn and
oats suffering severely. Early fall plowing and replowing early the following
spring are helpful under such conditions.

Three species are often found in houses attacking flour, meal, cereals and
dried fruits. One species, the Mediterranean Flour Moth (Fig. 245) ( Eyhestia
kuhniella Zell.) spins a web which causes flour to stick in loose masses, and in mills
and storage houses this becomes serious. The other two species are more liable
to be found in dried seeds, fruits, etc., and often cause considerable injury. In
storage houses and mills fumigation with Hydrocyanic acid gas is often used as a
control, and if the place can be heated to 125° F. for about 6 hr., this also has
proved effective.

The Bee Moth {Galleria mellonella L.) also belongs here (Fig. 246). It is an
enemy of the bee-keeper living in the bee hives where it feeds on wax and spoils
the honey. Strong colonies of bees can usually protect themselves from this

Fig. 246.

Fig. 247.

Fig. 246. — Adult Bee Moth ( Galleria mellonella L.), natural size. (Original.)

Fig. 247.— Cocoons of the Bee Moth from the inside of a hive. Natural size.
(Original.)

pest, particularly the Italian races. Where necessary, the bees can be transferred
to another hive and the infested one fumigated with Carbon disulfid (Fig. 247).

The European Corn Borer ( Pyrausta nubilalis Hbn.). — This pest of corn and
many other plants has only recent^ been discovered in this country, and in 1920
was found only in parts of Xew Hampshire, Massachusetts, New York,
Pennsylvania and Ontario. It is a borer in plant stems, in which it winters as
a partly grown larva (Fig. 248), finishing its feeding and pupating (Fig. 249) in
its burrow in the spring. The moths appear in June and lay 300 or 400 eggs in
small clusters on the leaves of their food plants and the larvae tunnel in the stems
(Fig. 250), becoming full-grown in about 6 weeks and the moths these produce
appear in July. Eggs for another generation are now laid and the larvae feed
until winter, when they hibernate in their burrows. In some places, instead
of two generations each year there is only one.

The moths spread from about an inch to an inch and a quarter. The male is
rather dull purplish or reddish-brown with yellow spots or a band on the fore
wings and grayish hind wings. The female has dull yellow fore wings more or
less marked with brown, and grayish-brown hind wings. The moths fly most
freely about dusk and are only slightly attracted to lights.

250

APPLIED ENTOMOLOGY

Corn, and particularly sweet corn, appears to be a favorite food of this insect,
and where it is abundant a large part of the crop may be destroyed. Large¬
stemmed weeds such as barnyard grass, pigweed, etc., are also attacked, as well as
dahlias, gladiolus and other cultivated plants, which complicates the problem of
control.

Control. — The best method for checking the ravages of this pest is the destruc¬
tion of all corn stalks to below the ground level, either by burning during the
winter or by using as ensilage.

Fig. 248.

Fig. 248. — Part of a corn plant showing effect on the tassels of the work of the Euro¬
pean Corn Borer ( Pyrausta nubilalis Hbn.). ( From a drawing by Snodgrass, XJ . S. D. A.
Bur. Ent.)

Fig. 249. — Corn stalk split, showing the larvae of the European Corn Borer and
their tunnels. About natural size.

Fig. 250. — Corn stalk cut into to show the pupa of the European Corn Borer.
Slightly enlarged. ( Both figures from, drawings by Snodgrass, U. S. D. A. Bur. Ent.)

Family Limacodidae (Slug Caterpillars) . — The insects belonging to this family
are of little importance from an economic standpoint, but their larvse are curious
in appearance, having little resemblance to ordinary caterpillars. Instead, they
are slug-like, short and rather stout, quite flat beneath, and appear to slide
along rather than crawl. Many have spines and rather showy, colored markings,
in some cases with soft, fleshy projections sometimes partly or entirely covered
with hairs. The Oriental Moth ( Cnidocampa flavescens Walk.) several times
imported into this country from Asia by accident, has established itself in Eastern
Massachusetts but is not apparently of much importance, though the spines on
the caterpillar cause a nettling of the skin of a person where the insect has been
touched.

Family Psychidae (Bag Worms). — The caterpillars of a few species of moths
in this country construct silken bags around their bodies, partly covered with

Fig. 249. Fig. 250.

THE LEPIDOPTERA

251

Fig. 251. — Common Bag Worm ( Thyridopteryx ephemerceformis Haw.): 10, bag, as
seen in winter; 11, same, cut open, showing pupa case and eggs; 12, eggs; 13, young larva;
14, cases of young larvae on a twig; 15, older larvae in their bags, one hanging by a thread
it has spun; 16, full-grown larva removed from its case; 17, full-grown larva, crawling;
19, adult (wingless) female Moth; 20, adult male Moth; 22, bag of male with empty pupa
case protruding from its lower end. All natural size except 12 and 13 which are greatly
enlarged. ( From Houser, Ohio Agr. Exp. Sta. Bull. 332: After Felt.)

252

APPLIED ENTOMOLOGY

twigs or other parts of the plant on which they feed. The female is wingless and
lays its eggs within the pupa case or skin she vacated on becoming adult. Only
one species, the Common Bag-worm ( Thyridopteryx ephemerae for mis Haw.) is of

much importance, but where this is plentiful
the plants on which it feeds may suffer con¬
siderably (Fig. 251). It occurs from Massa¬
chusetts west to Nebraska and south to North
Carolina, Tennessee and Texas. Spraying in¬
fested trees as soon as the eggs hatch in the
spring, with arsenate of lead, standard formula,
is usually a sufficient control without a second
application later.

Family Geometridae (Inch worms,
Span worms or Measuring worms). — This
is a large family in this country and the
moths vary greatly in size, some being
very small while others may spread nearly
two and one-half inches. They nearly all
have rather delicate wings and are fragile
creatures.

The larvae (Fig. 252) have a peculiar
appearance when moving, as the feet which
are usually present near the middle of the
body in most caterpillars, are lacking in
this group, leaving only the three regular
pairs near the front end and two pairs at
the hinder end. In consequence, walking
is accomplished by bringing the hinder
end up as closely as possible to the front
end, the body forming at this time a loop.
Then the front legs let go their hold and
the body is straightened out to find a
place where the front legs can grasp and
hold on. This striking method of locomo¬
tion has led to the common names given
to the caterpillars in this family.

Another feature of interest about these
larvae is that many of them are colored and
formed so as to resemble twigs. When
disturbed the caterpillar releases the grasp
of its front feet and straightens out, standing at an oblique angle to the
twig it is holding on to, and resembles a dead twig of the plant. Some
have markings which make them resemble twigs having buds, leaf-scars
or scales of the bark, thus increasing their deceptive similarity.

Fig. 252. — Two “Inch Worm”
larvae, the lower one crawling, the
upper one hanging outward like a
twig. Compare with real twig just
above, on opposite side. ( From
Linville and Kelly, General Zoology.)

THE LEPIDOPTERA

253

The food plants of the insects in this family are very numerous.
Trees and shrubs of many kinds including fruit trees, currant and goose¬
berry bushes, cranberries and other plants of value to man, suffer from
the attacks of these insects, though few are regularly injured, the pests
in most cases being destructive only for a year or two, then disappearing,
at least for the most part, during quite a period.

Canker Worms. — There are two species of Geometers which are
widely distributed over this country and which at times do serious damage
to fruit and shade trees. They are known as Canker Worms, and while
they differ in certain features, have much in common. In both species
the pupal stage is passed in the ground: in both, the female is wingless:
in both, the eggs are laid on the twigs of the trees, and in both the cater¬
pillars feed at about the same time in the spring.

The Fall Canker Worm ( Alsophila pometaria Harr.) occurs in nearly
all parts of the Northern United States as far west as Wisconsin, and
south at least through the Middle Atlantic States. It has also been re-

Fig. 253.

Fig. 254.

Fig. 253. — Male Fall Canker Worm (Alsophila pumelaria Harr.), about natural size.
(From Britton , Eighth Rept. Ent. Conn. Ayr. Exp. Sta. 1908.)

Fig. 254. — Adult Female Fall Canker Worm on a cluster of eggs. Abaut 2% times
natural size. ( From Houser, Ohio Agr. Exp. Sta. Bull. 332.)

ported from Colorado and California. The adult male moth (Fig. 253)
spreads about an inch and a quarter, its wings light gray with faint
markings. The female (Fig. 254) is light gray, and wingless. The
moths usually appear late in the fall, escaping from their pupae in the
ground, and the females crawl up the tree trunks to the twigs where they
lay their eggs (Fig. 254) in clusters. These eggs hatch the following
spring, as the leaves develop, and the caterpillars (Fig. 255) feed on the
foliage until full-grown some time in June in the Northern States, and
earlier farther south. During this time they often drop from the leaves

254

APPLIED ENTOMOLOGY

some distance, spinning a thread as they go, and up which they return
to resume their feeding. A sudden jar of an infested tree will cause
great numbers to drop or “spin down” several feet in this way. When
feeding has been completed the larvae enter the ground and pupate a
few inches below the surface in a silken cocoon, from which the moths
escape late in the fall.

Fig. 255. — Fall Canker Worm caterpillars feeding on Elm. Natural size. {.From Britton,
Eighth Rept. Ent. Conn. Agr. Exp. Sta. 1908.)

The Spring Canker Worm ( Paleacrita vernata Peck). — The adult
male of this species averages slightly less in its wing-spread than the
Fall Canker Worm and its wings are somewhat lighter in color. It
occurs throughout the Eastern United States except in the South and has
also been taken in Texas and California. It is particularly injurious
at times in the Mississippi Valley. This pest escapes from its pupa in
the ground, as the adult, very early in the spring, and the females crawl
up the trees on which they lay their clusters of eggs, frequently under

THE LEPIDOPTERA

255

loose bark or in crevices. These eggs hatch about the time the leaves
open and the larvae feed during about the same period as the other species,
and enter the ground to pupate at nearly the same time. This insect
also has the habit of spinning down on a thread when disturbed.

Control of Canker Worms. — The wingless condition of the females
which necessitates their crawling up the trunks of the trees in order
to reach the places where their eggs are laid, offers an opportunity
for control by banding the trunks, in the fall for the Fall Canker Worm,
and at the first warm days after winter has broken (even in February
in New England, in some seasons) for the spring species, either with
sticky bands which the insects are unable to cross, or with loose fluffy
cotton in which they become entangled. Care should be taken to keep
the bands fresh or in order so that no gaps through which they can crawl,
or bridges of their dead bodies over which they can cross, are formed.
If the caterpillars are already feeding when their presence is discovered,
spray with arsenate of lead, standard formula.

Fig. 256. — Silk Worm ( Bombyx mori L.) : adult moth and its cocoon. About natural size.

(< Original .)

Family Bombycidae (True Silk Worms). — The only representative of
this family in North America is the Silk Worm ( Bombyx mori L.) intro¬
duced many years ago because of the silk obtained from its cocoon.
It does not appear to have established itself anywhere in this country
and silk-raising has not proved profitable here because of the cost of
the labor required, as compared with that in the Orient.

The adult moth (Fig. 256) spreads about an inch and three-quarters
and is creamy-white in color, with two or three faint lines across the fore
wings. The larvae feed on the leaves of the mulberry and Osage orange
trees, and when full-grown leave their food and spin their cocoons (Fig.
256). When spinning has been completed these are gathered and the
insects within are killed by heat or fumigation. Now the loose silk of the
outside is removed and the cocoons are ready to market. Nearly
73,000,000 lb. of raw silk were produced in the world in 1918, and the
importance of the industry is enormous.

256

APPLIED ENTOMOLOGY

Family Lasiocampidae (The Lasiocampids). — This small family
includes several species which are common and at times quite important
pests. The moths are of only medium size, with rather stout bodies,
antennae fringed on one side (pectinate) and with a large shoulder at
the base of the hind wing, instead of a frenulum. The larvae feed on
the leaves of trees.

The Apple-tree Tent-caterpillar ( Malacosoma americana Fab.). —
This native insect is at times a pest for several years in succession, after
which it practically disappears for some time. It is found almost every¬
where from Canada to Florida and west to the Rocky Mountains. From

there to the Sierra Nevada Moun¬
tains another species having
similar habits occurs, while on
the Pacific Slope several others
are present.

The adult moth (Fig. 257) is
rather stout, with a reddish-
brown body and wings, the front

Fig. 257.

Fig. 258.

Fig. 257. — Adult Apple-tree Tent-eaterpillar ( Malacosoma americana Fab.), about
natural size. ( From Sanderson, Insects Injurious to Farm, Garden and Orchard; after Lowe.)

Fig. 258. — Egg belt of the Apple-tree Tent-caterpillar, encircling a twig. Natural
size. ( From Britton, Thirteenth Rept. Ent. Conn. Aqt. Exp. Sta. 1913.)

pair of which have two whitish lines crossing them. The male spreads
about an inch and a quarter and the female about half an inch more.
They fly at night and do not feed as adults. The wild cherry and apple
appear to be the preferred food plants of the caterpillar, but other fruit
and shade-trees are sometimes fed upon.

The moths appear during the early part of the summer and lay their
eggs (Fig. 258), 200 or 300 in number, in belts around small twigs, one
belt probably being all that is laid by one insect. These belts more
or less completely surround the twig, and after depositing a belt, the
insect covers the eggs with a layer of a brown, sticky substance, beveled

THE LEPIDOPTERA

257

down to the twig at each end, which soon hardens and glistens. Within
the eggs the larvae develop and are ready to hatch by winter, but remain
within the egg-shells until spring. They then leave the eggs and may
feed first on the material covering the eggs, but soon crawl together to
some near-by fork of the tree and there spin a web (Fig. 259) in which
to live. From this they go out during the day to feed, spinning a thread

Fig. 259. — Tent of the Apple-tree Tent-caterpillar, about half natural size. ( Original .)

as they go, perhaps to aid them in finding their way back. As they grow
the tent or web is enlarged by the addition of outer layers and may be
nearly a foot long and seven or eight inches across before the larvae are
full-grown, the feeding period being about 6 weeks.

Though at first very small, the larvae grow rapidly and when of full size
are about two inches long, black with a white stripe along the middle of
the back and a row of pale-blue spots on each side, with a velvety-black
spot in front of each blue one (Fig. 260). Fine yellowish hairs are also
present.

When about through feeding the caterpillars scatter and finally
spin rather large, quite thick, white cocoons in any protected places

17

258

APPLIED ENTOMOLOGY

they may find, and within these they pupate, taking about 3 weeks
in this stage before the moth appears.

An unusual feature in this life history is the long period spent in the
egg, which may be almost 10 months.

Control. — Although this insect has numerous enemies both among
birds and insects, there are periods during which these are unable to
prevent trees being stripped by the pest. In general, the calyx spray
used on apples and pears for the Codling Moth is sufficient to destroy

Fig. 260. — LarvaB of the Apple-tree Tent-caterpillar, natural size. ( From Britton,
Thirteenth Rcpt. Ent. Conn. Agr. Exp. Sta. 1913.)

this caterpillar also. On wild cherry and other trees not usually sprayed,
however, it finds a breeding place from which the fruit trees may be
restocked, and such trees should also be cared for, to prevent this.
Examination of such trees any time between August and March, to find,
cut off, and burn the eggs, and the destruction of the caterpillars while
in their tents on rainy days or at night, either by crushing or by burning
with a torch, are desirable auxiliary treatments in addition to spraying.
The torch method should not be used on young fruit trees, however, as
holding the torch at a fork a moment too long is liable to injure this

THE LEPIDOPTERA

259

place, and in later years the injury will show as the fork becomes an
important one, in the form of a splitting at that point under the weight of
the branches and fruit beyond.

The Forest Tent-caterpillar ( Malacosoma disstria Hbn.) is also a
native of North America. It greatly resembles the last species, both
in appearance and in some of its habits, but though occasionally found
feeding on some of the same food-plants, it appears to prefer the oak,
maple and other forest and shade-trees.

The adult (Fig. 261) is of about the same size and general appearance
as the Apple-tree Tent-caterpillar, but the general color is lighter brown
and the lines or bands across the fore wings are darker, instead of lighter

Fig. 262.

Fig. 261.

Fig. 263.

Fig. 261. — Adult Forest Tent-caterpillar ( Malacosoma disstria Hbn.), natural size.
(Original.)

Fig. 262. — Egg belt of Forest Tent-caterpillar, natural size. (Original.)

Fig. 263. — Full-grown larva of the Forest Tent-caterpillar. About two-thirds natural
size. (Original.)

than the ground color. The egg belts (Fig. 262) are similar but quite
squarely cut off at their ends instead of being rounded down to the twig:
the caterpillar (Fig. 263) has a row of rather oval white spots instead of
a white stripe along its back, and its sides are noticeably light blue,
with two broken, longitudinal, yellow lines. The caterpillars make
no tents but scatter after hatching. Otherwise the life history, time
spent in the different stages and the periods of the year during which
these occur are the same in both species.

Control. — Where the caterpillars can be reached by sprays, control is
comparatively simple as with the Apple-tree Tent-caterpillar. In
forests, however, where large trees are stripped of their foliage, this
method is rarely practicable. Destruction of the egg-belts is of value,
but these can seldom be reached in any numbers, being usually high up
on the small twigs. Jarring the trees where these are small enough for
this, will cause many of the caterpillars to drop to the ground, and by the
use of sticky or cotton bands they may be prevented from crawling
back again. The caterpillars frequently cluster in large numbers on the
trunks of the trees and at such times, spraying these clusters with any

260

APPLIED ENTOMOLOGY

strong contact insecticide is an effective treatment. For the most part,
however, little can be done and in “sugar bushes” extensive defoliation
with a consequent reduction of the vitality of the tree and of the sap
flow will follow, only relieved after a year or two by an increase in
the enemies of this insect to such an abundance as to reduce it to
unimportance.

Some of the western species of Tent-caterpillars make tents, while
others do not. Occasionally one species or another may become so
abundant as to strip everything in one place, and in such cases the larvae
crawl off in enormous numbers seeking for more food. In one instance
their line of march was across a railroad, where they were crushed by the
car wheels until the rails became so slippery that trains were unable to
run except by sweeping the caterpillars off or by blowing them off the
track ahead of the engine by jets of steam!

Family Lymantriidae (The Tussock Moths). — This family, though
small in numbers in this country, includes some serious pests. The
moths are of medium size, and the females in some cases are either
wingless or nearly so. The legs are rather thickly clothed with hairs.
The group as a whole is one of night-flying insects but a few fly freely
in the day time.

The larvae are often highly, even brilliantly colored, and are thickly
covered with hairs. These may be quite uniformly distributed, but in
some cases there are also bunches or “tussocks” of them projecting some
distance from the skin, and long, slender “pencils,” composed of a few
hairs which may be a quarter as long as the body of the caterpillar.
Most of them feed on the foliage of trees but some have a wide range
of food plants.

The White-marked Tussock Moth ( Hemerocampa leucostigma
A. & S.). — This common species is found along the entire Atlantic Coast

from Nova Scotia to Florida and westward at
least to Nebraska, and has also been reported
from Oregon. It is mainly a pest of shade-
trees, and most injurious in and near cities
and towns, but at times attacks fruit-trees and
causes much injury.

The adult male moth (Fig. 264) spreads about
an inch, and its wings are gray with wavy dark
bands and light marks. Its antenme are heavily
fringed. The female (Fig. 265) is wingless,
with a gray body.

The winter is spent in the egg stage, the larvse hatching in the spring,
feeding until full-grown, on foliage, then crawling away to pupate, some¬
times on the twigs but usually either on the bark of the trunk or lower
limbs, or on other objects near-by. The cocoons are composed of silk

Fig. 264. — Adult male of
the White-marked Tussock
Moth ( Hemerocampa
leucostigma A. and S.),
about natural size. ( From
Britton, Fifth Rept. Ent.
Conn. Agr. Sta. 1905.)

THE LEPIDOPTERA

261

mixed with hairs from the body of the caterpillar and are gray in color.
The female on emerging from the pupa stage crawls to the surface of
the cocoon and later lays there from 300 to 500 eggs (Fig. 265) which she
then covers with a white froth which soon hardens and forms a crust
covering and hiding the eggs. This white crust on the gray background
of the cocoon and the generally dark bark of the tree makes the eggs very
conspicuous objects.

The eggs soon hatch and the caterpillars thus produced feed on the
leaves until full-grown (Fig. 266) then pupate as in the preceding genera¬
tion and the moths appearing later, also lay their eggs on their cocoons
and cover them with white froth. It is probable that throughout the

Fig. 265.

Fig. 266.

Fig. 265. — Adult female of the White-marked Tussock Moth with an egg mass covered
by a white crust, resting on her cocoon. About natural size. ( Modified from N. Y . Agr.
Exp. Sta. Bull. 312.)

Fig. 266. — Caterpillar of White-marked Tussock Moth. Note the four “tussocks” of
hairs. Slightly reduced. (Modified from N. Y. Agr. Exp. Sla. Bull. 312.)

northern part of the territory inhabited by this insect, these eggs will be
laid so late in the season that they will not hatch until the following
spring and the white crusts covering them will therefore be prominent
objects during the winter. We accordingly find two generations of this
insect in the Middle States; one in the North, and there are probably
three in the South, corresponding to some extent at least, with the
length of time during which food is available.

The moths are seldom seen, though the males fly somewhat during
the day. The egg clusters, however, are objects which attract attention
and the caterpillars are highly colored and so peculiar in appearance as
to be very noticeable. A full-grown caterpillar is nearly an inch and a
half long, with a bright red head and also two red humps above, near the
hinder end. Between the head and the middle of the body is a row of
four large cream-colored tufts or “tussocks” of hairs standing up some
distance above the surface of the body. The side is grayish with a yellow
band above and below. Projecting upward, forward and outward from
just behind the head are two slender clusters of black hairs or “pencils”

262

APPLIED ENTOMOLOGY

about half an inch long, and a single similar but gray pencil of hairs
projects upward and backward from near the hinder end of the body.
These characters make the caterpillar of this insect a very striking and
noticeable animal.

Control. — Gathering and destroying the egg clusters or applying
creosote to them freely enough to penetrate the crust and reach all the
eggs beneath are methods which can be made use of whenever the clusters
are observed. Spraying for the caterpillars, using arsenate of lead,
standard formula, is also effective. Trees not infested, whose branches
do not touch those of other and infested trees, can be protected by the
use of sticky or cotton batting bands around their trunks during the
periods when the caterpillars are crawling.

The Antique or Rusty Tussock Moth ( Notolophus antiqua L.). — This
is a European insect but widely distributed in North America. The
male moth averages about as large as the White-marked Tussock Moth
and has rustv-brown wings, each fore wing with a small white spot.
The female is wingless. The eggs are laid on the cocoon of the parent
moth but without any white crust to conceal them, and the caterpillar
has a black head. Of the four tussocks on the back, the first two are
black at first but become whitish later, like the others. The pencils
of hairs just behind the head and at the end of the abdomen resemble
those of the other species and an additional pair is also present, one on
each side of the body a short distance behind the head.

The life history of this insect is probably similar to that of the last
species, though the number of generations in different parts of the country
does not appear to have been worked out. In the Northern States there
is one each year. Control measures are the same for both species.

The Gypsy Moth ( Porthetria dispar L.). — This European insect was intro¬
duced into this country near Boston, Mass., by accident, about 1869 and has
gradually spread until it now covers the greater part of the New England
States. It has also appeared in other localities but these places were dis¬
covered early and the insects exterminated.

The adult male moth (Fig. 267) is brown with some yellowish markings, and
spreads about an inch and a half. It flies freely during the day. The female
has nearly white wings, with dark markings; a stout, heavy body covered behind
with buff hairs: its wings spread about two inches, and though having well-de¬
veloped wings, this sex does not fly.

Winter is passed in the egg stage, the caterpillars hatching in the spring and
feeding on many kinds of leaves, though the apple, oak, willow, alder and birch
appear to be favorites, and shrubs and herbaceous plants do not escape. Ash
is not fed upon, nor is pine during the first two instars.

Feeding until early in July the caterpillars become full-grown (Fig. 268) and
may then be nearly three inches long and as large as a lead pencil. They are
brown, partially hairy, the hairs being somewhat clustered, and on the back bear
five pairs of blue spots, followed behind by six pairs of red ones. At the end of

THE LEPIDOPTERA

263

the feeding period the caterpillar crawls to any satisfactory place, usually the
underside of some limb or on the trunk, and there spins a few threads to hold its

Fig. 267. — Adults of the Gypsy Moth ( Porthetria dispar L.) ; female on left; male on right.
Natural size. ( From Britton, Fifth Rept. Ent. Conn. Agr. Exp . Sta. 1905.)

body in place rather than for concealment or protection, and in this exceedingly
scanty cocoon it pupates (Fig. 268) and after a period of from a week to 17 or
18 days, the moth emerges.

- - - -

Fig. 268. Pupae and larvae of the Gypsy Moth, natural size. ( From Britton, Fifth Rept.
Ent. Conn. Agr. Exp. Sta. 1905.)

The eggs are now laid in oval clusters throughly covered by buff hairs from
the abdomen of the moth, and each cluster may contain from four to five hundred.
There seems to be little choice where the clusters are placed, many being on the

264

APPLIED ENTOMOLOGY

trunks and limbs of the trees, but others are found in cavities in the trunks, on
the stones of stone walls, even in the middle of the wall, in tin cans, and in fact,
anywhere the female may crawl to. They hatch the following spring.

Distribution appears to be accomplished by the crawling of the caterpillars;
by carrying to other places objects on which egg-clusters have been deposited;
by caterpillars spinning down on threads from the trees onto passing vehicles;
and by the wind.

The injury caused by this insect is often very serious. The caterpillars
have voracious appetites and eat large amounts and their abundance has often
resulted in the stripping of large areas, which repeated several years in succession
usually causes the death of the trees. With evergreens, a single defoliation is
usually sufficient to kill the trees, and in many parts of Eastern Massachusetts
the thinning of woodland areas in consequence of the work of these insects, is
very evident.

Parasites and other enemies of the Gypsy Moth have been introduced in
large numbers by the Federal Government, and where these have become abun¬
dant they have done good work, though of course nothing like extermination of
the pest has been accomplished. A wilt disease present in favorable seasons,
kills many of the larvae at such times. In general though, outbreaks of this
insect in any locality are not repressed by their natural enemies for several years,
and in the meantime the damage is great. This condition therefore calls for
the use of control methods.

Control. — The egg clusters constitute one place where control measures can
be applied. It is much easier to kill 400 or 500 insects concentrated in a space
an inch square or less, than the same number in the larval stage, scattered over
a tree. Soaking the egg clusters at any time after they are laid until they hatch
the following spring, with creosote to which a little lampblack has been added
(to show by its color which clusters have been treated and which have not) is a
good treatment. Care must be taken, however, in using this material, to take
enough to reach all the eggs in the cluster. Usually a swab on the end of a
stick, soaked in the creosote, is used for this work. The difficulty with this
method is that of finding all the egg clusters in their varied places of concealment.

While the caterpillars are very small, spraying infested trees and other
plants with arsenate of lead, using about 5 lb. of the paste (2p£ lb. of the powder)
in 50 gal. of water, is a good treatment, but as the larvae become larger they
seem to develop a greater resistance to poisons and spraying becomes less
effective.

As the larvae feed largely at night and seek concealment during the day, put
loose bands of burlap around the trunks of infested trees, where they may hide
in the daytime. Success with this method of control is dependent upon daily
visits to the bands and the destruction of the caterpillars found under them.

Sticky bands around the trunks of non-infested trees will keep the caterpillars
off such trees as long as the bands remain fresh and in good order.

As the caterpillars do not feed on the pine until after they have passed their
second instar, pure stands of pine may be protected by removing all under¬
growth other than pine and banding the trees as above, to prevent older larvae
from crawling to them from places outside where they have obtained their earlier
food.

THE LEPIDOPTERA

2G5

Fig. 269. — Brown-tail Moth {Euproclis chrysorrhcca L.) : 2, adult male; 3, adult female
moth; 4, egg pluster on leaf, covered with hairs from body of parent; 5, caterpillars feeding.
About natural size. ( From U. S. D. A. Bur. Ent. Bull. 87.)

reaching there about 1892. Since that time it has spread as far as Nova Scotia
and New Brunswick, and also practically covers all of New England.

The moths are white except for the abdomen which has a few brown hairs,
and the tip is covered by a tuft, large in the female, of golden brown hairs —

The Brown-tail Moth ( Euproclis chrysorrhcca L., Fig. 269). — This is another
European pest which was accidentally introduced into this country near Boston,

266

APPLIED ENTOMOLOGY

the character which has given this insect its common name. The moths spread
about an inch and both sexes are strong fliers, appearing early in July. They
are somewhat attracted to lights but in most cases the females found thus
attracted, appear to have already laid their eggs. The moths lay 200 or 300
eggs in a cluster, usually on the leaves, and cover them with brown hairs from
the tip of the abdomen. They hatch in from 2 to 3 weeks and the little cater¬
pillars feed on the foliage in company during the early fall, leaving the veins, and
thus skeletonizing the leaves. Early in September they go together to the tip
of some twig and there spin a very tough, dense, silvery tent incorporating
some of the leaves in it, to use as their resting place for the winter. The size and
form of this tent will vary with the number of caterpillars contributing to its
formation, but it is usually three or four inches long and an inch or two in
diameter at its widest p lace. After the leaves fall these tents at the tips of
the twigs are very conspicuous objects during the winter. At the time of the
formation of the tent the caterpillars are about one-third of an inch long.

In the spring as soon as the leaf-buds begin to open, the caterpillars leave
their tents and scatter, feeding until June when they become fully grown and
are about an inch and a half long, brown, slightly mixed with orange, fairly well
covered with fine reddish-brown hairs, and with two bright red tubercles, one
behind the other, on the middle line of the body above, near the hinder end.
These red tubercles are very distinctive and give a positive recognition of this
caterpillar.

The hairs just mentioned are delicate, brittle, barbed in some cases, and
secrete a poisonous fluid very irritating to the skin. As the caterpillars molt
these hairs are liable to be broken off and carried through the air to persons or
onto their clothing, and a painful rash somewhat resembling that caused by
poison ivy is produced, known as the “brown-tail rash.”

Pupation usually occurs among the leaves and after about 20 days is followed
by the emergence of the adult moths. The cocoon, though more developed than
with the Gypsy Moth, is not very thick or dense, and the pupa can generally be
seen through its walls.

Control. — Cutting off and burning the winter tents at any time between Sep¬
tember and April is an effective method of control where the size of the tree is
such that the tents can easily be reached. Spraying with arsenate of lead,
standard formula, either in the fall if no fruit is involved, or when the larvse
first resume feeding in the spring, is also a good treatment.

Many of the parasites imported by the Federal Government to destroy
the Gypsy Moth, attack this species also and appear to have done good work.
For the last few years this insect has been rather less abundant than was pre¬
viously the case. Whether this condition will continue, or outbreaks will recur
from time to time cannot now be determined, but probably the latter will be
true.

Family Notodontidae (The Prominents). — The Prominents as the insects
of this family are often called, are of medium size as adults and usually not at all
brilliantly colored. Few of them are serious pests, and then generally only for
a year or two at a time. The caterpillars of the different species differ greatly
in appearance, some having dorsal humps or projections, others a much elongated
end of the body, or other modification of the typical form of caterpillar.

TIIE LEPI DOPTERA

267

One part of this family consists of moths known as the Datanas. The larvae
of these insects feed on orchard, shade and forest trees, keeping together in
groups, and when resting or disturbed they bend the ends of the body nearly at
right angles to the middle part, in a very characteristic attitude. They feed
during July and August and when full-grown are about two inches long. One
species is common on the apple (Figs. 270, 271) : others occur on the oak, walnut,
hickory and other plants. The presence of 100 or 200 caterpillars feeding to¬
gether on a single branch, and of
considerable size as they get older,
often disturbs the owners of infested
trees who unnecessarily fear serious
injury to their trees.

The fact that the caterpillars feed
in groups renders control easy, how¬
ever, either by removing the groups by
hand or by spraying the region at¬
tacked, with a stomach poison, which
is very effective for these insects.

Another Notodontid having similar
habits and found at the same season
is the Red-humped Apple-tree Cater¬
pillar ( Schizura concinna S. & A.,

Fig. 272). The larva (Fig. 273) has a
red head ; a red hump a short distance
behind; a double row of black spines

Fig. 270. Fig. 271.

Fig. 270. — Adult Moth of Yellow-necked Apple-tree Caterpillar ( Datana minislra
Dru.), slightly less than natural size. (Original.)

