Opening
A TEXT-BOOK OF ENTOMOLOGY
A TEXT-BOOK OF ENTOMOLOGY INCLUDING THE ANATOMY, PHYSIOLOGY, EMBRYOLOGY AND METAMORPHOSES OF INSECTS FOR USE IN AGRICULTURAL AND TECHNICAL SCHOOLS AND COLLEGES AS WELL AS BY THE WORKING ENTOMOLOGIST
BY
ALPHEUS S. PACKARD, M.D., PH.D.
PROFESSOR OF ZOÖLOGY AND GEOLOGY, BROWN UNIVERSITY AUTHOR OF “GUIDE TO STUDY OF INSECTS,” “ENTOMOLOGY FOR BEGINNERS,” ETC.
New York THE MACMILLAN COMPANY LONDON: MACMILLAN & CO., LTD. 1898
All rights reserved
COPYRIGHT, 1898, BY THE MACMILLAN COMPANY.
Norwood Press J. S. Cushing & Co.—Berwick & Smith Norwood Mass. U.S.A.
Preface
In preparing this book the author had in mind the wants both of the student and the teacher. For the student’s use the more difficult portions, particularly that on the embryology, may be omitted. The work has grown in part out of the writer’s experience in class work.
In instructing small classes in the anatomy and metamorphoses of insects, it was strongly felt that the mere dissection and drawing of a few types, comprising some of our common insects, were by no means sufficient for broad, thorough work. Plainly enough the laboratory work is all important, being rigidly disciplinary in its methods, and affording the foundation for any farther work. But to this should be added frequent explanations or formal lectures, and the student should be required to do collateral reading in some general work on structural and developmental entomology. With this aim in view, the present work has been prepared.
It might be said in explanation of the plan of this book, that the students having previously taken a lecture course in the zoölogy of the invertebrates, were first instructed in the facts and conclusions bearing on the relations of insects to other Arthropoda, and more especially the anatomy of Peripatus, of the Myriopoda, and of Scolopendrella. Then the structure of Campodea, Machilis, and Lepisma was described, after which a few types of winged insects, beginning with the locust and ending with the bee, were drawn and dissected; the nymph of the locust, and the larva and pupa of a moth and of a wasp and bee being drawn and examined. Had time permitted, an outline of the embryology and of the internal changes in flies during their metamorphoses would have been added.
This book gives, of course with much greater fulness and detail for reference and collateral reading, what we roughly outlined in our class work. The aim has been to afford a broad foundation for future more special work by any one who may want to carry on the study of some group of insects, or to extend in any special direction our present knowledge of insect morphology and growth.
Many of our entomologists begin their studies without any previous knowledge of the structure of animals, taking it up as an amusement. They may be mere collectors and satisfied simply to know the name of their captures, but it is hoped that with this book in their hands they may be led to desire farther information regarding what has already been done on the structure and mode of growth of the common insects. For practical details as to how to dissect, to make microscopic slides, and to mount and preserve insects generally, they are referred to the author’s “Entomology for Beginners.”
It may also be acknowledged that even in our best and latest general treatises on zoölogy, or comparative anatomy, or morphology, the portion related to insects is scarcely so thoroughly done as those parts devoted to other phyla, that of Lang, however, his invaluable Comparative Anatomy, being an exception. On this account, therefore, it is hoped that this hiatus in our literature may be in a degree filled.
The author has made free use of the excellent article “Insecta” of Newport, of Lang’s comprehensive summary in his most useful Text-book of Comparative Anatomy, of Graber’s excellent Die Insecten, of Miall and Denny’s The Structure and Life-History of the Cockroach, and of Sharp’s Insecta. Kolbe’s Einführung has been most helpful. But besides these helps, liberal use has been made of the very numerous memoirs and monographic articles which adorn our entomological literature. The account of the embryology of insects is based on Korschelt and Heider’s elaborate work, Lehrbuch der Vergleichenden Entwicklungsgeschichte der Wirbellosen Thiere, the illustrations of this portion being mainly taken from it, through the Messrs. Swan Sonnenschein & Co., London.
Professor H. S. Pratt has kindly read over the manuscript and also the proofs of the portion on embryology and metamorphoses, and the author is happy to acknowledge the essential service he has rendered.
The bibliographical lists are arranged by dates, so as to give an idea of the historical development of each subject. The aim has been to make these lists tolerably complete and to include the earliest, almost forgotten works and articles as well as the most recent.
