PROPER, r OF r- I LI B R ARY OF IQ85-I056 Property of 1 C. EXPERIMENT STATION P^ '-"rirnent of Entomology t- ECONOMIC ENTOMOLOGY FARMIiR AND FRUIT-GROWER, AND FOR USE AS A TEXT-BOOK IN AGRICULTURAL SCHOOLS AND COLLEGES BV JOHN B. SMITH, Sc.D. Ftofessor of Entomology in Rulgers College ; Entomologist to the Neiv Jersey Agricultural College Experiment Station and the New Jersey State Board of Agriculture ; President of the Association of Economic Entomologists, of the Brooklyti Entomological Society, and of the New Jersey State Microscopical Society; Fellow of the American Association for the Advancement of Science, etc., etc. ILLUSTRATED PHILADELPHIA J. B. LIPPINCOTT COMPANY Copyright, 1S96, BY J. B. LippiNcoTT Company. Electrotyped and Printed by J. B. Lippincott Company, Philadelphia, U.S.A. C O N T E N TvS. r^ART I. STRUCTURE AND CLASSIFICATION. CHAPTER I. PAGE The General Structure ok Insects ii CHAPTER II. liiE Head and its Api-endages ...... 14 CHAPTER III. Thorax and Abdomen 23 CHAPTER IV. Muscles, Digestion, and Circulation . 27 CHAPTER V. The Respiratory System 33 CHAPTER VI. Nervous System and Senses of Insects 39 CHAPTER VII. The Reproductive System . • 45 CHAPTER VIII. Growth and Metamorphosis 48 iv CONTENTS. PART II. THE INSECT WORLD. CHAPTER I. PAGE General Classification 52 CHAPTER II. The Thysanura 55 CHAPTER III. The Neuroptera and Pseudo-Neuroptera 58 Order Ephemeroptera 59 Order Odonata 60 Order Plecoptera 63 Order Platyptera 6/; Order Neuroptera 72 CHAPTER IV. The Orthoptera 79 CHAPTER V. The Hemiptera, or Bugs 100 CHAPTER VI. The Coleoptera, or Beetles 164 CHAPTER VII. The Lepidoptera . 240 CHAPTER VIII. The Diptera, or Flies 327 CHAPTER IX. The Hymenoptera 370 CONTENTS. V PART III. INSECTICIDES, PREVENTIVES, AND MACHINERY. CHAPTER I. PAGE Predaceous Insects, Parasites, and Fungous Diesases . . . 418 CHAPTER II. Farm Practice to prevent Insect Attack 423 CHAPTER III. Preventives 430 CHAPTER IV. Insecticides 434 CHAPTER V. I^Iachinlry 454 ACKNOWLEDGMENTS. The illustrations in this book are derived as follows : Electro- types were loaned for the purposes of the work by the Agricul- tural College Experiment Station of New Jersey, of figures Nos. 4, 5, 6, 7, II, 13, 14, 15, 28, 29, 30, 32, 34, 35, 36, 37, 38, 39, 41, 43, 44, 45, 50, 53, 64, 72, 83, 84, 85, 88, 89, 95, 99, 103, 104, 105, 114, 127, 128, 129, 130, 131, 132, 133, 134, 136, 137, 138, 142, 143, 144, 146, 147, 149, 157, 158, 160, 161, 162, 164, 166, 167, 170, 171, 172, 173, 174, 175, 176, 178, 179, 180, 181, 182, 183, 188, 189, 190. 192, 194, 195, 200, 201, 202, 204, 206, 212, 214, 216, 217, 218, 219, 221, 222, 225, 227, 228, 229, 230, 231, 232, 233, 234, 236, 238, 239, 241, 242, 243, 246, 247, 255, 263, 264, 265, 274, 278, 279, 281, 283, 286, 287, 288, 289, 290, 291, 296, 297, 298, 299, 300, 307, 314, 321, 332, 333, 334, 341, 342, 343. 349. 350, 351. 352, 357. 362, 366, 368, 369, 375, 377, 380, 386, 387, 392, 393, 394, 395, 396, 397, 398, 399, 401, 409, 410, 411, 412, 413, 416, 417, 418, 419. 424, 425, 426, 430, 432, 434, 435. 437. 438, 440, 441. 444. 445. 44^, 447- 448, 449, 450, 454, 455. 457. 458, 459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469. 471, 473, 475, 480, 481, 482. By the courtesy of the Secretary of Agriculture and of the Division of Illustrations in the United States Department of Ag- riculture, electrotypes were obtained for figures Nos. 22, 23, 48, 56, 58, 73. 74. 75. 76, 81, 82, 86, 87, 90, 91, 92, 93, 100, loi, 112, 116, 117, 118, 120, 121, 122, 124, 148, 151, 152, 168, 193, 198, 209, 223, 224, 226, 244, 245, 292, 293, 294, 295, 315, 316, 318, 339, 340, 358, 360, 363, 364, 365, 371, 374, 376, 383, 389, 390, 391. 402, 404, 405, 406, 407, 408, 431, 452, 474, 483. The J. B. Lippincott Company kindly loaned the following from Saunders's " Insects Injurious to Fruits" : Nos. 55, 59, 60, 6ia, 65, 79, 80, 94, 97, 98, 102, 109, 125, 159, 165, 169, 191, 197, 199, 203, 211, 213, 220, 240, 254, 259, 270, 271, 275, 276, vui ACKNOWLEDGMENTS. ^n, 284, 302, 308, 309, 310, 311, 312, 313, 324, 325, 326, 327, 328, 329, 330, 331, 337, 338, 347, 353, 354, 367, 372, 373, 400, 403, 422, 428, 429, 443 ; and from French's " Butterflies of the Eastern United States," Nos, 253, 260, 261, 262, 268, 269, 273. From Prof Lawrence Bruner, of the University of Nebraska, were purchased electrotypes of figures Nos. i, 26, 31, 33, 42, 46, 47, 51, 52, 6ib, 62, 68, 70, 71, 96, 107, no, 115, 139, 140, 141, 156, 163, 186, 256, 319, 320, 335, 336, 355, 421, 433. From Houghton, Mifflin & Co., pubhshers of the " Riverside Natural History," were purchased Nos. 12, 17, 77, 78, 106, 177, 378, 414, 423, 451, 472. From the Entomological Society of Ontario electrotypes were obtained for figures Nos. 207, 208, 258, 420, 456. From the Cornell Experiment Station, through the kindness of Mr. M. V. Slingerland, electrotypes were secured of figures Nos. 40, 119, 145. Mr. G. C. Davis, of the Agricultural Experiment Station of Michigan, furnished stereotypes of figures Nos. 196, 235, 301, 370, 388, 439. Prof Herbert Osborn, of the Iowa Agricultural College, kindly loaned for reproduction figures Nos. 108, 356, 382. Dr. Otto Lugger, State Entomologist of Minnesota, supplied electrotypes of figures Nos. 280, 427, 442. Dr. F. H. Snow, of Lawrence, Kansas, loaned for reproduc- tion figures Nos. 123, 210. Mr. F. M. Webster, of the Ohio Experiment Station, per- mitted the reproduction of figures Nos. 205, 237. Mr. A. D. Hopkins, of the West Virginia Experiment Station, granted the same favor for figures Nos. 384 and 385. Dr. A. S. Packard kindly supplied electrotypes of figures Nos. 16 and 470. To Dr. G. Brown Goode, Director of the United States Na- tional Museum, I owe electrotypes of figures Nos. 27 and 381. From Mrs. C. V. Riley were purchased electrotypes of figures Nos. Ill and 361. Dr. J. A. Lintner, State Entomologist of New York, kindly supplied an electrotype of figure No. 282. Prof S. A. Forbes was equally courteous concerning figure No. 187. ACKNOWLEDGMEXTS. ix Prof. C. P. Gillette loaned for reproduction figure No. 150. Mr. Frank Sempers, of Philadelphia, kindly gave figure No. 49. Mr. H. G. Hubbard, of Washington, obligingly loaned figure No. 359. Of the machinery illustrated, an electrotype of No. 476 was supplied by Mr. McGowen, of 478 by Mr. William Stahl, and of 479 by W. & B. Douglas. The following are originals, and were especially prepared for this work : Nos. 2, 3, 8, 9, 18, 19, 20, 21, 24, 25, 54, 57, 63, 66, 67, 69, 113, 126, 135, 153, 154, 155, 184, 185, 215, 248, 249, 250, 251, 252, 257, 266, 267, 272, 285, 304, 305, 306, 322, 323, 344, 345, 346, 348, 379, 415, 436, 453, 477. Of these original figures, some are photographs, others are from drawings by the author, some are redrawn, and a few are duplications of published figures where no plates were known to be in existence. To all who have in any way aided in the preparation of this work, and especially to Mr. L. O. Howard, of Washington, who kindly read my chapter on Hymenoptera, and Prof. Lawrence Bruner, who kindly read my chapter on Orthoptera, I tender my sincere thanks. INTRODUCTORY. Insect injurj' to agricultural products amounts each year to millions of dollars, and, as a whole, shows a tendency to increase rather than otherwise. It is not only the actual devouring of plant tissue that causes loss ; the effect upon the product may be to reduce its grade, or make it more or less unsalable and unprofitable. In the competition for markets, the grower of the best will always have an advantage ; first-class fruits and vegetables rarely fail to bring some profit, where low-grade products cannot be sold at any price ; and no fruit that is wormy, defaced, or otherwise injured by insects ever ranks as first-class. Progressive farmers have long been aware of this, and the science of economic entomology has grown up in response to their demands for information concerning insect depredation and for means of protection against it. It is a science far from sys- tematized as yet ; made up of fragments published here, there, and everywhere, rarely complete in themselves and often con- tradictory as to the remedial measures suggested. There have been efforts, more or less successful, to compile books of infor- mation concerning the insects attacking certain crops or kinds of crops ; but there is not now in existence any work which gives the agriculturist and student of economic entomology that basic knowledge that enables