Fig. 271. — Yellow-necked Apple-tiee Caterpillars on a branch, showing characteristic
attitudes assumed when disturbed. Natural size. ( From Britton, Eighteenth Rept. Ent.
Conn. Agr. Exp. Sta. 1918.)

along its back; and its body is narrowly striped with yellow, black and white.
Control is the same as for the Datanas.

Family Dioptidae. — This family appears to have but one North American
representative, found only on the Pacific Slope. It is known as the California
Oak Worm ( Phryganidia calif ornica Pack.), and the caterpillar feeds upon the
leaves of the live oak and deciduous oaks. The adult moth (Fig. 274) is light
brown with darker veins and a wing-spread of about an inch and a quarter.
The eggs are laid on the leaves of the oaks and various other plants in October

268

APPLIED ENTOMOLOGY

and November, and hatch during the 5 months following. Those on the decidu¬
ous oaks fall with the leaves, and larvse from them rarely find anything to feed
upon and therefore die. The eggs laid on the live oak, eucalyptus and chestnut,
however, produce caterpillars (Fig. 275) which can generally obtain food and
they become full-grown in May and
June and pupate in any protected
place, spinning no cocoon. The
moths from these pupae emerge after
about 2 or 3 weeks and lay their eggs
for a second generation, the larvae of
which feed during the last of July,

August and September. Pupation fol¬
lows, after which the moths appear
and lay their eggs as already indicated.

Fig. 272. Fig. 273.

Fig. 272. — Adult Moth of Red-humped Apple-tree Caterpillar ( Schizura concinna S.
and A.), natural size. {Original.)

Fig. 273.— Red- humped Apple-tree Caterpillar in feeding position. Somewhat en¬
larged. ( From Britton, First Ript. Ext. Conn. Agr. Exp. Sta. 1901.)

When abundant, the trees upon which these insects feed are liable to be
entirely stripped of their foliage and this sometimes happens over large areas.

Control. — Spraying the trees when the caterpillars are abundant, as they
begin to feed, with Arsenate of lead, 4 or 5 lb. of the paste (2 or 2 lb. of the

Fig. 274.

Fig. 275.

Fig. 274. — California Oak Worm Moth {Phryganidia calif ornica Pack.), about natural
size. ( After Essig, Inj. and Benef. Ins. of Cal.)

Fig. 275. — Caterpillar of the California Oak Worm, natural size. ( Modified from
Essig, Inj. and Benef. Ins. of Cal.)

powder) in 50 gal. of water is effective where the size of the trees permits this
treatment. Power sprayers and nozzles giving a fine mist are the most effective
for this purpose.

Family Noctuidae (The Owlet Moths). — The Noctuids form the largest
family of moths in this country and are everywhere abundant. Within

THE LEPIDOPTERA

269

the group there are great differences in the appearance of the moths
and in the habits of their larvae. Lochhead has divided the family into
nine sections, based mainly on differences of larval habits.

Some members of the Noctuidae are known as the Catocalas or “Under¬
wings.” Some of these are quite large, spreading three inches or more, the fore
wings with quiet colors and marked so that they resemble the bark of trees (Fig.
276). One has fore wings similar to the bark of the white birch : another resembles
the bark of the beech, and many kinds of trees are thus imitated in color and
markings. The hind wings are brightly, often brilliantly colored and it appears
to be the habit of the moths, which fly at night, to rest during the day on the tree
trunks whose bark their fore wings resemble, folding these over their gaudy hind
wings, in this way obtaining through concealment, protection from their enemies.
How far in the course of thousands of generations, the weeding out by these
enemies of those least closely resembling the bark, leaving behind to continue

Fig. 276. — Catocala Moth, natural size. (Original.)

the race the closest imitators of the bark, has resulted in giving to the present
members of the group a closer resemblance than their ancestors, is a question for
speculation. The larvae of the Catocalas feed on foliage but are rarely if ever
injurious enough to be of importance.

The largest Noctuid found in this country is known as the Black Witch
( Erebus odorata L.). It does not live in the United States, being an inhabitant
of the tropics, but its size and powerful wings which often spread six inches,
enable it to fly long distances and it is often captured in the late summer and
fall in the Northern United States. It has dark wings of various shades of
brown, and a small “eye” spot in each fore wing.

The Cotton Worm ( Alabama argillacea Hbn.). — The Cotton Worm is not a
native of this country but of more tropical countries, from which it frequently
comes and attacks cotton in the Southern States. The moths (Fig. 277) are of a
nearly uniform reddish-brown or tawny color, and spread a little over an inch.
They lay their eggs singly on the cotton leaves and these eggs hatch in from 3
to more than 20 days, according to the temperature. The caterpillars are at
first yellowish-green with pale yellow heads. Later they vary much in color and
markings, some changing little, while others acquire a black stripe along the
middle of the back, with a fine central yellow line, and each segment has four

270

APPLIED ENTOMOLOGY

black dots above. The full-grown larva webs a leaf or two together and pupates
in this place, remaining there a varying length of time before the adult emerges.

Fall flights northward of Cotton worm moths occur frequently and may
extend into the Northern States and Canada, where these insects are sometimes
found abundantly in September and October.

Control. — Dry arsenate of lead dusted over the plants when these insects
first appear, using from 2 to 4 lb. per acre, according to the size of the plants,

appears to be a satisfactory treatment.
It is usually applied while the dew is on
the plants.

The Dagger Moths are leaf feeders on
various shrubs and trees in their larval
stages. The fore wings of the moths are
various shades of gray in most cases, and
the larvae are usually quite well covered by
rather uniformly distributed gray hairs.

Several species are known as Green Fruit
worms, the caterpillars being greenish, with¬
out hairs, and feeding on the leaves and
small fruit of apple and other trees during
the later spring months. They are not often seriously abundant.

Some of the Noctuids are Stalk Borers, tunneling in the stems of cultivated
and other plants, among the plants affected in this way being corn, tomatoes,
potatoes, asters, dahlias, etc. The larva feeds during the summer months and
as a rule pupates in the lower part of its tunnel. Accordingly, all wilted plants
should be examined, and if a borer is present the plant should be destroyed
with the borer either as larva or pupa, within it.

The Corn Ear Worm ( Chloridea obsoleta Fab.). — This widely distrib¬
uted pest is known by several common names, such as the Cotton boll-
worm, tomato fruitworm and false budworm of tobacco, in addition to
the one first given. In the South it attacks cotton bolls and tobacco seed
pods, as well as tomatoes and corn which are its usual food in the North.
It is present practically everywhere in the world between the parallels of
50° north and south latitude, and its original home is problematical.

The adult insect (Fig. 278a) spreads about an inch and three-quarters
and is extremely variable in color, so that several varieties have been
recognized. It ranges from a pale reddish-brown to olive, with a greenish
tinge toward the outer margin of the fore wings, with darker bands and
spots, and the hind wings are lighter, with dark veins and a blackish
shade crossing from one outer angle to the other, leaving more or less of a
lighter color between this and the outer margin.

The insect appears to pass the winter as a pupa in the ground, the
adult emerging in the spring, earlier in the South and later farther North.
The eggs, varying in number from less than 500 to nearly 3,000 are now
laid on different parts of the food plants and on weeds or even on the
ground. They hatch in a week or less, according to the temperature, and

Fig. 277. — Adult moth of the
Cotton Worm ( Alabama argillacea
Hbn.) , about natural size. {Original.)

THE LEPI DOPTERA

271

the larvae (Fig. 278 b) begin feeding, at first on the surface of the plant
but soon boring into it at some tender place.

With cotton, injury is caused by eating out the squares and the more
tender bolls. In the case of corn the first attack is by boring into the
bud and eating down into the developing leaves. Later, the tassels are
often injured before they open, and after the silk appears eggs are laid on
this and the caterpillars which hatch from them bore into the ears of corn to
varying distances, often entirely destroying the ears, particularly in the
case of sweet corn. Tomatoes are injured mainly by the larvae boring

.d

Fig. 278. — Corn Ear Worm ( Chloridea obsoleta Fab.) : a, adult moth; b, larva; d, pupa: all
enlarged. ( From U. S. D. A. Farm. Bull. 890.)

into the green or partially ripened fruit, and in some cases by boring into
the tips of the plants or eating the blossoms. With tobacco the larvae
attack the bud leaves at the tip of the plant and later bore into the pods.
Peaches, peas, beans, etc., are also sometimes injured and the average
annual loss by the ravages of this pest in the United States has been esti¬
mated as over eighteen million dollars.

There are several generations of this insect each year, four or five
being produced in the far South and this number reducing northward
until in the Northern States and Canada there is but one. The larvae
vary greatly in color and markings and are most easily recognized by the
nature of their work. When full-grown they are about an inch and a
half long.

272

APPLIED ENTOMOLOGY

Control. — Late fall plowing to break up the earthen cells in the ground
where the insects winter as pupae, provided the plowing is rather deep,
is a helpful procedure. As the larvae feed for a short time on the surface
of the plants before boring into them, the application of arsenate of lead
at or just before this time, is advantageous. With the increasing num¬
bers in the later generations of the insect, fertilization, culture and any
methods possible for hastening the maturity of the crop are desirable.
Green corn is the preferred food plant of this insect and rows of corn
planted in and near cotton fields, if in tassel and silk about the first of
August will attract most of the moths, leaving the cotton much more free
than otherwise. On corn itself, dusting powdered arsenate of lead onto
the silks, as soon as these appear, seems to reduce the damage to quite an
extent if applied at 3 or 4-day intervals while the silk is developing.

In the Noctuidae are a number of species where some of the abdominal
feet of the caterpillars are not functional or are absent, as a result of
which these larvae travel like those of the Geometers or “inch worms”
already described. Several of these species are occasionally injurious to
cultivated plants. In most cases at least, such larvae can be controlled
by the application of arsenate of lead.

The Army Worms also are members of the Noctuidae, this name being
given to the insects because of their habit of marching from place to place
all together, like armies. They are periodically injurious insects, appear¬
ing in great abundance at times, but
rarely troublesome for more than one
season at a time in the same place.

The Army Worm ( Cirphis uni-
puncta Haw.). — This pest is probably
a native of North America. It occurs
over the entire eastern United States
as far west as Kansas and Nebraska,
and has been reported from the
Southwestern States and California.
The adult moth (Fig. 279) spreads
about an inch and a half, and is quite uniformly brownish-gray with a
tiny white spot near the middle of each front wing and a rather dusky
outer margin on the hind wings. The moths fly at night and are often
attracted to lights.

In what stage this insect passes the winter does not appear to have
been conclusively proved, but it is probably as the partly grown cater¬
pillar hiding in rank, dense weedy growth. In late spring, at least,
the nearly full-grown larvae have been found feeding on grasses primarily
and then on small grain. The larvae mature quite rapidly, pupate in the
ground and produce the moths in June, at least in the North. Eggs
are now laid on grass and similar plants and hatch in 8 or 10 days

Fig. 279. — Adult Moth of the Army
Worm (Cirphis unipuncta Haw.), slightly
reduced. (Original.)

THE LEPIDOPTERA

273

and the larva feeds for 3 or 4 weeks until about an inch and a half long.

It is now a nearly naked caterpillar (Fig. 280), somewhat variable in

color but generally rather
greenish, with a broad dark
stripe along its back with a
fine, broken, white line along
its middle, and a dark stripe
along each side.

Before this size has been
attained all the food where
these insects are, may have
been consumed if the larvse
are abundant, and in this case
they march off in armies to
find new feeding grounds,
and it is these marching
armies which usually attract
attention in July or August.
When feeding has been com¬
pleted they pupate in the
ground and the moths emerge
in September or October and
probably lay eggs which soon
hatch, the caterpillars thus
produced, feeding to some ex¬
tent before winter. The
spring-feeding generation ap¬
pears to be little noticed, the
destruction seen being by the
summer generation.

When the caterpillars are
abundant numerous flies re¬
sembling, but larger than
house-flies, and called “ta-
china flies,” are usually
noticed flying about the
army. These are, nearly al¬
ways at least, parasites laying
their eggs on the caterpillars.
The maggots which hatch
from these eggs bore into the
caterpillars and feed upon and
finally kill them. There are
Army Worm.

18

Fig. 280. — Army Worm Caterpillars feeding on
corn. Natural size. (From Britton , Fourteenth
Rept. Ent. Conn. Apr. Exp. Sta. 1914.)

also several other insect enemies of the

274

APPLIED ENTOMOLOGY

Control. — If Army Worms are discovered before they begin their
march, spraying all the plants where they are with a stomach poison
is an effective treatment, or if the infested area is small, straw can be
spread over it and burned. Once on the march, protection of any crops
towards which the caterpillars are marching, either by destroying the
insects or by preventing their reaching the crops, is the aim of any treat¬
ment. Poisoned baits (see under “ Cutworms,” page 276) may be used for
this purpose, or where the ground over which the insects are marching
is fairly smooth and firm, the use of a heavy roller is possible. A ditch
dug across their line of march or around an infested area is often used,
and a log dragged along in the ditch as the caterpillars become thick in it
will kill multitudes. Food in a strip ahead of their line of march, sprayed
with a stomach poison will result in the poisoning of those which feed
there, and in some cases the caterpillars while marching can be reached
and killed by a strong contact insecticide.

The Fall Army Worm (Laphygmci frugiperda S. & A.). — This insect in
many ways resembles the true Army Worm. It has numerous common
names such as the “grassworm,” “ overflow worm,” “alfalfa worm,”
etc., and it is called the Fall Army Worm only in the Middle and Northern
States, as it does not appear there before fall.

Fig. 281. Fig. 282.

Fig. 281. — Moth of Fall Army Worm {Laphygma frugiperda S. and A.), about natural
size. {Modified from U. S. D. A. Farm. Bull. 752.)

Fig. 282. — Full-grown Caterpillar of Fall Army Worm, somewhat enlarged. {Modified
from U. S. D. A. Farm. Bull. 752.)

This insect is probably a native of this country. While most destruc¬
tive in the South it may spread during the season far to the North,
reaching the New England States, southern Wisconsin and south¬
eastern Montana, and extending westward to the Rocky Mountains.

The moth (Fig. 281) spreads about an inch and a quarter. Its front
wings are mottled gray, usually with a light spot near the tip, and the
hind wings pearly white, edged with a rather narrow, dark line. It does
not seem to be able to live over winter north of the southern parts of the
Gulf States. The caterpillar (Fig. 282) feeds upon native grasses pri¬
marily, but when these are not sufficiently abundant it may attack
grains, sorghum, alfalfa, clover, cotton and other crops.

In what stage this insect spends the winter does not seem to have
been positively determined, but it is probably the pupa. The eggs,

THE LEPIDOPTERA

275

Fig. 283. — Dingy Cutworm ( Feltia
subgothica Haw.) : a, moth, wings
spread; b, larva (Cutworm); c, Moth,
wings folded. All somewhat enlarged.
( From U. S. D. A. Farm. Bull. 856.)

from 50 to several hundred in number, are laid preferably on grass blades
and in the South hatch in a few days. The caterpillars feed 2 or 3 weeks
before reaching full size and are then very similar to those of the Army
Worm. They then pupate for 10 to 14
days in the ground, after which the adult
moths emerge. Many of these moths
now fly northward, often several hundred
miles, before laying their eggs, and in
this new location another generation is
produced, the adults of this generation
also flying northward to lay their eggs.

In this way the northern part of the
country becomes infested in the fall but
frost puts an end to the development of
these insects near their northern limits
before more than one generation can be
produced. Going southward, more are
possible, and in the Gulf States there
may be six in the course of a season.

Where corn and cotton are grown the
destruction caused by this insect is often
very great, the caterpillars as they get large having voracious appetites.
They usually feed more at night than during the daytime, and like the

Army Worm, march to
other places to find food
when the supply where they
are becomes exhausted.

In general the methods
used for controlling the
Army Worm apply to this
insect also.

A number of other
species of Noctuids have
the habit of marching in
armies when their food be¬
comes scarce. Their life
histories and habits are for
the most part quite similar
to those of the two species
already described, and con¬
trol methods for them are
generally the same.

Still another section of this family occurs, widely distributed, and
causing much injury. The insects of this division are called Cutworms
(Figs. 283 and 284) because of the habit of the larvse of feeding on the

Fig. 284. — Cotton-boll Cutworm ( Prodenia ornitho-
galli Guen.) : a, light form of Cutworm; b, dark form;
dark form of Moth above; pale form below. All some¬
what enlarged. ( From U. S. D. A. Farm. Bull. 890.)

276

APPLIED ENTOMOLOGY

stems of succulent plants at about the level of the ground and thereby
either partially or entirely cutting them off at this point. Several
hundred species have this habit and many kinds of garden and field
crops suffer in this manner during the spring and early summer months.
A few have the habit of climbing up the plants at night and feeding
there, some distance above the ground.

The moths are usually of medium size, spreading from an inch to
about two inches, and are generally quiet colored, gra}r, brown or blackish,
more or less mottled, streaked or banded on the fore wings while the
hinder pair are nearly white and unmarked except for darker margins in
some cases. Some species are more strongly marked, however, and have
brighter colors.

Most of these insects winter either as pupae or partly grown cater¬
pillars. In the spring the latter pass the day in the ground, coming up
at night to feed. They are generally dull colored with rather faint spots
and lines and without a hairy covering, and when full-grown will average
an inch to an inch and a half in length. When feeding has been completed
they pupate a few inches deep in the ground. Some species have one
generation each year; others two.

Control. — Late fall plowing to bring up and expose the insects to the
fluctuating temperatures of the cold season and its rains, is a useful
treatment, but other measures are also necessary. When Cutworm
work is seen the use of a poison bait is desirable. For this purpose one
good formula is:

Bran .

Paris green .

Cheap molasses . . .
Oranges or lemons
Water .

Large For Small

Quantity Gardens

50

lb.

or

1

pk.

2

lb.

or

lb.

2

qt.

or

l

pt.

3

fruits

or

l

fruit

3

to 7 gal.

or

4

to 6 qt.

The second formula is for use where onty a small quantity is desired.

Mix the bran and Paris green together thoroughly, dry: add the
juice of the fruit to some of the water and chop up the rest of the fruit
finely and add this and the molasses. Now combine this mixture with
the bran and Paris green and stir thoroughly, adding enough more
water to finally produce a rather stiff dough. This can be used in
gardens, placing about a teaspoonful close to the base of each plant liable
to attack, but should be put on toward night so that it will not dry up
in the sun and lose its attractiveness to the Cutworms. Fowls should
be shut up while this treatment is being used, to prevent their feeding
on the bait and being poisoned.

Where large fields are to be treated, a modification of this formula
is desirable, reducing the amount of water to a point where the mixture
is dry enough to spread broadcast, yet wet enough so that each flake of

THE LEPIDOPTERA

277

bran has been moistened by the molasses and fruit juice sufficiently to
make it attractive, and also bears a little of the poison. The amount of
water to add to obtain this condition must be determined by testing the
mixture at intervals to see that the bran is dry enough to spread, and
also that it has been able to take up the other materials. In any case the
mixture should stand for several hours before use, to allow the bran time
to take up the other constituents. The larger quantity given above is
sufficient to spread broadcast over several acres.

The size of the family Noctuidae and the abundance of its members
in all parts of the country, as well as the various methods of feeding
present in the group make it one of the most destructively important
families of Lepidoptera in the United States.

Family Arctiidae (The Tiger Moths). — The Arctiids are mainly medium-sized
moths, often brilliantly colored. Most of the group are not serious pests, but
individuals, particularly in their larval stage, are often seen. Many of these
caterpillars are quite densely and uniformly covered with long hairs and are
sometimes called “woolly bears.” One of them often seen crawling about in the

Fig. 285. Fig. 286.

Fig. 285. — Isabella Tiger Moth {Isia Isabella S. and A.), slightly reduced. (Original.)

Fig. 286.: — Hickory Tiger Moth (Halisidota caryce Harr.), natural size. ( From
Britton , Seventh Rept. Ent. Conn. Agr. Exp. Sta. 1907.)

fall is covered with reddish-brown hairs at each end, and black ones in the middle,
and is sometimes given the particular name “hedgehog caterpillar.” The adult
(Fig. 285), not often seen, is an orange-buff moth, its hind wings tinged with
pinkish, and spreads a little over two inches. It is called the Isabella Tiger Moth
(Isia isabella S. <fc A.). Another caterpillar, the “salt-marsh caterpillar '’ ( Estig -
mene acrcea Dru.) has a blackish head and body, well covered with long, tufted,
brownish hairs. The adult is about the size of the Isabella Tiger Moth, the male
having wrhite fore wings spotted here and there with black, while the female has
all its wings white and spotted. The abdomen of both sexes is orange. The
Hickory Tiger Moth (Halisidota caryce Harr., Fig. 2S6) is quite common in the
northeastern United States and Canada, west to Minnesota and south to North
Carolina and Ohio. The larvae, which occur in the summer and fall, feed on
many kinds of trees and are sometimes rather injurious. At first they feed in
company but during the latter part of their larval life they scatter. The full-

278

APPLIED ENTOMOLOGY

grown larva (Fig. 287) is an inch and a quarter or more in length, covered with
grayish-white and black hairs. Along the middle of the back is a row of tufts
of black hairs and there may also be longer, slender black tufts or “pencils.”
The insect winters as the pupa under rubbish on the ground, and the moths
emerge in late spring and early summer and are yellowish in color, the fore wings
sprinkled with brown dots and two brownish streaks. These wings are rather
narrow for their length, and somewhat pointed. The hind wings are nearly

transparent and almost white. The moths
spread about two inches. Control is by
spraying with a stomach poison as soon
as the work of the caterpillars is noticed.

The Fall Webworm ( Hyphantria
cunea Dru.). — This insect is a pest on
shade, fruit, and ornamental trees.
It is found everywhere in the eastern
United States and as far west as
Montana and Texas. In the South
and northward about to New York
there are two generations each year
and a correspondingly greater amount
of injury than where one is the rule.

Fig. 287. Fig. 288.

Fig. 287. — Full-grown Caterpillar of the Hickory Tiger Moth, natural size. ( From
Britton, Seventh Rept. Ent. Conn. Agr. Exp. Sta. 1907.)

Fig. 288. — Fall Webworm ( Hyphantria cunea Dru.), about natural size. {Original.)

The adult moth (Fig. 288) spreads about an inch, and in the north
has pure white wings. Farther south black spots are present on them
and this difference has led to the belief, still held by some persons, that
there are really two species concerned. The winter is spent as the pupa
in the ground, the moths emerging in the late spring and laying their
eggs in clusters, often 200 or 300 in number, on the under side of the
leaves. These hatch in about 10 days and the larvae pass together
to the outer foliage of some branch, where they form a thin white web
over the surface, feeding on the leaves enclosed within the web (Fig.
289). As the caterpillars grow and consume this foliage, the web is
extended to cover more leaves and by the time full size has been attained
by the caterpillars, the web may be as large as a bushel basket. The
full-grown larva (Fig. 290) is over an inch long, quite hairy but not

THE LEPIDOPTERA

279

sufficiently so to conceal the body which is generally “pale-yellowish or
greenish, with a broad, dusky stripe along the back and a yellow stripe
along the sides; they are covered with whitish hairs which spring from

Fig. 289. — Branch covered by web of the Fall Webworm. ( From N. H. Agr. Exp. Sta.

Bull. 139.)

black and orange-yellow warts” (Packard). The head is black. The
larvae pupate in the ground.

Where there are two generations the moths appear in June or even
earlier and the second generation moths develop early enough in' the
fall for the larvae from their eggs to become full-
grown before the leaves drop. Where there is
but one generation the webs appear the last of
July and in August, and reach full size in
September.

Control. — There are several ways by which
to check the ravages of this insect. When the
webs first appear they may be stripped off by hand and the then
small larvae crushed. Branches attacked may be cut off if the tree is
of sufficient size not to be marred in this way. Spraying all around
the tent with a stomach poison, standard formula, will poison the leaves
next to be brought within the web by its further enlargement, and thus
provide the caterpillars with poisoned food.

Fig. 290. — Full-grown
larva of the Fall Webworm,
natural size. {Original.)

280

APPLIED ENTOMOLOGY

Family Ceratocampidae (The Royal Moths). — In this family are included
several very large moths and a few smaller ones. The Regal Walnut Moth
( Citheronia regalis Fab.) may have a wing-spread of six or seven inches (Fig. 291).
Its fore wings are rather dusky but the veins are lined with orange-red and there
are numerous yellow spots. The hind wings are lighter, with some yellowish areas,
and veins lined as in the other pair. The stout body is brownish-orange with

Fig. 291. — Regal Walnut Moth ( Citheronia regalis Fab.), about half natural size. ( From
Felt, N. Y. State Mus. Mem. 8.)

narrow yellowish cross lines. The caterpillar (Fig. 292) which feeds upon various
trees, is four or five inches long when full-grown and has a green body bearing
numerous black spines and, just back of the head, a number of very long reddish
spines bending backward and tipped with black. The head is red. The terri¬
fying appearance of this caterpillar has probably been the reason for calling it

Fig. 292. — Full-grown larva of the Regal Walnut Moth, slightly less than half natural size.
( From Packard, Mem. Nat. Acad. Sci., IX, Part II.)

“The Hickory Horned Devil.” The insect is found from Massachusetts to Loui¬
siana, Texas and Missouri, but is not very abundant and therefore does little
injury. It feeds on the black walnut, butternut, hickory and a number of other
trees, and has once or twice caused some damage to cotton. It winters as a pupa
in the ground.

THE LEPIDOPTERA

281

Another large moth belonging here is the Imperial Moth ( Basilona imperialis
Dru., Fig. 293) which has about the same distribution as the Regal Walnut Moth.
The adult often spreads six inches and is yellow, with lilac or purplish-brown

Fig. 293. — Imperial Moth ( Basilona imperialis Dru.), slightly more than half natural size.
( From Felt, N. Y . State Mus. Mem. 8.)

areas or bands and spots. The caterpillar (Fig. 294) is green (or brown sometimes) ,
from three to four inches long when full-grown, rather well covered with long,
white hairs, and has two pairs of rather stout, upward projecting tubercles or
horns behind the head. It feeds on quite a list of trees including some of the

Fig. 294. — Full-grown larva of Imperial Moth, somewhat reduced. ( Reduced from
Packard, Mem. Nat. Acad. Sci. IX, Part II.)

evergreens, and pupates in the ground during the winter. Like the last species
it is rarely if ever abundant enough to be of economic importance.

Several insects in this family are quite common at times and locally may be
numerous enough to cause some injury to oaks, maples and other trees they feed
upon, but their presence is noticed for only a year or two at a time.

282

APPLIED ENTOMOLOGY

Fig. 295. — Cecropia Moth ( Samia cecropia L.) , slightly over half natural size. {Original.)

Fig. 296. — Polyphemus Moth {Telea polyphemus Cram.), about three-quarters natural size.

{Original.)

THE LEPIDOPTERA

283

Family Saturniidae (The Giant Silkworms). — In this family belong most of
the common, very large moths found in North America. Though their size
and that of their caterpillars attracts attention, these insects are of little economic
importance as the number of eggs laid by an individual is not very large and
they are generally well scattered so that few larva; are often found on any one
tree. If the silk of their cocoons could be utilized they would become industrially
important, but the thread is frequently broken so that reeling it is difficult and
expensive.

One of the more common species in this family is the Cecropia Moth ( Sarnia
cecropia L.), a very large, brownish-gray insect (Fig. 295) with a whitish, crescent¬
shaped spot partly shaded with brown, near the center of each wing. Outside
this spot a whitish line crosses the wing and the outer margin is more or less
broken by black spots on a whitish ground. The abdomen is brown with white
crossbands. The caterpillar (See Fig. 21), which when full-grown is from three

Fig. 297. — Male Promethea Moth ( Callosamia promethea Dm.-), about two-thirds natural

size. {Original.)

to four inches long, is green with tubercles along its back, two pairs near the
head being coral red and the others yellow except the first and last pair which are
blue. The insect feeds on many kinds of plants, including some fruit and shade-
trees. The moths appear in late spring, the larvte feed during the summer, and
in the fall spin rather dense cocoons on the twigs of the trees, in which they
pupate and pass the winter

A rather similar moth, though usually a little smaller, is the Polyphemus
Moth ( Telea polyphemus Cram.), with brown wings crossed near the outer
margin by a blackish band (Fig. 296). The front wing has a transparent “eye”
spot with a yellow margin, around which is a black line. The hind wing has a
somewhat similar spot, but the black around it covers quite an area, particularly
toward the base of the wing. ’ The caterpillar is green with a yellow, oblique
line on the side of most of the segments of the abdomen and it feeds on many
fruit and forest trees. The cocoon is spun among leaves on the ground.

Somewhat smaller, spreading about four inches, is the Promethea Moth ( Call¬
osamia promethea Dru.). The male moth (Fig. 297) is dark brown except toward

284

APPLIED ENTOMOLOGY

the outer margin of the wing where the color lightens somewhat outside a whitish
cross line, and the outer margin is light-grayish with fine brown lines. Near
the apex of the front wing is a black “eye” spot, margined on the inner side with
blue. The female (Fig. 298) is brown with a triangular, white spot near the
center of each wing, a short distance outside of which the brown ends abruptly
in a very irregular edge against white which shades off into brown again.
The outer margin is as in the male and the eye spot is also present on the
fore wing.

The caterpillar is pale green with very small black tubercles in pairs
above, except two pairs not far behind the head, which are coral-red and
larger than the others, and a yellow one above, near
the hinder end. The larvae feed on many kinds of
trees and shrubs, appearing to prefer the sassafras,
wild cherry and ash, and when through feeding, each
selects a leaf, the petiole of which it spins around,
fastening it in this way to the twig on which it
grew, so that it cannot drop off in the fall. It then

Fig. 298. Fig. 299.

Fig. 298. — Female Promethea Moth, about two-thirds natural size. {Original.)

Fig. 299. — Cocoon of the Promethea Moth, natural size. {From Britton, Thirteenth
Kept. Ent. Conn. Agr. Exp. Sta. 1913.)

forms its cocoon with the leaf as a partial wrapping, drawing the edges around
the cocoon (Fig. 299). Here, in this hanging cocoon, swaying in the winds,
the insect passes the winter.

The Japanese Silkworm Moth ( Philosamia cynthia Dru.) was introduced
into the United States in a futile attempt to use its cocoons for silk. Some
of the insects escaped and this species is now occasionally captured in Southern
New England and the Middle Atlantic States. The moth (Fig. 300) spreads about
six inches and is of a rather rich shade of brown. On each wing is a large white
crescentic spot, edged in front by a black line, and a white band, shading on its
outer side into lilac, then into brown, crossing the wing, touches the outer angle
of the crescentic spot. On the front wing a white band runs from the inner
angle of this spot to the body and another to the costa or front margin of the
wing. On the hind wing a similar band curves across about halfway between

THE LEPIDOPTERA

285

the crescent spot and the base of the wing. The caterpillar feeds on the leaves
of the Ailanthus tree and has tufts of white hairs on its body. The cocoon
is made within a partly rolled leaf as in the case of the Promethea Moth.

One of the largest insects in this family is known as the Luna Moth ( Tropcea
luna L.). Its body is densely covered with white hairs giving it a woolly appear¬
ance, and its wings are pale green, with more or less complete purplish margins,
particularly strong along the costa of the fore wing (Fig. 301). In the front
wing is a rather oval “eye” spot connected by a purplish band with the costa.
The hind wing also has an “eye” spot, more circular in outline, shaded with
darker on the side nearest the body, and the wing itself extends backward into a
long, narrow tail. The green caterpillars, between two and three inches long when

Fig 300. — Japanese Silkworm Moth ( Philosamia cynthia Dru.), about two-thirds natural

size. {Original.)

full-grown, feed upon a number of kinds of trees and pupate among leaves on the
ground in the fall. The insect is found from Canada southward throughout the
United States east of the Rocky Mountains.

One of the smaller, very common moths of this group is the Io Moth ( Auto -
meris io Fab.) which spreads between three and four inches (Fig. 302). The two
sexes differ in color, the ground color in the male being yellow, while in the fe¬
male that of the fore wings is purplish-red. The yellow of the male fore wing has
irregular spots and a wavy line of brownish: in the female the ground color is
broken by irregular shadings and a lighter wavy line. The striking feature of
the hind wing in both sexes is a large, circular, bluish “eye” spot with a white
dot forward of its center. The bluish shades into black outside, and is surrounded
by the yellow ground color. Between the eye spot and the outer margins are a
black line and a dull-rose band, and the base and hinder margin are dull rose.