Much care has been taken to give due credit either to the original sources from which the illustrations are copied, or to the artist; about ninety of the simpler figures were drawn by the author, many of them for this work. For the use of certain figures acknowledgments are due to the Boston Society of Natural History, to the Division of Entomology, U. S. Department of Agriculture, through the kind offices of Mr. L. O. Howard, and to the Illinois State Laboratory of Natural History, through Professor S. A. Forbes and Mr. C. A. Hart. Professor W. M. Wheeler, of the University of Chicago, has kindly loaned for reproduction several of his original drawings published in the Journal of Morphology. A number are reproduced from figures in the reports of the United States Entomological Commission.
PROVIDENCE, R. I., March 4, 1898.
I. MORPHOLOGY AND PHYSIOLOGY
PAGE POSITION OF INSECTS IN THE ANIMAL KINGDOM 1
RELATIONS OF INSECTS TO OTHER ARTHROPODA 2
The Crustacea 4 The Merostomata 5 The Trilobita 5 The Arachnida 6 Relations of Peripatus to insects 9 Relation of Myriopods to insects 11 Relations of the Symphyla to insects 18 Diagnostic or essential characters of Symphyla 22
INSECTA (HEXAPODA) 26
Diagnostic characters of insects 26
1. EXTERNAL ANATOMY
a. Regions of the body 27
b. The integument (exoskeleton) 28
Chitin 29
c. Mechanical origin and structure of the segments (somites, arthromeres, etc.) 30
d. Mechanical origin of the limbs and of their jointed structure 35
THE HEAD AND ITS APPENDAGES 42
a. The head 42
The labrum 42 The epipharynx and labrum-epipharynx 43 Attachment of the head to the trunk 46 The basal or gular region of the head 46 The occiput 48 The tentorium 49 Number of segments in the head 50 The composition of the head in the Hymenoptera 55
b. Appendages of the head 57
The antennæ 57 The mandibles 59 The first maxillæ 62 The second maxillæ 68 The hypopharynx 70 Does the hypopharynx represent a distinct segment? 82
THE THORAX AND ITS APPENDAGES 86
a. The thorax: its external anatomy 86
The patagia 89 The tegulæ 89 The apodemes 92 The acetabula 94
b. The legs: their structure and functions 95
Tenent hairs 99 Why do insects have but six legs? 100 Loss of limbs by disuse 101
c. Locomotion (walking, climbing, and swimming) 103
Mechanics of walking 103 Locomotion on smooth surfaces 111 Climbing 116 The mode of swimming of insects 116
d. The wings and their structure 120
The veins 121 The squamæ 123 The halteres 124 The thyridium 124 The tegmina and hemelytra 124 The elytra 124
e. Development and mode of origin of the wings 126
Embryonic development of the wings 126 Evagination of the wing outside of the body 132 Extension of the wing; drawing out of the tracheoles 133
f. The primitive origin of the wings 137
The development and structure of the tracheæ and veins of the wing 144
g. Mechanism of flight 148
Theory of insect flight 150 Graber’s views as to the mechanism of the wings, flight, etc. 153
THE ABDOMEN AND ITS APPENDAGES 162
The median segment 163 The cercopoda 164 The ovipositor and sting 167 The styles and genital claspers (Rhabdopoda) 176 Velum penis 181 The suranal plate 181 The podical plates or paranal lobes 182 The infra-anal lobe 183 The egg-guide 183
THE ARMATURE OF INSECTS: SETÆ, HAIRS, SCALES, TUBERCLES, ETC. 187
The cuticula 187 Setæ 188 Glandular hairs and spines 190 Scales 193 Development of the scales 195 Spinules, hair-scales, hair-fields, and androconia 197
THE COLORS OF INSECTS 201
Optical colors 201 Natural colors 203 Chemical and physical nature of the pigment 206 Ontogenetic and phylogenetic development of colors 207
2. INTERNAL ANATOMY
THE MUSCULAR SYSTEM 211
Musculature of a caterpillar 213 Musculature of a beetle 213 Minute structure of the muscles 215 Muscular power of insects 217
THE NERVOUS SYSTEM 222
a. The nervous system as a whole 222
b. The brain 226
The optic or procerebral segment 231 Procerebral lobes 232 The mushroom or stalked bodies 233 Structure of the mushroom bodies 234 The central body 237 The antennal or olfactory lobes (Deutocerebrum) 237 The œsophageal lobes (Tritocerebrum) 237
c. Histological elements of the brain 238
d. The visceral (sympathetic or stomatogastric) system 238
e. The supraspinal cord 240
f. Modifications of the brain in different orders of insects 240
g. Functions of the nerve-centres and nerves 243