him to recognize the nature of the insect he finds causing injury, or makes it possible to decide what sort of remedies should be applied. In other words, the underlying facts upon which the scientific application of remedial or preventive measures is based are not accessible to the very class that most needs them. In this book an attempt is made to present these matters com- pletely enough to give a foundation upon which further informa- tion may be added ; for whatever changes may occur in our xii INTRODUCTORY. battery of insecticides, the philosophy of their application will remain the same. To do this it is necessary to give an outline of the characteristics of insects generally ; of those features that distinguish them from all other animals, and of those peculiarities upon which we must base our hope of conquering them. Enough of the structure is described to show how they are built up, and all the different orders are referred to, so that the intelligent reader may recognize at least the group to which a specimen belongs and may be able to determine whether or not an injurious species is in hand. The direct needs of the agriculturist have been kept constantly in mind ; but the effort has been to give also a general information on the subject of insect life, and the work should be useful to students in all save advanced college courses, where technical or systematic studies outrank all others. AN ECONOMIC ENTOMOLOGY. PART I. STRUCTURE AND CLASSIFICATION. CHAPTER I. THE GENERAL STRUCTURE OF INSECTS. Insects are animals made up of a series of rings or segments stiffened by a hard substance called chitine, and connected by a membrane which allows of more or less freedom of motion be- tween them in one or more directions. In this they agree with the worms, differing from them, however, in the adult stage, in that the segments are grouped into three regions ; the head, thorax, and abdomen, as shown in the diagrammatic sketch of the grasshopper. In the larval stage of many insects these re- gions are not well marked, and they resemble worms decidedly, but nearly always have a distinct head and more or less distinct legs. If neither head nor legs are visible, the larvae are chunky and maggot-like or grub-like, rarely long and cylindrical. In fact, we have very few terrestrial worms in our country, and most of the so-called ' ' worms ' ' are really insect larvae. As a rule, an insect is made up of thirteen rings, counting the head, and in the larval stage they are usually easy to make out, especially in caterpillars, which may be abundantly secured at any time during the summer. In the adult they are often more or less obscure. Following the head we have three segments which form the thorax or trunk, and these bear all the organs of loco- motion in the adult. In the larva, when organs of locomotion are present, one pair of legs is found on each of these segments. 12 AN ECONOMIC ENTOMOLOGY. Nine rings are assigned to the abdomen, though some of them may be modified into structures faciHtating egg-laying or other special purposes. In the adult no appendages of any kind, ex- cept ovipositors, anal filaments, or cerci, are found ; but in the larva, where there is often no real separation between thorax and abdomen, the latter may bear organs of locomotion which differ in their general appearance and structure from the true legs, and are therefore called "false feet," or pro-legs. The number of these pro-legs sometimes enables us to recognize the order to which a larva belongs, where it otherwise closely resembles another. For instance, all the true caterpillars are larvae of Lcpidoptera, or butterflies and moths, and these never have more than four pairs of pro-legs at the middle of the body and one pair on the last segment, making, with the true legs, eight pairs in all. In the larvae of the sawflies, a family of the Hymen- optera in which the resemblance to caterpillars is very close, there are at least five pairs of pro-legs at the middle and one pair at the end of the body, or no less than nine pairs of legs instead of eight as before. No insect has more than two pairs of wings, and these are attached to the second and third thoracic segment. Some have only a single pair, as in the true flies, and then they are on the second or intermediate segment. The prothorax, or first seg- ment, never bears wings. Each thoracic segment bears a pair of legs, which are themselves divided into joints or segments, and their structure will be described more in detail later on. This division into three distinct regions and the limitation to six legs in the adult separate the insects from crustaceans, like lobsters, crabs, shrimps, and the like, and from the spiders ; none of which have the head separate from the thorax, while all have eight legs instead of six. An insect in the adult stage is there- fore a jointed animal, the rings, thirteen in number, separated into a head of one, a thorax of three, and an abdomen of nine segments ; moving by means of three pairs of jointed legs. Some differences between ' ' larva' ' and ' ' adult' ' have been spoken of, and it has been indicated thereby that at different periods of their lives insects are unlike in appearance. This branch of the subject is exceedingly interesting, and will be treated more fully in Chapter VIII. It is only necessary to say here that, in speak- STRUCTURE AND CLASSIFICATION. 14 AN ECONOMIC ENTOMOLOGY. ing of the difference between larva and adult, reference is particu- larly made to those forms in which the two stages are totally unlike each other in appearance. Some of them resemble each other throughout their entire life, and here the term ' ' nymph ' ' is often employed instead of larva. It remains to say a few words concerning the chitine, which forms so large a part of the outer skeleton or crust. This sub- stance is found in insects and in certain of ■ ■ the crustaceans, and is a flaky, horny, or shell-like material which may become very hard, and is impenetrable to most liquids not absolutely corrosive in character. The Section through insect importance of this fact it is necessary to crust, showing layers of . . , . ^ . ... chitine at c, the cellular recognize in our Selection of insecticides, layer or hypodermis at bccausc nothing that wc Can apply with any h, and basal membrane r ^ ^ ^-l i ^ • re • ^i ^j ^ saiety to the plant is sumciently active to eat through or penetrate the outer skin into the insect body except under peculiarly favorable circumstances. None of the oils penetrate it readily, even gasoline, benzine, or kerosene being resisted. Alcohol, chloroform, and ether are also unable to make their way through any but a very thin coating. CHAPTER II. THE HEAD AND ITS APPENDAGES. The head of an insect bears structures of great interest from the economic stand-point, and of these the mouth parts are the most important. In most cases a glance at the structure of the mouth gives a clue to the food habits of the species, and may convict a culprit whose work has been discovered, or determine the character of the remedy to be applied. Roughly speaking, two types of mouth structure are found in insects, — the biting or mandibulate, and the sucking or haustel- late ; though there are modifications of both which are somewhat intermediate in character. In the typical "mandibulate" or biting mouth, the mandibles STKi'CTL'KE A. YD Cl.ASSIFICATIOX. 