286

APPLIED ENTOMOLOGY

The caterpillar is about two inches long when full-grown, with a rather wide
reddish-brown stripe edged with white below, on each side of the body. It
has many spines which branch, the branches being tipped with black. Touching

Fig. 301. — Luna Moth ( Tropoea luna L.), slightly over half natural size. ( From Felt,

N. Y. Slate Mus. Mem. 8.)

the caterpillars produces a nettling of the skin, due to poison conveyed through
the tips of the spines. The larvae feed on fruit, forest and shade-trees and usually
make their cocoons among leaves on the ground.

Fig. 302. — Female Io Moth ( Automeris io Fab.), about two-thirds natural size. ( From
Felt, N. Y. State Mus. Mem. 8.)

There are quite a number of kinds of Giant Silkworms, the family being
represented in all parts of the country. One generation a year; the moths appear¬
ing earlier or later in the spring according to the length of the season; the larv*

THE LEPI DOPTERA

287

feeding during the summer; and pupation in the fall, with the winter spent in
this stage, appears to be the general rule, though with some exceptions, for most
if not all of the species.

Family Sphingidae (The Hawk Moths). — This large and widespread
group of insects has long and rather narrow fore wings and its members
have a strong flight. Most of them are of quite large size (Fig. 303) and
fly chiefly at dusk, visiting flowers for the nectar, upon which they feed.
They do not alight on the flower but hover over it, running the tongue,
which is often much longer than the body, into the nectary. The body

Fig. 303. — Hawk Moth ( Sphinx chersis Hbn.), natural size. (Original.)

is usually rather stout, spindle-shaped, and it and the wings are often
beautifully colored with combinations of black, gray, olive, tan and rose
or pink. The antennae are large, usually somewhat thickened near the
middle, and the end is in some cases curved a little, like a hook.

The larvae feed upon the leaves of various trees and other plants.
They are naked; generally green, though frequently of other colors, and
in the former case often have oblique white streaks on the sides of the
body and a long horn projecting upward and backward from the upper
side near the hinder end. Some when full-grown, may be two or three
inches long. Pupation is usually in earthen cells underground, though
some form partial cocoons of leaves and .silk on the surface. In some
species the tongue at the time of pupation is not enclosed by that part
of the pupal skin which covers the body, but by a separate portion which
joins the remainder at the front of the head and touches the body about
halfway back, which makes it resemble the handle of a pitcher or jug
in its relation to the pupa as a whole.

288

APPLIED ENTOMOLOGY

A few species have their wings only partially covered by scales.
These are among the smaller species and they fly during the day (Fig.
304).

Of the various species of Hawk, or Humming Bird Moths as they are
sometimes called, only two or three are usually
of any great economic importance.

The Tobacco and Tomato Worms. — There
are two closely related Hawk Moths whose
larvse feed on tobacco and tomato leaves.
One of these is known as the Northern
Tobacco (or Tomato) Worm ( Phlegetliontius
quinquemaculata Haw.) and the other as the
Southern Tobacco Worm ( Phlegethontius sexta
Johan.). The former is present nearly every-
Moth ( Hemaris diffinis Bdv.), where m the United States, the latter fiom
about natural size. {Original.) Massachusetts southward, and westward to

the Pacific Coast.

The adult is a moth (Fig. 305) spreading from four to five inches,
but in the Northern Tobacco Worm the color of the fore wings is ashy-
gray and the abdomen has a row of yellow spots, usually five in number

Fig. 305. — Northern Tobacco Worm Moth ( Phlegethontius quinquenaculata Haw.), natural
size. {From Britton , Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.)

on each side, while in the Southern Tobacco Worm the fore wings are
brownish-gray and there are usually six yellow spots on each side of the
abdomen.

THE LEPIDOPTERA

289

Fig. 307. — Full-grown larva of Southern Tobacco Worm, natural size. ( From Britton,
Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.)

has a separate case in the pupa. The moths appear in the spring
and lay their eggs singly on the leaves of their food plants, and the

19

The life history in both species is quite similar. Winter is passed
as a pupa (Fig. 306) in the ground and in these insects the tongue

|r

Fig. 306. — Pupa of the Southern Tobacco Worm (left) and of the Northern Tobacco
Worm (right), natural size. Note difference in length of the tongue case. ( From
Britton, Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.)

290

APPLIED ENTOMOLOGY

caterpillars feed for 3 or 4 weeks, becoming three or four inches long,
green or sometimes brown in color. In the Northern Tobacco Worm
each abdominal segment is marked on the side by an oblique greenish-white
stripe joining a similar horizontal one at its lower end, forming a series
of whitish Fs. On the hinder end of the body above, is a projecting
green horn with black sides. The larva of the Southern Tobacco Worm
(Fig. 307) has only the oblique bands and the horn is usually reddish.
In the northern part of the range of these species there is one generation
a year. Farther south, two seems to be the rule, while in the Gulf
States three or four are claimed to occur.

Control. — Hand picking is a frequent method of control where the
larvae are not abundant. Spraying when the caterpillars are first seen,
with arsenate of lead, standard formula, has proved effective. Applied
as a dust it has also given good results, but this material either as a spray
or as a powder should not be used on tomatoes after the fruit is half
grown.

The remaining families of Lepidoptera to consider are those of the
suborder Rhopalocera, or butterflies. Most of the insects in this section
are rarely of much economic importance, their larvae feeding chiefly on
plants not utilized in any way as food. Occasionally some species may
cause local injury, but only a few need special consideration from this
standpoint.

Fig. 308.

Fig. 309.

Fig. 308. — Skipper Butterfly ( Epargyreus lityrus Fab.), natural size. {Original.)

Fig. 309.— Little Copper Butterfly ( Heodes hypophleas Bdv.), about natural size.
{Original.)

Family Hesperiidae (The Skippers). — These are rather small butterflies
which have a curious “skipping” style of flight. They are most frequently
black, or yellow and black in color, often with silvery spots or streaks (Fig. 308).
The larvie in this family have heads much larger than the part of the body next
behind, making them easy to recognize. One of the larger members of this
group, found in the South feeds as a caterpillar on the bean, and is known as the
Bean Leaf-roller.

Family Lycaenidae.— In this group belong the little blue butterflies spreading
in most cases at least, less than an inch; similar sized dark-brown butterflies; and
others which are of a red or coppery color (Fig. 309), with black spots. Many

THE LEPIDOPTERA

291

of these insects are very common but are of no importance economically. One
species here departs from the general rule as to the food of Lepidoptera, its larva
being carnivorous and feeding on plant lice. Unfortunately it is not common
enough to be very beneficial.

Some of the species in this family have more than one generation each year
and the adults of the two generations are so different that until one kind was
bred from eggs laid by the other they were supposed to be different species.
Difference in color, markings or both, may therefore be correlated with the season
of the year, and insects having two different forms according to the season,
present cases of what is called seasonal dimorphism.

Fig. 310. — The Monarch ( Danaus archippus Fab.), natural size. {Original.)

Family Danaidae. — This small family is of interest in the United
States mainly because it includes one of our largest and widely distributed
butterflies, the Monarch ( Danaus archippus Fab.). This is common
in nearly all parts of the country and has a striking way of sailing about
in the air. The ground color of the wings is tawny brown marked
with black lines along the veins, and broad black borders containing
white spots (Fig. 310). The caterpillars feed upon milkweed and are
greenish-yellow with black cross-bands and a pair of soft, fleshy projec¬
tions on the back a little behind the head, and another pair not far from
the hinder end of the body. The pupa (chrysalis) is usually attached to
the plant and is about an inch long, stout, bright green with golden dots.

Though the Monarch breeds in the Northern States during the
summer, it appears to come from the South each spring, and in the fall
multitudes often gather and fly southward together. Whether they

292

APPLIED ENTOMOLOGY

succeed in reaching climates where they can successfully winter is perhaps
questionable, but if not, others at least, make their way North each
spring.

This insect is practically free from attack by birds, probably because
it is able to produce a disagreeable odor.

Family Nymphalidae. — This large family includes many familiar
forms, most of them large or of at least fair size. Their fore legs have
been reduced so much they they are no longer used but are carried
folded up against the thorax.

Several of the common species in this group are found in Europe
as well as in this country and a few occur nearly everywhere in the
world where food and temperature permit their existence. The larvae
of some species feed on the currant, gooseberry and hop in the list of
cultivated plants, but are not often important pests.

Fig. 311. — The Viceroy ( Basilarchia archippus Cram.), natural size. {Original.)

In one section of the family the insects are usually black with blue
or green, and occasionally red spots, and one or two species have a white
band across the wings. One of this group, however, differs greatly in
color from all the rest of its relatives, being reddish-brown with black-
lined veins, black wing borders enclosing white spots, and so closely
resembling the Monarch that it has been called the Viceroy (Fig. 311)
It differs from the Monarch, to the eye, however, by the presence of
a narrow black band across the hind wings and by its somewhat smaller
size.

This radical departure in color and pattern of this insect from that
of all its near relatives is believed to be because this group is one freely
attacked by birds for food, while the Monarch, perhaps because of a
disagreeable odor, escapes. Any imitation which would deceive the
birds, would accordingly protect insects possessing it and enable them

THE LEPIDOPTERA

293

to avoid destruction. How such a change could be rapidly developed,
however, to such a degree as to enable its possessors to benefit by it,
has not been satisfactorily explained, and if it were not so developed
the individuals in which the change began could hardly differ enough
from their former condition to escape. Here remains one of the unsolved
problems of insect life.

Family Satyridae (The Satyrs). — The insects belonging in this family are of
medium size, and nearly all have gray or brown wings with spots more or less
resembling eye spots (Fig. 312). They are common near the edges of woods and
sometimes drift out into the fields. One species is found only on the tops of the
White Mountains in New Hampshire and on the higher Rocky Mountains.
How these colonies became so widely separated is a question, though explanations
for it have been suggested.

Fig. 312.— Satyr Butterfly ( Cercyonis alope Fab.), natural size. {Original.)

Family Pieridae. — In this family belong the medium sized or small
yellow butterflies of various shades and the white ones, common in all
parts of the country. About 50 kinds occur in the United States and
some of them are occasionally, and others almost always, injuriously
abundant in one place or another.

The Imported Cabbage Butterfly ( Pontia rapce L.). — This insect, a
native of Europe, appears to have reached Quebec about 1859. It spread
rapidly and ten years later had reached Massachusetts. Other specimens
arriving at New York and Charleston, N. C., also established centers
from which the insect spread in all directions, and it is now found nearly
everywhere in the United States.

The adult (Fig. 313a) spreads a little less than two inches. Its wings
are white, the tip of the front wing grayish. In the male there is a black
spot near the center of the front wing and one on the front margin of
the hind wing, while in the female the front wing has a second black
spot behind the other.

294

APPLIED ENTOMOLOGY

The insect passes the winter as a pale brown chrysalis (Fig. 313d)
about three-quarters of an inch long, attached in some protected place.
The adults emerge in the spring and lay their eggs singly (Fig. 3136)
on the leaves of cabbage, cauliflower, mustard, nasturtium and other
plants of the family Cruciferse, and about a week later the caterpillar
hatches and begins to feed. At first it is pale green, but when full-
grown, after about 2 or 3 weeks, is a soft, velvety-green, and about an
inch long (Fig. 313c). At first it feeds on the under surface of the

Fig. 313. — Cabbage Butterfly ( Pontia rapce L.) : a, adult, slightly enlarged; b, egg,
from side and from above, considerably enlarged; c, caterpillar, somewhat enlarged; d,
chrysalis, somewhat enlarged. ( From U. S. D. A. Farm. Bull. 856.)

leaf, but after growing, eats holes through and may leave only the veins.
It often bores into the forming heads also, in search of more tender food.
It feeds for from 2 to 3 weeks, then pupates for a rather shorter period,
at the end of which time the adult emerges and lays eggs for a second
generation. There are usually two or three generations in the Northern
States and as many as five or six in the South.

Where these insects are abundant they cause considerable injury,
not only to the leaves but by boring into the heads, reducing their value.

Control. — Spraying with a stomach poison, preferably arsenate of
lead, a little stronger than the standard formula, as soon as the cater¬
pillars appear in the spring, is a successful treatment, but as the spray
tends to run off the smooth leaves of the plants, the addition of a little
soap as a “sticker” is desirable. If the larvae of the first generation
are killed for the most part by this, later applications will generally prove
unnecessary. In some cases the poison is dusted on instead of sprayed.

TIIE LEPIDOPTERA

295

If treatment is needed after the heads are half grown, they may
be dusted with pyrethrum, though the danger of poisoning them by the
use of arsenate of lead is practically none.

A native cabbage butterfly closely resembling the last, was formerly
common in the North, but appears to have suffered from competition
with its imported rival. A southern native species has also become
somewhat reduced in abundance, but less so than the northern one.

Fig. 314. — Male Sulfur or Yellow Butterfly ( Eurymus philodice Godt.), natural size.

(Original.)

The common sulfur-yellow butterflies (Fig. 314) with more or less of black
markings on their wings are for the most part, feeders on clover in their larval
stages. One of them, the Alfalfa Caterpillar ( Eurymus eurytheme Boisd.) is
frequently a pest on alfalfa. It occurs everywhere in the United States west of

Fig. 315. — Alfalfa Butterfly ( Eurymus eurytheme Boisd.), about 1^2 times natural size.
(From U. S. D. A. Bull. 124.)

the Allegheny Mountains and has been taken occasionally along the Atlantic
Coast, but is chiefly of importance in the Southwest.

The adult (Fig. 315) spreads about two inches and its wings are orange-
yellow with black outer borders; a black spot in front of the center of the fore
wing and two reddish-orange spots which touch each other, near the center of

296

APPLIED ENTOMOLOGY

each hind wing. In the female the black wing border has yellow spots in it.
Sometimes the orange color in the female is replaced by whitish. The cater¬
pillar is brown at first but later becomes dark-green with a white stripe on each
side (Fig. 316). Alfalfa, clovers, vetches and other legumes are fed upon.
The number of generations seems to vary in different parts of the country
from two in the North to six or possibly more, in the far South. The colder, or

Fig. 316. — Caterpillar of the Alfalfa Butterfly, about three times natural size. ( From U.

S. D. A. Bull. 124.)

in the Southwest, the dry months may be passed either as larva, pupa or adult.
Treatment is by cultural methods such as pasturage, or early and close cutting of
the crop, followed if necessary by rolling or brush dragging.

The spreading of an insect introduced into a country is always of
interest, even if no financial factor is involved, and several of the species
considered in this chapter supply good examples of this. Its method of
introduction; its establishment; the rapidity with which it spreads, and
the final limits of its distribution, are all topics for investigation.

In the case of the Gypsy Moth its introduction was apparently inten¬
tional, though it was far from the plan of the scientist who brought it to
this country that it should escape. It is stated that this scientist had in
mind testing the silk-producing possibilities of various Lepidoptera and
imported a number of species for that purpose. Unfortunately in some
way, some of the Gypsy Moth specimens escaped and as he could not
find them, he issued a notice calling attention to the fact, and warning
the public of the possible menace they might become.

The Brown-tail Moth appears to have been brought to this country
as a winter tent containing young caterpillars, on an importation of
roses from Europe. This occured before the inspection of nursery stock
imported into this country was required by law. How the Cabbage
Butterfly arrived, is not known, but it was probably the chrysalis on
some material brought as freight.

It is evident that in any case, either an adult female able to deposit
fertile eggs, or else several individuals at least, in some early stage,
must be imported at about the same time, if the species is to obtain a
start. Then with an individual ready to lay its eggs, suitable food

THE LEPIDOPTERA

297

plants for its young must be found. There can be no doubt, in theory
at least, that there have been many cases in the past where failure to
succeed in this has resulted in the failure to establish themselves, of
many species which would have been serious pests.

Once started, however, even in a small way, an increase in numbers
and in distribution becomes possible. If some of the insects, however,
were parasitized and the parasites escaped, as well as those not so affected,
the spread might be checked because of the small number of the pests
which would not be found by the parasites.

The spreading of a species from the point where it starts, has been
aptly compared to that of a ripple caused by throwing a stone into water,
which passes out in every direction on its surface. Such a spread will
extend as far as the insect can find food on which it can live and a tem¬
perature and humidity under which it can survive. It follows that for
many insects adapted to northern climatic conditions, a point will be
reached in its southward spread where the temperature and humidity are
such as to prevent its going farther. A lofty and continuous mountain
range may, by producing such conditions, also prove a barrier to farther
extension in that direction, even though beyond the range a favorable
climate may again be found. Absence of any food upon which an insect
can live will also put an end to distribution in that direction, and a pest
adapted to the moist climate of the Eastern States may find itself unable
to establish itself in arid regions. The rapidity with which it spreads
appears to be determined by its fecundity, power of flight in many cases,
and food supply, at least generally; an insect having a high rate of in¬
crease, abundant food, and strong in flight sometimes spreading several
hundred miles in a year. The much larger area to the north and north¬
east of Boston than to the south and west, now occupied by the Brown-
tail Moth appears to be due, in part at least, to strong southwesterly
winds while the moths are flying.

Study of these and other factors involved, shows that northern insects
as they spread southward are found chiefly at least, on higher land. One
living at near the sea level in the Northern States will generally be found
in the mountains in the South, and if it extends into Mexico it will there
occur only on the higher Cordilleras, gaining by its elevation the lower
temperature it has lost by its change of latitude.

Thus we find that with sufficient information at hand, the distribution
of many insects can be mapped, and that there is a division of the country
into regions, the insects of one region rarely spreading far beyond its
limits, and then only forming outposts of the species.

It is true that some species are less affected than others by these
conditions. The Monarch Butterfly, the House Fly and many others
appear to be able to live under wide differences of temperature, humidity
and the other factors concerned. As a wrhole though, an insect will

298

APPLIED ENTOMOLOGY

spread within certain limits, but only within these, and this applies to
other animals and to plants as well.

Family Papilionidae (The Swallow-tails). — The butterflies of this
group are nearly all large, and with a backward-projecting lobe or
tail on the hind wing. One species or another may be seen in almost
every part of the country but they rarely do much injury, feeding for the
most part on plants of little importance. The Black Swallow-tail
Butterfly ( Papilio polyxenes Fab.) is probably the most important species,
as it occurs all over the United States and feeds on celery, carrots, par¬
snips and other plants.

Fig. 317.— Celery Butterfly ( Papilio polyxenes Fab.): a, full-grown caterpillar; b,
head of same showing osmaterium extended; c, male butterfly; d , outline of egg; e, young
larva; /, chrysalis. All about natural size except d, which is much enlarged. ( From U.
S. D. A. Farm. Bull. 856.)

The butterfly (Fig. 317c) spreads between three and four inches, and
its wings are black with two rows of yellow spots crossing each wing, with
blue shadings between the two rows on the hind pair. There is also a
black spot surrounded by orange on the outer part of the hinder margin
of the hind pair. In the male the inner row of yellow spots becomes a
band on the hind wing.

In the South the butterflies winter over, but in the North this period is
spent as the pupa. Eggs are laid singly on the leaves of the food plants,
and hatch in about 10 days. The caterpillars feed for from 10 days to
several weeks, then form their chrysalids (pupae) on some part of the plant
(Fig. 317/) and in from ten days to 2 weeks more the adult butterflies
emerge. There are two generations in the North and more in the South.

THE LEPIDOPTERA

299

The caterpillar when full-grown (Fig. 317a and b ) is about two inches
long, green with a black cross band on each segment , which may enclose six
yellow spots or may fail to close these in on the front side of the band.
Just back of the head is an opening out of which a soft, widely forked
horn can be protruded when the insect is distributed. Such structures
are called osmeteria and give off a disagreeable, pungent odor, and are
probably to drive away enemies which may attack them.

This insect is rarely if ever important enough to call for any control
other than destroying the larvae by hand, though in most cases spraying
with a stomach poison would be entirely effective if such a treatment were
needed.

A similar species present on the Pacific Coast, has the same habits.

CHAPTER XXX

THE MECOPTERA

The Mecoptera is a small order of insects, both in numbers and in the
size of its members. The adults usually have wings which are mem¬
branous, long, and generally narrow, with numerous veins. In a few
cases, however, they are reduced or even rudimentary. The head is
elongated on its underside, forming a sort of beak or rostrum, at the end
of which are the chewing mouth parts (Fig. 318). In the males of one
genus the terminal segments of the abdomen are drawn out and curl up¬
ward, suggesting the position of the end of the body in the scorpion, and
from this the common name ‘‘Scorpion Flies” has been applied to the

order, though some of its members do not
have this character. The larvae considerably
resemble small caterpillars.

The distinctive characters of the order
are:

Insects which when adult nearly always
have four membranous wmgs, long and narrow
and with numerous veins: head prolonged
downward forming a beak, bearing chewing
mouth parts at its end. Larvae more or less
caterpillar-like. Metamorphosis complete.

Mecoptera occur in nearly all parts of the
world but nowhere appear to be very abundant.
They seem to prefer to live in places having rank
growth, and in low, damp woods, and are apparently carnivorous both
as larvae and adults. A few species are found on snow during the winter
months and are wingless or nearly so, but most of the group have wings
longer than their bodies and fly quite well. The eggs are usually laid
in masses in the ground and the larvae live in burrows in the ground,
coming out to feed. They have legs supporting the abdomen and these
are more numerous than in caterpillars. As far as known they pupate in
earthen cells in the ground.

The adults certainly feed upon other insects: larvae in confinement
can be fed upon meat, but their natural food is probably any animal
material they can obtain. Under such circumstances, these insects
must be regarded as being, at best, of little economic importance. Fossil
forms belonging to the Mecoptera have been discovered in different parts
of the world.

In a general way this order appears to have the Diptera, Trichop-
tera and Lepidoptera as its nearest relatives.

300

Fig. 318. — Adult Meeopteron
( Panorpa nuptialis Gerst.)
natural size, showing beak pro¬
jecting downward from the
head, on the end of which are
the mouth parts. {Original.)

CHAPTER XXXI

THE DIPTERA

The Diptera or Flies are small insects, the largest species known being
slightly more than two inches long, but the majority are much smaller,
and many are almost microscopic. The flies as a group are distinguished
from other insects by the presence of only one — the front — pair of wings,
attached to the mesothorax. Sometimes these are absent, the insect
being entirely wingless, but there are only a few such cases. The hind
wings have been transformed into a pair of curious structures known as
halteres. They are small and each resembles a sort of knob joined to the
body by a stalk, usually slender, and variable in length. They are
believed to have special functions but what these are is far from settled.

The wings are usually transparent though sometimes smoky or other¬
wise colored, and in some instances scales are present either along the
veins or elsewhere, and in one family they entirely cover both the body
and wings. The veins are usually quite numerous but often show a
tendency to unite toward the outer margin of the wing, forming closed
cells in this way as well as by the more usual method with cross veins.
In some families, the veins are very few and sometimes several appear
only as faint traces. The hinder margin of the wing not far from its
attachment to the body frequently has a notch called the axillary incision
or sinus, and the membrane from here to the base may form one lobe,
or by other incisions consist of two or even three lobes. The one nearest
the base in some instances appears to become enlarged and lie over the
base of the halter, often partly or entirely concealing this structure from
above.

The head of the fly is connected with the thorax by a small neck which
permits considerable rotation. Much of its surface is occupied by the
very large compound eyes which frequently meet above, particularly in
the males. Between the two eyes, or behind their point of meeting,
are usually three ocelli on the top of the head.

The antennse vary greatly. They may consist of as many as 16
segments or as few as three, in the latter case a bristle, frequently feathered,
being often present, joined to the outer segment.

In one section, a crescent-shaped cleft occurs above the attachment
of the antennse to the head, curving downward on each side. This slit
is called the lunula, and at the time when the fly escapes from its pupa
case a large, bladder-shaped structure is pushed out through this from
the inside of the head, and pressing against the end of the case, forces it
off, enabling the fly to escape. Later, this structure which is called tLe
ptilinum is drawn back into the head.

301

302

APPLIED ENTOMOLOGY

The mouth parts of flies are for sucking, and in some cases for piercing,
also. True “biting flies” do not exist, the “bite” being really caused by
the plunging of the sharp-ended, piercing mouth parts into the object
attacked. There seems to be little doubt that the mouth parts of flies have
been derived from ancestors with chewing structures, but the changes
have been so great that to identify the different pieces with the corre¬
sponding ones of chewing insects is very difficult, and different views on
this have been advanced by students of the subject.

Fig. 319. — Mouth parts of A, a Tabanid; B , a mosquito: a, antenna; aw, compound
eye; hp, hypopharynx; Ibr, labrum; md, mandible; mx , maxilla; mx 2, labium; oc, ocellus;
pm, maxillary palpus. ( Modified from Laug's Lehrbuch.)

Without going into details, it may be stated that in the more typical
fly mouth parts there are six bristle-shaped structures enclosed by a
sheath, and one pair of segmented palpi (Fig. 319). The sheath is
generally regarded as representing the labium or hinder lip, while the
bristles represent the front lip or labrum, the tongue or hypopharynx,
the two mandibles and the two maxillae. At the outer end of the sheath
is a pair of lobes, often large, and these are considered as the labial
palpi, leaving the segmented pair to represent the maxillary palpi.
In some cases, the surfaces of the lobes regarded as labial palpi are
roughened and adapted to the rasping of surfaces. Bringing together
certain of the bristle-like mouth parts forms two tubes, or, in some cases,
grooves more or less completely closed, through which fluids can be
drawn into the body, and saliva be led into the wound made by the
tips of the bristles. Solid food is utilized only by first dissolving it in
saliva.

THE DIPT ERA

303

The thorax, though composed of three segments as usual, has these
very closely and firmly united. In the abdomen, the number of visible
segments varies from nine to five, or even four in some instances. The
legs, usually at least, are well developed, with a pair of claws at the tip
and a pulvillus at the base of each claw. Between the claws there is
often an membranous pad, similar to a pulvillus, or it may be a bristle.
In either case, this centrally placed structure is called an empodium.

On the surface of the body, bristles are often present which have
definite positions and are of aid in identifying the species.

Fly larvae are usually called maggots. Some have well developed
heads while in others no structure of this nature can be recognized.
True legs appear to be absent, though projections of the body which can
be utilized in moving about are common and often bear circlets of hooks.
These vary in their position in different species. The larvae breathe
through spiracles, but the location of these differs greatly, dn some they
are found along the sides of the body as usual; in others there is a pair
near each end of the body; in still others there is only one pair at the
hinder end, and these may occur at the tip of a very extensible tube
which, when fully stretched out, may be several inches long. Nourish¬
ment is sometimes obtained by osmosis directly through the body wall
of the larva but it is generally taken into the mouth. The mouth parts
in the least modified forms are of the chewing type but in most members
of the order they are greatly modified. In some cases, a pair of claws or
hooks appear to be the only structures, while in others a chitinous “rake”
consisting of a cross-bar bearing a row of teeth and connected with a
single rod running backward, serves to rasp and break open the vegetable
cell walls and expos© their fluid or semifluid contents of which the larva
avails itself.

Some flies construct regular cocoons but the pupa is usually either
naked or located in a puparium which is the last larval skin. In this
case, the larva, when ready to pupate, shrinks away from its skin and
pupates within it, using this skin or puparium as a protection instead
of making a cocoon. Escape from the puparium may be either through
a T-shaped split on the back near the front end; a transverse split
between the eighth and ninth abdominal segments in a few cases; or
through a circular opening in the front end.

The chief distinctive characters of the Diptera are:

Insects which when adult have, with a few wingless exceptions, only two
wings, these attached to the mesothorax; the hind wings greatly modified,
each consisting of a small knob attached to the metathorax by a stalk, these
structures being called halteres; mouth parts for sucking, and sometimes
for piercing also. The larvae are called maggots and are without true
legs. Metamorphosis complete.

This is one of the large orders of insects and members of the group

304

APPLIED ENTOMOLOGY

are found in all parts of the world. They differ greatly in their habits,
food, and general modes of life. Some are serious pests either of crops
or of man, while others are among the most beneficial insects known,
acting as parasites. A number of species function as carriers of disease-
producing organisms and are of importance in that way.

About fifty families of Diptera are recognized, many of them very
large while others contain few species.

Fig. 320. — Large Crane-fly {Tipulid) , head bent downward and almost wholly concealed;
halter of right side showing plainly. Natural size. {Original.)

Family Tipulidse (The Crane-flies). — This is a large and widely distributed
family composed of Diptera having long and rather slender bodies and very long
legs; in fact resembling enormous mosquitoes in appearance though a few are
very small (Fig. 320). The antennae are generally thread-like and there is a broad
Y-shaped groove or suture on the top of the thorax.

The larvae of crane-flies in most cases live in the ground and feed on the roots
of grasses and grain and at times cause much injury in this way. Some exceptions
live in decaying wood,' on leaves, in water or elsewhere. There seem to be two
generations each year, adults appearing in the spring and fall, and winter is
passed as the partly-grown maggot. Injury is most often noticed on low or poorly
drained land or where a field has been left in grass for a number of years. Control
of these insects, when they are sufficiently injurious to make it pay, is by drain¬
ing, rotation of crops and plowing early in the fall, when the insects are in the
pupa stage just below the surface of the ground, to crush them there.

THE DIPT ERA

305

Family Culicidae (The Mosquitoes). — These are small insects, famil¬
iar to everyone as they attack man and other animals, and in most
species the females feed upon blood. A few species appear to consume
plant juices. The mouth parts of the males are much reduced and the
members of this sex rarely, if ever, feed. There are many kinds of
mosquitoes but the larvse of all live in water and generally not in large
ponds but in more or less stagnant water, and the most abundant species
develop in temporary pools.

The adults have scales fringing their wings and also along the veins.
The antennae of the males are plumose (feather-like) and very noticeable.
The winter is passed either as the
egg, larva or adult, according to
the species concerned.

The eggs may be laid either
singly, in small clusters, or in
masses often called “rafts” on the
surface of standing water or even
on the ground, hatching in the
latter case after rains or the melt¬
ing of the snow in spring. The
number of eggs laid by one insect
varies in different species but
probably averages several hundred.

The larvae or “wigglers” live
in water and move with a motion
which has given them their com¬
mon name. The head and thorax
are large and distinct, while the
abdomen is slender, and projecting
from next to the last segment of
this section of the body is a re¬
spiratory tube which is usually

rather long and near the end of which the breathing organs open by
a sort of spiracle. When air is desired, the larva floats to the surface
and projects the tip of the respiratory tube just above the water level,
to renew its supply (Fig. 321).

The larvse have mouth parts of the chewing type, and some are plant
feeders. Most of them, however, are predaceous, feeding on tiny water
animals and even on other mosquito larvse, a pair of small brushes
at the mouth being used to cause currents in the water and bring food
within their reach. They molt four times and, after a varying length
of time (a week or 10 days in many cases) in different species and at
different seasons of the year, transform into pupse. These are quite

different in appearance from the larvse, the head and thorax forming a
20

Fig. 321. — Breathing position of larva
of Culex (below), and feeding and breath¬
ing position of Anopheles (above). Much
enlarged. ( Modified from. U. S. D. A. Div.
Ent. Bull. 25, n. s.)

306

APPLIED ENTOMOLOGY

large, rounded mass, joined by a slender abdomen. Differing from
most insect pupae, the pupal mosquito is active, moving through the
water by a curious tumbling end over end. On the top of the thorax
in this stage are two breathing tubes (Fig. 322), and when air is desired
the tips of these are pushed above the surface of the water. The animal
swims by making use of a pair of leaf-like appendages at the end of the
abdomen.

After a brief pupal stage, usually lasting only a few days, the animal
comes to the surface of the water and a split of the pupal skin along the
middle of the back of the thorax appears, through which the adult
mosquito escapes, balancing itself on this skin until it is ready for flight.

Fig. 322. — Pupa of Anopheles (left) and of Culex (right) showing position when breath¬
ing. Difference of form, position in the water and in the breathing tubes are shown.
Greatly enlarged. ( Modified from. U. S. D. A. Div. Ent. Bull. 25, n. s.)

Of the many kinds of mosquitoes known, a small number are of
particular importance aside from their habit of attacking man, being
disease-carriers.

The House Mosquito ( Culex pipiens L.). — This is a very common
species almost everywhere in the Northern United States east of the
Mississippi River and north of North Carolina. It is probably a native
of the Old World where it is also abundant. Though as far as known it
is not a carrier of any human disease yet it is a most irritating pest, and
its control is important on that account.