THE SENSORY ORGANS 249
a. The eyes and insect vision 249
The simple or single-lensed eye (ocellus) 249 The compound or facetted eye (ommateum) 250 The facet or cornea 250 The crystalline lens or cone 251 The pigment 253 The basilar membrane 253 The optic tract 253 Origin of the facetted eye 255 Mode of vision by single eyes or ocelli 255 Mode of vision by facetted eyes 256 The principal use of the facetted eye to perceive the movements of animals 259 How far can insects see? 260 Relation of sight to the color of eyes 260 The color sense of insects 260
b. The organs of smell 264
Historical sketch of our knowledge of the organs of smell 264 Physiological experiments 268 Relation of insects to smelling substances before and after the loss of their antennæ 269 Experiments on the use of the antennæ in seeking for food 270 Experiments testing the influence of the antennæ of the males in seeking the females 270 Structure of the organs of smell in insects 271
c. The organs of taste 281
Structure of the taste organs 282 Distribution in different orders of insects 282 Experimental proof 286
d. The organs of hearing 287
The ears or tympanal and chordotonal sense-organs of Orthoptera and other insects 288 Antennal auditory hairs 292 Special sense-organs in the wings and halteres 293
e. The sounds of insects 293
THE DIGESTIVE CANAL AND ITS APPENDAGES 297
a. The digestive canal 302
The œsophagus 303 The crop or ingluvies 303 The “sucking stomach” or food-reservoir 305 The fore-stomach or proventriculus 306 The œsophageal valve 311 Proventricular valvule 313 The peritrophic membrane 313 The mid-intestine 314 Histology of the mid-intestine 316 The hind-intestine 316 Large intestine 316 The ileum 317 The gastro-ileal folds 317 The colon 317 The rectum 318 The vent (anus) 319 Histology of the digestive canal 320
b. Digestion in insects 324
The mechanism of secretion 326 Absorbent cells 328
THE GLANDULAR AND EXCRETORY APPENDAGES OF THE DIGESTIVE CANAL 331
a. The salivary glands 331
b. The silk or spinning glands, and the spinning apparatus 339
The process of spinning 340 How the thread is drawn out 343 Appendages of the silk-gland (Filippi’s glands) 345
c. The cæcal appendages 347
d. The excretory system (urinary or Malpighian tubes) 348
Primitive number of tubes 353
e. Poison-glands 357
f. Adhesive or cement-glands 360
g. The wax-glands 361
h. “Honey-dew” or wax-glands of Aphids 364
i. Dermal glands in general 365
DEFENSIVE OR REPUGNATORIAL SCENT-GLANDS 368
Eversible coxal glands 369 Fœtid glands of Orthoptera 369 Anal glands of beetles 372 The blood as a repellent fluid 374 Eversible glands of caddis-worms and caterpillars 375 The osmeterium in Papilio larvæ 377 Dorsal and lateral eversible metameric sacs in other larvæ 377 Distribution of repugnatorial or alluring scent-glands in insects 382
THE ALLURING OR SCENT-GLANDS 391
THE ORGANS OF CIRCULATION 397
a. The heart 397
The propulsatory apparatus 401 The supraspinal vessel 403 The aorta 404 The pericardial cells 405 Pulsatile organs of the legs 405
b. The blood 407
The leucocytes 407
c. The circulation of the blood 409
Effects of poisons on the pulsations 412
THE BLOOD TISSUE 419
a. The fat-body 419
b. The pericardial fat-body or pericardial cells 420
Leucocytes or phagocytes in connection with the pericardial cells 421
c. The œnocytes 423
d. The phosphorescent organs 424
Physiology of the phosphorescence 426
THE RESPIRATORY SYSTEM 430
a. The tracheæ 431
Distribution of the tracheæ 432
b. The spiracles or stigmata 437
The position and number of pairs of stigmata 439 The closing apparatus of the stigma 441
c. Morphology and homologies of the tracheal system 442
d. The spiral threads or tænidia 444
e. Origin of the tracheæ and of the “spiral thread” 447
Internal, hair-like bodies 451
f. The mechanism of respiration and the respiratory movements of insects 451
g. The air-sacs 456
The use of the air-sacs 457
h. The closed or partly closed tracheal system 459
i. The rectal, tracheal gills, and rectal respiration of larval Odonata and other insects 463
j. Tracheal gills of the larvæ of insects 466
Blood-gills 475
k. Tracheal gills of adult insects 476
THE ORGANS OF REPRODUCTION 485
a. The male organs of reproduction 494
The testes 495 The seminal ducts 496 The ejaculatory duct 497 The accessory glands 497 The spermatozoa 497 Formation of the spermatozoön 498