15 Fig. 7v or upper jaws are distinct and prominent. They work horizon- tally, from side to side, instead of vertically, or up and down, as is the case in the higher animals, and their form and general shape often furnish an indication to the character of the species, — that is, whether it is predace- ous, living upon ani- mal food, or whether it is phytophagous, feeding upon plant tissue. This alone, in some orders, suffices to tell us whether we have to deal with a friend or an enemy. If the jaws are rather long, sharp-pointed, with slender, sharp teeth on the inner side (Fig. 3, c, d), it may be safely classed as predaceous ; if they are broad, stout, con- cave within, the edges meeting broadly, even if toothed, or if they are gouge-shaped (Fig. 3, a, e), we can say with great confi- dence that the species feed upon vegetable tissue. Of course some uncertainty may result in intermediate types (Fig. 3, b) ; but the rule holds good generally, and where it leaves a doubt, some other character will readily determine the question. Forming the front of the mouth and covering the base of the mandibles is the upper lip, or labrum ; on the inner side of which there is usually a sensitive structure, the epipharyyix, which con- tains the organs of taste, and corresponds as nearly as may be to the palate in higher animals. It has no special function in feed- ing, and often seems to form part of the front of the head itself Below the mandibles we have a second pair of jaws or fuaxillce, Mouth parts of a mandibulate insect : different types of mandibles at a,b, c, d,e ; /, the labrum-epipharynx ; g, h, types of maxillae ; the cardo at c ; stipes, st ; sub- galea.j^,- galea as marked ; palpus bearer, ;>/V,- palpus at mxp ; lacinia at lac ; and digitus at dig- ; i, the labium with sub-mentum, sm, mentum, m, ligula, lig, para- glossa,/a>-, and palpi. I 1 6 ^A" ECONOMIC ENTOMOLOGY. much more complicated in structure, and made up of a number of more or less well-marked smaller pieces, which vary consider- ably in form and shape according to the food habits of the insect. Attached to each maxilla is a palpus, or feeler, which often bears organs of special sense, and is probably used by the insect to recognize the character of its food. In function this maxilla is auxiliary to the mandibles, which cut and tear the food, and de- liver it in coarse shape to the maxillae. These assort and break it up yet more to better its mechanical condition, and deliver it to the labium, or lower lip, which also takes part in mixing the food. There are great differences in this maxillary structure, corresponding to the food habits ; and there may be teeth, brushes, or other appendages suited to the requirements of the insect. It is rarely necessary to study these in detail, and Fig. 3 illustrates sufficiently a typical form, with all the parts named. The labium, or lower lip, closes the mouth opening beneath, forming its floor, on which is another sensitive surface, the hypo- pharytix, which may be compared in function to the tongue of the higher animals. As a rule, this labium is much less complex than the maxilla, and it may be only a single piece or plate, though, like the maxilla, furnished with a pair of palpi or feelers. A typical labium is shown at Fig. 3, and the names of the parts are given. Close study shows that originally the labium was made up of just as many parts as the maxilla, but they have grown together, in the course of time, for the more complete closure of the mouth opening. Insects with the mouth as above described, no matter what their feeding habits, are always susceptible of being poisoned through their food ; that is, they may be reached by means of stomach poisons. Sometimes, of course, they feed in such positions that we cannot apply the poison satisfactorily, — e.g., inside of plant tissue ; but this does not alter their susceptibility ; it simply means that we cannot take advantage of it. Of the hatistellate or sucking mouth there are several varieties, functionally quite diverse and indicating difference in habit. Butterflies and moths differ from all other insects in having the mouth formed into a flexible tube, coiled like a watch-spring under the head and between the labial palpi, which are the only visible mouth appendages present. The mandibles have disap- STRUCll.'RE AXD CLASSIFICATION. 17 peared entirely, and all the other structures have been so modi- fied that nothing remains except this flexible sucking tube. I use the term "tube," although it is not such in reality, being made up of two hollow crescents, more or less firmly held to- gether, so that, practically, it serves all the purposes of a complete tube. When the insect feeds the tongue is extended, the muscu- lar structure being accommodated in the walls of each half of the tube. Fig. 4 illustrates a section through a butterfly tongue, showing the way in which the two parts '^' 4- are united. At its tip there are often more or less devel- oped processes which serve as taste cups, and also to assist in gathering up the minute globules of nectar. Section through a butterfly tongue. A tongue of this description indicates a type which can never be harmful to vege- tation, because it is not fitted for either piercing or eating plant tissue ; but it is, on the contrary, of direct use in pollenizing flowers. Butterflies and moths are never injurious in the adult stage, however much their larvae may offend ; but many are especially adapted for pollenizing certain flowers. Thus the " Hawk-moths," with tongues five and six inches in length, are able to reach to the very base of flowers like the petunias, even- ing primrose, "Jimpson weed," and many orchids. A widely different type of sucking mouth is found among the "bugs," or Hetniptera. Here, instead of a flexible tube, there is a jointed, rigid beak or rostrum, made up of either three or lour segments, inside of which run four pointed lancets. This beak is not a complete tube, but narrowly open in front and at the tip, to permit the protrusion of the lancets. Insects with this structure gain their food by piercing the plant tissue and sucking the juices, and such a structure always leaves its possessor open to the suspicion of being injurious. As a matter of fact, many of the Hemiptera are really predaceous upon other insects ; but, as yiA' ECONOMIC ENTOMOLOGY. a rule, they will bear close watching. One thing is certain, how- ever : no insect with this type of mouth structure can be reached by means of a stomach poison. Destruction through its food is, therefore, absolutely impossi- ble, because we cannot poison the plant juices by any method thus far at our command. An insect of this kind is incapable of eating any solid food what- ever, and no matter how thor- oughly covered with a corro- sive poison the outside of our plants may be, it would get none, since it only punctures the tissue without absorbing any portion of the outer sur- face. Thus the determination of the type of mouth structure often limits or decides the char- acter of the remedy to be used in destroying the insect. Among the Diptera, or flies, we have a number of interest- the ing modifications of the suck- ing mouth. One series is fur- nished with lancets similar to those in the bugs, but more numerous, representing different mouth structures, and not always carried into the head itself. The sucking structure is also quite different, and never forms a rigid, jointed beak. Mosquitoes and horse-flies are examples of this kind ; but gradually the lancets disappear, and in most of the flies only the sucking lip, often greatly and interestingly developed, remains. The common house-flies and blow-flies are types of this modified form, and are capable of taking liquid food only, though often seen attacking solids. If the mouth of a fly be examined under the microscope, there will be seen at the tip of the lip a series of deep grooves, stiffened with chitinous loops, and armed with sharp projecting edges. When the fly wishes to feed on a solid, it scrapes the surface by means of these rasp-like projec- Mouth parts of a plant-louse jointed beak ; b, the lancets, much enlarged c and d illustrate the feeler and foot. STRUCTURE AND CLASSIFICATION. 19 lions, securing a small amount of fine shreds and scraps. These it moistens with a drop of saliva, which has great solvent properties, and then draws up the mixture by means of a sucking or pump- ing stomach. Licjuids are taken in the same way, and the insects may be said to lap as well as suck their food. Flies as adults are not injurious to vegeta- tion, whatever may be Fig. 6. said of their larvie ; but some of those fitted for piercing, like the mos- quitoes, horse-flies, and gnats, are often trouble- some or injurious to stock, and occasionally render regions infested by them scarcely habit- able for man. The bees seem to combine the features of „. . .... <■ ..u « .. .v. Piercing; mouth structures of a horse-fly : the a biting and sucking sucking lip is omitted. Much enlarged. mouth ; the mandibles being fully developed and the labium greatly elongated, that they may gather the nectar upon which they feed and which they store, even from the deepest flowers. This modification will be more fully described in speaking of the bees themselves. All the types of mouth structures above described and figured are derived from one original form by gradual modifications of the different pieces ; but this can be traced only in a long series of preparations from many different