Winter is passed as the adult (Fig. 323) in protected places and, in
spring, egg clusters containing from 100 to about 300 eggs are laid on the
surface of water. These eggs hatch in from 1 to 4 or 5 days and the
larval stage usually continues for a week or two (Fig. 324). During this
period, the larvae spend much of their time at the surface, the respiratory
tube projecting slightly above the water-line and the body hanging
downward. Pupation for a few days follows, after which the adult
appears. There are a number of generations each season. The adult

THE DIPTERA

307

has unspotted wings and, when at rest, its body is parallel to the object on
which it has alighted (Fig. 325).

A number of other species not concerned in carrying disease are
'also liable to be pests. Near salt marshes of the eastern and southern

Fig. 323. Fig. 324.

Fig. 323. — Male House Mosquito ( Culex pipiens L.), greatly enlarged. Note the
large feathery autennae of this sex. ( From U. S. D. A. Div. Ent. Bull. 25, u. s.)

Fig. 324. — Larva of House Mosquito, greatly enlarged. ( After Howard, Dyar and
Knab.)

Fig. 325. — Alighting positions of Anopheles (left) and Culex (right) Mosquitoes. ( From
U. S. D. A. Div. Ent. Bull. 25, n. s.)

United States, the Salt Marsh Mosquito (Aedes sollicitans Walk.) is
very troublesome, and this species may fly quite a long distance inland.
In the West, other species are abundant.

The Malarial Mosquitoes (Anopheles quadrimaculatus Say and
others). — The species of Anopheles are carriers of malaria. The adults
(Fig. 326) are larger than those of the House Mosquito and their wings

308

APPLIED ENTOMOLOGY

are marked with dark spots. In alighting on an object, the body is
tipped at quite an angle to the object on which it rests (Fig. 325) and
these two differences will at once serve to distinguish the malarial mosqui¬
toes from other species. Another distinction is in the length of the palpi
of the female which in the House Mosquito are short, while in the Malarial
Mosquito they are as long as the beak and therefore quite noticeable.

The species of Anopheles named above is found from Canada to
Mexico, east of the Rocky Mountains.

Fig. 326.

Fig. 327.

Fig. 326. — Female Malarial Mosquito ( Anopheles punctipennis Say) much enlarged.
Antenna of male at right. ( From U. S. D. A. Div. Ent. Bull. 25, n. s.)

Fig. 327. — Larva of Malarial Mosquito, greatly enlarged. ( After Howard, Dyar
and Knob.)

Winter is passed as the adult, and the eggs are laid singly on the
surface of water and hatch 2 or 3 days later. The larvae (Fig. 327)
resemble those of the House Mosquito but have a shorter respiratory
tube and lie horizontally just below the surface instead of hanging head
downward. (Fig. 321). The larval period is about 2 weeks, followed by
a pupal stage lasting 2 or 3 days. Accordingly, a new generation of
these mosquitoes may appear about every 3 weeks.

Most species of Anopheles attack man chiefly during the twilight
and early morning hours. The various species of Culex seek their food
at night though often beginning their work late in the afternoon.

THE DIPT ERA

309

Different species of Anopheles appear to be connected with different
types of malaria. Anopheles quadrimaculatus has been proved to carry
the organisms causing both the tertian and quartan forms while Anopheles
crucians is a carrier of the organisms producing the sestivo-autumnal
type of the disease, and, in other parts of the world, other species play
similar roles in relation to these forms.

The animals causing malaria are believed to be of three closely
related kinds, belonging to the Protozoa. In its form when introduced
into the blood of man, the animal is a rather long and slender spindle
with pointed ends. It now assumes an amoeboid form and attacks a
red blood corpuscle, working into it, feeding on its haemoglobin contents
and producing black granules. It feeds on the haemoglobin in the
corpuscle until this has all been consumed and grows until it nearly fills
the corpuscle. It now divides into many parts, each similar to the one
which first entered the corpuscle, and these proceed to attack other
corpuscles in a similar way. This breaking up of the animal into parts
coincides with the “chill” of the disease and the interval of time between
successive chills determines which type of malaria is present, a period of
2 days indicating the tertian type; 3 days the quartan type, while a
varying period indicates the sestivo-autumnal type. As the parasites
increase in abundance and consume more of the corpuscles, the patient
becomes ansemic and weaker.

Some of the products of division in the corpuscle, however, do not
proceed to attack other corpuscles and increase in numbers but are of
two different kinds which are the sexual stages. When these are taken
into the stomach of an Anopheles which attacks a person having malaria,
the two kinds fuse and the resulting animal penetrates the cells of the
stomach wall of the mosquito and there remains, forming a cyst. Divi¬
sion of the animal here results finally in the production of cells like those
which enter human blood, and these now escape into the body cavity of
the mosquito and gradually gather in its salivary glands whence, they
are expelled into the wounds caused by the feeding of the mosquito there¬
after. The time which must elapse after a mosquito has received the
malarial parasites before it can transmit these to man varies, but is
usually at least 10 or 12 days and may in some cases be more than this.

The Yellow Fever Mosquito ( Aedes cegypti L.). — This insect, for¬
merly known as Stegomyia fasciata, is the carrier of Yellow Fever. It
occurs in the tropics throughout both hemispheres and, during warm
weather, may extend to the temperate regions but can survive there
only while the temperature is fairly high.

The adult (Fig. 328) is a small mosquito with silvery lines along the
back of the thorax and its legs are banded with white. It flies in the
daytime and occurs mainly in towns and cities, being only rarely found
in the country. Its eggs are laid singly or in small clusters on, or close

310

APPLIED ENTOMOLOGY

to, water in houses or near by, it having apparently become a “wholly
domesticated” species. The eggs hatch in from 10 hr. to about 3 days,
and the larvae hang downward from the surface. After a week or 10
days in this stage, they pupate for 2 or 3 days before the emergence of the
adult. Feeding by the adult appears to be mainly during the warmer
hours of sunny days though extending somewhat into the evening.

Repeated investigations show that the unknown germ or organism
producing Yellow Fever is conveyed to man only by the attacks of this
insect. Apparently about 12 days is required after feeding on a Yellow
Fever patient before the mosquito is able to transmit the organism caus¬
ing the disease, but from that time on it can do
this for well over a month.

Dengue and Filariasis, two other important
diseases of man in tropical and subtropical
regions, are also known to be carried by
mosquitoes.

Control of Mosquitoes. — There are many
ways by which mosquitoes can be more or less
effectively controlled. The thorough screening
of houses to keep them out is a desirable prac¬
tice and is also of value as a protection against
house-flies. Nettings over beds for the same
purpose are often used where entire houses are
unscreened. Out-of-doors, veils covering the
head, and gloves for the hands are often necessary
in places where these insects are extremely
abundant. Protective materials rubbed on ex¬
posed parts of the body are also often used and
various substances have proved of value for this purpose. Among these
are spirits of camphor, oil of pennyroyal and oil of citronella which seem
to be the favorite substances used in this way. Smudges will keep away
mosquitoes where the smoke is, and burning insect powder in a room
stupifi.es the insects so that they fall to the floor and can be swept up.
Other materials for use in a similar way are also available.

Destruction of the larvae, pupae and eggs is the most direct way in
which to control mosquitoes in large numbers, and many methods for
accomplishing this have been tried. As mosquitoes develop only in
water, the removal of the places where they can breed, such as the drain¬
age of marsh land, filling up small pools, hollows in trees containing
standing water, and all such situations will accomplish a great deal.
The drainage of the salt marshes of the New Jersey coast and elsewhere
has resulted in a marked relief from the attacks of mosquitoes in those
localities. Where the water can not be drained off, covering it with a
film of kerosene will suffice to destroy the eggs on the surface, larvae and

Fig. 328. — Adult Yellow
Fever Mosquito (A fries
cegypti L.), considerably en¬
larged. Note black and
white banding of the legs.
(After U. S. D. A. Farm.
Bull. 547.)

THE DIPTERA

311

pupae at or coming to the surface for air, and any adults which may alight
on the water to lay their eggs. Rain water barrels and cisterns for storing
water for use can be screened, and ponds where the use of oil is undesirable
may be stocked with small fish (sun-fish or top minnows) which feed
voraciously on these insects. Recent experiments indicate that where
the water must be used for drinking purposes, making the use of oil
objectionable, sprinkling powdered formalin on its surface will kill
mosquito larvse but not fish present, without making the water impossible
to drink!

The catch-basins of sewer openings are usually favorite breeding places
for mosquitoes and these must be given attention, along with cess-pools
and any tin cans or other receptacles containing rain water which can be
found.

Oil used should be sprayed on the water, working preferably along its
windward side and using about 1 fl. oz. to every 15 sq. ft. of surface.
The oil will spread if simply poured onto the water, but rather more of it
will be required by that method. It is important to be sure that little
detached pools along the shore receive their film of oil also. This treat¬
ment should be repeated every 10 to 15 days unless heavy rains carry off
the oil soon after a treatment, in which case the oil should be renewed
sooner. Sawdust soaked in kerosene has been found to give up the oil
slowly and thereby preserve the film on the surface longer, when this
material is scattered along the edge of the water.

Family Itonididae (The Gall Midges). — These tiny flies are very
numerous. Most of them produce galls on plants, living in these galls,
but some suck plant juices without producing galls, and a few live in
decaying wood or fungi, or even feed on Aphids. The adults have long
antennae with, in the majority of the species, a whorl of hairs on each
segment. All parts of the plant are attacked by one species or another,
and the galls produced are typical for the species in each case.

The gall appears to be the result of the irritation caused by the larva
feeding, and to some extent its size is dependent upon the number of
larvse present. AVinter is frequently spent as the larva inside the gall
and, in many cases, there is but one generation each year though, on the
other hand, some species have several generations.

The larvse are small, often brightly colored maggots. The method of
pupation varies in different species, some forming true cocoons while
others have a puparium and others are without any covering.

Among the species not producing galls is the Clover-flower Midge ( Dasyneura
leguminicola Lint.) which lays its eggs in the flower heads of mammoth, red,
crimson and white clover and is probably present everywhere in America where
these clovers occur. There are two generations each year. The larvre feed on
the flowers and prevent their forming seed. As the insects do not affect other
parts of the plant, they are not of serious importance except where seed is grown,

312

APPLIED ENTOMOLOGY

but in those localities they are very injurious pests. The usual methods of control
are to pasture the fields before starting a seed crop, to destroy all the midges
present in the heads then available: by early cutting, to dry up the heads before
the maggots in them have finished feeding, which in the northern districts would
mean cutting early in June. Sometimes, cutting the clover back between the
fifteenth and twenty-fifth of May will prove advantageous as the new blossoms
will not develop until after the adults of the first generation are gone, and will
have progressed beyond danger of injury by the time the adults of the second
generation appear. Clover so cut can be fed green to stock.

The Hessian Fly ( Phytophaga destructor Say). — This insect, which
like the last is one of the non-gall-making Itonididse, is a native of Europe
and was first noticed in this country about 1779 on Long Island, N. Y.
Since that time, it has spread over a large part of the United States and

Canada and is now one of the most
injurious insect pests in the country,
often destroying wheat valued at
millions of dollars. It feeds on wheat,
barley, rye, and several other species
of grasses.

Its life history differs somewhat in
different places, apparently being
modified by the different methods of
wheat growing. Where wheat is
planted in the fall, the eggs are laid
on the leaves of the plants soon after
they come up, the time varying with
the latitude from late August and
September in Michigan, to the last of
November or early December in
Georgia. The eggs are placed in ir¬
regular rows of about half a dozen,
generally on the upper surface of the leaf, and each fly lays 100 to 150 in
all. They hatch after a few days, and the tiny pinkish or reddish maggots
work their way down between the leaf and the stem to a point just above
the joint (Fig. 329). Here they remain, sucking the sap until the
approach of cold weather, turning more nearly white in color. Their
presence at this time is at first indicated by the dark color of the leaves,
missing stems which would otherwise begin to show, and later, the yellow¬
ing and death of the plants. After feeding about a month, the larva
pupates within its larval skin which therefore becomes a puparium and so
greatly resembles a flax-seed that, in this condition the insect is generally
spoken of as being in the “flax-seed” stage. In this condition, it spends
the winter and the adult flies (Fig. 329) emerge in the spring; early in the
South; later in the North. These now lay their eggs on the wheat and,

Fig. 329. — Hessian Fly ( Phytophaga
destructor Say): a, adult fly; b, wheat
plant affected; c, maggot. Hair lines
show true length of a and c. ( From
Berlese.)

THE DIPTERA

313

as by this time the plants may be a number of inches high, the eggs
can be laid at different heights on the plant, and the larvae will pass down
to the joints immediately below the leaves on which the different eggs
are laid. Feeding at these joints continues during the spring and the
flax-seed stage is reached at or before harvesting time. Some of the
flax-seeds will be in the straw cut and harvested while many more will
remain in the stubble and the flies emerge from the flax-seeds during the
early fall as already indicated, ready to attack the fall-planted wheat as
soon as it comes up.

In regions where the wheat is planted in the spring, the insect winters
in the flax-seed stage in stubble and volunteer wheat, and the adults
appear in May. The second generation quickly follows the first, particu¬
larly in wet seasons, and there seems to be no period of delay such as
occurs during midsummer in the fall-wheat regions.

Control. — The Hessian Fly has numerous parasites which are undoubt¬
edly of much value, as where great loss occurs these insects are few in
number. It is so often the case, though, that the fly is abundant, that
parasites can not be relied upon and other measures, largely preventive
in their nature, must be taken.

It is evident that, if fall planting can be delayed until the adults
which appear at that time are gone, the crop will be protected from
attack. To carry out this plan, however, latitude, elevation and humid¬
ity perhaps, as well, must be taken into consideration. Investigations
along this line, though far from complete, now indicate that it is generally
safe to plant wheat in northern Michigan after the first of September:
in southern Michigan and northern Ohio, about the twentieth of that
month: in southern Ohio, after October 7: in Kentucky, after October
15 : and in Georgia, from the last week in October to the middle of Novem¬
ber. Thus in general, the farther south, the later the planting date
should be, though very high land in any region can probably be planted
earlier than low land if the area and elevation are sufficient to give it the
more northern conditions.

The rotation of crops is also of advantage, driving the flies elsewhere
to lay their eggs and making them more liable to destruction while
en route.

Many of the flax-seeds are left in the stubble at harvesting and
anjr method of destroying these is beneficial. Where the grain is cut
rather high and a mowing machine is then run over the field, cutting
the stubble as close as possible, burning this cut stubble after a few days’
drying is effective. Unfortunately, however, the general custom of
planting grass and clover in such fields, to come up as the grain progresses
toward harvesting, too often makes this control impracticable.

Volunteer wheat as it is called, coming from grain scattered through
and around the wheat fields by accident, starts early and provides plants

314

APPLIED ENTOMOLOGY

for the Hessian Fly to lay its eggs on before the main planting is avail¬
able. This will produce an abundance of the insects to attack the crop
the following spring. All such plants should be destroyed before the
maggots in them have reached the flax-seed stage.

The use of good seed, planted in soil that has been thoroughly culti¬
vated to break up all the lumps of dirt and thus provide a compact,
fine soil, is very helpful, and the addition of plenty of fertilizer is also of
importance.

One writer has summarized control methods for the Hessian Fly
as follows: “Sow the best of seed in thoroughly prepared, fertile soil
after the major portion of the fall brood has . . . passed out of existence,
and, if possible, sow on ground not devoted to wheat the preceding year.
In the spring-wheat section late seeding will not apply. It seems likely,
on the contrary, that the earlier it is sown in spring the less it will suffer
from the Hessian Fly,” (Webster).

Another Itonidid attacking wheat, and also barley, rye and oats occasionally
is the Wheat Midge ( Contarinia tritici Kirby), a native of Europe, first noticed
near Quebec about 1819, and which has now spread over the wheat-growing
regions of the East, and through the Mississippi Valley. The adults are very
small, yellow or orange colored, and appear in June. They lay their eggs in the
chaff covering the growing kernels of grain, and the reddish maggots suck the
juice from the kernels causing them to shrivel, blighting the heads. When full-
grown, the maggots pupate in the ground, usually passing the winter in this stage.
There is generally only one generation each year.

For many years, this was a very serious enemy of wheat, the loss in New York
being estimated at $15,000,000 in 1854, but since about 1860 it has been less
destructive and only local in its attacks. Plowing infested land deeply in the fall
so that the insects wintering there will be buried too deeply for them to escape
the following spring: burning the chaff and screenings after threshing the grain
from infested fields, and rotation of crops are the control methods used for
this pest.

Family Tabanidae (The Horse Flies or Gad Flies). — Those pests of
cattle, horses, and occasionally of man also (Figs. 330 and 331) are in many
cases quite large insects, with bodies an inch long though most of them
average a third to half an inch in length. The head of the adult is large
and fits onto the thorax somewhat like a cap. Only the females feed
on blood, the males lacking some of the mouth parts necessary with
which to pierce the skin. They therefore feed on such plant juices as
they may be able to obtain, honey dew and other similar materials.

The eggs are laid in masses on plants over water or marshes, and the
larvae live in water, damp places, or in the earth when it is soft, and are
carnivorous, feeding on snails, small insect larvae, etc.

The family is a large one, both in this country and elsewhere. The
larger species, (one has a black body and smoky wings), are often noticed

THE DIPTERA

315

around domestic animals because of their size. Many of the smaller kinds
have wings banded with dark. Some of these are called" Green-heads”
because of the bright green color of their eyes (Fig. 331). Their attacks
irritate and disturb the animals and, in the case of milch cattle,' this
may reduce the amount of milk produced.

As these insects attack domestic animals only for their blood, any
repellent measures which prevent this are sufficient. Fly-nets covering
the greater part of the animals are sometimes used for this purpose: and
smearing the ears and legs with substances having an odor objectionable
to the flies is also practiced. One of several materials often applied is
fish oil, either alone or mixed with tar. The following mixture has proved

Fig. 330. — Large Horse Fly ( Tabanus stygius Say), slightly reduced. {Original.)

Fig. 331. — Small Horse Fly ( Chrysops vitlatus Wied.), over twice natural size.
{Original .)

effective against those Tabanids which preferably attack the ears and the
region around the eyes of the animals: pine tar, 1 gal.; fish oil or crude
carbolic acid, 1 qt. ; powdered sulfur, 2 lb. These materials are thor¬
oughly mixed and rubbed on the parts most liable to be attacked. As so
many Tabanids pass their early stages in stagnant water, the treatment
of such breeding places with kerosene will destroy the larvae as they hatch
and enter the pools.

Family Simulidae (The Black Flies or Buffalo Gnats). — The small flies which
compose this family feed upon the blood of man and other animals, attacking
them at all exposed places. As in the Tabanidse, only the females are concerned
and these are active only during the daytime. The eggs are laid in such places
that the larvae can enter water, and in most cases, swiftly running streams where
they feed on small animals. They usually anchor themselves to some object in
the water and have a pair of fan-shaped structures at the mouth which are used
to produce currents toward the mouth. In the South, all domestic animals suffer
severely from the attacks of these insects, and many are even killed by them.
There are usually two or three generations each year, particularly in the South.
The best control methods known are the use of repellent materials on the animals,
such as fish oil three parts, kerosene one part, applied about twice a day. Ani¬
mals kept in dark stables are not attacked while there.

316

APPLIED ENTOMOLOGY

Family Asilidae (The Robber Flies). — These insects as adults prey
upon other insects, attacking any species they are able to overcome (Fig.
332), but using little discrimination as to the importance to man of their
captures. They can hardly be regarded as more than accidentally
beneficial to man. Some species (Fig. 333) so closely resemble bumble¬
bees that a careful examination of the number of wings present is necessary
to determine what the insect is. The larvae are found chiefly under bark,
in decaying wood or in the ground where decaying vegetable matter occurs,
and feed upon insect larvae present in such places.

Fig. 332.

Fig. 333.

Fig. 332. — Robber Fly ( Scleropogon picticornis Loew), about twice natural size.
(From U. S. D. A. Bull. 124.)

Fig. 333. — Bee-like Robber Fly ( Dasyllis grossa Fab.), slightly reduced. (Original.)

This family is one of the largest in the order and its members average
large, ranging from a length of about a fifth of an inch to nearly two inches.

Family Syrphidae (The Syrphus Flies). — This is one of the largest
families of Diptera. The adults range from quite small to rather large
insects which visit flowers, feeding on the pollen and nectar, and are most
noticeably abundant in bright, sunny weather. They are usually rather
brightly colored.

The larvse of these insects vary greatly in their appearance, five types
of them having been recognized. Some are rather flattened, elongate,
often green with white spots, and are found with clusters of plant lice on
which they feed. Others have nearly cylindrical bodies and bore into
the bulbs of various plants. Others live and feed in filth and have short
extensible tubes for respiration. Another class which also inhabits filth
has extensible respiratory tubes which, when extended to their limit, may
be several times the length of the body. Still another group are short,
broadly rounded, flattened beneath and high above, somewhat hemispher-

THE DIPTERA

317

Fia. 334. — Adult female Bot Fly ( Gastrophilus nasalis L.), nearly twice natural size.

(From U. S. D. A. Bull. 597.)

Fig. 335.- — Nearly full-grown larvae (bots) of a Horse Bot Fly attached to the inside wall
of the stomach. ( From U. S. D. A. Bull. 597.)

318

APPLIED ENTOMOLOGY

ical in form. These are usually found under logs and in ants’ nests and
may easily be mistaken for rather peculiar snails.

Though the adults consume pollen, their visits to flowers are valuable
to man for the cross-pollination and the resulting “setting” of seed.
The insect-eating larvae often destroy enormous numbers of insect
pests, and the filth-inhabiting forms are at least cleaning up decay¬
ing matter, which is generally considered desirable. On the other hand,
some are injurious by boring into the bulbs of cultivated plants, and sev¬
eral species cause myiasis in man and some of the domestic animals, these
insects in one way or another entering the body and passing through their
larval development there.

Family (Estridae (The Bot Flies). — The bot flies in their early stages
are parasites on mammals. The adults are of medium to large size,
with rather stout, thick-set bodies and frequently with reduced mouth-
parts, not feeding in this stage (Fig. 334). Though the group is not a
large one, its members are included among the more important pests of
domestic as well as of other animals. The parasitic part of the life of
these insects is in some species spent in the stomach (Fig. 335) or intes¬
tines, in others in the pharynx or nasal cavities and frontal sinus, while
others live under the skin.

Fig. 336. — Ox Warble Fly ( Hypoderma lineata Vill.) . Real length shown by hair
line. ( From U. S. D. A. Div. Ent. Circ. 25.)

Fig. 337. — Full-grown Warble (larva), dorsal view (left) and side view (right).
Real length shown by hair line. ( From. U. S. D. A. Div. Ent. Circ. 25.)

The Ox Warbles ( Hypoderma lineatum Vill. and Hypoderma bovis De
G.). — These two insects, both natives of Europe, are present in this
ocuntry, the former widely distributed, the latter most abundant in
Canada and a few of the Northern States. The adult fly (Fig. 336) is
about half an inch long. The eggs of both species are laid on the hairs of

TIIE DIPTERA

319

cattle on almost any part of the body during the late spring or summer
months, and the larvae bore through the skin into the connective tissue
and then wander through the body in the connective tissues until late fall
or winter when they locate along the back, a few inches from the back¬
bone. Here each makes a hole through the skin through which to escape
but remains inside, feeding on the pus and bloody matter produced by its
presence there, and the swelling caused by the insect is called a “warble.”
Finally the maggot, now nearly an inch long (Fig. 337; and grayish-white
in color, works its way out through the hole and drops to the ground which
it enters for an inch or two, and forms a pupa within a brown puparium
from which the adult fly appears from 3 to 6 weeks later, the larval period
within the cattle being 9 or 10 months.

The presence of the maggots of the ox warbles in the cattle is shown
by a loss of flesh, reduction of the milk in the case of milch cattle, and by
the presence, during late fall and winter, of the sores on the back.

Control. — The chief control method in general use is squeezing out the
larvae in the back whenever they are observed there. With a little
practice, pressing with the thumbs on the skin at the sides of the opening
will result in the expulsion of the maggots. During the egg-laying season,
cattle in the field may be protected to a considerable extent by the appli¬
cation of repellents such as are used to keep off Tabanids.

Various other bot flies attack different animals. Among them are
the Horse Bot Flies ( Gastrophilus of several species), the larvae of which
live in the stomach of the horse during the fall, winter and spring and the
Sheep Bot Fly ( (Estrus ovis L.) which in the larval stage inhabits the
nasal cavities and frontal sinuses of sheep during the same period.

Family Trypetidae (The Fruit Flies). — Some of these small flies attack
various fruits in which their maggots tunnel, ruining the fruits. Others
mine the leaves of plants, occur in blossoms or form galls in the stems or
roots of plants. Those which live in fruit are of economic importance.
Most of the flies belonging here have dark bands, or dark markings
enclosing transparent spots on their wings. Two species attack cherries;
one feeds in currants and gooseberries; one in the apple, thorn, blueberry
and huckleberry, and other species injure citrus fruits.

The Apple Maggot or Railroad Worm ( Rhagoletis yomonella Walsh). — This
insect is apparently a native of this country and its original food seems to have
been the berries of the thorn and possibly the blueberry. It has been found in
various parts of Canada and the eastern United States as far south as North
Carolina and west to Minnesota, South Dakota and Colorado, but is most serious
in the northern and eastern portion of this territory.

The adult (Fig. 338) is about a fifth of an inch long and has a wing spread of
about half an inch. Its body is black with light marks on the upper side of the
abdomen, and the wings have heavy dark bands. The flies first appear in the
orchards early in July in New England (somewhat earlier farther south) and

320

APPLIED EN TOMOLOG Y

attack the early varieties of apples. Later appearing flies may sometimes be
found until into September, and these select fall and winter fruit for egg laying.
Some varieties of apples are much more subject to the attacks of this insect
than are others.

Egg laying begins about 20 days after the fly emerges and probably continues
for 2 or 3 weeks, the total number of eggs laid being several hundred. These
are inserted singly under the skin of the apple and preferably where the surface
is not exposed to sunlight. They hatch in 4 or 5 days and the little whitish
maggots tunnel through the pulp of the fruit in all directions. At first, the
rapid growth of the fruit may fill up these tunnels, but after a time the walls
around the tunnels instead of filling in, turn brown and the fruit softens, decay
may follow, and the entire apple is spoiled for sale. The maggot (Fig. 339) has
no real jaws with which to tunnel but has a pair of small hooks at the mouth
opening with which the pulp is rasped and torn, freeing the juice upon which
the insect feeds.

Fig. 338.

Fig. 339.

Fig. 338. — Adult, Fly of the Apple Maggot ( Rhagoletis pomonella Walsh), slightly
over three times natural size. ( Reduced from Nova Scotia Dept. Agr. Bull. 9.)

Fig. 339. — Puparium (left) and full-grown maggot (right) of the Apple Maggot.
About three times natural size. {Modified from Nova Scotia Dept. Agr. Bull. 9.)

The length of the larval stage depends upon the temperature and upon the
ripeness of the fruit. In warm weather and with rather soft pulp, about 2 to 4
weeks is usually the time necessary, but with colder weather and in late-maturing
varieties, growth toward maturity is delayed and some maggots may possibly
even winter in this stage in extreme cases. When the larva has completed its
feeding, however, it leaves the fruit (usually as this becomes ripe) and enters the
ground where it burrows below the surface often some distance, and pupates in
a puparium (Fig. 339) remaining here until the following summer when the flies
emerge. Where infested fruit is gathered and stored before the maggots leave it,
the puparia may be found on the bottom of the barrels or bins where the fruit is
kept. A few of the earlier pupating maggots appear to transform to flies the
same season, giving a second generation, but so few d© this that it is of little or no
economic importance. On the other hand, a few seem to require 2 years for
the completion of their life history.

The amount of injury caused where this inseot is abundant is often very great,
particularly with early apples, a large percentage of which may prove entirely
worthless. Among the varieties which suffer severely are the Early Harvest,
Gravenstein, Porter, Red Astrachan, and Wealthy, sweet and sub-acid summer

THE DIPTERA

321

and fall varieties being in general the greatest sufferers though winter varieties,
as the Northern Spy and others, often do not escape.

The adult flies feed freely and also seem to require water during their life,
specimens supplied with food but no water dying within a few days. They do
not appear to fly freely for long distances at least, and orchards in which they are
abundant and others where they are rather few in number may occur not very
far from each other.

Control. — Infested fruit falls to the ground early, and the maggots in it rarely
leave it for the ground to pupate until about a week later. Gathering and
destroying this fallen fruit promptly should, therefore, be of much assis¬
tance in controlling the insect but the amount of labor involved in carrying
out this plan makes it impracticable in many cases. Cultivation of the ground
under the trees has proved ineffective and allowing poultry and hogs to run in the
orchards has not resulted in much improvement.

It has been found that where orchards are carefully sprayed just about the
time the flies appear, using slightly less arsenate of lead than the standard formula
and repeating this treatment 2 weeks later, excellent residts are obtained. The
addition of molasses has sometimes been advised, but comparative tests thus far
made indicate little advantage from this considering the extra expense and trouble.
To know just when to apply the first spray is a difficulty with this treatment,
however, and it has been suggested that owners of infested orchards can place
infested apples in a box containing several inches of earth and leave it out during
the winter. In the spring, cheese-cloth can be placed over the top and the spray
should be applied as soon as the first flies are seen on the under side of the cloth.

Family Muscidae (The Muscid Flies). — This large family contains
many species which are important to man though none appear to be crop
feeders. The adults range from small to medium size and are very
abundant in most cases.

The House-fly ( Musca domestica L.). — This insect, always a house¬
hold pest, has during the last 25 years assumed a greater importance
to most people because of the discovery that it is a carrier of a number of
serious human disease-producing agents, among these being the germs
of typhoid fever, cholera, dysentery, etc.

The adult flies (Fig. 340) hardly need any description. They are
rather small, with reddish-brown eyes, transparent wings and blackish
bodies. Their mouth parts are for sucking and a “biting” fly found in a
house at any time is of some other species.

Winter is at least usually spent as the pupa or perhaps in some cases
as the larva. As the weather becomes warm in the spring, the flies
emerge, and, in temperate regions, begin breeding early in June, though
it is probable that in warmer climates this may continue throughout the
year. Most of the flies breed in manure piles, particularly those exposed
to light, but almost any decaying animal or vegetable matter may be
selected for the purpose. The eggs (Fig. 341) are laid in clusters, about
125 at a time and about 500 to 600 in all. They hatch in from 8 to 12

21

322

APPLIED ENTOMOLOGY

hr. during warm weather but may take 2 or 3 days if the temperature
is low. The larvae (Fig. 342) feed on the manure or other material in
which they are located, for a varying number of days but probably
averaging about 5 days. Pupation for about the same length of time
follows, but many of the maggots may leave the place where they feed
and travel a short distance away to pupate. Thus, pupae may be found
in the ground around a manure pile within a foot or two. Pupation is
within a puparium, the fly pushing off the front end by means of its

Fig. 340. — House Fly

( Musca domestica L.), rather more than twice natural size.
duced from Hewitt: The House Fly.)

Rc-

DP111^

•

A *■ ,i - • ■

Fig. 341. Fig. 342.

Fig. 341. — Eggs of the House Fly, much enlarged. (Original.)

Fig. 342. — Full-grown maggots of the House Fly, much enlarged. (Original.)

ptilinum. After the emergence of the adult fly, a period of about 14
days elapses before egg laying begins so that the time from one of these
periods to the next during warm weather is about 24 days. From 7
to 10 generations are liable to be produced, therefore, in a long season in
the North or under ordinary conditions in the South, and it has been
calculated that the descendants of a single fly which deposits its eggs
the middle of April would number 5,598,720,000,000, by the middle of
September, if all the eggs hatched and lived to adults which reproduced
in their turn. Fortunately, this is not actually the case, eggs failing to
hatch and many larvae never reaching maturity.

House-flies as disease carriers are of extreme importance. Crawling
over and feeding upon filth of any kind, their legs and bodies are liable
to gather the germs of various diseases, which may also be taken into the
flies with their food. Later, visits to houses and human food over which

THE DIPTERA

323

the flies crawl lead to leaving some of the germs there, and the well-
known habit they have of disgorging some of the food already eaten and of
expelling feces, both of which may contain the germs swallowed, is pretty
certain to infect the human food over which they crawl.

Doubtless many of the microorganisms thus placed on food are
entirely harmless to man but among these are also liable to be those
which cause diseases. Milk exposed to the visits of flies may become
infected in a similar way.