b. The female organs of reproduction 500
The ovaries and the ovarian tubes 500 Origin of incipient eggs in the germ of the testes 504 The bursa copulatrix 505 The spermatheca 506 The colleterial glands 506 The vagina or uterus 507 Signs of copulation in insects 507
II. EMBRYOLOGY OF INSECTS
a. The egg 515
Mode of deposition 518 Vitality of eggs 520 Appearance and structure of the ripe egg 520 The egg-shell and yolk-membrane 520 The micropyle 522 Internal structure of the egg 524
b. Maturation or ripening of the egg 525
c. Fertilization of the egg 525
d. Division and formation of the blastoderm 526
e. Formation of the first rudiments of the embryo and of the embryonic membranes 531
Formation of the embryonic membranes 532 The gastrula stage 535 Division of the embryo or primitive band into body-segments 536 Differences between the invaginated and overgrown primitive band 538 Revolution of the embryo where the primitive band is invaginated 540
f. Formation of the external form of the body 542
Origin of the body-segments 542 The procephalic lobes 544 Fore-intestine (stomodæum) and hind-intestine (proctodæum), labrum 547 Completion of the head 548
g. The appendages 548
The cephalic appendages 548 The thoracic appendages 550 The abdominal appendages 550 Appendages of the first abdominal segment (pleuropodia) 551 Are the abdominal legs of Lepidoptera and phytophagous Hymenoptera true limbs? 552 The tracheæ 553
h. Nervous system 554
Completion of the definite form of the body 555
i. Dorsal closure and involution of the embryonic membranes 556
j. Formation of the germ-layers 558
k. Farther development of the mesoderm; formation of the body-cavity 563
l. Formation of organs 566
The nervous system 566 Development of the brain 567 Development of the eyes 567 Intestinal canal and glands 569 The salivary glands 570 The urinary tubes 572 The heart 572 The blood-corpuscles 574 Musculature; connective tissue; fat-body 574 The reproductive organs 575 Development of the male germinal glands 579
m. Length of embryonic life 582
n. The process of hatching 583
The hatching spines 585
III. THE METAMORPHOSES OF INSECTS
a. The nymph as distinguished from the larval stage 593
b. Stages or stadia of metamorphosis 594
c. Ametabolous and metabolous stages 594
THE LARVA 599
a. The Campodea-form type of larva 600
b. The eruciform type of larva 602
c. Growth and increase in size of the larva 608
d. The process of moulting 609
The number of moults in insects of different orders 615 Reproduction of lost limbs 619 Formation of the cocoon 619 Sanitary conditions observed by the honey-bee larva, and admission of air within the cocoon 623
THE PUPA STATE 625
a. The pupa considered in reference to its adaptation to its surroundings and its relation to phylogeny 631
b. Mode of escape of the pupa from its cocoon 632
c. The cremaster 636
Mode of formation of the cremaster and suspension of the chrysalis in butterflies 637
FORMATION OF THE PUPA AND IMAGO IN THE HOLOMETABOLOUS INSECTS (THE DIPTERA EXCEPTED) 640
a. The Lepidoptera 642
The changes in the head and mouth-parts 646 The change in the internal organs 647 The wings 654 Development of the feet and of the cephalic appendages 654 Embryonic cells and the phagocytes 655 Formation of the femur and of the tibia; transformation of the tarsus 656 The antennæ 657 Maxillæ and labial palpi 658 Process of pupation 660
b. The Hymenoptera 661
Ocular or oculo-cephalic buds 665 The antennal buds 665 The buds of the buccal appendages 665 The buds of the ovipositor 665
DEVELOPMENT OF THE IMAGO IN THE DIPTERA 666
a. Development of the outer body-form 668
Formation of the imago in Corethra 668 Formation of the imago in Culex 670 Formation of the imago in Chironomus 671 Formation of the imago in Muscidæ 673
b. Development of the internal organs of the imago 678
The hypodermis 678 The muscles 680 The digestive canal 681 The tracheal system 683 The nervous system 684 The fat-body 685 Definitive fate of the leucocytes 685 The post-embryonic changes and imaginal buds in the Pupipara (Melophagus) 686
c. General summary 687
HYPERMETAMORPHISM 688
SUMMARY OF THE FACTS AND SUGGESTIONS AS TO THE CAUSES OF METAMORPHISM 705
Theoretical conclusions; causes of metamorphosis 708
TEXT-BOOK OF ENTOMOLOGY