families and species. Next to the mouth parts, the most important appendages of the head are the antennae or feelers. These are variable in form, and in certain orders their structure indicates, unfaiHngly, the food habits of the insect. They are made up of a variable num- ber of joints, differing greatly in their proportion to each other, in their shape, and in their functions. Ordinarily the antennae are intended as tactile organs, — that is, for touching, as the com- mon name "feeler" indicates ; but it is very certain that other sensory structures are also located there. The perception of odors, or the sense of smell, is a very important function, and AN ECONOMIC ENTOMOLOGY. more than likely there is also a sense of hearing connected with them. In some of the nocturnal moths they are broadly feath- ered or pectinated, much more prominently in the male than in the female. It is believed that the reason for this is that the insects are compelled to find their mates entirely by the sense of Fig. 7. Tip of the mouth of a lapping fly, showing the pseudo-trachea on the inner face of the lips. Much enlarged. smell. That it is not food they seek is proved by the fact that where these feelers are most developed the mouth parts are often entirely aborted and the insect takes no food at all. Certain "carrion beetles," also nocturnal in habit, are attracted for long distances to their food, and, even where purposely hidden, they find it without difficulty ; proving that the sense of smell alone is used. It may be convenient to consider here a few of the com- STRUCTC'RF. AND CLASSIFICATION. 21 mon types of antennal structure, which occur in all insects, that they may be referred to hereafter without especial description. The antennae are said to h& filiform, or thread-like, when the joints are nearly even throughout, cylindrical, tolerably equal in length, and similar in general appearance. A serrate or saw- toothed antenna has the joints more or less triangular in shape and so fitted that one margin resembles the toothed edge of a saw. Quite frequently antennae of this type are distinctly flat- tened. From such a serrated form we pass gradually into the Fig. 8. Antennal types. — a, filiform and pubescent; b, serrate; c, singly pectinate; d, bipecti- nate; e, clavate ; y, capitate; g, geniculate; h, lamellate. pectinated or comb-toothed type, where the joints are furnished laterally with processes of variable length. When both sides of the joints have these processes the antenna is said to be bipec- tinated or feathered ; when the processes become very slender, almost hair-like, and exceedingly numerous, it is said to be plumose. A feeler is clubbed, or clavate, when the joints toward or at the tip suddenly or gradually enlarge to form a more or less evident club or bulb, and this type is widely distributed in all the orders, a variety of terms being in use to indicate the particular form of the club. A lamellate feeler has at its tip a series of elongate, flattened or leaf-like joints, usually applied close together to form a solid mass that conceals and protects y4A^ ECONOMIC ENTOMOLOGY. the delicate sensory structure on the inner surface. An antenna is vioniliform, or bead-like, when the joints are more or less spherical and set together in such a way as to resemble a series of beads on a string. As a rule, the antennae are straight, without break from base to tip ; but occasionally they are geniculate, or elbowed ; tliat is to say, there is one very long basal joint, the "scape," fol- lowed by a series of smaller Fig. io. Fig. 9. _ ,, ^ , Head of wasp, to show regions: a, '^' iT ■o^O'^ 'C^ compound eyes ; b, clypeus ; c, la- Antennal types: a, moniliform ; 6, joints ciliated; brum; rf, mandibles; 6", ocelli ; /.place c, bristle-tufted; d, plumose; e, setaceous. where antennae are inserted. segments set in at right angles to it. Usually an elbowed an- tenna is also clubbed at the tip, and so we divide the structure into "a scape" at the base, the "club" at the tip, and the " funicle" embracing the intervening portion. The feelers may be clothed with fine, soft, more or less dense hair, and are then pubescent ; or furnished with lateral hairs of moderate length set in regularly, and are then ciliated or fringed ; or they may have single or bunches of stiff bristly hair, and are then said to be bristled, or bristle tufted. These are all the movable appendages of the head, and there remain only the organs of sight, which are perhaps better con- sidered under the heading of sense organs. It is only necessary to say here that the compound eyes are often very prominently developed, and that they are usually set at the sides, often form- ing the greater portion of the head itself. The ocelli, on the other hand, are always very small structures ; in the adults, never more than three in number, and quite variably arranged. STRUCTURE AND CLASSIFICATION. 23 CHAPTER III. THORAX AND ABDOMEN. The thorax, or middle region of the body, is, as has been already stated, composed of three rings, termed in their order the pro-, meso-, and metathorax ; meaning fore, middle, and hind thorax. These rings vary greatly in their proportion to each other : it is rare that they are equally well developed, and whenever this is the case it indicates a low type of insect, — that is to say, one very little specialized. Usually they are grown together to some extent, and this tendency continues until we find in the flies and bees the entire thoracic region apparently composed of one solid mass, — the rings being not at all movable upon each other. Insects of this type are highest in the scale and the most specialized. In other orders, notably the Coleop- tera, or beetles, the prothorax only is free and well developed, the two other rings being united together and not movable one upon the other. This forms a sort of intermediate type, and the rank of insects is determined, to some extent, by the development of this region of the body. If the thorax of a grasshopper, a beetle, or a wasp be rather closely examined, it will be found that it is made up of a large number of little pieces, divided by impressed lines, and sometimes these pieces are movable one upon the other. They are called sclerites, and a sclerite, whenever that term is used, always means a solid piece bounded by impressed lines, or sutures, as they are termed. Perhaps ' ' seams ' ' better represents the actual case than "lines," because they mark the places where pieces have been joined together, even if the joint be now a solid one. Though these pieces seem confused at first sight, yet there is a distinct plan in their arrangement, and, while it is not necessary to go much into detail, it is well to know at least the regions of the segments and the terms applied to them. In Fig. 11 will be found an illustration of the under side of a beetle, in which all the sclerites of that part of the body are named. Those who wish a more accurate knowledge can compare a series of -'4 AN ECONOMIC ENTOMOLOGY. Fig. II. maxinaru /T7 ^"^'1 puzbtcs . 7 "^ Tv mqxdi A beetle, Harpalus caliginosus, from the under side, with all the pieces named. STKl'CTURE AND CLASSIFICATION. 25 insects with this tigure, and by identifying the different pieces observe for themelves what modifications have taken place. The upper side is always called the dorsum, or dorsal surface, while the under side, between the legs, is the sternum, or breast. Laterally, between the sternum and the dorsum we find the pleurum, whicli is a region rarely referred to in general descrip- tion. The "dorsum," " dorsal surface," and "sternum," on the other hand, are terms of frequent occurrence in the literature of economic entomology, and it is well to know exactly what is meant by them. As has been previously said, all the organs of locomotion in the adult insect are attached to the thoracic segments ; never more than three pairs of legs, one pair to each segment, and usually two pairs of wings, borne on the meso- and metathorax. The prothorax never bears wings, and, when only a single pair is present, as occurs normally in the flies, or Diptera, this is on the meso- or middle thoracic segment. Of the wings, or organs of flight, all that need be said here is, that they are more or less membranous, flattened, and stiff- ened by "veins" or chitinous rods. They vary greatly in char- acter, and must be especially described for each order, their general structure being all