Among the disease germs often transmitted thus are the typhoid
fevers, anthrax, tuberculosis, cholera and yaws, while others are suspected
of being carried in this way also. The habit flies have of visiting spit¬
toons; of alighting on sores on persons and, in fact, of crawling over
everything where disease germs are liable to occur, makes them par¬
ticularly dangerous to man. It should be noted, however, that there
seems to be no development of any of these diseases while on or in the
flies themselves, the insects acting as passive carriers only, of the germs.
The relation of the insect to the disease, therefore, is a totally different
one from that of mosquitoes and the diseases in which they are concerned,
where the disease-producing organism actually passes through a part of
its life cycle in the insect.

Control. — As over 90 per cent of the house-flies breed in manure,
treatment of this to destroy the larvae and pupae there becomes an
important line of attack. But, as in most cases this manure is used as
fertilizer, the treatment should be, if possible, something which will not
affect the value of this material for use. Most of the larvae live near
the surface of the manure piles, and it has been found that treatments
with materials which will penetrate six or eight inches into the piles will
reach most or all of the insects. Three-quarters of a pound of common
borax dissolved in 3 gal. of water and poured over the pile will be suffi¬
cient to properly treat 10 sq. ft. of surface of the pile to the depth of a
foot, so that applying this amount of fluid to 15 sq. ft. should reach all,
or nearly all, of the larvae and pupae in this space. It should also be
applied to the ground around the pile for a foot or two as many of the
larvae crawl outside the pile to pupate.

Too much borax in the manure injures it as a fertilizer, and, in many
cases, it is better to use Hellebore instead. Half a pound of this in 10
gal. of water is enough for 10 cu. ft. or to cover 15 sq. ft. to a sufficient
depth to reach the insects. This treatment is somewhat more expensive
than the other but the increased value of the manure is likely to more than
make up the difference.

Open latrines and any places in which house-flies are breeding should
be treated to destroy the larvae and pupae present or covered in such a
way as to prevent the flies from reaching them. Chloride of lime and
iron sulfate have been used with considerable success to kill fly larvae

324

APPLIED ENTOMOLOGY

ancl pupae or drive away the adults, particularly when sprinkled around
in stables. Hauling the manure directly to the fields and spreading it
there, when practicable, preserves more of its value than letting it stand
in piles where leaching and other processes going on reduce this. The
destruction of garbage and of the organic matter at public “dumps,”
in which flies breed, is also important. Screening houses, food and gar¬
bage pails or cans and trapping the adult flies either by poisoned or sticky
fly papers or by the use of fly traps are all methods for reducing the fly
pest which, when these insects are abundant, should be made use of.

Almost any fly having habits similar to those of the house-fly may be¬
come a disease carrier in a similar way, and the above methods are of
value against them all.

Some of the flies in this family lay their eggs on meat, either decaying
or fresh, which is then spoken of as “blown.” The flies which do this
are usually the ones commonly called “blue-bottle” and “green-bottle”
flies.

Fig. 343. — Screw-worm Fly ( Chrysomyia macellaria Fab.), greatly enlarged. ( From

U. S. D. A. Farm. Bull. 857.)

The Screw -worm Fly ( Chrysomyia macellaria Fab.). — This pest occurs in
South America and northward into Canada. It is a serious pest to live stock and
other animals, chiefly in the Southwestern States, though occasionally it becomes
important farther north and east.

The adult fly (Fig. 343) is of a dark bluish-green color and has three black
stripes along its back. It is considerably larger than the house-fly. Its eggs
are laid in any decaying animal matter and also in wounds such as are caused
by barbed wire, hooking, etc., in living animals. The larvae (Fig. 344) hatch in
from a few hours to a day or two and burrow into the tissues, if the eggs were laid

THE DIPT ERA

325

on living animals, producing an irritating substance. The action of this and the
feeding on the tissues cause the animal to become thin, lose its appetite and
frequently death follows, for fresh eggs are repeatedly laid in the same wounds
by the adults. The larvse mature in 4 or 5 days in living animals and more
slowly in dead ones, and, on becoming full-grown, drop to the ground which
they burrow into a few inches to pupate. The pupal stage lasts from 3 days to
2 weeks and, at the end of this time, the adult flies emerge, completing the life
cycle in from 1 to 4 weeks according to the conditions of the weather.

Fig. 344. — Full-grown Screw-worm Maggot, greatly enlarged. {From U. S. D. A. Farm.

Bull. 857.)

Control. — Most of the breeding of these insects is in dead animals and there¬
fore all carcasses should be promptly buried or burned. To protect living live
stock, efforts to prevent their injury must be made and all cases of injury cared
for as soon as possible. This may be done by pouring a little chloroform into the
wound. It is then generally advisable to remove the maggots and clean the
wound with water containing 5 per cent of carbolic acid. Pine tar over the out¬
side at the wound will act as a repellent to the flies. In serious cases, the services
of a veterinarian will be needed. Tick wounds are often the starting points for
screw-worm injuries, and ticks should, therefore, be controlled as far as possible.

The Tsetse Flies ( Glossina of several species). — These Muscid flies
are the conveyers to man of the dreaded disease known as “sleeping
sickness.” The insects occur only in parts of Africa where they are
found along wooded streams and where large game animals are present.
The mouth parts of these flies include piercing structures and the insects
normally attack the wild game, but man is also liable to their visits.
The disease is caused by a Protozoan animal ( Trypanosoma gambiense )
obtained by the flies while feeding on infected animals, and the trypano¬
somes may be directly conveyed into another animal during the next
day or two, after which the fly becomes innocuous for about 4 weeks:
by this time, those of the parasites which entered the stomach of the fly
have gone through a development in the body of the insect and have
gathered in the salivary glands. The fly is now dangerous for about 3
months. In man, the disease appears as an irregular fever, and an en¬
largement of the glands followed after a time by nervousness and sleep,
the patient becoming comatose and finally dying. The earlier stage of
the disease may last for several years but the last usually continues only
from 4 to 8 months.

32G

APPLIED ENTOMOLOGY

Thus far no cure for the disease has been discovered but protection
while in Tsetse districts can be obtained by screens, veils, gloves, etc.,
and by keeping away from the localities in these districts where the flies
occur. Its importance is indicated by the estimate that in 10 years
between four and five hundred thousand natives died from this disease.

Another species of trypanosome carried by Glossina flies causes the
disease of domestic animals, particularly horses and dogs, known as
Nagana. This is almost always fatal to these animals.

Family Sarcophagidae (The Flesh Flies, Fig. 345). — This is a large
family of flies, some of which lay their eggs on dead animals. Others

breed in manure, decaying matter
and similar materials, and because
of these habits, there is always the
possibility of their becoming car¬
riers of disease-producing germs,
though as they seldom visit human

Fig. 345. Fig. 346.

Fig. 345. — Adult Sarcophagid Fly ( Sarcophaga sp.), much enlarged. ( From U. S.
D. A. Farm. Bull. 857.)

Fig. 346. — Adult Tachinid Fly ( Tachina mella Walk.), over three times natural size.
( From Britton, Tenth Rept. Ent. Conn. Apr. Exp. Sta. 1910.)

food in houses, the chance that this may result in disease is much less
likely than in the case of the house-flies.

Family Tachinidae (The Tachina Flies). — This family has by some
students of the subject been regarded as the most useful family of insects
from an economic standpoint, its larvae being parasitic on other insects
and being very abundant. This estimate of their importance is probably
too high but the group is certainly very valuable in the control of injurious
forms. The adults (Fig. 346) somewhat resemble the Muscidae, but the
abdomen is liable to be stouter and in many cases bears numerous stiff
bristles which are very noticeable. The eggs (or larvae in some cases)

THE DIPTERA

327

are laid on caterpillars and other insects, or, in some cases, on the leaves
which these will feed upon, and, on hatching, the maggots bore their
way into the host and feed upon its tissues, finally killing it. The adults
are common around flowers and also in places where plants are growing
rankly, and there are many species.

Family Anthomyiidae (The Anthomyiids). — This family contains
many injurious species, the larvae of some mining in the roots and of others
in the stems and leaves of important crop plants. Others breed in
decaying vegetable and animal materials and excrement and from their
habits it is suspected that they may be disease
carriers like the house-fly.

The Cabbage Maggot ( Hylemyia brassicce
Bouche). — The Cabbage Maggot is a native of
Europe but has been present in this country
for many years. The adult (Fig. 347) is a small,
clear-winged fly about two-tenths of an inch long,
not often noticed or at least distinguished from
other small flies present in the fields. Winter is
passed as the pupa in its puparium underground,
and also possibly to some extent as the adult, in
protected places. At all events, the adult flies
are present in the spring as soon as the cabbage

Fig. 347.

Fig. 347. — Adult male and female flies of the Cabbage Maggot ( Hylemyia brassicce
Tiouche). About three times natural size. ( After N. Y. Agr. Exp. Sta. Bull. 419.)

Fig. 348. — Young Cabbage Plant showing Maggots on its stem. Natural size.
( Modified from Britton, Fourteenth Re.pt. Ent. Conn. Agr. Exp. Sta. 1914.)

and other cruciferous plants are available. The eggs are now laid on
or close to the plants. They hatch in a few days, and the maggots
(Fig. 348) attack the stem just below the level of the ground where
they feed for about 3 weeks, lacerating the cell walls and feeding on
the softer tissues, using for the first process a pair of stout, black
hooks attached at the mouth which seemingly are extremely modified
mouth parts. When full-grown, the larvae leave the plants, enter the
ground and form puparia from their larval skins within which they
pupate for a period of from 12 to 18 days in most cases, after which the
adults emerge and eggs are laid for a second generation.

Fig. 34S.

328

APPLIED ENTOMOLOGY

The number of generations in a season has been worked upon by
several investigators with somewhat differing results. It seems probable,
however, that in the latitude of Xew York, the insect as a rule has three
generations though in favorable seasons four are possible, and in unfavor¬
able ones only two may occur. Presumably, the number farther north
will usually be two, and farther south four may prove the usual number.
Weather conditions apparently have an influence on this — hot, dry
weather hardening the roots of the food plants so that feeding is slower
than would otherwise be the case, and this same kind of weather also
seems to lengthen the pupa stage. It is interesting to note that the
insect though present in the Gulf States does not seem to be a serious pest
south of the latitude of southern Pennsylvania. It has been found as
far west as Colorado.

Fig. 349.- — Cabbage Plant protected by a tar-paper disk around its stem. {Modified from
Britton, Fourteenth Kept. Ent. Conn. Agr. Exp. Sta. 1914.)

Whatever the number of generations a season, the insect seems
able to reach the pupa stage before winter, and possibly become adult
in some cases.

The Cabbage Maggot is most serious as a pest on cabbages and cauli¬
flowers. It also attacks turnips, radishes, mustard and other cruciferous
plants, however, and late generations may live more on these plants
as the cabbage and cauliflower roots get older, tougher and less attractive
to the insects.

Control. — Cabbage and other plants, liable to attack while in seed¬
beds, can be protected by covering these places with screens of cheese¬
cloth. When the plants are set in the fields, tar-paper disks may be

THE DIPT ERA

329

placed around their stems close to the ground (Fig. 349) and usually
give good results. These disks may be cut by hand from ordinary tar
paper, though where many are required, the use of a cutting stamp is
advantageous. The piece is usually cut six-sided for economy of the
paper, and from one corner a cut to a little beyond the center is made
and also a short cut crossing this at the center, giving four points between
which the stem is passed. The disk is then pushed down to the ground.
In cultivating later, care should be taken to brush off any dirt which
gets on the upper side of the disk as in such cases the fly often attacks
the plant. The destruction of all the refuse of the plants on harvesting
the crop, and also of all mustard and other cruciferous plants near by,
is desirable to prevent further increase of the insect there before winter.

Various other treatments have been suggested but have not given
entire satisfaction. The tar-paper disks are not entirely effective as
protectors, and to apply them carefully requires time, but they give the
best results of any control method thus far discovered.

Recently, one ounce of corrosive sublimate dissolved in 10 gal. of
water, poured around the bases of the plants, has given quite good results.

Fig. 350. — Adults of the Onion Maggot (Hylemyia antiqua Meig.), twice natural size.

(Fro7n Britton , Eleventh Rept. Ent. Conn. Ayr. Exp. Sta. 1911.)

The Onion Maggot ( Hylemyia antiqua Meig.) is often a serious pest,
mining in the bulbs and quickly causing their decay. Like the Cabbage
Maggot, it is a European insect but has been known in the United States
for many years and is now widely distributed. Details of its life history
are not as well known as could be desired, but it is probable that the
insects pass the winter as pupse and perhaps as adults also. The flies
(Fig. 350) lay their eggs on the onions soon after they come up in the
spring, and these hatch in a few days forming whitish maggots which
attack the bulbs and feed during a period varying according to weather
conditions for from 2 to 4 or 5 weeks, after which they pupate in the
ground, or, occasionally, in the outer layers of the onion itself. During
the summer, this stage continues about 2 weeks, after which the adult
flies appear and in about 10 days begin to lay eggs for a second generation.

In some parts of their range there are probably only two genera¬
tions a year, but elsewhere there seem to be three. The injury caused
by this insect when abundant is sometimes large, entire fields con-

330

APPLIED ENTOMOLOGY

sisting of many acres having nearly every onion affected. It varies
greatly in importance in different years, however, there being in some
seasons practically no maggots.

Control. — The adult flies feed freely both before and during the
egg-laying period. Making use of this fact, a poisoned bait spray issued,
consisting of 34 oz. of white arsenic or sodium arsenate dissolved in 1 gal.
of boiling water to which is then added from 34 to 1 pint of strong¬
smelling molasses. This is sprayed in coarse drops in strips across the
field, it not being necessary to cover the entire area in this way. Repeat
twice a week from the time the onions show until the middle of June.
This treatment has given good results but the cost of the labor involved
in so many applications is considerable.

Other members of this family are frequently injurious, and, among
these, the Seed-corn Maggot, often attacking peas and beans also, the
Beet and Spinach Leaf-miner and the Radish Maggot may be mentioned.
Methods of control for these insects are at present far from being as
satisfactory as could be desired. The Lesser House-fly and several
other small, house-inhabiting flies which belong here are also of some
importance as probably being disease carriers.

There are several families of extremely modified aberrant forms
which are generally classed together as a suborder of the Diptera called
the Pupipara. Some of these insects are winged while others are wing¬
less when adult. The majority of them suck the blood of birds or mam¬
mals though one species not thus far reported from America is found
on the body of the honey bee. Swallows appear to be favorite hosts
for some of these insects and bats for others, while the most familiar
insect belonging here lives on the sheep and is commonly called the
Sheep Tick. A number of others of the group are also wrongly called
ticks, probably because of their color which is similar to that of some
common ticks, their leathery external skin, and the places where they
are found. True ticks have eight legs, however, and never have wings,
while six legs only are present in the Pupipara as with the other insects.

The Sheep Tick ( Melophagus ovinus L.). — This pest of sheep is a
wingless, brown insect about a quarter of an inch long. It occurs in
most of the countries where sheep are raised and is present practically
wherever sheep are found in the United States, though most abundant
in the West in the large flocks. The adult lives in the fleece of the host
except when feeding, at which time it moves to the surface of the skin
of the animal, punctures it and sucks the blood and lymph causing irrita¬
tion which, when many of the insects are present, makes the sheep rest¬
less, preventing their feeding considerably, and resulting in their failure
to grow and fatten as they should.

The adult (Fig. 351) does not deposit eggs, these being retained within
the body of the parent until they have hatched into larvae (Fig. 352) and

THE DIETER A

331

Fig. 351. — Adult engorged female Sheep Tick ( Melophagus ovinus L.), greatly enlarged.
{From. Marion Ines, Bur. An. Ind., U. S. D. A. Farm. Bull. 798.)

Fig. 352. — Young Sheep Tick just after emerging from its puparium. Greatly enlarged.
{From Marion Imes, Bur. An. Ind., U. S. D. A. Farm. Bull. 798.)

332

APPLIED ENTOMOLOGY

during this period being nourished by the secretions from glands in the
body of the parent. When the development of the larva has been nearly
completed, it leaves the parent and is then covered by a soft, white
membrane which, after some hours, turns brown and hard and becomes a
puparium within which the animal pupates for a period of from 19 to
24 days after which the adult emerges. After about 10 to 14 days more,
their first pupae appear. A' pupa is produced by a female every 7 or 8
days, 12 to 15 being about the usual number in all per individual.

Control. — The most widespread method for controlling these insects
is by dipping the sheep in some material which will kill the ticks. Some of
the dips used for this purpose are coal-tar-creosote, cresol, nicotine and
lime-sulfur-arsenic. Selection of the best dip for the purpose must
be determined by the availability of soft water, ease of obtaining the
materials and other local factors. In general, two dippings are necessary
and, if this is done during the early fall, these should be 24 days apart.
Where shearing is done in the spring, the dipping should be in July and
August unless the lambs become thickly infested soon after shearing, in
which case dipping should be as soon as the shear cuts heal. Many
details connected with dipping make it necessary to become thoroughly
acquainted with the process before treatment is actually attempted,
if the best results are desired.

CHAPTER XXXII

THE SIPHONAPTERA

The Siphonaptera or Fleas are curious, small insects ranging from
about a twentieth to a sixth of an inch long. They are evidently related
to the flies in many ways but are much modified. Most of the members
of the group have their bodies laterally compressed so that they are
narrow (Fig. 353). The head is not sharply separated from the body and
the antennae are short and stout. The mouth parts are for piercing
and sucking, and modified in a different way from those of other insects
which feed in this manner. While the identity of the various parts has

Fig. 353. — Adult Cat and Dog Flea ( Ctenocephalus cams Curtis), greatly

(.Original.)

enlarged.

not been conclusively proven, it seems probable that a long median
pricking structure is the labrum or else the hypopharynx; a pair of
similar structures are the mandibles; a pair of rather short, stout struc¬
tures at the sides, each with a palpus, are the maxillae, and that the
labium is represented by a rather stout basal portion bearing two long
segmented pieces, perhaps the palpi, so shaped as together to form a
loose sheath for the piercing parts. Compound eyes appear to be
absent.

Backward-projecting spines occur on the body, largely at least,
preventing backward movements between the hairs on the body of the

333

334

APPLIED ENTOMOLOGY

host animal. Rows of stout spines may be present on the head just
above the mouth or on the pronotum or in both places. These are called
taenidia and are useful in identifying the species. The legs are long
and powerful. Wings are absent but flat scales present on the meso-
and metathorax are generally regarded as their rudiments. The larvae
are worm-like, with chewing mouth parts and pupate within a cocoon.

The characters distinguishing these insects are:

Insects which as adults have their bodies strongly compressed sideways;
are without wings and compound eyes but have legs. Mouth parts for pierc¬
ing and sucking. Larvce worm-like. Metamorphosis complete.

Adult fleas feed entirely upon the blood of mammals and birds,
but while each species has what may be termed its preferred host, there
seems to be some latitude in this, and other animals may also be attacked.

The eggs are laid loosely among the hairs of the host and drop to
the ground where they hatch. The larvae which are slender, whitish,
and rather worm-like, with chewing mouth parts, feed on decaying vege¬
table and animal matter for a period varying from a few days to several
months. When feeding is completed, the larva spins a silken cocoon in
which it pupates. Here it may remain only a few days or for a time
which may be more than a year, according to circumstances, before
emerging as the adult. The adults in hot weather and with no food will
live only a few days but when food is available they may live a month
or even nearly a year. Winter in the North is usually spent in one or
another of the early stages, but in the South the adults may be present
on their hosts at any time.

Hot, dry weather is not favorable to the rapid breeding of these
insects but, in damp, rainy weather, they increase rapidly, particularly
in sandy localities as the moisture there is more uniform where the early
stages live, though too much moisture is injurious to them.

Fleas are mainly household pests, coming in on cats and dogs, the cat
flea being the most common generally, though in the West and South
the human flea is also abundant. The eggs dropped by the fleas fall to
the floors and the larvae feed on any material found under rugs and mat¬
tings, in floor cracks and similar places, and, on reaching maturity, attack
the first animal they can reach.

Various animals besides those already mentioned serve as hosts.
Among them are hogs, poultry and other birds. Horses, cattle and
sheep are not often attacked.

Fleas have become of importance to man aside from their attacks on
his person with the discovery that they may carry the germs of the
bubonic plague. This much dreaded disease with its high mortality
caused by Bacillus pestis occurs in rats’ blood, and by feeding on this
the flea brings the germs into its own body. When a flea attacks a
person, it often ejects partly digested blood and also feces near the

THE SIPHON APT ERA

335

“bite” and if, while the wound is still open, this place is rubbed or
scratched the germs are liable to thus be introduced into the blood of the
person. Their absence from the mouth parts and the saliva of the flea
so far as observations have yet gone indicates therefore that inoculation
with the germs from fleas is accidental, but as most persons generally
scratch a flea bite, it is at least frequent enough to produce many cases
of the disease. In California, the disease has also been found in ground
squirrels and in one species at least of squirrel flea so that these fleas are
also a menace to man.

Control of Fleas— In houses, flea control must be both by destroying
the adults and also the early stages. On small animals which arc
infested, a thorough washing with a . soap coal-tar creosote material
used as a “stock dip” of which a number of kinds are for sale gives
satisfactory results if the animal is thoroughly scrubbed and partic¬
ular care given to see that the head — to which the insects collect when
the animal is put into the wash — shall receive particular attention.
Keep the animal in the wash for five to ten minutes. If it has a tender
skin, this treatment may be followed by washing in warm water with
soap.

Other ways for treating infested animals are by rubbing powdered
naphthaline into the hair, or by dusting thoroughly with Pyrethrum.
Give these treatments over paper on which the stupified fleas fall so
that they may be gathered and burned. Animals which are attacked by
fleas should not be allowed under houses as is so often the case in the South
when no cellars are present and the house is placed on low posts. In such
cases, these places are excellent locations for fleas to breed and when adult
enter the houses.

To destroy the early stages successfully, the food of the larvae should
be kept in mind and all such material be removed. Thorough cleaning,
removing all dust, much of which is flea food, soaking cracks, where it
might gather, with kerosene; airing and beating rugs, carpets, straw mat¬
tings and, in fact, all floor coverings, are important control measures.

There are other ways in which fleas may be controlled. One is to
sprinkle 5 lb. of flake naphthaline over the floor of an infested room and
close tightly for 24 hr. ; then open and sweep it into any other room needing
treatment and manage in the same way. Several rooms can be treated
with the same material. Fumigation with sulfur, using 4 lb. to each 1,000
cu. ft. of space if the young are present and 2 to 3 lb. if only adult
fleas are involved, the fumigation to continue 12 hi., is also a successful
control. Cellars infested should be thoroughly cleaned and whitewash
used freely.

Flea “bites” if troublesome may be relieved by the use of carbolated
vaseline, camphor, or a 3 per cent solution of carbolic acid in water.

336

APPLIED ENTOMOLOGY

One of the fleas commonly called the “sticktight” flea ( Echidnophaga galli-
nacea Westw.) is a rather important pest of fowls in the South and Southwest,
causing trouble as far north as Kansas. These fleas gather chiefly on the heads
of the birds where they are noticeable around the eyes and on the wattles and
comb, but may occur elsewhere on the animal. Chickens are often killed by
these fleas but older fowls are more resistant. This flea differs from most other
species by remaining most of its life on the fowl, whence its common name.

Where the infestation is severe, the use of carbolated vaseline, or a mixture of
lard 2 parts and kerosene 1 part, carefully applied only to the places where the
fleas are on the fowl; the destruction of rats which also harbor this pest, and a
thorough cleaning of the poultry houses are desirable. Salt on the soil where the
fleas are breeding, followed by a liberal application of water by sprinkling, this
last repeated two or three times a week, will destroy the young, but no salt
should be left for the poultry to feed upon.

One species of flea differs somewhat in its habits from most of these
insects. It is known as the Chigoe or Jigger flea ( Tung a 'pene¬
trans L.) and occurs in the tropical and subtropical portions of America
and also in Africa and India. It should not be confused with a tiny mite
(Class Arachnida) which has somewhat similar habits and is found as far
north as Massachusetts and Lake Erie, which is abundant on bushes, and
which on man burrows into the skin causing considerable irritation.

a b c

Fig. 354; — Chigoe (Tunga penetrans L.) : a, an Unfertilized female; b, onefertilized,
which has penetrated the skin and is beginning to enlarge; c, one enormously enlarged
by the development of eggs. All enlarged. ( From Berlese.)

The Chigoe is found on domestic animals, birds and man. The
female (Fig. 354a) is at first about a twenty-fifth of an inch long but its
abdomen may later become as large as a small pea. The adults move
about but when the female has been fertilized it burrows into the skin
of the host and its body begins to enlarge (Fig. 3546 and c) by the develop¬
ment of eggs, causing a painful wound like an ulcer. The eggs are expelled
into this ulcer or may fall to the ground but, in either case, hatch in a few
days, and those in the wound then work out and drop to the ground.

The regions usually attacked in persons are the bare feet, though no
part of the body is entirely free from the danger of being attacked. Pus

THE SIPHON APTERA

337

is produced in the wounds and when many of the fleas are present the
ulcers may run together and cause serious results. Protection from these
pests is best obtained by keeping the floors clean, using naphthaline as
recommended above; cleaning floors and walls with kerosene; and wearing
shoes or other foot coverings to keep the insects from reaching the skin.
When the fleas are already burrowing they may be removed by the use of
a needle which has been sterilized by passing it through a flame, followed
by a dressing of the wound. A drop of turpentine at each spot attacked
will kill the fleas and, if ulceration has not gone too far, the wound will
generally ulcerate enough more to expel the animal and then gradually
heal.

Fleas occur in nearly all parts of the world, and, though less than 500
kinds are known, their habits and their relation to disease make them an
important group of insects.

22

CHAPTER XXXIII

THE HYMENOPTERA

The insects which belong in this large order have no general common
name, but many of them are well known as bees, ants and wasps. The
larger portion of the group, however, consists of small insects seldom
noticed except by those looking for them.

Most Hymenoptera have wings when adult. These are four in num¬
ber, membranous, and the front pair is the larger. They have rather few
cross veins as a rule, and in some cases nearly all the veins are missing.
The two wings on the same side of the body are united by a row of hooks
along the middle part of the costa of the hind wing, which catch in a fold
of the membrane on the hinder margin of the wing in front, the two wings
in this way acting together and much as though they were one. The
structures uniting them are called the frenal hooks or hamuli, and the
frenal fold.

The body in insects of this order may be quite large and stout, as in
the bumblebees; or long, being two or more inches in length in some trop¬
ical wasps, but most of them are much smaller insects and in some the
body may be only about a fiftieth of an inch long and the entire animal
almost microscopic in size. The first abdominal segment is very closely
and firmly joined to the thorax, to which it apparently belongs. In a
few families the front end of the second abdominal segment is as large as
the rest of this portion, and the connection between the first and second
segments is full-sized, but in most of the groups the front end of the second
segment is constricted to form a small, stalk, pedicel, or petiole which
connects the rest of the abdomen with the first segment. This condition
is a deceptive one, leading to the idea that the constriction is, as is true
of most other insects, between the thorax and abdomen rather than be¬
tween the first and second segments of the latter. The first segment,
closely joined to the thorax is called the propodeum or median segment.
The petiole in nearly all cases joins the propodeum close to the lower side
of the body.

Over the base of each fore wing except in the ants, is a small, arched
scale called a tegula, which roofs over the place where this wing articulates
with the body.

In the female Hymenoptera an ovipositor, used either for making
holes in which to deposit eggs, or modified to become a weapon, is almost
always present. When developed for its original purpose as an organ

338

THE HYMENOPTERA

339

connected with egg-laying, it may have projections along its lower edge
and be used like a saw to cut slits in leaves or other structures in which
to insert the eggs. In other cases it becomes a sort of boring organ used
in making holes in leaves, stems, wood, or animals, in which the eggs are
placed. Sometimes the ovipositor is very prominent and is not retractile,
while in other species it can be drawn entirely within the body. In a
large section of the order, however, regarded as containing the more
highly developed members of the group, deposition of the eggs is not
within objects but on surfaces, and a hole being no longer needed, the
ovipositor has become modified in most cases, glands connected with it
produce a more or less poisonous fluid (possibly it is more or less poison¬
ous in the lower forms also) and the sting is thus produced, a structure no
longer needed for its original purpose having been transformed into a
weapon for defense. In the ants, however, various degrees of reduction of
this structure occur, some ants having no stinging power whatever while a
few are quite effective in this way. From these facts the reason why drone
bees and the males of the other Hymenoptera are harmless, is evident.

The two sections of the order thus distinguished, are called the
Terebrantia or boring, and the Aculeata or stinging Hymenoptera.
Another distinction also separating these divisions may be seen by an
examination of the mouth parts. In the Terebrantia these are quite
typical chewing organs, but in the Aculeata the maxillae and labium
have been modified to form organs for sucking and lapping up fluids,
though the amount of this modification differs in different families.
A third distinguishing feature is that in the Terebrantia the hind leg
has two trochanters while in nearly all the Aculeata there is only one.

Development in this order is by a complete metamorphosis. The
larvae differ much in appearance in the various families, some feeding-
on leaves and greatly resembling caterpillars. Others are borers in
wood and are modified to adapt them to life under such conditions.
Still others, particularly those which are parasitic within the bodies of
other insects, may be so changed as to make it seem almost impossible
that they can be insect larvae. Many of those living on food provided
for them during this stage of their existence greatly resemble and are
sometimes called maggots. At pupation a marked change in appearance
takes place, antennae, legs, wing stubs and body characters nearly like
those of the adults now showing, and the legs and antennae project, en¬
cased by sheaths of the pupa skin, the pupa in this order being a pupa
libera as already described for some beetles (see page 99, and Fig. 30).

The characters by which Hymenoptera may be recognized are:

Insects which when adult have in most cases, four membranous wings
with few or even no cross veins, the hinder pair the smaller. Mouth parts
for chewing, or for chewing and also for sucking. The females have in nearly
all cases either an ovipositor or a sting. The metamorphosis is complete.

340

APPLIED ENTOMOLOGY

The Hymenoptera are important from an economic standpoint. A
rather small number are injurious, destroying crops of various kinds
but the majority are either directly or indirectly beneficial, as parasites
of destructive insects, or by aiding in the fertilization of flowers, and in
the case of the honey bees by the value to man of their products.

There is a great diversity of structure in the order, which has led
to the establishment of many families which fall into about 10 larger
divisions, generally called Superfamilies, and these may serve as the
basis for more detailed consideration.

Superfamily Tenthredinoidea (The Saw-flies and Stem Borers). —
This group is one of the divisions of the Terebrantia as already described,
its members having no constriction of the abdomen. Most of the families
belonging here are leaf-feeders and their eggs are usually laid in slits in
the leaves sawed by the ovipositors of the adult females. Some families,
however, have the ovipositor constructed for boring and they make
holes, either in herbaceous or woody stems, in which to deposit their
eggs.

The plant-feeders are spoken of in a general way as saw-flies and all
are injurious to the plants they live on, though of course many of these

are of little or no importance to
man, but a few injure various
crop-producing plants.

The Currant Worm ( Pteronidea
ribesii Scop.). — This common in-
j urious saw-fly is a native of Europe
but has been in this country for
many years and is widely dis¬
tributed. It feeds on the leaves
of wild and cultivated currants
and to some extent, on those of
gooseberries also, and when abund¬
ant the plants are quickly and
thoroughly stripped of their foliage
soon after it develops, which checks or almost entirely prevents the
production of the fruit.

The adult saw-fly (Fig. 355) is about a third of an inch long, with a
pale or reddish-yellow, rather stout body with blackish spots. It passes
the winter in the ground within an oval cocoon, rather papery in texture
and brown in color. In spring, about when the currant leaves become
partly developed, the adults begin to emerge from their cocoons and the
females lay their eggs in rows on the leaves, generally along the veins on
the underside. The larvae, at first very small and whitish, feed and grow
rapidly, and when full-grown are nearly three quarters of an inch long,
greenish in color and shaded with yellowish at both ends. During the

Fig. 355.— Currant Worm ( Pteronidea
ribesii Srop.), adult and larvae, about natural
size. ( From Minn. Agr. Exp. Sta. Bull. 84.)

THE HYMEN OPT ERA

341

intermediate larval instars the green color of the body is modified by the
presence of many black spots. After feeding from 2 to 3 weeks the larvae
crawl down to the ground and pupate, the cocoons resembling those al¬
ready described. Adults from these pupae appear in late June or July
and lay eggs for a second generation, and in some cases a few of the
insects have a third generation before winter. The second and third
generations (when present) do not attract much attention generally, as
interest in the currants in most cases ceases for the season with the
gathering of the crop.

Control. — Spray the currants as soon as the leaves have developed
or as soon as the “worms” appear, with arsenate of lead, standard
formula or a little weaker. If treatment is necessary after the fruit
has begun to turn red, dust fresh hellebore over the plants, using 1 lb. of
hellebore thoroughly mixed with about 5 lb. of air-slaked lime or flour.
The great difficulty in controlling
these pests is that the adults ap¬
pear and lay their eggs during a
rather long period and it is often
necessary to spray for those larvse
which appear early, before all the
leaves are fully developed. Ac¬
cordingly, those leaves which come
out after the spray has been applied
are not protected and larvse ap¬
pearing afterwards can feed on
them without being poisoned, and
a second spray is often needed on
this account.

Fig. 356. — Pear Slug (Caliroa cerasi L.) :

The Pear Slug ( loliroo C€TOsi .L). a, adult; b, larva with slime removed; c,

—This insect feedson the leaves ,Iarva from above, coveredby its slime; d,
r ,, , , , , leaf showing work of the insect and with

O the peal, plum and cherry, and larvae present: a, b and c much enlarged;
though a native of Europe is now d, somewhat reduced. ( From Berlese,
found almost everywhere in this circ^Q) ^ V' A' ^ EnL

country (Fig. 356).

The adult is a saw-fly about a fifth of an inch long, with a black body. It
appears after the leaves develop in spring and lays its eggs in slits sawed in the
leaves, forming a sort of blister at each place. The larvse soon produce a dark-
brown glossy slime which covers them and conceals their true outline, making
them somewhat similar to soft snails in appearance. They feed on the leaf tissue,
skeletonizing it, and molt four times. After the fourth molt the slime disappears
and the larva is orange-yellow and does not feed. It now passes to the ground in
which it pupates. A second generation follows, but a few of the pupse remain
unchanged in the ground until the following spring. In the South there are three
generations, at least in some cases.

342

APPLIED ENTOMOLOGY

Control. — Spraying with arsenate of lead, standard formula; Nicotine sulfate
40 per cent, 1 pt. in 100 gal. of water, with 3 or 4 lb. of soap; 1 oz. of white helle¬
bore in 3 gal. of water; or dusting with freshly slaked lime, are effective treatments
for this insect, but it is not very often abundant enough to call for the use of
control measures.

A similar saw-fly often attacks the rose, feeding on the leaves, its dark-colored
and slimy, though small, larvae being very noticeable when abundant. When
treatment is necessary the methods given for the pear slug are equally effective
with this insect.

A few of the stem and wood borers in this superfamily are of considerable
importance, but most of them are seldom noticed. The Wheat-stem borer
(Cephus pygmceus L.) in the East and the Western grass-stem borer ( Cephus
cinctus Nort.) in the West often attack growing wheat. The adult (Fig. 357)

Fig. 357. — Western Grass-stem Borer {Cephus cinctus Nort.): 3, base of wheat plant
showing larva in winter position; 5, adult Saw-fly; 6, full-grown larva. All natural size.
{Modified from Can. Dept. Agr. Ent. Branch, Bull. 11.)

punctures the wheat stem in the spring and deposits an egg inside the stalk and
the larva which soon hatches, tunnels in the stem and as the grain ripens,
works its way downward, and by harvesting time most of them have reached
the roots. They then prepare for winter, cutting the stalk partly off, generally
less than an inch above the surface of the ground. Each now plugs the cavity
of the stem below this point for a short distance, leaving about half an inch of
space between the plug and the lower end of the cavity, in which it spins a cocoon.
The larva winters thus, pupates in March or April in New York at least, and
the adult appears in May. The life history of the western species is much the
same.

Where grass-seed is not planted with the wheat, plowing the stubble under,
deeply, at any time between harvest and the following May, or burning the stub¬
ble when this is possible, are two fairly efficient methods of control. Where it is
desired to lay down a field to grass and the insect is abundant it would be better
where practicable to use oats rather than wheat with the grass-seed.

THE HYMENOPTERA

343

One of the stem borers attacks currant stems. The adult girdles the stem after
laying its egg, and the larva feeds below the girdled place, which shows plainly,
the part above wilting or breaking over. Cutting off such stems as soon as they
are seen, eight or ten inches below the girdled place, will control this insect.

Most of the borers of this superfamily which tunnel in wood are
generally called Horn-tails, the straight, stiff ovipositor somewhat
suggesting a horn. Various trees, both deciduous and evergreen, are
attacked by different species, and the circular exit holes of the borers
after they have become adult permit the entrance of moisture and the
spores of fungi, thus providing starting places for decay. Healthy,
vigorous trees are seldom attacked, but the death of others is hastened
by these insects. One species

Fig. 358.— Pigeon Tremex ( Tremex columba
L.), somewhat reduced. {Original.)

known as the Pigeon Tremex
( Tremex columba L.) bores in the
maple, apple, pear, elm, beech, oak
and sycamore. It varies from
three-quarters of an inch to twice
as much in length (Fig. 358) and
its body is cylindrical and nearly
as large as a lead pencil. Its color
varies from nearly black with
yellow spots on the abdomen to
yellow with some black marks.

This insect is often noticed on the
tree trunks during the summer
months. The larva tunnels its
course through the wood, going

sometimes several inches into the tree, but as the end of its feeding
period approaches, turns outward and makes a hole to the outside,
leaving only a thin piece of bark to close the opening. It then goes
back into the hole a short distance to pupate and the adult on emer¬
gence gnaws away the piece of bark and escapes from the tree. An
interest ing and remarkable looking parasite of this insect will be considered
later in the chapter.

Superfamily Ichneumonoidea (The Ichneumon Flies). — In this very
large and important group the insects have the abdomen constricted as
already described, between the propodeum and the second abdominal
segment. In one family (the Evaniidse or Ensign flies) of rather small
insects (Fig. 359) the petiole of the second segment does not join the pro¬
podeum near the lower side of the body but near the upper surface, giv¬
ing these insects a very peculiar appearance.

The Ichneumon flies (Fig. 360) are all parasites, attacking Lepidop-
tera, Coleoptera, Diptera, and some Homoptera ,Orthoptera and Hymen-

344

APPLIED ENTOMOLOGY

optera, and also Spiders in their early stages, at least in most cases, and
a few are injurious as they are parasites of beneficial forms. Thus
among the Coleoptera parasitized are some of the Lady beetles. In
other cases it is the parasites themselves which are parasitized. In
this last case the destruction of a beneficial parasite by another makes
the latter an injurious insect. There are also some which appear to
attack the parasites of the parasites, which places these last as beneficial
in their turn. Primary parasites attack non-parasitic forms; secondary
or hyperparasites attack primary ones; tertiary parasites attack the
secondary ones, etc.

Fig. 359. — An Evaniid { Brachygaster minutus Oliv.), about five times natural size.
{Modified from Kiefer.)

Fig. 360. — Example of an Ichneumon Fly ( Ophion ), natural size. {Original.)

The importance of the Ichneumon flies as parasites is very great as
they are abundant and destroy enormous numbers of injurious forms
each year. One group devotes its attention to plant lice, puncturing
the bodies of these insects and laying an egg in each puncture. The
tissues of the plant louse are fed upon by the parasite and the body of the
host gradually becomes brown, swollen and rather globular, and it dies,
holding on to the place where it was feeding at the time of its death.
After pupation within the body of the host, the adult parasite cuts a
circular opening in the surface of its host and escapes, and plant lice
bodies, swollen, brown, and with a hole in each are abundant when these
insects occur in large numbers. As each parasite obtains all the food
necessary for its entire development from the body of a single louse, these
insects are naturally extremely small (See Figs. 199 and 200).

Another Ichneumon fly which is often noticed has a body an inch and
a half or more long and an ovipositor often over three inches and which has
been recorded in a few cases as nearly six inches in length. There are two
kinds of about this size, one with a black body and a few yellow spots,
the other brown with yellow markings, while other and smaller species
also occur. These insects attack the Horn-tails already described and

THE HYMENOPTERA

345

may often be seen during the summer on trees in which Horn-tail larvae
are present. These Ichneumon flies are called the “Long-tailed Thales-
sas.” The female Thalessa (Fig. 361) crawls about over the trunk of a
tree which in some way she discovers is infested by Horn-tails, until a
satisfactory place is found, when she settles at that point and begins to
force her ovipositor into the bark and wood. The length of the ovipositor

Fig. 361.- — Long-tailed Thalessa ( Megarhyssa lunator Fab.): a, larva; c, pupa; e, adult
female;/, side view of abdomen of adult female, showing attachment of ovipositor; g, adult
male. About natural size. (Modified from Felt , N. Y. State Mus. Mem. 8; after Riley.)

is suggestive of the distance it must be pushed in, in some cases, to reach
the tunnel of the Horn-tail larva, and it seems almost impossible for
such a slender structure to be forced so far through hard wood. When
the tunnel of the Horn-tail is reached, the Thalessa lays an egg in it and
then draws its ovipositor out of the tree. Sometimes this process results
in the death of the Thalessa, the ovipositor becoming so firmly fixed

346

APPLIED ENTOMOLOGY

in the wood either on its way in, or during the withdrawal, that it cannot
be removed and the Thalessa dies.

The egg left in the tunnel of the Horn-tail soon hatches and the larva
travels along the burrow until it finds the borer, to which it attaches
itself, and feeds upon its juices. It is probable that death of the Horn-
tail is not permitted as a result of this feeding, before the host has pre¬
pared an outlet to the surface of the trunk for its escape, as it does not
seem likely that the adult Thalessa could tunnel its way out successfully.

Superfamily Cynipoidea (The Gall Insects). — This group of small
insects (Fig. 362) includes species having very diversified habits, but the
majority of them pass their early stages within abnormal growths on

plants, called galls, which develop in connection
with their presence. Some insects other than
those of this group also produce galls, particu¬
larly many of the dipterous family Itonididse,
but the greater number of the more noticeable
galls are produced by Cynipids.

The cause of the production of the gall has
been much discussed, some investigators claiming
that at the time the female insect punctures the
plant for egg-laying she also injects a little
poison into the wound which stimulates the
plant cells of that region to grow in an abnormal
manner. But the general belief now seems to be that the larva when
it hatches gives the stimulus for this abnormal growth, either by its
presence as a moving body, by its gnawing, or by its pouring out of
irritating fluids.

The gall includes either one larva or many, according to the species
concerned. It stops its growth about the time the larva finishes feeding,
and dries, forming a protective covering within which the insect pupates
and escapes subsequently by gnawing its way out.

In some species such an adult will attack a totally different kind of
plant from the one it itself fed upon and the gall produced will be entirely
different from the other. Adults from such galls will deposit their eggs
in plants of the first kind, however, giving us a series of generations in
which two different kinds of plants alternate in supplying food. This •
may be complicated by one generation consisting only of females, the
other evidently being derived by agamic reproduction (parthenogenesis).

Galls may occur on roots, stems, twigs or leaves, and the type of gall
produced is always the same on any one kind of plant, for the same spe¬
cies (Fig. 363), so that a student of the subject can tell from the gall
alone, the species which produced it, in nearly every case: one found on
oak leaves is nearly an inch in diameter, globular, with a parchment-like
covering, and is often called an “oak apple. ” Within the outer covering

Fig. 362. — Example of a
Gall insect ( Trigonaspis
megaptera Panz.), about
twice natural size. ( Reduced
from Henneguy.)

THE IIYMENOPTERA

347

is a mass of radiating fibers and at the center a small cell in which the
insect lives. Protuberances of various forms on the leaves of many kinds
of plants are produced by different species of these insects.

Gall insects are often not alone in their habitations. Some members
of the same superfamily as the gall-makers are frequently found in the
galls, living as “guests,” profiting by the work of the producers of the
galls but not injuring them in any way. These are usually called in-
quilines and often greatly resemble their hosts. In addition to the
inquilines, parasites not only of the host but also of the various kinds of
inquilines may also be present, adding greatly to the population of the
gall. Some of these may be of the same superfamily as their hosts.
Ivieffer lists 10 species of guests and 41 species of parasites which he
obtained from a root gall on oak, besides the gall maker itself!

Fig. 363. — Various types of Galls, about natural size. (Original .)

Galls are not usually of any great economic importance, for though
they may injure the appearance of a plant or tree for two or three sea¬
sons, and also check its growth somewhat, the abundance of parasites
usually stops the work of the gall makers before serious injury has been
accomplished.

Superfamily Chalcidoidea (The Chalcid Flies).— This is an extremely
large group, containing thousands of kinds of insects, most of which are
very small, and a few are only about a fiftieth of an inch long. Some of
them live in galls, parasitic either on the gall maker or on inquilines:
others are parasitic on various insects, parasitizing the egg, larva or
nymph, pupa, or adult according to the species; and a few are plant
feeders of more or less economic importance. The wings, except in some
wingless species, have very few veins, the most prominent one running
out from the body about half way to the tip, then bending forward to the
costa, after which it bends back into the wing a short distance and ends.

348

APPLIED ENTOMOLOGY

This is the only one in a great many cases, though a few other weaker
veins are often present.

The plant feeders in this group produce small galls or at least swellings
of the portion of the plant where they live, and one or two, by attacking
crop plants, are of importance to man. A number of species of the genus
Harmolita attack different kinds of small grains such as wheat, oats and
barley, and at times do considerable injury.

The Wheat Straw -worm ( Harmolita grande Riley). — This insect extends from
New York to Colorado and from the Great Lakes to Virginia and Tennessee and
is also present on the Pacific Coast, but has thus far been of little importance east
of the Mississippi River. The adult is a tiny black insect somewhat resembling
an ant, with red eyes, and legs banded with yellow. One generation has wings;
the other is wingless.

The winter is spent in the pupa stage in the stubble of wdreat fields and the
adults emerge in April and May in the more northerly states; earlier in the South.
These are the wingless forms and are very small. They lay their eggs in the
wheat plants which at this time have grown only a short distance above ground,
and the larva feeds in the short stem, usually producing a swelling there, and
when full-grown it has worked its way to the crown of the plant where it entirely
consumes the head, thus preventing the formation of any grain. By the last of
May these larvae have completed their feeding and pass through a brief pupal
period, the adults — winged in this generation — emerging in early May in the
South, and in June in the North. These individuals fly freely and spread to other
fields. Eggs are now laid in this wheat, preferably well up toward the head
where the joints are most tender and juicy. The larvae from these eggs feed
and reduce the yield of wheat by consuming nourishment which would otherwise
go to the grain. Full growth has been obtained before the straw hardens, and
pupation occurs during the fall. Whether the insects will be taken off in the straw
or remain behind in the stubble depends on the degree of advancement of the
plants, and the height above ground of the cutting.

Control. — Crop rotation, raising no wheat on the same land for 2 years in
succession is a good treatment, as the wingless generation cannot migrate to other
fields. Volunteer wheat in or near such fields should of course be destroyed if
the rotation is to be most effective. Burning over, or plowing under of the
stubble is also desirable, though less effective. Winter and spring wheat should
never be grown near each other.

The Wheat Joint -worm ( Harmolita tritici Fitch, Fig. 364). — This is a species
closely related to the last, found throughout the East to the Mississippi River and
south to about the same limits as the other species. Its life history differs from
that of the Wheat Straw-worm in there being only one generation a year. Winter
is passed as the larva in wheat straw or in the stems of various grasses, and the
adults appear in May or June. Eggs are deposited as high up the wheat stems
as the adult can find an uncovered stem. The larvae have completed their feeding
by harvest-time but do not pupate until the following spring. Apparently a
rotation of crops, and care that waste lands, fence borders, etc., do not provide
grass stems in which it can breed and winter are about our only methods for the

THE HYMENOPTERA

349

control of this pest. The injury these two species of Harmolita do varies all the
way from very little to an almost entire loss of the crop.

Where clover seed production is extensive, considerable injury to the crop is
often caused by the Clover-seed Chalcid (Bruchophagus funebris How.). Red and

Fig. 364. — Adult female Wheat Joint-worm ( Harmolita tritici Fitch), greatly enlarged.
( From U. S. D. A. Farm. Bull. 1006.)

crimson clover, and alfalfa to some extent, are attacked by this tiny insect which
feeds as a larva within the seed. Another species works in a somewhat similar
way in apple seeds.

A Chalcid whose presence is essential in connection with the produc¬
tion of Smyrna figs, which is now becoming an important industry in
some parts of this country, is of interest for that reason. This insect,

Fig. 365. — Fig fertilizer ( Blastophaga grossorum Grav.). A, male, about fourteen times
natural size; B, female, about ten times natural size. {Reduced from Henneguy.)

known as Blastophaga grossorum Grav. (Fig. 365), and its relation to fig
production, are well described by Kellogg as follows:

“The male Blastophagas are grotesque, wingless, nearly eyeless creatures
which never leave the fig in which they are bred, but the females are winged and

350

APPLIED ENTOMOLOGY

fly freely about among the trees. A fig is a hollow, thick, and fleshy-walled
receptacle in which are situated, thickly crowded over the inner surface, the
minute flowers. The only entrance into the receptacle (or fig) is a tiny opening
at the blunt free end of the young fig, and even this orifice is closely guarded by
scales that nearly close it. The eggs are laid by the females at the base of the
little flowers in certain figs. The hatching larvae produce little galls in which
they lie, feeding and developing. They pupate within the galls, and the wingless
males when they issue do not leave the interior of the fig, but crawl about over
the galls, puncturing those in which females lie, and thrusting the tip of the
abdomen through the puncture and fertilizing the females. The fertilized winged
female gnaws out of the galls, and leaves the fig through the small opening at the
blunt free end. She flies among the trees seeking young figs, into which she
crawls, and where she lays her eggs at the bases of as many flowers as possible.
But it is only the wild, inedible, or ‘caprifigs’ that serve her purpose. The
flowers of the cultivated Smyrna seem to offer no suitable egg-laying ground and
in them no eggs are laid. But as the female walks anxiously about inside the
fig, seeking for a suitable place, she dusts all the female flowers with pollen
brought on her body from the male flowers of the caprifig from which she came,
and thus fertilizes them. This process is called caprification. Without it no
Smyrna fig has its flowers fertilized and its seeds ‘set.’ It is the development
of the seeds with the accompanying swelling of the fleshy receptacle and the
storing of sugar in it that makes the Smyrna fig so pleasant to the palate. The
trees may grow large and bear quantities of fruit, but if the fig (really the fig-
flowers) are not caprified, the size, sweetness, and nutty flavor of the perfect
fruit are lacking. To insure caprification, branches laden with caprifigs con¬
taining Blastophagas just about to issue are suspended artifically among the
branches of the Smyrna fig. Of course the female Blastophaga entering a
Smyrna fig and dying there leaves no progeny, for she lays no eggs. It is there¬
fore necessary to maintain a plantation of caprifigs in or near the Smyrna orchard.
These bear three crops or generations of figs: one, the ‘profichi,’ ripening in the
spring; another, the ‘mammoni,’ ripening in the late summer; and the third,
or ‘mammae’ generation, which hangs on the tree through the winter. By
means of these successive generations of caprifigs a series of three generations
(or sometimes four) of Blastophaga appear each year.”

The great importance of the Superfamily Chalcidoidea to man does
not rest either upon the importance of its destructive members or upon
the Blastophaga, but on the enormous number of parasitic forms included
in the group. These work in various ways as has already been indicated,
but only one can be considered here. It is a parasite on various species
of butterflies, particularly the Cabbage butterflies, and is known as
Pteromalus puparum L., having no common name.

This insect (Fig. 366) is probably a native of Europe. It was noticed
here about 1870 and is now present wherever its host insects occur and
frequently destroys great numbers of them.

The adult has a green body about a tenth of an inch long. The
female punctures the chrysalids of the host and lays her eggs within the

THE HYMENOPTERA

351

body, in these punctures, and the larvae which hatch from the eggs feed
upon the chrysalis, finally killing it about the time they become full-
grown. They then leave the chrysalis and spin small, white cocoons,
usually in a rather compact mass somewhere near what remains of their
deserted host, emerging from these cocoons after a time, as adults which

Fig. 366. — Pteromalus puparum L., a Chalcid parasite of the Cabbage Worm and
other insects: male (left), and female (right). Hair lines show the natural size. ( After
Chittenden , U. S. D. A.)

start another generation. It has been discovered that egg-laying in this
species (and in many other parasites also) may continue during quite a
long period provided the adult can obtain food, and this in many cases at
least is accomplished by puncturing the body of the insect in which eggs
are to be, or have just been laid, and feeding on its juices.

Superfaviily Serphoidea. — This superfamily, long known as the
Proctotrypoidea, contains a large number of insects, nearly all very

Fig. 367. — Pelecinus polyturator Dru.: a, female; h, male. Natural size. {Original.)

small, and most of them parasitic on other insects or on spiders. Para¬
sitism of insect eggs seems to be very frequently the habit in the
group. Some of the forms attacked by this group are Hemiptera,
Diptera, Orthoptera, Lepidoptera, Neuroptera (Aphis lions) and Cole-
optera, and some are found in ants’ nests, parasitic on these insects.
None of the members of the Superfamily is liable to attract the attention
of those not entomologists, with one exception, an insect known as the
Long-tailed Pelecinus ( Pelecinus polyturator Drury), the female (Fig. 367a)
of which has a long, slender body often between two and three inches long,

352

APPLIED ENTOMOLOGY

and glossy black in color. The extremely long abdomen of this insect
which in flight is generally carried partly curled up beneath it, and its odd
appearance also when at rest, sometimes cause it to be noticed and the
remark made that it must be a dangerous animal. This is not the case,
however, as the insect is harmless. It is a parasite on June bug larvae
which it evidently seems to hunt for in the ground and it is particularly
abundant in sandy localities. The writer has seen over 80 of these
insects resting on fences, walls and elsewhere in the course of a single
early morning walk in the streets of Nantucket, the distance covered
being not over four city blocks. The male (Fig. 3676) which is extremely
rare or at least seldom seen, has a short, club-shaped abdomen and is
about an inch long.

A general survey of the habits of the parasitic groups of the Hymenop-
tera reveals several diversities of life and habits worthy of being presented
together. In the first place all stages of the host may be subject to
parasitic attack. The egg seems to be selected in some cases and the
pupa or the adult in others: larvse however appear to be particularly
liable to be parasitized. Where the egg stage is the one endangered,
the parasite may consume its host before the latter can develop to the
point where it is ready to hatch, thus preventing any injury whatever
if the host be an injurious species. In other cases the host though para¬
sitized is able to complete its embryonic development, hatch, and feed
for a time as a larva before it concedes victory to the parasite feeding
within it and dies. In the case of larvse the parasitism may cause the
death of the host before it becomes full-grown, or the latter may pupate,
but progress no farther. Pupse parasitized are destroyed before becoming
adult and adults attacked may or may not be able to live until they
reproduce.

These various relations of parasite and host have a bearing on
the effectiveness of the parasite. In the majority of cases it is the
next generation which is cut off, most of the injury normally caused
by the host concerned being done before the parasite stops it, except
in the case of the egg parasites which destroy the host before it hatches.
Egg parasites of this kind therefore, are generally regarded as the most
beneficial, though the great numbers of the other forms make their work
very effective.

Sometimes one parasite only, feeds upon its host. In other cases
there may be many, as with some of the Ichneumonoidea, where in one
instance over 1,200 were bred from a single caterpillar. It would seem
that the parent parasite is able to calculate the amount of food furnished
by a host and deposit only a sufficient number of eggs to correspond with
the food supply. The more probable explanation, however, is that

THE HYMENOPTERA

353

parasites laying many eggs regularly attack only those species of insects
large enough to provide for the progeny, while those which lay only one
egg in or on a host require all the food provided there for the single
parasite. No case is known where a parasite normally laying many eggs
in a host will select a smaller one and deposit only one or a few in it.

1< ig. 3G8. Hawk-moth larva with cocoons of parasites which have fed upon it, on its back.

( From Felt, N. Y. State Mus. Mem. 8.)

Variations in the location of the pupa also occur. Some parasites
pupate within the body of the host; others on its surface (Fig. 368) while
still others leave the insect entirely, pupating singly or in groups, away
from it. Tomato worms and other large caterpillars are often seen in
the fall, either dead or dying, and with many small, wrhite, oval bodies
on their backs. These are cases where the numerous parasites after
having completed feeding within the body of the host, have come out and
pupated on its back, the white bodies being the cocoons of the parasites.

Superfamily Chrysidoidea (The Cuckoo Wasps).— This is a rather
small group of the Hymenoptera, the insects (Fig. 369) being seldom over
half an inch in length and generally considerably
smaller. Their bodies are green, of a metallic or
bluish shade which quickly distinguishes them
from certain of the bees which are also green
but brighter. The surface of the body is gen¬
erally closely covered with fine indentations
which give it a roughened appearance.

These insects are able to sting but no poison (cE^^),CuCso°mewhat
gland seems to be present. The abdomen which cnlarsed. ( From Bischoff.)
has only a few (three to five) visible segments, is flat beneath, and
when attacked the insect can roll itself into a ball for protection.

The Chrysids are parasitic, chiefly on wasps and bees, though a
few are claimed to attack saw-flies and one is a parasite on the Oriental
Moth. The parent Chrysid watches its opportunity to visit the nest of
its host and lays an egg in a cell with that of the host. On hatching,

354

APPLIED ENTOMOLOGY

the larva of the Cuckoo Wasp may eat the host or it may consume the
food stored there, thus starving the proper inmate of the cell. Adult
bees and wasps know these enemies of their young and sometimes drive
them away from their nests, though frequently without success, the Cuckoo
Wasp watching its chance to return later unobserved. Taking into con¬
sideration the nature of the hosts of the Chrysids it is probable that as
a whole the group should be considered injurious rather than beneficial.

Superfamily Sphecoidea (The Digger Wasps). — The insects of this
group vary much in size, some being very small while others, particularly
tropical species, may be more than an inch and a half long. Some of
them are bright-colored, yellow, orange, green and black being the more
usual colors, and the wings are frequently smoky and with an iridescent
luster. A functional sting is present.

Fig. 370. — Bembecid Wasp ( Bembidula quadrifasciata Say), natural size. {Original.)

Fig. 371. — Sphecid Wasp ( Sceliphron ccementarium Dru.), natural size. {Original.)

Some of the insects (Fig. 370) in this superfamily (Families Bembecidie
and Cerceridse) have the petiole connecting the mass of the abdomen
with the propodeum very short, but in the others (Fig. 371) it is long and
slender, the entire first segment behind the propodeum and sometimes
a part of the second being very slender and elongate. These insects are
often spoken of as the “thread-waisted wasps.”

The digger wasps are all solitary in their habits. The females of
many species dig holes in the ground, in some cases several inches deep:
others dig out the pith in plant stems: still others make nests of mud,
gathered where there is moist earth, placing them under projecting
stones, under eaves of buildings or in houses where access is easy through
open doors or windows: in some species the nest is excavated in wood,
and a few kinds have either not developed the nest-making habit or have
lost it and use holes or the deserted nests of other species for themselves.
In many instances the nest is subdivided into chambers separated from
each other by partitions of mud.

Wherever the nest, and whatever the material which composes it,
its purpose is the protection of the young of the insect and of the food

THE HYMEN OPT ERA

355

which is stored there. After constructing the nest, either by digging,
building, or otherwise, the parent starts out to provision it. The food
differs with different species. Some take certain species of grasshoppers,
others, flies: Homoptera, Hemiptera, Hymenoptera, Lepidoptera larvae,
some Coleoptera, and Spiders, are also listed as the prey of digger wasps
of various species.

When one of the wasps finds an insect of the desired kind she attacks
and stings it, generally not killing, but only partly paralyzing it and ap¬
parently chiefly the locomotor centers, so that it cannot escape. The
prey is then grasped by the wasp and carried to the nest. In some cases
flight is possible to the wasp carrying this load, but in many cases the
prey is far too heavy for transfer in this way, at least in the case of those
wasps which burrow in the earth, and it is therefore dragged along the
ground to the nest. How the wasp knows the direction to take and
how finally to locate the hole it is practically impossible to determine,
but in most cases the insect seems to have little difficulty.

Once arrived at the nest the prey is dragged into it and if it alone
provides a sufficient food supply for the young wasp to be developed
there, the parent now lays an egg on it and then closes up the opening
of the nest. In the case of nests in the ground this is accomplished by
scratching in dirt from around the hole and packing it in firmly. In
three or four cases, species of the wasp genus Sphex have been seen by
different observers to pick up a tiny pebble with their mandibles and,
using it like a hammer, pound down more firmly the earth filled into the
hole. This may perhaps be interpreted as representing the “Stone
Age” in the development of insects!

If the single insect captured will not provide enough food for the
young wasp, the parent proceeds to bring in more, until sufficient has
been supplied, after which the opening is closed and another nest or
cell, according to the kind of wasp concerned, is begun. In a few species
the prey, instead of being paralyzed, appears to be killed and it is claimed
that the wasp brings fresh supplies of food from day to day for the food
of its young.

Detailed studies on the lives and habits of these wasps have been
recorded by many observers, and the remarkable traits these insects
possess form one of the most interesting topics in Entomology.

One species (Fig. 372) deserves particular attention because of its
singular ways. It is a large wasp often called the Cicada-killer ( Sphecius
speciosus Drury) its body being over an inch long, its abdomen black with
yellow marks. It is found over a large portion of the United States and
appears during the dog-days in summer. It makes its nests in the ground
and provisions them with adult dog-day cicadas (Homoptera), larger
and heavier than itself, which it catches in the trees. The prey cannot
be carried to the nest by flight but the wasp starts from the point of

356

APPLIED ENTOMOLOGY

Fig. 372. — Cicada-killer ( Sphecius speciosus
Dru.), about natural size. {Original.)

capture with its paralyzed prey and flies as far as possible before striking
ground. It has been claimed that at times the wasp drags the cicada
up trees or bushes several times en route, in order to gain elevation for a
fresh start toward its nest. The nests themselves may branch under¬
ground several times, each having
a terminal chamber for the recep¬
tion of one or two cicadas and an
egg of the wasp.

Superfamily Vespoidea (The
Social Wasps). — This common
name for the Superfamily is mis¬
leading, as a number of families
included here do not live in colonies,
but no other term at present ap¬
plied to the group is at all ex¬
pressive, and some at least of the
insects included are colonial in
their habits.

Some of the Vespoids are very
small, being less than a sixth of an
inch long, while others found in
the tropics measure more than two inches, their bodies having a bright
blue luster, and with orange or yellow wings. Forms present in the
United States except in the South and Southwest are smaller, some
having bodies marked with black and yellow. The families included
in the group differ much in appearance and in habits, and it is probable
that further study will result in the group being dismembered and
several Superfamilies being formed instead of one.

Some of the Vespoids are solitary, dig nests in the ground which
they stock with spiders, and perhaps with some kinds of insects: others
are parasites, some of the insects attacked being beetle larvae and cater¬
pillars, but in these a nest to which the prey is taken does not seem to be
formed, an egg of the wasp being laid on its host wherever it is found, and
the wasp larva feeding there. Some appear to be parasites on bees and
wasps, living in the cells of the bees and feeding on their young. Still
others are not parasites but feed on honey, pollen, etc.

In one family, known as the Velvet Ants or Stinging Ants (Mutillidse),
many of the insects live in the nests of wasps and bees while others dig
holes in the ground and store flies and other small insects there, it has
been claimed. The males (Fig. 373) are winged, while the females (Fig.
374) are wingless and very active. Both sexes are generally densely
covered with hairs, often long, and generally of two or three contrasting
colors, such as black with a red cross-band, or white, yellow and black.
The females sting very effectively. Northern species are nearly all quite

THE HYMENOPTERA

357

small but in the South are forms which are nearly an inch long and stout-
bodied.

In another family of this group one species known as the Tarantula-
killer (Fig. 375) digs nests which it stores with tarantulas, the large hairy

Fig. 373.

Fig. 374.

Fig. 373. — A male Mutillid ( Traumatomutilla colorata Gerst). About twice natural
size. ( After Andre.)

Fig. 374. — A female Mutillid ( Ephuta occidentalis L.), slightly enlarged. ( After
Andre.)

spiders of the South and Southwest where this insect is found. It is a
large and powerful wasp, about two inches long, but in its battles with
the tarantula it is not always the victor.

Fig. 375. — Tarantula-killer (Pepsis marginata Fab.), somewhat reduced. ( Original .)