that it is necessary to give here. In their origin wings are merely collapsed sacs, — that is, each is a bladder-like outgrowth from the body wall, that assumes definite form, but remains filled with liquid until ready to assume its final shape. Then it is gradually distended to full size, the liquid is absorbed, and the walls of the bladder unite and become so closely welded together that it is impossible afterward to separate them. The wing seems like a single thin membrane, or horny shell, as the case may be, and the veins appear like hollow rods or cylinders, though originally they were mere thickened grooves on opposite sides of the distended bladder. The arrangement of the veins, or " venation," is of very great importance in classifi- cation, but needs no particular exposition here. The legs, always six in number in the adult, are jointed, or made up of a definite number of parts or pieces. They are fixed into the thorax at the sides of the sternum, or between the breast and the sides, and are fitted into a body cavity by means of a ball-and-socket joint, giving a great range of motion. The ball 26 AN ECONOMIC ENTOMOLOGY. portion belongs to the leg and is called a " coxa," and the socket is the " coxal cavity." Attached to the coxa is the "femur," or thigh, usually the stoutest part of the leg, and corresponding to the same portion of the leg in the higher animals, most of the muscular system being found in it. It is often strengthened at the base by a small supplementary piece called the ' ' trochan- ter, " which sometimes forms an intermediate segment between coxa and femur, and may be even two-jointed, as in the parasitic Hymenoptera. At the end of the femur is attached the " tibia," or shank, which varies greatly in structure according to the habits of the insect, being modified for digging, tearing, swim- ming, clasping, or other special functions. It is armed in many ways, and becomes an index to the life history of the insect, furnishing, also, many good characters of use in classification. Economically, it is useful in that it is a guide from which we can often get an idea of the kind of existence that the insect leads, — whether it is a digger, a swimmer, or a carnivorous type. The terminal part of the leg is the " tarsus," or foot, and this is also jointed, — five joints being usual, though variations frequently occur. The last joint is armed with a pair of claws, and between them we may have "pulvilli," or small pad-like structures, by means of which flies and other insects cling to smooth surfaces and are able to walk back downward on ceilings. The differ- ences in the leg structure are easily seen with a little experience, and In some orders, notably the Coleoptera, they serve to divide the insects into large groups or series. The abdomen normally contains nine segments, but these are rarely all distinct. As a rule, one or more are modified to form sexual organs or appendages, or shields, or other accessory structures. It sometimes happens that the segments on the dorsal, or upper, and ventral, or under, side do not correspond, one part of the ring being lost or modified. In the adult the ab- domen never bears organs of locomotion, and, as a rule, no appen- dages of any kind, except an ovipositor in the female of certain groups, or a pair of claspers in the male. In some of the lower orders it bears jointed filaments or appendages resembling feelers, and these are called " cerci." Only in the lowest of all types do we find traces of rudimentary legs on the abdominal segments, indicating a relationship between the insects and myriapods. STRUCTURE AND CLASSIFICATION. 71 CHAPTER IV. MUSCLES, DIGESTION, AND CIRCULATION. Insects have no internal skeleton or bony structure, the body wall serving for the attachment of muscles and to protect the inner organs. Cutting transversely through the thorax of an insect at its mid- dle, we find the greatest portion of the body cavity occupied by muscles, which are arranged in bundles attached to the entire inner surface of the body wall, proceeding to all the appendages, and thus providing the power that moves the animal. Centrally, the alimentary canal occupies a part of the body cavity, its size Fig. 12. Ideal section through an insect.— a, alimentary canal; h, heart; n, nerve-cord; s, stig- mata ; t, tracheal tubes ; /, legs ; w, wings. depending considerably upon the kind of insect in hand. Just below the dorsal surface is a small tubular structure, at once the heart and only blood-vessel, while just above the ventral surface is a white, knotted cord,— the nervous system. Laterally, there is an opening on each side, from which a ringed tube leads into the body, dividing and subdividing almost immediately into innumerable branches, and this is the respiratory or breathing system. Frequently we find around the alimentary canal a con- siderable fatty mass, while everywhere through the insect body 28 AN ECONOMIC ENTOMOLOGY. we meet with a whitish or sHghtly greenish Hquid, much more abundant in the larva than in the adult ; and this is the blood. These various systems are of economic importance, for upon our full understanding of some of them depends the success with which we can apply insecticides of a certain character. Perhaps the least important in this view is the muscular sys- tem. It has been stated that the muscles are found in the form of bands, which extend from the body walls to the various ap- pendages, and, of course, they are numerous and strong in pro- portion to the power required. Thus, for a leaping insect the muscles moving the legs are very much more developed than they are in an insect which simply walks or runs, and in a run- ning insect they are better developed than in one that simply walks or moves slowly. Where powerful appendages must be moved, as for instance the mandibles or jaws, several bundles of muscles frequently converge to a chitinous point or tendon, which in turn is attached to the appendage, and thus a great amount of force is exerted at one point, the muscular attach- ments on the body wall covering a considerable surface and con- verging all their effectiveness upon one lever only. It is this arrangement that gives some insects the gnawing power to bur- row in the hardest woods, and to cut through foreign substances, like lead, in order to escape from captivity. Under the microscope it is found that the ultimate structure of insect muscle does not differ in essentials from that of the higher animals ; that is to say, it is made up of narrow fibres divided into cells, and transversely striated. The voluntary muscles of insects are, therefore, practically like the voluntary muscles of the higher animals or of men. The digestive system is of much more importance from the economic stand-point. On a previous page it has been shown that two general types of feeding habits exist, the chewing and the sucking, and the digestive system changes somewhat as the needs of the organism vary. The mandibulate type, in which the insect chews its food and subsists upon more or less solid material, will be first considered. Most insects in the larval stage, and sometimes also as adults, are voracious feeders, seeming determined to devour as much as they can possibly contain, in the shortest possible time ; and the food is in such cases rather Fig. t,^. Mandible of a carpenter-bee, with bundles of muscular fibres attached, each bundle converging to a tendon, and the latter attached to a mandibular procesb. STRUCTURE AND CLASSIFICATION. 29 Fig. 14. Digestive systems : of a katydid, at a; of a grasshopper, at b ; and of a roach, at c. All the parts are named save the thread-like Malpighian tubules. 