The insects of the family Eumenidse are very abundant in this
country. Most of them are rather small (Fig. 376), and black with yellow
markings seems to be the favorite color combination, as so frequently is
the case with the other groups of wasps. Some make burrows in the

358

APPLIED ENTOMOLOGY

ground; others tunnel in wood and divide the tunnel into cells by cross
partitions of mud; while others build cells of mud. some kinds of which,
attached to twigs are like jugs or urns (Fig. 377) in form, with an upper
flaring lip which, after the nest has been stocked with food for their young,
is sealed with mud. The mud workers of this
family are often called the Mason-wasps. All
the wasps of this group are predaceous.

In the family Vespidie we come to the social
wasps, living in colonies, and with three types of
members, the males, females and workers, these

Fig. 377.

Fig. 376. — Eumenid Wasp ( Eumenes fraternus Say), natural size. {Original.)
Fig. 377. — Two nests of Eumenes fraternus, natural size. {Original.)

last being females in which the reproductive organs have undergone
little or no development and the insects themselves are smaller than the
true females.

The colonial life of these insects continues only during the summer,
all but the females dying as winter approaches. In the spring the

Fig. 378. Fig. 379.

Fig. 378. — Social Wasp {Polistes pallipes Lep.), about natural size. {Original.)

Fig. 379. — Nest of Polistes pallipes , as found before the colony has increased much
in numbers. Reduced slightly. {Original.)

female (Fig. 378) starts a colony, first building a cluster of six-sided cells
which are in some cases attached to the under side of some projecting
rock, eaves, or in a similar position (Polistes). These cells (Fig. 379) are
made from weathered wood, chewed up by the insect into a sort of gray

THE HYMENOPTERA

359

paper pulp and then molded into the desired form. In these cells she
now places eggs and the young which hatch are fed upon insects partly
chewed up, with perhaps the addition of some pollen. The young feed
upon this until full-grown, then pupate in their cells. The adults which
emerge are workers and they now begin to
construct additional cells all in the same
layer; feed the young and do the other work
of the colony. Later in the season males and
females are also produced and mate. Late
fall stops further growth of the colony and all
but the females die.

Other insects of this family (Vespula, Fig. Fig. 380. — Social Wasp
380) use wood partially decayed, with which (Vespula vulgaris Fab ) about

to construct their nests, and an outside wrap¬
ping is added. Here one layer of cells will not accommodate the colony
and several layers or tiers of cells surrounded by these wrappings are pro¬
duced, leaving only one or two exit openings. Sometimes these nests are
placed in holes in the ground and the wasps locating in such places are

Fig. 381. — Nest of a Hornet ( Vespula maculata Kirby.), about one-eighth natural size.

(Original.)

often called “yellow-jackets.” Other species construct their nests in
trees or bushes (Fig. 381), attaching them to a branch or branches.
There are several outside wrappings of gray papery wood pulp surround¬
ing the tiers of cells within, of which there may be three or four, and the
exit opening is usually at or near the bottom of the nest. Insects making
nests of this kind in trees or under eaves, gable-ends of buildings or

360

APPLIED ENTOMOLOGY

similar places, are generally called hornets, though there is really no
sharp distinction between them and yellow-jackets, in the usual use of
these names. The life of the colony in the case of these insects does not
differ from that of the forms described above which make only one
layer of cells with no outside wrappings ( Polistes ), but in the yellow-
jackets and hornets the colony increases much more rapidly and by fall
may number several hundred individuals.

Taking the wasps as a whole, we find an interesting progressive
development in the different groups. As regards their habitations, we
may perhaps regard the holes dug in the ground as being the simplest,
followed by excavations of the pith of woody stems, the construction
of mud nests and finally along this line the formation of artistically
shaped urns, as progressive steps in architectural ability. The con¬
struction of hexagonal cells of paper pulp, first in a single layer, then in
several layers surrounded by a paper wrapping and finally much more
substantially built to resist exposure to the weather above ground may
be regarded as continued progress in this line, the nest of the hornet
marking the climax of the series.

Somewhat parallel to this is the nature of the food. The nests
in the ground, in plant stems, and in mud cells, are provisioned with
insects stored as food for the young of the forms constructing them:
in other words these wasps are parasitic insects. With the appearance of
cells of paper pulp the food changes to a mixture of insects killed and
partly chewed up, and of plant materials such as pollen. At this same
point also, a change from a solitary to a colonial life begins and as the
colony becomes larger the nest increases in size and strength.

There is therefore a progressive development in the insects of these
Superfamilies, illustrated in nest structure, food, and the advance from
solitary life to that of a large colony.

Superfa?nily Apoidea (The Bees). — The bees familiar to everybody,
are the bumblebees and the honey bee, but these form a very small part
of the insects belonging in this superfamily. Many of the bees are
solitary in their habits; are rather small insects and little attention
is paid to them. They are important insects, however, valuable to man
as they visit flowers and cross pollinate the blossoms.

The bees have the first segment of the hind tarsus somewhat enlarged
and flattened, and in those which carry pollen there, hairs are present
to aid in this. In addition, the hairs on the thorax are branched or
plumose while in the other Hymenoptera they are simple.

Some of the bees are solitary (Fig. 382) and dig holes in the ground,
generally with side pockets in which pollen or pollen and honey are

THE HYMENOPTERA

361

placed as food for the young. An egg is then laid in each pocket.
Others lay their eggs in the nests of other bees and are parasites upon
them, or inquilines in some cases, consuming the food provided for the
rightful inhabitant and starving it. Some construct mud nests while
others cut off pieces of leaves or sometimes flower petals, with which
they line cavities they excavate in wood, for their nests, and still others
tunnel in wood but use no leafy lining. The colonial forms establish
their homes in various places and build combs of wax in which to store
the pollen and nectar which is their food and that of their young.

Though many of the bees are solitary there is in some species a
tendency to make their holes in groups forming what are frequently
called “bee villages.” In a number of species this goes
still further, several bees uniting in the excavation of
a central burrow but each making lateral passages
from this to cells which are her own and in which her
own young are produced. If the former could fairly be
called “villages” it would seem that these last could
with equal propriety be described as “apartment Fig. 382.— Soii-
houses,” as has been done. Some of the bee villages ta£yt Bee- ^ome-
will include several thousand nests within a few square {Original.)
feet and might even be termed “bee cities.”

Some bees have a rather short hinder lip and are known as the “short-
tongued bees,” but in the majority of these insects the central portion is
long and slender, enabling such forms to reach the nectar in long-tubed
flowers that would otherwise be inaccessible to them.

The leaf-cutter bees are usually rather small. Their nests are not
often noticed, being made in holes (frequently in wood) sometimes
dug by the bees themselves, but the leaves which they cut are familiar
objects as the cut is frequently a very true circle or double circle, the
piece removed in the latter case being rather oblong with rounded ends.

The large Carpenter Bees ( Xylocopa ) are about the size of bumble
bees but in most cases are easily distinguished from them by the smooth
and glossy upper surface of the abdomen. These insects tunnel in
wood, often to quite a distance. The tunnels are divided into cells by
partitions of wood chips, a partition being built across after each cell
has been provided with a mixture of pollen and nectar and an egg.

Bumblebees ( Bombas , etc., of many species). — There are many kinds
of bumblebees widely distributed over the globe but none are found native
in Australia. They live in colonies during the summer but only the queens
(females) survive the winter. In spring the queen (Fig. 383) seeks some
suitable place for a nest, generally a hole in the ground, and frequently
the deserted nest of a field mouse is chosen for the purpose. Here she
places a mass of pollen on which she lays some eggs, and the larvae which
hatch, feed upon the pollen, and when full-grown pupate in silken cocoons

3G2

APPLIED ENTOMOLOGY

Fig. 383. — Queen Bumblebee ( Bom-
bus pennsylvanicus De G.), natural size.
{Original.)

from which workers emerge. These are undeveloped females, smaller
than the queen, and they now take up the work of the colony, strengthen¬
ing the cocoons with wax and using them to store honey in. The colony
increases in numbers and late in the season males (drones) and females
(queens) are also produced and live together until the approach of cold
weather, when all but the young queens die, these going to protected places
to pass the winter.

The value of the bumblebees to man is apparently based upon the
fact that in these insects the middle part of the hinder lip (tongue)
is longer than in most of the other bees, and that therefore they visit and

cross pollenize flowers having a
nectary so long that the nectar in it,
from which honey is made, cannot
be reached by the other species,
which accordingly do not visit such
flowers. One such plant is the com¬
mon red clover which in the United
States is enabled to produce seed,
chiefly as a result of the visits of
bumblebees, which makes these
insects important aids to those who
raise clover seed.

Insects so closely resembling bumblebees that it has incorrectly
been said that the latter cannot distinguish them from themselves, are
often found in bumble bee nests, living there as inquilines. The females
of these inquilines (genus Psithyrus) however, have no structures on
their hind tarsi for carrying pollen. In these inquilines there is no worker
caste. The eggs are laid in the bumblebee cells and on hatching the
young are fed by the bumblebee workers like their own, and the adults
go in and out of the nest without molestation. Whether they have some
function beneficial to the insects with which they live and which provide
for them is as yet unknown.

The Honey Bee ( Apis mellifera L. ). — There are a number of species
of honey bees in different parts of the world, but in the United States
our knowledge and experience with these insects is limited to the above
named kind, often called also, the Hive Bee.

This insect is a native of Europe but was introduced into America
centuries ago. In many instances, colonies have escaped from domesti¬
cation and wild honey bees are abundant as a result. There are several
races of the Honey Bee, the most common one, at least wild, being the
Black or German bee, as this was the first race to be brought to this
country. The German bee has a black abdomen; is not a particularly
good honey producer and has a decidedly bad temper, besitdes being less
able to protect itself from some of the insects such as the bee moth, which

THE HYMENOPTERA

363

live in its nests, than are some of the other races. The Italian bee is a slightly
larger insect with dull yellow stripes on its abdomen; an excellent honey
producer, gentle in disposition; can protect itself quite well from other
insects, and at the present time is the most popular race in this country.
Other races more or less frequently met with are the Carniolan having a
gray abdomen, the Cyprian with a yellow abdomen and a very bad tem¬
per, and the Caucasian with a yellow-gray abdomen. Interbreeds of the
black and Italian bees are very common and have more black on the
abdomen than the pure-bred Italians.

a be

Fig. 384. Honey Bee (Apis mellifera L.): a, drone; b, queen; c , worker. About natural

size. (Original.)

A honey bee colony consists of a queen or fully developed female;
workers which are partly developed females; and drones or males during
a part of the year (Fig. 384). The queen lays eggs in the cells and the
young are cared for by the workers which also gather food for themselves
and the young bees, make the comb, put the nest in good condition and
keep it so, and in fact do all the work necessary for the colony. The
drones exist solely to fertilize the queens, taking no part in the work of the
colony, and feeding on the stores brought in. On the first tarsal segment
of the hind leg in the workers is the “ pollen basket,” a flattened or slightly
hollowed oval surface surrounded by a fringe of long hairs.

An ordinary colony in good condition will consist of several thousand
bees, the number at any time varying and determined by the rapidity of
the production of young, the departure of many by swarming, and other
factors. Swarms containing over fifty thousand bees have been seen,
and the colony they left behind also contained at least a few thousand.

A laying queen bee has a body about three quarters of an inch long:
the drone has a shorter but stouter abdomen, and the workers are about
half an inch long.

The life of the queen may be several years. Ordinarily, workers live
only a month or two, but those produced in the fall live over winter and
far enough into the spring to care for the young produced at that time.
Drones live only a few months and are killed by the workers when their
usefulness is ended.

The life of the honey bee has been modified in many ways by its
relation to man. Under natural conditions where no human interference

364

APPLIED ENTOMOLOGY

occurs, the following may be regarded as an outline of the life of a bee
colony.

Starting with a “swarm/’ which consists of a laying queen and a
mass of workers, which has left its former home, this swarm flies to a new
place in which to establish itself, such as a hollow tree. Here the workers
clean out the cavity, removing loose particles of wood and such other
debris as can be carried out. All cracks and openings to the exterior
except one or two, are then stopped up with Propolis, a dark-colored,
sticky material which the bees gather from the buds of trees, particularly
poplars where these trees occur, and carry to the nest in their pollen
baskets.

The production of wax with which to make cells in which food is
stored and the brood raised, is next in order. To obtain this, some of
the workers feed freely and hang upon the walls of the nest but do no
work. Soon tiny scales of wax appear on the under side of the abdomens
of these workers, produced by wax glands along the inner side of the chi-
tinous wall of the body there, and poured out through openings leading
from these glands to the surface. This wax is gathered, worked over and
molded into the form of sheets of “comb,” attached at their tops to
some part of the hive and hanging downward. Generally these sheets
are more or less parallel to each other and with only a narrow space left
between them when their construction has been completed.

Each sheet of comb consists of two layers of cells back to back, each
cell being six-sided. The long axis of the cell is nearly at right angles to
the plane of the sheet of comb as a whole, but tipped slightly upward.
Comparing cells on the two sides of the comb it is seen that a cell of one
side backs against parts of three of the opposite side, and that the parti¬
tion at the inner end of each cell slopes so that the center is its deepest
point. Mathematical study of the construction of the cells shows that
by this form and arrangement of the cells the greatest amount of storage
space is obtained with the least expenditure of wax, of any form which the
bees could use. In some of these cells, usually those around the top and
sides of the comb, food is stored, while the central and lower portions
are used for the production of the young.

As soon as comb is available the storing of food and the production of
young begin. The workers go out and visit flowers, gathering the pollen
in their pollen baskets and bringing it to the nest where it is stored in
cells. They also collect nectar from the blossoms, carrying it to the nest
in the honey sac, an enlargement of the oesophagus just in front of the
stomach (Fig 24, hs). On reaching the nest this nectar is expelled into a
cell and the cells selected for this purpose are gradually filled. From time
to time workers visit these cells and draw the nectar from them into their
honey sacs, then driving it back into the cell again and repeating the
process, which removes water from it and concentrates it into honey.

THE HYMENOPTERA

365

The queen lays her eggs on the bottoms of the cells selected for the
raising of brood, one egg in the bottom of each cell. The eggs hatch into
stout, white, maggot-like larvse (Fig. 385) which are fed by the worker
bees with a material generally called “bee bread” which appears to be
pollen mixed with some honey. When the larvae are full-grown and ready
to pupate the workers cap over with wax the openings of the cells occu¬
pied by such larvae and these proceed to pupate (Fig. 385). After the
changes undergone during pupation have been completed the adult thus
produced bites away the cap closing the cell it is in and emerges as the
adult.

Fig. 385. — Section of comb of Honey Bee: FL, feeding larva in the bottom of its cell;
SL, larva ready to pupate, spinning its cocoon; N, pupa; an, antenna; ce, compound eye;
co, cocoon; e, excrement; ex, exuvium; m, mandible; sp, spiracle; t, tongue; w, wing. ( After
Cheshire.)

In the case of eggs which are to become drones (males) the cells in
which such eggs are laid are apparently of a slightly greater diameter than
those where workers are to be produced, though this is denied by some
students of the subject, and they are longer, projecting out beyond the
line of the general surface of the brood cells, at least after being capped, so
that they are easily recognized.

The queen is fertilized but once, at which time the sperms of the drone
are stored in the seminal receptacle of the queen. She lays both fertilized
and unfertilized eggs, the latter producing the drones. By the Dzierzon
theory, whether the egg is to be fertilized or not depends upon the will of
the queen. If the cell in which the egg is to be laid is a worker cell, at the
moment the egg passes down the oviduct by the opening of the seminal
receptacle the muscles surrounding the receptacle are slightly contracted
and sperms are expelled, one of which fertilizes the egg, while if the egg
is deposited in a drone cell the muscles are not contracted and the egg is
unfertilized and produces a drone. While this is the more generally
accepted theory, the alternative view is held by some persons that the
smaller diameter of the worker cell produces pressure on the abdomen
of the queen which forces some of the sperms out, and that in case of
drone cells their greater diameter prevents this.

Queens are produced only during the late spring and summer months
when swarming is desired. At such times the workers select a cell already

366

APPLIED ENTOMOLOGY

containing a worker egg and tear down those around it and construct a new
cell about the shape and size of a small peanut, to enclose the egg, and with
its opening usually facing downward. When the egg in this cell hatches
the larva is fed on “royal jelly” which is probably bee bread mixed with
an albuminous secretion derived from glands situated in the heads of the
workers, and which is richer and more nutritious than bee bread. With
this richer food and a larger space in which to develop, the workers are
thus able to produce a queen from a worker egg. There are often a num¬
ber of queen cells of different ages in a nest at once.

The time required to produce a queen from egg to adult is about 15^
days: for a worker, 21 days; and for a drone 24 days.

Swarming is for the double purpose of relieving colonies whose nests
would otherwise become over-crowded, and for the establishment of
new ones. Though many of the details of this process may vary on
different occasions, the usual story of swarming is about as follows.

When the colony is in such a condition during late spring or summer
that swarming will soon be desirable, drone cells and queen cells are con¬
structed and after a time the first of the new queens completes pupation
and begins to bite off the wax cap over the mouth of her cell. At this
time she makes a peculiar noise commonly called a “piping” sound, and
when the old queen hears this she becomes greatly disturbed and begins
to hunt for the young queen to sting and kill her before she can escape
from her cell, if possible. If a swarm just at that time is not desired by
the workers for any reason, she may be allowed to do this, but if swarm¬
ing is to take place workers cluster so thickly over and around the young
queen cell that, the old queen cannot reach it. This opposition to her
wishes, passive though it is, or the knowledge that another queen will
quickly be present in the colony seems to arouse and excite the old queen
greatly and this excitement spreads to the workers, particularly the
younger ones. Scouts now go out to find a home for the swarm and
finally the old queen and a mass of workers leave the hive together. In
some cases they go directly to their new home, but most often they fly
only a short distance before clustering on the limb of some bush or tree
for a time before flying to the new nest. Once arrived there, the work of
preparing the place, stopping the cracks and the production of comb
begins, as already described.

That part of the colony remaining behind now consists of workers,
drones and a young, unfertilized queen. The queen on escaping from
her cell usually explores the brood cells and if she finds other queens
developing she stings them in their cells to assure her supremacy, unless
prevented by the workers. A few days later the queen leaves the nest on
a pleasant day for a flight during which she mates, after which she returns
to take up her duties as queen of the colony.

Several possibilities may become realities in connection with swarm-

THE HYMENOPTERA

367

ing. One of these is the chance that two young queens may emerge
at almost the same time. If this should happen it is stated that the
two meet sooner or later and struggle for supremacy until one or the
other is killed. A second possibility is that both of the queens may
be so injured that they will die, or as probably is more often the case,
the queen while out on her mating flight may be killed by a bird or in
some other way. In either case the colony becomes queenless as a result.
If other queen cells are present in such cases, the workers carry on the
work of the hive until the new queen appears, mates and takes charge:
but if there ai'e no more queen cells the workers look about for a worker
egg or a larva not more than 3 days old. If one is found, its cell walls
are torn down and a queen cell built around it and its food is changed
from bee bread to royal jelly and in this way a queen will be produced.
If an egg or a worker larva under this age cannot be found, however, the
colony cannot hope to obtain a queen and it gradually dwindles away and
is lost.

Drones, serviceable to the colony during the swarming season, are
not needed thereafter and would consume stores gathered for winter.
Therefore after all swarming is over they are dragged out and killed
by the workers.

The value of the honey bee to man comes from the honey and wax
it produces. The amount obtained varies greatly from year to year
but averages over fifty million pounds a season in the United States
and at a recent average retail price of forty cents, would represent about
twenty million dollars. This is probably more though, than is actually
received by the beekeepers. About a million pounds of wax are now
produced annually and at about forty cents per pound this would add
nearly half a million dollars more to the value of the industry in this
country.

Superfamily Formicoidea (The Ants). — These familiar and plentiful
insects occur from the frigid regions to the equator, being present in
abundance practically everywhere, and it has been claimed that there
are more individuals of ants than of all other terrestrial animals. They
live in colonies which are quite permanent, enduring for many years in
some cases, and the life of an individual ant may continue for several
years.

Ants are nearly always easily recognized by the presence of a petiole
which is enlarged near or behind its middle (Fig. 386e), being either
swollen or having a portion projecting upward there, followed behind
bv a constriction where this segment joins the rest of the abdomen.
In some ants the following segment is also more or less similarly shaped.
This gives these insects a rather elongate, narrow portion between the
thoracic and abdominal masses, enlarged at one or two places, according
to the number of segments concerned.

368

APPLIED ENTOMOLOGY

Three classes of ants always compose a colony — males, queens
(females) and workers — and there may be subdivisions of each of these
in some cases. The males and females usually have wings during a
portion of their lives, these having a simple arrangement of the veins:
the workers are wingless though some have vestiges of these structures.
The queens and workers are provided with a well-developed sting in some
groups of ants, while in others it is vestigial or entirely absent. The
usual colors of ants are yellow, brown, black, red, dull red, or brownish
yellow.

Fig. 386.- — Little Black Ant ( Monomorium minimum Em.): a, male; b, pupa; c, female;
d , winged female; e, worker;/, larva; g, eggs; workers in line of march below. All enlarged,
hair lines showing true length. ( From U . S. D. A. Farm. Bull. 740.)

Colonies of ants occur in many kinds of locations. Some are in
the ground and these may be of different types of structure; some occur
in the cavities of plants, either preformed or else tunneled out by the ants:
some form nests on branches, making them of various materials; and
some nest in timbers, or other unusual places, while a few kinds have no
fixed homes.

The food of ants is as varied as are their nest locations. Probably
the original food of the group was insects, either dead or helpless, and
many species feed on this material. Others take the honey-dew supplied
by scale insects, leafhoppers and particularly by plant-lice. Some raid

THE HYMENOPTERA

369

the nests of other species of ants and feed on their larvse and pupae.
Plant seeds, bulbs, and the bark on tender roots also form the food of
some ants, and one tribe raises a fungus in order to feed upon its hyphae.
Sweet materials such as cake, candy, sugar, molasses, etc., in houses,
often attract ants, which find in these substances satisfactory foods.

Colonies in the ground may vary from those having a single tiny
entrance and a few tunnels and galleries below the surface, to large
ant hills several yards in diameter and several feet high, with extensive
galleries both above and below the general ground level ( Fig. 388). In
these nests may be found a queen (frequently several) ; males, at least at
times; and often many thousands of workers. The queen or queens
produce the eggs which are carried away and cared for by the workers,
who also feed the larvae, clean them, transfer them from one part of
the nest to another, according to the temperature and other conditions
they need, and finally aid them in escaping from their cocoons. They
also feed the queen and do all the work of the colony.

The eggs laid may develop either into males or females and workers,
and Dzierzon’s theory given above for bees has been applied to ants also,
though some evidence that unfertilized eggs may in certain cases produce
workers tends to throw doubt on the applicability of this theory to ants.

At certain seasons of the year swarming occurs. At such a time
enormous numbers of winged males and females, previously produced in
the nest, leave it and take flight. Mating occurs in the air and the
females soon return to the ground where they remove their now useless
wings, either by pulling them off with their legs or jaws, or by rubbing
them against the ground, stones or grass-stems. The queen now prepares
a nest by digging a hole in the ground, in rotten wood or elsewhere,
forming a small chamber at the inner end and closing the entrance.

“In her cloistered seclusion the queen now passes days, weeks, or even
months, waiting for the eggs to mature in her ovaries. When these eggs have
reached their full volume at the expense of her fat-body and degenerating wing-
muscles, they are laid, after having been fertilized with a few of the many thou¬
sand spermatozoa stored up in the spermatheca during the nuptial flight. The
queen nurses them in a little packet till they hatch as minute larvse. These she
feeds with a salivary secretion derived by metabolism from the same source as
the eggs, namely, from her fat-body and wing-muscles. The larvse grow slowly,
pupate prematurely and hatch as unusually small but otherwise normal workers.
In some species it takes fully 10 months to bring such a brood of minim workers
to maturity, and during all this time the queen takes no nourishment, but
merely draws on her reserve tissues. As soon as the workers mature, they break
through the soil and thereby make an entrance to the nest and establish a com¬
munication with the outside world. They enlarge the original chamber and con¬
tinue the excavation in the form of galleries. They go forth in search of food
and share it with their exhausted mother, who now exhibits a further and final
change in her behavior. She becomes so exceedingly timid and sensitive to

24

370

APPLIED ENTOMOLOGY

light that she hastens to conceal herself on the slightest disturbance to the nest.
She soon becomes utterly indifferent to her progeny, leaving them entirely to
the care of the workers, while she limits her activities to laying eggs and imbibing
liquid food from the tongues of her attendants. This copious nourishment
restores her depleted fat-body, but her disappearing wing-muscles have left her
thoracic cavity hollow and filled with air which causes her to float when placed
in water. With this circumscribed activity, she lives on, sometimes to an age of
15 years, as a mere egg-laying machine” (Wheeler).

Of course there are many fatalities in such a history as this. Birds,
dryness in their burrows, excessive moisture or cold, underground insects
attacking them, together destroy the great majority of these ants just
starting new colonies. Then too, the amount of nourishment stored in
the individual is an important factor, some species having so little that
they are wholly unable to start new colonies. An individual of such a
species therefore either joins a colony already established, a queenless
colony of a related species if she can induce the colony to accept her, or
she may enter a colony of a very different species and, killing its members,
raise their young until they emerge when they will accept her as their
queen. Rarely two queens may start a colony together.

After the colony is well under way the queen limits her duties to egg
laying, and may live many years. In one case a queen lived nearly
15 years in confinement and may have been older! This is the greatest
age known to have been attained by any adult insect. The males die
soon after mating.

The relation of ants to plant lice is most interesting and has already
been referred to (pp. 197 and 203). It does not exist with all species
of ants but in at least a large number honey-dew is an important part
of their diet and in some cases it may be their only food. There is every
evidence that the benefit is mutual, the ants protecting the aphids, driv¬
ing away the enemies of these insects or carrying the aphids to protected
places. Ants that care for root-feeding aphids keep them in chambers or
galleries, conduct them to their sources of food supply, collect and store
their eggs for the winter, and in spring take the young to their food.

The Corn-root Aphis so injurious to corn, as already described, is
thus cared for by ants. Scale insects which produce honey-dew are also
cared for in a sense, for ants are very attentive to them and to quite an
extent prevent the attacks of the enemies of the scales by their presence
and activities. Thus in an indirect way the protection by ants of
plant lice, scale insects, white flies, leaf hoppers, and in fact any insects
which produce honey-dew, establishes such ants as injurious.

Some kinds of ants have most remarkable habits worthy of a brief
reference here. Some species may make raids on the nests of other
kinds, and carry off their worker larvae and pupae to their own nests,
where many probably serve as food but a few may be reared and become

THE HYMENOPTERA

371

slaves. Slavery is not essential with all the kinds of ants where it is
known, colonies having no slaves being able to carry on their lives unaided
by slaves. With certain species, however, the situation is different.
In these the workers have mandibles so constructed that they are unable
to gather food, excavate their nests or care for the young. Accordingly
they make forays on the nests of other species, bringing back larvae and
pupae which on becoming adult are slaves which do the work of the colony
and care for their captors, both as adults and during their early stages.

The honey ants, so-called, include those species in which the crop is
capable of great distention, and this power is made use of by collecting
honey-dew and storing it until the abdominal mass is enormously dis¬
tended and (in some species) about the size of a large currant, such in¬
dividuals becoming animated food reservoirs. These members of the
colony hang on the ceilings of their galleries, withdrawing from the
regular duties of the other workers. The reason for the existence of
such a peculiar habit is suggested by the fact that the honey ants arc
confined to dry plains and desert regions, being found in North America,
South Africa and Australia. They are therefore probably true reservoirs
of nourishment which may be drawn upon during periods of drought,
when the ants must remain for some considerable time in their nests.

Some ants raise fungi upon which to feed, about one hundred kinds
which do this being known. These insects in most cases go in large num¬
bers to trees and some climb the trees and cut off the leaves while other
members of the colony pick these up from the ground where they have
fallen and carry them to their nests where the fungus is grown on them.

A few species of ants are obnoxious to man, either by invading houses,
making their nests in lawns or in trees, or by to some extent protecting
injurious insects.

The Argentine Ant ( Iridomyrmex humilis Mayr.) is a native of
South America which probably reached this country between 1880 and
1890 at New Orleans and now is present nearly everywhere in most of the
southern tier of states, and in California as far north as San Francisco.

The adults (Fig. 387) are brown in color. The queens are about a
quarter of an inch long, the males about half that length, and the workers
about a tenth of an inch long. Their summer nests “may be located
anywhere — under sidewalks, under the sills of houses, in brick piles, stone
piles, under a piece of board or a piece of tin, in an old tin can — in fact,
in any place convenient to the food supply. In the winter months there
is a tendency to concentrate into larger colonies, and they seek warm,
dry, secure nesting places in which to hibernate” (E. R. Barber).

Egg production is probably quite large — perhaps 50 or more per day
under favorable conditions — and an average of 40 days in warm weather
is required for development from the laying of an egg to the emergence
of the adult worker.

372

APPLIED ENTOMOLOGY

This is one of the worst of house pests known in the regions where it is
abundant. Its small size enables it to enter through the smallest cracks
and it goes everywhere in houses after its food. It will eat practically
everything in the way of foods, both raw and cooked, and no part of a
house is free from its presence. The cold of ice chests does not repel
them and beds are not entirely protected by placing the bedposts in dishes

Fig. 387. — Argentina Ant ( Iridomyrmcx humilis Mayr.): 1, wingless female; 2, worker,
3, early stages: a , eggs; b, young larva; c, full-grown larva; d, side view of pupa; e, ventral
side of pupa; /, dorsal view of pupa, 4, male. All greatly enlarged. ( From U. S. D. A.
Farm. Bull. 740.)

of water or kerosene, as after a few hours a film of dust forms on the
surface of this, over which with their light bodies they are sometimes able
to pass. Though they do not sting, they bite freely and are able to
cause some pain in this way. Young children asleep have been found
with ants in the nose, ears and mouth, and older persons are frequently
inconvenienced by them in a similar way. They visit plant lice, soft
scales and other insects for honey-dew and to some extent at least, their
presence is favorable to these pests and makes their control more difficult.

THE HYMENOPTERA

373

Control. — Heavy rains, causing a flooding of the nests is a natural means
of checking the ravages of these insects, many being killed, particularly
in cold weather. Barriers on the legs of tables, beds, etc., consisting of
tape, soaked in a saturated solution of corrosive sublimate (Hg Cl2),
dried, and then fastened around such places will keep the ants away for
several months at least. A generous supply of naphthaline in the form
of moth balls, placed in a dish in which a leg of a piece of furniture rests is
also effective, provided each leg is thus treated. Kerosene instead of moth
balls, as already described, is generally of some value as a protection.

Various ant poisons have been tested, and a syrup of granulated
sugar, water, tartaric acid, sodium arsenite and honey has been found
to be very effective, and it also keeps well. Placed in a tight tin with
two sides dented in and with a tin cover, the ants can enter and feed
while the syrup remains protected from the weather. A gill or two of
syrup and a fairly large piece of sponge floating in it will complete the
trap for use. Traps should be placed both in and around the house, of
course out of the reach of children, and by adding a bail or handle can
be hung on walls, the branches of trees and in similar situations. Eight
or ten of these are sufficient for an ordinary city house and lot and will
be effective at least for 6 or 8 weeks.

House Ants. — These are of several kinds but the one most usually
troublesome is the Little Red Ant ( Monomorium pharaonis L.), probably
a native of Europe but now abundant in nearly all countries. It is very
small, red in color, and makes its nests in walls, floors, sills or other
timbers, whence it explores all parts of the houses, paying particular
attention to those places where food is found. Oftentimes regular lines
of these pests may be found marching from some article of food they
have discovered to their nest, and another line beside the first, on their
way to obtain food. In such cases it is sometimes easy to trace their
line of march back to where they enter some timber in which their nest
is placed, and then the injection into the holes where they enter,
of carbon disulfid or benzine may prove sufficient to kill the queen
or queens and terminate the life of the colony. In too many cases
though, it is impossible to locate, or perhaps io reach the nest. Where
this is true it has been found that small pieces of sponge, soaked in mo¬
lasses and water, and a little arsenic, placed where ants are will generally
attract the pests, which will feed upon the poisoned syrup and be killed.
In this way the number of individuals is frequently reduced more rapidly
than the colony increases and the ants gradually become less abundant
and finally disappear. Simple protection of food or other materials can
usually be obtained by placing around such articles a continuous, liberal
band of powdered cloves.

Where ants are nesting in living trees they usually enter where some
limb has been lost, and their entrance holes in the wood can be found.

374

APPLIED ENTOMOLOGY

Pouring carbon disulfid or benzine into these and then stopping the
holes with putty or mud is in most cases, sufficient to kill the queen, and
in consequence, the colony.

Ants in lawns or elsewhere may make mounds (Fig. 388) or may
simply loosen the soil and more or less injure the grass at such places.
To destroy such nests a stick, such as a cane or a broom handle, should be
driven down to the bottom of the nest, at which point the loosened earth
ends and driving becomes hard. These holes should be about a foot

Fig. 388. — Ant hills. ( From a photograph by H. B. Peirson.)

apart and enough of them be made to cover the entire surface of the nest
at this distance. Into each hole a tablespoonful or two of carbon di¬
sulfid is now poured and each opening closed at the top, which is suffi¬
ciently done by pressing the earth together at each hole with the foot.
The carbon disulfid gas penetrating through the underground galleries
of the ants will kill them, including the queen, and the colony will
disappear.

This treatment should be applied on a warm, dry day, to hasten the
change of the liquid to the gas and its rapid dissemination through all
parts of the nest.

INDEX

A

Abdomen, 14

Abdominal feet, 14, 232, 252, 272, 300
Acrididae, 81-85
Aculeata, 339
Adalia bipunctata, 133
Aedes a;gypti, 309
sollicitans, 307
.Egeriidae, 243-246
Agamic reproduction, 154, 196
Agglomerate eyes, 9
Air tubes, 18
Alabama argillacea, 269
Alaus oculatus, 108
Aleyrodes vaporariorum, 207
Aleyrodidae, 187, 206-208
Alfalfa caterpillar, 295
weevil, 143
worm, 274

Alsophila pometaria, 253
Amblychila cylindriformis, 101
Ambrosia beetles, 146
Ambush-bugs, 182
American roach, 78
Ametabola, 25

development of, 26
Anabrus purpurascens, 87
Anatis 15-punctata, 134
Angoumois Grain Moth, 247
Anisolabris maritima, 95
Annulata, 1

Anopheles crucians, 309
quadrimaculatus, 307
Anoplura, 164-167

mouth parts of, 164
Ant, Argentine, 371
-lions, 224-225
little brown, 204
red, 373

Ants, 186, 196, 197, 204, 367-374
house, 373
in lawns, 374
Antennae, 8
Anthomviidae, 327-330
Anthonomus grandis, 140

Anthrax, 323

Anthrenus scrophulariae, 104
Antique tussock moth, 262
Anuraphis roseus, 198
Anus, 15
Aorta, 19
Apex, 14

Aphididae, 133, 187, 194-206, 291, 344,
368, 370
Aphis bakeri, 199
-lions, 222
maidi-radicis, 203
pomi, 198
Apis mellifera, 362
Apoidea, 360-367
Apple aphids, 198
grain aphis, 198
leafhoppers, 192
maggot, 319

-tree tent-caterpillar, 256
Apterygota, 60, 62
characters of, 62
Arachnida, 2

characters of, 4
Arctiidae, 277-279
Armored scales, 208, 209-216
Army worm, 272
Arsenate of lead, 46

standard formula, 47
of lime, 47
Arsenic, 44

Arthropod characters, 1
groups of, 2

distinctive table of, 5
Arthropoda, 1

Artificial control methods, 38
Asilidae, 316
Asparagus beetle, 123
Aspidiotus perniciosus, 211
Attagenus piceus, 104
Aulacaspis rosae, 214
Australian roach, 78
Automeris io, 286
Axillary incision, 301
Axillary sinus, 301

376

INDEX

B

Bacillus pestis, 334
Back-swimmers, 184
Bacterial wilt, 118, 197
Bag worms, 250-252
Bark beetles, 146-149
Basilarchia archippus, 292
Basilona imperialis, 281
Bean weevils, 128-130
Bedbug, 182
Bee bread, 365
moth, 249
Bees, 360-367;
bumble, 361
carpenter, 361
honey, 362
leaf-cutter, 361
solitary, 360
Beetles, 98-149
Beet-root louse, 205
Belostomidae, 185
Bembecidse, 354
Bilateral symmetry, 2
Bird lice, 161-163
Birds, 1; and insects, 35, 36
Biting lice, 161-163
Black-beetle, 78

carpet beetle, 104
flies, 315
lady beetle, 135
scale, 135, 216, 220
swallow-tail butterfly, 298
witch, 269

Blastophaga grossorum, 349
Blatella germanica, 76
Blatta orientalis, 78
Blattidae, 76-78
Blissus leucopterus, 174
Blister beetles, 135-136
Blood, 20

vessels, 19
Blue-bottle flies, 324
Bombus, 361
Bombycidae, 255
Bombyx mori, 255
Book-lice, 159
Borax, 50

Bordeaux mixture, 54
Bot flies, 318
Brain, 21

Breathing organs, 17
Broad bean weevil, 129

Bromius obscurus, 125
Brown-tail moth, 265, 296, 297
Bruchidee, 128-130
Bruchophagus funebris, 349
Bruchus chinensis, 129
obtectus, 129
pisorum, 128
quadrimaculatus, 129
rufimanus, 129
Bubonic plague, 334
Bud-worm (of corn), 120
Buffalo carpet beetle, 104
gnats, 315
Tree-hopper, 190
“Bug vs. bug,” 220
Buhach, 53
Bumblebees, 361
Buprestidae, 105-107
Burning insects, 40
Butterflies, 290-299

(and moths), 230-299

C

Cabbage butterfly, imported, 293
maggot, 327
Caddice flies, 226-229
Caeca, 16

California devastating grasshopper, 83
grape-root worm, 125
oak worm, 267
Caliroa cerasi, 341
Callosamia promethea, 283
Calosoma sycophanta, 100
Camel crickets, 86
Camnula pellucida, 84
Camphor thrips, 158
Canker worms, 253
Cantharidin, 136
Capsidae, 180
Carabidae, 100
Carbon disulfid, 55
Carnivorous diving beetles, 101
Carolina grasshopper, 84
Carpenter bees, 361
moths, 234-236
worm, 234
Carrion beetles, 103
Case-making clothes moth, 236
Caterpillar, 232
Catocalas, 269
Cecropia moth, 283
Cells, 13

INDEX

377

Centipedes, 2

characters of, 3
Cephalothorax, 3, 151
Cephus cinctus, 342
pygmaeus, 342
Cerambycidae, 130-133
Ceratocampidse, 280
Cerceridae, 354
Cerci, 14

Ceresa bubalus, 190
Chalcid flies, 347-351
Changa, 90

Characters of Arthropods, 1
Chermidae, 187, 193
Cherry plant lice, 205
Chigoe, 336

Chi loco rus bivulneras, 134, 213
Chilopoda, 2

characters of, 3
China wax, 209
Chinch bug, 174
bug fungus, 176
Chinese mantis, 79
Chionaspis furfura, 210
pinifoliae, 215
Chitin, 2, 7

Chloridea obsoleta, 270
Cholera, 321, 323
Chordata, 1
Chrysalis, 234
Chrysidoidea, 353
Chrysobothris femorata, 106
Chrysomelidae, 115-128
Chrysomphalus aurantii, 215
Chrysomyia macellaria, 324
Chrysopidae, 222-223
Cicada-killer, 355
Cicadas, 187-190, 355
Cicadidae, 187-190
Cicindelidae, 101
Cimex lectularius, 182
Cimicidae, 182
Circulatory organs, 19
Cirphis unipuncta, 272
Citheronia regalis, 280
Citrus mealy bug, 218
thrips, 157
white fly, 207
Classification, 59-61
Clean culture, 39
Clear-winged grasshopper, 84
moths, 243-247
Click-beetles, 107-110

Closed cells, 13
Clothes moths, 236-238
Clover aphis, 199

-flower midge, 311
root-borer, 147
-seed chalcid, 349
Cnidocampa flavescens, 250, 353
Coccidae, 187, 208-220
Cocci nella novemnotata, 134
Coccinellidae, 133-135
Coccotorus scutellaris, 139
Cochineal, 209
Cocoon, 29

in Lepidoptera, 233
Codling moth, 238
Coelenterata, 1
Coleomegilla fuscilabris, 134
Coleoptera, 98-149
Coleoptera vera, 99-136
Collembola, 62, 63-64
Colon, 16

Colorado potato beetle, 115
Comb, 364

Combinations of sprays, 54
Commissures, 21
Common bean weevil, 129
Compound eyes, 8
Conotrachelus nenuphar, 137
Contact insecticides, 43, 49-53
Contarinia tritici, 314
Control by natural methods, 35
Coreidae, 172-173
Corixidae, 184
Corn borer, European, 249
ear worm, 270
Cornicles, 195
Corn-root aphis, 203, 370
worms, 120-122
Corrodentia, 159-161
Corydalis cornuta, 221
Cossidae, 234-236
Costa, 14

Cotton boll weevil, 140
Stainer, 174
worm, 269

Cottony cushion scale, 135, 219,
220

maple scale, 217
Cowpea weevil, 129
Coxa, 12
Crab louse, 166
Crane flies, 304
Crickets, 88-90

INDEX

378

Crioceris asparagi, 123

duodecimpunctata, 124
Crop, 16

rotation, 39
Croton bug, 76
Crude petroleum, 50
Crustacea, 2

characters of, 3

Cryptolannus montrouzieri, 135
Cuckoo wasps, 353
Cucurbit mosaic disease, 118
Culex pipiens, 306
Culicid®, 305-311
Curly-leaf disease, 193
Currant worm, 340
Cursorial Orthoptera, 75-81
Cutworms, 275
Cydnid®, 172
Cylas formicarius, 145
Cynipoidea, 346

D

Dagger moths, 270
Damsel-flies, 68-69
Danaid®, 291
Danaus archippus, 291
Darkling beetles, 135
Dasyneura leguminicola, 311
Datana, 267
Death watch, 160
Dengue, 310
Dermaptera, 95-97
Dermestes lardarius, 103
Dermestid®, 103-105
Diabrotica duodecimpunctata, 120
longicornis, 121
soror, 122
trivittata, 119
vergifera, 122
vittata, 118
Dialeurodes citri, 207
Diapheromera femorata, 81
Differential grasshopper, 83
Digestion, 16
Digestive organs, 15
formation, 15
Digger wasps, 354—356
Dimorphism, seasonal, 291
Dioptid®, 267
Diplopoda, 2

characters of, 3
Diptera, 301-332

Diseases carried by insects, 166, 167,
183, 309, 321-323, 325, 334
Diseases of insects, 178
Dispersion of insects, 296
Dissosteira Carolina, 84
Dobson, 221
Doodle-bug, 224
Dog-day harvest-flies, 189
Dorvphora clivicollis, 117
Dragon-flies, 68-71
Drill-worm, 120
Drones, 362, 363
Dry sulfur compounds, 52
Dusting poisons, 43
Dynastes tityrus, 114
Dysdercus suturellus, 174
Dysentery, 321
Dytiscid®, 101
Dzierzon theory, 365, 369

E

Earwigs, 95-97
Eccoptogaster rugulosus, 147
Ecdysis, 27

Echidnophaga gallinacea, 336
Echinodermata, 1
Eggs, 25

Ejaculatory duct, 24
Elaterid®, 107-110
Electric-light bugs, 185
Elm leaf beetle, 126
Elytra, 98
Embiidina, 74
Emergence, 30
Empoa ros®, 193
Empoasca mali, 192
Empodium, 12, 303
Engraver beetles, 136, 146-149
Ensign flies, 343
Ephemerida, 65—67
Ephestia kuhniella, 249
Epi pharynx, 9
Erebus odorata, 269
Eriosoma lanigera, 199
Estigmene acr®a, 277
Eucosmid®, 238-243
Eulecanium nigrofasciatum, 217
tulipifer®, 216
Eumenid®, 357
Euproctis chrysorrhoea, 265
European corn borer, 249
earwig, 95

INDEX

Eurymus eurythcme, 295
philodice, 295
Evaniidae, 343
Excretory organs, 21
External skeleton, 2
Eyed elater, 108
Eyes, 8

agglomerate, 9

F

Fall army worm, 274
canker worm, 253
webworm, 278

False budworm of tobacco, 270
Farm practices, 38
Femur, 12

Fever: Relapsing, 166
Trench, 166
Typhus, 166
Fidia viticida, 125
Field crickets, 88
Fifteen-spotted Lady beetle, 134
Fig fertilization by Blastophaga, 349
Filariasis, 310
Fire blight, 181, 197
-flies, 100
Fishes, 1
Fish-flies, 222

Flat-headed apple-tree borer, 106
borers, 105-107
Flax-seed stage, 312
Flea-beetles, 122
Fleas, 333-337
Flesh flies, 326
Flies, 301-332
Fluted scale, 135, 219, 220
Forceps in Thysanura, 63
in Dermaptera, 95
Fore-intestine, 15
Forest tent-caterpillar, 259
Forficula auricularia, 95
Formicoidea, 367-374
Four-spotted bean weevil, 129
Frankliniella tritici, 154
Frenal fold, 338
hooks, 338
Frenulum, 232
Froghoppers, 191
Fruit flies, 319-321

tree bark-beetle, 147
Fumigation, 18, 55

G

Gad flies, 314
Galerucella luteola, 126
Galleria melonella, 249
GalL insects, 346
midges,' 311

Galls: Aphid, 196, 202, 205
Chalcidoid, 347
Cynipoid, 346
Itonidid, 311
Trypetid, 319
Gasoline torches, 40
Gastric caeca, 16
Gastrophilus, 319
Gelechiidae, 247
Geometridae, 252-255
German honey bee, 362
roach, 76
Gerridae, 184

Giant silkworms, 283-287
water-bugs, 185
Glossina, 325
Glow-worms, 100
Goat moth, 234
Golden-eyes, 222
Grape Phylloxera, 201
-root worm, 125
Grass-feeding Froghopper, 191
Grasshoppers, 81-85
thrips, 158
worm, 274

Green apple aphis, 198
-bottle flies, 324
fruit worms, 270
grasshoppers, 85-87
-heads, 315
Japanese beetle, 114
Greenhouse thrips, 155, 158
white fly, 207
Ground beetles, 100
Groups of Arthropods, 2

distinctive characters of, 5
Grouse locusts, 85
Gryllidae, 88-90
Gryllus luctuosus, 88
Guests in galls, 347
Gypsy moth, 100, 262, 296
Gyrinidae, 101

H

Halisidota caryae, 277
Halteres, 14, 301

INDEX

380

Hamuli, 338
Hand picking, 40
Harlequin bug, 171
Harmolita grande, 348
tritici, 348

Harpalus caliginosus, 100, 117
Harvest flies, Dog-day, 189
Hawk moths, 287-290
Head, 7

Healthy crops, 39
Hearing: in crickets, 88
in grasshoppers, 85
in green grasshoppers, 87
Heart, 19
Heat, 41

Hedgehog caterpillar, 277
Heliothrips haemorrhoidalis, 155
Hellebore, 48
Hellgrammite, 221
Hemerocampa leucostigma, 260
Hemielytra, 168
Hemimetabola, 26
Hemiptera, 168-185
Hemispherical scale, 218
Hesperiidse, 290
Hessian fly, 312
Heterocera, 234
Heterometabola, 26
Hexapoda, 2

characters of, 5
as a class, 59

“Hickory horned devil,” 280
tiger moth, 277
Hind-intestine, 15
Hippodamia convergens, 134
Hive bee, 362
Holometabola, 26

development of, 27
Homoptera, 186-220
Honey, 364
ants, 371
bees, 362
-dew, 186, 194, 195, 217, 368, 370
sac, 364
Hornets, 360
Horn-tails, 343, 344
Horse bot flies, 319
flies, 314
House ants, 373
fly, 297, 321
mosquito, 306
Human body louse, 165
Humming bird moths, 287-290

Hydrocyanic acid gas, 57
Hydrophilidse, 102
Hylemyia antiqua, 329
brassicaj, 327
Hymenoptera, 338-374
Hyperparasites, 344
Hyphantria cunea, 278
Hypoderma bovis, 318
lineatum, 318
Hypodermis, 7
Hypognathous, 8
Hypopharynx, 10

I

Icerya purchasi, 135, 219
Ichneumon flies, 343-346
Ichneu monoidea, 343-346
Ileum, 16
Imaginal buds, 28
Imago, 28
Imperial moth, 281
Imported cabbage butterfly, 293, 296
Inch worms, 252-255
Inquilines, 347, 361, 362
Insecticides, 43
classes of, 43

Insect orders; their relations, 60
powder, 53
Insects, 2

characters of, 5
external structure of, 6
internal structure of, 15
Instar, 27

Introduced insects, 35, 296
Io moth, 286
Ipidse, 146-149
Iridomyrmex humilis, 371
Isabella tiger moth, 277
Isia isabella, 277
Isoptera, 91-93
Italian honey bee, 363
Itonididae, 311-314

J

Japanese beetle, Green, 114
Japanese silkworm moth, 284
Jelly-fish, 1
Jerusalem crickets, 87
Jigger flea, 336
Jugum, 232

Jumping plant lice, 187, 193
June bugs, 110

INDEX

381

K

Kala-azar, 183
Katydids, 85-87
Kellogg, 349
Kerosene emulsion, 49

L

Labia minor, 95
Labial palpus, 10
Labium, 10
Labrum, 9
Lace bugs, 179
Lace wings, 222

Lady beetles, bugs or birds, 133-135
Lamellicorn beetles, 110-115
Lampyridae, 100
Laphygma frugiperda, 274
Larder beetle, 103
Lasiocampidae, 256-260
Lasius niger americanus, 204
Laspeyresia pomonella, 238
Leaf beetles, 115-128
-cutter bees, 361
hoppers, 187, 190, 191
insects, 81
Legs, 10, 12

abdominal, 14
Lenticels, 216
Leopard Moth, 234
Lepidoptera, 230-299
Lepidosaphes beckii, 215
ulmi, 209

Lepisma saccharina, 63
Leprosy, 183

Leptinotarsa decimlineata, 115
Lesser migratory grasshopper, 84
Lice: biting, 161-163
on animals, 166
sucking, 164-167
Limacodidae, 250
Lime-sulfur wash, 51
self-boiled, 52
Little brown ant, 204
earwig, 95
Lochhead, 269
Longicorn beetles, 130-133
Long-tailed mealy bug, 219
Pelecinus, 351
Thalessa, 345
Losses by insects, 32
crop, 32

difficulties of estimation, 33

Losses, health, 32
figures on, 34
increase in, 34
“Lubber” grasshoppers, 84
Luminous organs, 100, 109
Luna moth, 286
Lunula, 301
Lycaenidse, 290
Lygaeidae, 174
Lygus pratensis, 181
Lymantriidae, 260-266

M

Macrodactylus subspinosus, 113
Macrolepidoptera, 234
Maggots, 303

Malacosoma americana, 256
disstria, 259
Malaria, 309
Malarial mosquitoes, 307
Mallophaga, 161-163
Malpighian tubes, 21
Mammals, 1
Mandibles, 9
Mantidae, 78
Mantis, common, 79
Chinese, 79
European, 79
religiosa, 79
Mantispa, 224
Mantispidae, 224
Marlatt, 142
Mask, 71

Masked bedbug hunter, 182
Mason wasps, 35S
Maxillae, 9
Maxillary palpus, 10
May beetles, 110
-flies, 65-67

Meadow plant-bug, ISO
Mealy bugs, 208, 218-220
destroyer, 135
Measuring worms, 252-255
Mecoptera, 300
Median segment, 12, 338
Mediterranean flour moth, 249
Melanoplus atlanis, 84
bivittatus, 84
devastator, 83
differentialis, 83
femur-rubrum, 83
spretus, 82

Melittia satyriniformis, 245

382

Meloidae, 135-136
Melophagus ovinus, 330
Metamorphosis, 25
Microlepidoptera, 234
Mid-intestine, 15
Millipedes, 2

characters of, 3
Miridae, 180
Miris dolobratus, 180
Miscible oils, 50

Miscellaneous control methods, 41
Mites, 2

Mole crickets, 88
Mollusca, 1
Molting, 26

number of molts, 27
Monarch, 291, 297
Monomorium pharaonis, 373
Mosquitoes, 305-311
Moths, 234-290

(and butterflies), 230-299
Mouth cavity, 15
parts, 9

in Anoplura, 164
in Apterygota, 62
in Diptera, 302
in Hemiptera, 168
in Homoptera, 186
in Hymenoptera, 339
in Lepidoptera, 230
in Siphonaptera, 333
in Thysanoptera, 153
Murgantia histrionica, 171
Murky ground beetle, 100, 117
Musca domestica, 321
Muscidae, 321-326
Mutillidae, 356
Myiasis, 318
Myrmeleonidae, 224-225

N

Nagana, 326

Natural control methods, 35
Necrophorus, 103
Negro-bugs, 172
Nepidae, 185
Nerve ganglia, 21
Nervous system, 21
Neuroptera, 221-225
Neuters, 22
Nicotine, 50, 56
sulfate, 51

INDEX

Nine-spotted lady beetle, 134
Noctuidae, 268-277
Nodus, 68

Northern tobacco worm, 288
Notodontidae, 266
Notolophus antiqua, 262
Notonectidae, 184
Notum, 7

Novius cardinalis, 135, 219
Number of segments, 6
Nymph, 27, 31
Nymphalidae, 292

O

Oak worm, California, 267
Oat blight, 197
Ocelli, 8
Odonata, 68-71
(Esophagus, 16
(Estridae 318
(Estrus ovis, 319
Onion maggot, 329
thrips, 155
Orcus chalybeus, 135
Orders: their relation, 60
Oriental moth, 250, 353
roach, 78
Orneodidae, 248
Orthoptera, 75-90
Ovary, 23

Overflow worm, 274
Oviduct, 23
Oviparous insects, 25
Ovipositor, 14, 338
Owlet moths, 268-277
Ox warbles, 318
Oyster-shell scale, 209, 220

P

Pacific peach borer, 243
Paleacrita vernata 254
Papilionidae, 298
Papilio polyxenes, 298
Paradichlorobenzine, 245
Parasites 36, 344, 347
Parasitism, 352
Paratenodera sinensis, 79
Paris green, 45

Parthenogenesis: in aphids, 196
in gall insects, 346
in Thysanoptera, 154

INDEX

383

Patagiae, 231

Pea and bean weevils, 128-130
louse, 205
weevil, 128
Peach Borer, 243

“stop-back,” 181
Pear Psylla, 103
slug, 341
thrips, 150
Pedicel, 338

Pediculus humanus, 105
Pelecinus polyturator, 351
Pentatomidae, 171
Pentilia misella, 134
Periodical cicada, 187
Periplaneta americana, 78
Periplaneta australasise, 78
Petiole, 338, 354, 307
Phasmidae, 80
Philaenus lineatus, 191
Philosamia cynthia, 284
Phlegethontius quinquemaculata, 288
sexta, 288

Phryganidia californica, 207
Phthirus pubis, 1GG
Phyllophaga, 110
Phylloxera vitifoliae, 201
Phymatidae, 182
Phytonomus posticus, 143
Phytophaga destructor, 312
Picking by hand, 40
Pieridae, 293-296
Pigeon Tremex, 343
Pine-leaf scale, 215
weevil, white, 142
Pissodes strobi, 142
Pitiful lady beetle, 134
Plague, 183

Plant lice, 133, 187, 194-206, 291, 344,
368, 370

Planting, time of, 40
Plecoptera, 72-73
Pleuron, 7
Plowing, 39
Plum curculio, 137
gouger, 139
Porthetria dispar, 262
Poison baits, 47
Polistes, 358
Pollen baskets, 363
Polyphemus moth, 283
Pontia rapae, 293
Popillia japonica, 114

Potato plant louse, 205
-stalk weevil, 145
Praying mantids, 78
Primary parasites, 344
Prionoxystus robiniae, 234
Proctotrypoidea, 351
Prognathous, 8
Promethea moth, 283
Prominents, 266
Propodeum, 12, 338
Propolis, 364

Prospaltella pemiciosi, 220
Protective imitation, 292
Protozoa, 1
Proventriculus, 16
Pseudococcus citri, 218
longispinus, 219
Pseudoscorpions, 2
Psithyrus, 362
Psocids, 159-161
Psyllia pyricola, 193
Psvchidae, 250-252
Pteromalus puparum, 350
Pteronidea ribesii, 340
Pterophoridae, 248
Pterygota, 60, 65
Ptilinum, 301

Pulchriphyllium scythe, 81
Pulvillus, 12, 303
Pulvinaria vitis, 217
Pupa, 29

libera, 99, 339
obtecta, 30, 99
Puparium, 29, 303
Pupipara, 330-332
Purple scale, 215
Pyralidae, 248-250
Pvrausta nubilalis, 249
Pyrethrum, 53
Pyrophorus spp. 109
Pyrrhocoridae, 173

R

Railroad worm, 319
Raphidiidae, 224
Rear-horses, 78-80
Rectal gills, 71
Rectum, 16

Red-humped apple-tree caterpillar, 267
-legged grasshopper, 83
scale, 215
Reduvjidae, 182

384

Relapsing fever, 166, 183
Relations of insect orders, 60
Repellents, 40
Reproductive organs, 22
Reptiles, 1
Respiration, 17
Reticulitermes flavipes, 93
Rhagoletis pomonella, 319
Rhinoceros beetles, 114
Rhizobius ventralis, 135
Rhopalocera, 234, 290-299
Rhopalosiphum prunifolise, 198
Rhynchophora, 99, 136-149
Roaches, 76-78
Robber flies, 316
Rocky mountain locust, 82
Rose chafer, 113
leafhopper, 193
scale, 214
Rostrum, 168

Round-headed apple-tree borer, 131
borers, 130-133
Rove-beetles, 102
Royal jelly, 366
moths, 280

Rusty tussock moth, 262
S

Saltatorial Orthoptera, 81-90
Salt marsh caterpillar, 277
mosquito, 307
Samia cecropia, 283
San Jose scale, 211, 220
Saperda Candida, 131
Sarcophagidse, 326
Saturniidse, 283-287
Satyridae, 293
Saw-flies, 340-343
Scale insects, 187, 208-220
Scapteriscus vicinus, 90
Scarabandae, 110-115
Scarabaeus, 110
Schizura concinna, 267
Scirtothrips citri, 157
Sclerites, 7
Scolytidae, 146-149
Scorpion flies, 300
Scorpions, 2
Screw-worm fly, 324
Scurfy scale, 210
Scutellista cyanea, 220
Scutellum, 168

INDEX

Sea urchin, 1
Seasonal dimorphism, 291
Secondary parasites, 344
Seminal receptacle 23
Sense organs, 22
Serphoidea, 351
Sesiidae, 243

Seventeen-year locust, 187
Sexes of insects, 22
Shad-flies, 65
Sheep bot fly, 319
tick, 330
Shell gland, 23
Shellac, 209
Shot-hole borer, 147
Sialidae, 221
Silk, 29, 255

glands, 227, 233
worm, 255

Silpha americana, 103
Silphidae, 103
Silver fish, 63
Simulidae, 315
Siphonaptera, 333-337
Sitotroga cerealella, 247
Skeleton, 7
Skip-jacks, 107-110
Skippers, 290
Slave-making ants, 370
Sleeping sickness, 325
Slug caterpillars, 250
Snails, 1

Snapping-beetles, 107-110
Snout beetles, 136-149
Snow fleas, 64
Soap, 50

Social wasps, 356-360
Sodium fluorid, 48
Soft scales, 208, 216-218
Solitary bees, 360
Soothsayers, 78
Sooty mould, 207
Sounds produced by crickets, 88
by grasshoppers, 85
by green grasshoppers, 87
Southern corn-root worm, 120
Southern tobacco worm, 288
Spanish flies, 136
Span worms, 252-255
Spermaries, 24
Sphecius speciosus, 355
Sphecoidea, 354-356
Sphingidae, 287-290

INDEX

385

Spiders, 2
Spinneret, 231, 233
Spiracles, 18
Spittle insects, 191
Sporotrichum globuliferum, 176
Spotted lady beetle, 134
Sprays, 44

combinations of, 54
Spring canker worm, 254
“Spring” of Collembola, 63
Springtails, 63
Squash bug, 172
Squash-vine borer, 245
Stagomantis Carolina, 79
Stalk borers, 270
Staphylinidaj, 102
Starfish, 1

Steel-blue lady beetle, 135
Stegomyia fasciata, 309
Stem-mothers, 196
Sternum, 7
Sticktight flea, 336
Sting, 14, 339
Stinging ants, 356
Stink bugs, 171
Stomach, 16
poisons, 43

their action, 17
Stone-flies, 72

“Stop-back” of peaches, 181
Strawberry thrips, 154
Strepsiptera, 150-152
Striped cucumber beetle, 118
Stylops, 150-152
Subcesophageal ganglion, 22
Sucking lice, 164-167
Sulfur, 52, 56

compounds, 52
Sutures, 7

Swallow-tail butterflies, 298
Swarming; of ants, 369
of honey bees, 365
of white ants, 92
Sweet potato weevil, 145
Synanthedon exitiosa, 243
Svnanthedon opalescens, 243
Syrphidse, 316
Syrphus flies, 316

T

Tabanidae, 314
Table of classification,, 61^

25

Tachina flies, 273, 326
Tachinidse, 326
Taenidia, 334

Taeniothrips inconsequens, 156
Tapestry moth, 237
Tarantula-killer, 357
Tarnished plant-bug, 181
Tarsus, 12
Tegulae, 231, 338
Telea polyphemus, 283
Tenebrio molitor, 135
Tenebrionidac, 135
Tent-caterpillars, 256-260
Tenthredinoidea, 340-343
Terebrantia, 339
Termites, 91-93
Terrapin scale, 217
Testes, 24
Tettigoniidae, 85-87
Thalessa, long-tailed, 345
Thorax, 10

Thread-waisted wasps, 354
Three-spotted Doryphora, 117
Thrips, 153-158
Thrips tabaci, 155
Thyridopteryx ephemerseformis, 252
Thysanoptera, 153-158
Thysanura, 62
Tibia, 12

Tibicen linnei, 189
Tibicina septendecim, 187
Ticks, 2

Tiger beetles, 101
moths, 277-279
Time of planting, 40
Tinea pellionella, 236
Tineidse, 236-238
Tineola biselliella, 236
Tingididse, 179
Tipulidae, 304
Tobacco worms, 2S8
Tomato fruitworm, 270
Tortoise beetles, 128
Trachea, 18
Tracheal gills, 19, 71
Trap crops, 40
lanterns, 40
Tree crickets, 90

hoppers, 187, 190
Tremex columba, 343
Trench fever, 166
Trichobaris trinotata, 145
Trichophaga tapetzella, 237

386

INDEX

Trichoptera, 226-229
Tropsea luna, 286
True bugs, 170
Trypanosoma gambiense, 325
Trypetidse, 319-321
Tsetse flies, 325
Tussock moths, 260-266
Twelve-spotted asparagus beetle, 124
cucumber beetle, 120
Twice-stabbed lady beetle, 134, 213
Twisted-wing parasites, 150-152
Two-spotted lady beetle, 133
-striped grasshopper, 84
Tuberculosis, 323
Tulip tree scale, 216
Tunga penetrans, 336
Typhoid fever, 321, 323
Typhus fever, 166

U

Underwings, 269

V

Vagina, 23

Value of honey and wax, 367
Vas deferens, 24
Vedalia, 135, 219, 220
Velvet ants, 356
Veratrum, 48
Vespidse, 358
Vespoidea, 356-360
Vespula, 359
Viceroy, 292

Viviparous insects, 25, 196, 212
W

Walking-sticks, 80-81
Wasps, progressive development in, 360
Water-boatmen, 184
“Water bugs,” 76

-scavenger beetles, 102
-scorpions, 185

Water skaters, 184
Wax, 364

Weather conditions and insects, 36
Webbing clothes moth, 236
Webster, 314

Western corn-root worm, 121
cricket, 87

grass-stem borer, 342
striped cucumber beetle, 119
twelve-spotted cucumber beetle, 122
Whale-oil soap, 50
Wheat joint- worm, 348
midge, 314
-stem borer, 342
straw-worm, 348
thrips, 154
Wheeler, 370
Whirligig beetles, 101
White ants, 91-93

flies, 187, 206-208
grubs, 110-113
marked tussock moth, 260
pine weevil, 142
Wingless grasshoppers, 86
Wings, 12-14
veins, 13
Wireworms, 108
Woolly apple aphis, 199
bears, 277

X

Xylocopa, 361

Y

Yaws, 323
Yellow-jackets, 359
fever, 309
fever mosquito, 309
meal-worm, 135

Z

Zoraptera, 94