30 AN ECONOMIC ENTOMOLOGY. coarsely ground up by the mouth parts, and forced through the gullet or oesophagus into the crop. The oesophagus is simply a slender tube, usually straight or only a little bent, at the mouth of which salivary glands open, and the food, mixed with saliva, passes through it into the crop. This crop is a more or less muscular, but always distensible sac, and usually the largest single organ in the body. It is used, primarily, as a place to store food when the insect has the opportunity of obtaining it, and is capable of containing a comparatively enormous amount of material. At its posterior end it opens into a gizzard, or grinding stomach, and this receives the food in small quantities, to be further reduced and put into better mechanical condition for assimilation. For this purpose it is armed with a complicated set of plates and teeth, not alike in any two species, while its muscular coatings are dense and powerful, giving great twisting and grinding force. Sometimes the gizzard is well developed and prominent ; but often it is greatly reduced, appearing as little more than a slight specialization of the end of the crop. Its development depends very largely upon the character of the food and the feeding habits. Insects that eat indiscriminately all sorts of material, like roaches and crickets, have it best developed. From this gizzard the food, now in excellent mechanical con- dition, passes into the true stomach, ox ckylific ventricle, receiving at its mouth the secretions of the ccecal tubes or pouches. This secretion is digestive in character, like a similar liquid in higher animals, and assimilation begins in this part of the system. The stomach varies greatly in length in the different kinds of insects, and as much in relative size and the strength of its muscular coating. At its posterior end we find the long and slender Mal- pighian tubules, which often envelop the whole system in a ver- itable net-work of fine, thread-like masses. These structures are supposed to represent kidneys and to have a similar excretory function. They open at the junction of the stomach with the iletiin,ox small intestine, and in this the assimilation or absorption of food products is completed, the remnant being forced into the large intestine, or colon, where it is prepared for excretion through the rectiim. A pair of glands near the end of the rectum secretes a mucus, probably intended as a lubricant only. The salivary glands vary in number, and one or more may be STKC'CrUKE AND CLASSIFICATION. 31 Fig. 15. modified for special purposes ; as in some of the piercing insects like bugs or the mosquitoes, where an irritant poison is secreted, or in certain beetles, where the saliva has both a staining and a burning effect upon the skin, or in many larvae, where the se- cretion forms a silk when hardened by ex- posure to the air. The anal glands may be similarly modified, but much more rarely than those at the anterior end of the body. In the "Bombardier beetle" their secretion volatilizes suddenly when expelled into the air, and forms a blue smoke, like the discharge from a small cannon. In Hymenoptera, including bees and wasps, the secretion is poisonous, and accessory to the functions of the sting. More rarely a silk is produced from these glands. Taken altogether, the digestive system varies greatly in length, being .sometimes a straight tube only, the various portions very incompletely divided off. In other cases it is quite complex, coiled upon itself, the parts well defined, and the sys- tem as a whole two or three times the length of the entire insect, different kinds of structure being found in the various parts. The figures given herewith illustrate some of these differences. In the sucking or haustellate type the essential structure of the alimentary canal and the differentiation of the parts are much the same. There is, however, a great reduction in the size of the gizzard, which is very often entirely wanting. If present, the armature is reduced to a mere ridging, or a slight, irregular thickening of the walls of the posterior end of the crop. In the Lepidoptera there is often a peculiar accessory pouch, which seems to serve the purpose of a storage reservoir, or secondary crop, and this is attached by a narrow neck to the opening of the true crop. In the bees the crop is unusually elastic, and capable Salivary gland of the cat- erpillar of Melittia ceto, modified for silk spinning: mandible of the same, above. 32 AN ECONOMIC ENTOMOLOG\. of enormous distention compared with the size of the insect, and this is to accommodate the honey collected by the insects to be carried into the hive. In the use of poisons acting through the stomach, the arsenic, which is usually employed, is taken in with the food and gener- ally carried into the chylific ventricle before it becomes effective. In the crop the food is generally too dry to cause the necessary solution of the caustic properties of the arsenic, which is neces- sarily applied in its least soluble form ; but by the time it has passed through the gizzard and has reached the stomach, becom- ing moistened and mixed with the secretions that have been already mentioned, it becomes active. Some insects are able to take a very large quantity of poisonous material without injury ; succumbing only after two or three days to the effects of a poi- sonous meal. It is probable that in such cases the digestive liquids exercise a less solvent effect upon the toxic mixture. Ordinarily, digestion in insects is exceedingly rapid. Among caterpillars, for instance, feeding is often almost continuous, and twenty-four hours are sufficient to pass through the entire diges- tive system food two or three times the weight of the larvae themselves. Fig. i6. Heart of a stag-beetle, showing the wings and chambers : at the side, the interior of a chamber, to show the valves. Insects have no system of arteries and veins, and only one real blood-vessel, which serves also as the heart. This, as has been S7'A'CV7('A'/-: AND CLASSIFICATION. 33 indicated, lies just under the back, and in a cavity formed by a series of peculiar triangular muscles known as the ' ' wings of the heart;" and these serve to prevent undue pressure upon it. The organ is simply a long tube, open at both ends, and divided into a variable number of chambers, into which the blood is admitted at the sides, at intervals along its length. The heart- beat consists of a wave of contraction beginning at the posterior end, forcing the blood forward and out into the head. Some- times one wave is completed before another one starts, and sometimes two or even three waves may be on the road at one time. Sometimes the beat is exceedingly sluggish, and some- times, in active insects, it is very rapid. After the blood has been forced out of the heart it first bathes the head parts, and then makes its way between the muscles and other organs through the body cavity and into the appendages. Part of it bathes the alimentary canal, where it receives the products of digestion, and these are carried everywhere and assimilated by the various tissues, the blood eventually finding its way back to the heart, to begin its journey anew. The fact that there is no closed system of blood circulation is peculiar, and in this insects differ from all the higher animals. It necessitates a very decided modification of the respiratory or breathing system, and this forms the subject of the next chapter. CHAPTER V. THE RESPIRATORY SYSTEM. The respiratory or breathing system of insects is adapted to the system of blood circulation. It is important from the eco- nomic, as well as interesting from the scientific, stand-point, for upon this rests the basis for the application of contact insecticides. Insects have no lungs, and nothing which at all corresponds to them. They have no means of taking in air at the head or through the mouth ; but breathe from the sides, where there is a series of breathing-pores, or spiracles, through which the air is taken into the body cavity. Typically, one pair of spiracles 3 34 AN ECONOMIC ENTOMOLOGY. occurs on each body segment ; but as a matter of fact some of the segments, especially in the adult, lose them, the insect de- pending upon a more limited number as the main trunks become enlarged. The insect blood requires oxygen, as in the higher animals, and, as there -are no lungs to which the blood can be carried, it is necessary that the air itself should be taken to all parts of the body, and this is accomplished by means of tubes called trachea. Tracheae occur in insects, in spiders, and in myriapods, all of which are, therefore, called " Tracheates. " Spiders have eight legs instead of six as in the true insects, and have the head and thorax combined in one piece or cephalo- thorax. They have also a decided tendency to the formation of lung-sacs. The "myriapods" or "centipedes" are more worm- like in structure, and are furnished with many legs,» — one or two pairs on each body segment, — sometimes exceeding one hundred in number. One tracheal trunk or tube starts from each spiracle, and be- gins at once to divide and subdivide, sending its ramifications to all parts of the body, even to the tips of all appendages, so that air permeates every part of the insect, and tracheal tissue is present everywhere. The structure of these tubes is interesting : they consist of a membranous cylinder, stiffened by chitinous rings or spirals, in appearance very much like the closely-coiled springs in automatic shade-rollers. This gives rigidity to the tubes, keeping them always open, while at the same time it allows the utmost freedom of motion. A series of longitudinal tubes on each side of the body unite the main trunks from each spiracle, and in some cases there are transverse tubes joining the longitudinal tracheae. The entire system is thus connected in one or two ways, and at a pinch an insect is able to get its air supply from one spiracle only and from almost any part' of its body. Where so many openings into the insect body exist there must, necessarily, be some arrangement for protecting them and preventing the entrance of foreign material. There is, therefore, a great variety of sifting structures, their character depending largely upon the habits of the insects. There may be a series of teeth or spurs on each side of a narrow, irregular slit ; a series of hairs or bristles crossing in front of the opening ; a covering S7'R('CTCKE .hVD CLASSIFICATIOX. 35 Fig. 17. Tracheal tube, showing the structure and methods of branching. Fig. 18. Spiracles and their protection. — a, plate-like covering 01 white grubs, cross-sec- tioned at b, to show how air enters; c, a toothed slit; rf, spiracle set on a teat-like process; d", conical spiracle set in a pit, protected by crossed hairs as shown at y in section ; g, lip-like spiracle ; h and /, unprotected round or slit-like openings. Fig. 19. Fig. 20. Tracheal gills. — d, leaf-like anal plate or Agrion ; b, thread-like tuft of Corydalus ; c, plate-like gill of Ephemera. Air-bladder at end of tracheal tube in Bom- bus. 36 -/^V ECONOMIC ENTOMOLOGY. shield, beneath which the air must enter, or some other variety of screen, — all intended to sift out of the air the foreign particles which might injure the insect. Yet it is through these spiracles that most of the contact insecticides must act, as will be more fully detailed hereafter. In many heavy insects there are at- tached to the tracheae numerous air-sacs or bladders, the object of which is to reduce the specific gravity of the insect to enable it to fly more readily. A common example is the well-known " May-beetle" or "June-bug," which has the entire body cavity filled with such little bladders. If one of these beetles be watched when it emerges from its hiding-place early in the evening, it win be noted that it first crawls to the top of some blade of grass or twig, or even upon a stone, and rests there a few minutes. If it be closely observed it will be seen to be pumping in air,— that is to say, the body pulsates rapidly, and the abdomen seems continually to increase in size. This is because the insect is fill- ing the air-bladders, and, as soon as this has been accomplished, it tries its wings, causing the preliminary "whirr" which is so familiar to the observer in the early evening of a June day. After two or three trials the insect becomes confident of its ability to sustain itself, and flies off" heavily, with a steady hum. If such a beetle be found at mid-day and thrown into the air it will fall heavily, and will be absolutely unable to sustain itself in flight until it has had an opportunity to inflate its air-sacs. While the vast majority of all insects are air-dwellers, yet many live underground, a very large number in water, and a consider- able percentage in decaying or excrementitious matter, Vy-here pure air is very difficult or impossible to obtain. All sorts of devices to enable them to breathe under such conditions have been developed, and in all cases without any essential modifica- tion of the system. Underground dwellers usually find air suffi- cient for their needs in the earth in which they live, and the development here is principally in the direction of more perfect coverings for the spiracles to prevent the entrance of dirt. Among insects living in or under water, or spending a portion ot their life there, we note a great variety of modifications. Many beetles, and some insects of other orders, have the \ving- covers dome-shaped, and so closely fitted that they are able to carry a little supply of air between them and the abdomen. STRUCTURE AND CLASSIFICATION. 37 When this supply is exhausted of oxygen, the insect rises to the surface, allows the drop of tainted air to escape, and at the same time takes in another bubble of pure air. It is then supplied for another period, varying in length in the different species. Cer- tain other forms have the body covered with very fine hair, so dense that the water cannot penetrate it, and these carry a thin film of air that surrounds them entirely while they are in the water ; they really do not get wet at all. This air supply must usually be renewed from time to time ; but occasionally oxygen is absorbed from the water itself, and the filmy covering is thus kept constantly purified. Yet other insects have their surface so absolutely smooth and polished that the water cannot touch it, and here also a slight film of air may be carried about. There are other devices to the same end, which it is needless to special- ize, and we pass to those insects that never come to the surface at all, and yet secure a sufficient supply of oxygen. These crea- tures are mostly larvae, and in them we note the development of structures resembling the gills of fishes in function. That is, in certain leaf-like or thread-like appendages there are a great num- ber of very fine tracheal tubes with very thin walls. Through them the insect absorbs the oxygen contained in the water itself, and we have exactly the same process that we find in the fishes, except that here air instead of blood is brought into contact with the oxygen in-the water. These gill-like appendages vary greatly in number and shape, but do not differ in function, and will be further described when necessary in connection with the insects themselves. Yet another type of structure is found where the absolute con- nection with the air really never ceases, — that is to say, the in- sects have a rigid or an extensile tube attached to the anal end of the body, and this they keep pointing above the surface while they walk about on the bottom of the ponds. Insects so pro- vided are inhabitants of shallow water, and the tubes rarely ex- ceed an inch or an inch and a half in length. The common "rat-tailed larvae, " often found in the filthiest of all excrementi- tious material, are good examples of this method of breathing. They may be entirely imbedded in the pasty mass ; but the tip of the ' ' tail' ' is kept above the surface to enable them to secure fresh air. Finally, we have those cases where insects live 38 AN ECONOMIC ENTOMOLOGY. in the water, yet get all their air from above it without any power of storing. This is the case with creatures like the mosquito larvae, which are unable to breathe without coming to the surface. They have only a single spiracle at the tip of the body, and are compelled to rise to the surface at intervals to breathe, and, having done so, are able to sustain Hfe beneath it for only a short time afterward. This much for the general characteristics of the respiratory system ; it remains to show how it is important from the eco- nomic stand-point. It has been previously said that the insect crust is of chitine, which is impervious to a great variety of ordinarily penetrating substances. It resists alcohol, chloroform, ether, the light mineral oils, benzine, turpentine, kerosene, and other similar substances ; acetic acid penetrates slowly and so does carbolic acid. This accounts for the difficulty which we find in destroying many insect eggs, for there are no openings in them that are sufficient for the penetration of these substances, and they are unable to act through the egg-wall itself To get a liquid insecticide to kill an insect by contact, it must be forced into the body through the spiracles, or they must be so gummed or clogged as to close them completely, thus preventing the in- sect from breathing at all. Kerosene is the most reliable of the penetrating liquids, and even where the spiracles are well pro- tected this material penetrates into the smallest openings. It has the advantage of actually wetting everything ; that is to say, it is not repelled by small hairs, as globules of water would be, and therefore, as it really comes into direct contact with them, is enabled to work its way through the spiracles. That is what makes the kerosene so much better than any watery mixtures alone ; for whatever the material extracted by or dissolved in water, it may perhaps be repelled by the insect body, and never have the opportunity of exercising an effect. The various soaps act in another way ; as the moisture evaporates, a film of sticky or gummy material remains which clogs the spiracles, and thus chokes the insect by depriving it of air. Soapy mixtures also wet and stick well to insects through the caustics they contain, and which have the power of cutting the repellent material of their bodies. In some kinds of insects the spiracles are so feebly protected STRUCTURE AND CLASSIFICATION. 39 that dry insecticides penetrate them readily, if finely ground ; and all such are effective in proportion to their fine mechanical condition, enabling them to enter the tracheae through the sieve of the spiracles. Thus, sawfly larvae or " slugs," like the " cur- rant-worm" and " pear-slug," succumb readily to dry hellebore, pyrethrum, or even fine road dust. Many parasites may be reached in this way, and some animals and all fowls keep them- selves tolerably free from vermin by frequent dustings. This is not the place to go into the eftectiveness of insecticides ; but it may be repeated that contact poisons usually act through the spiracles only. Dry powders are effective in proportion to their fineness and to their peculiar poisonous properties ; liquids are effective in proportion to the thoroughness with which they are applied, and to their penetrating or clogging characters. Caustics and chlorides act differently, and may actually corrode a thin insect crust. But this matter also comes more appro- priately under another heading, and will not be further discussed here. CHAPTER VI. NERVOUS SYSTEM AND SENSES OF INSECTS. The nervous system in insects consists of a series of white disks or ganglia lying on the bottom of the body cavity, con- nected by a double cord extending the full length of the insect. Insects have no true brain, as do the higher animals, and the ganglion situated in the head, which is usually called " brain," is larger than the others simply because of the great number of special organs — eyes, antennae, and mouth parts — that must be innervated from it. In its structure it is precisely like the other ganglia, though in some of the social types there is an appearance of specialization. Nerve-fibres start from all ganglia in every direction, and all parts of the body are reached ; the nervous system in one direction being exceedingly well devel- oped. In the larval forms and in the lower types, a ganglion is present in every segment of the body, including the head ; and thus each segment contains its own nerve-centre, the cords from 40 AN ECONOMIC ENTOMOLOGY. which are primarily sent out to the organs and appendages lying within that particular segment. In adults there is a tendency to a union of the thoracic gangUa, and in the abdomen two are usually confluent toward the anal end of the body. The digestive system is usually in- FiG. 21. nervated by a spe- cial ganglion, and has its own, partly distinct system. In the higher insects the thoracic ganglion is the most important in the body for the life of the insect, and if this be cut or destroyed the insect dies at once. Any other ganglion may be cut without pro- ^ ducing immediate , , . , , , . death, and the brain, Nervous system of the honey bee at a, and of its larva at b. usmg that term for the ganglion con- tained in the head, may be entirely removed without necessarily killing the insect itself While, as stated, the nervous system is well developed and all the organs are well furnished with nerve endings, yet it is prob- able that insects are not particularly sensitive. The oft- cited case of the butterfly that was captured and pinned while alive, then escaped from the collector, and returned at once to its feeding among the flowers without apparent inconvenience, is known to most readers. If a dragon-fly be captured and held by the wings loosely, so as to prevent its escape but not to injure it, and the tip of its abdomen is then presented to its mouth, it proceeds at once to eat it as far as it can reach, with- out any apparent knowledge of what it is doing. It will thus devour, with the greatest portion of the abdomen, half its diges- tive system, nearly half its entire nervous system, and a large part of its heart ; yet, if it be then released, it will fly ofl", little STRUCTURE AND CLASSIFICATION. 41 the worse, except that it is unable to balance itself. Insects may lose a considerable number of their members without apparent inconvenience : a tly may lose a leg or two without seeming in the least worried, or one or both of its wings may be torn off without causing death or even a manifestation of pain. I once made a series of experiments to test, not so much the sensibility of flies, as the effect that cutting the various organs would exercise upon it. I found that if I cut off the abdomen completely, the fly would live for twenty-four hours thereafter ; with practically no digestive system, with very little nervous system, and with most of its heart gone. Turning the matter, I cut off the head, and found that it would live without a head for just about as long a time as it would without an abdomen. Of course death was bound to result from this mutilation in time, but the interesting feature is that no apparent symptom of pain was developed. I found, however, that just as soon as I cut the large ganglion in the middle of the thorax I terminated life. What- ever sentimental feeling there may be in the matter of causing unnecessary pain, there is no reason to believe that insects have any well-developed sensitiveness, as we understand that term. The character of the insect nervous system is so entirely different from our own that we are left without real guides in our interpre- tation of the various sensory structures. Man judges most things by himself, and where this guide fails he is at a loss, and cannot be certain that he interprets what he sees correctly. The eyes are perhaps the most prom.inent and best understood of the organs of special sense. They are of two kinds, simple and compound, and both may be present in the same species. The simple eyes are termed ocelli, and consist of a more or less convex, often bead-like lens or facet, by means of which an image _ is thrown on a retina, and thus transferred to the perceptive centres. In larvae simple eyes, or ocelli, are the rule, except in types with incomplete metamorphosis, where the eyes resemble those of the adults. In larvae the simple eyes may be situated at almost any point on the head ; but usually they are grouped at the sides : sometimes only a single ocellus at each side, sometimes a group of a dozen or more, forming the rudiments of a com- pound eye. In adults there are rarely more than three ocelli, usually situated in a triangle either close together or widely sep- 42 AA^ ECONOMIC ENTOMOLOGY. arated ; or there may be only two, one on each side, near the base of the antenna, as is usual in butterflies and moths. Fig. 22. Sensory organs of insects. — A, one element in eye of a roach ; B, section of compound eye ; C, organs of smell in May-beetles ; D, sense organs in abdominal appendages ; E, sensory ear ; F, ear on foreleg of locust ; (7, ear found on the basal segment of grass- hopper abdomen. .All greatly enlarged. Compound eyes are so termed because they are made up of a great number of simple eyes, or ocelli, set very close together. If the head of a bee or house-fly is examined, it will be noted that the brown eyes occupy a very large portion of its surface, and if one of those eyes be viewed under the microscope it will be found to be faceted, or to consist of thousands of little hexagonal disks, resembling in appearance the top of a honey- comb. Each one of these facets represents a complete eye, capable of forming an image upon its own little retina, and the combination of all the little retinal pictures is what a fly or other insect sees. In some cases the eyes are so enormous that the in.sect can see everything going on in front, at each side, above and beneath, and even back, except directly behind it. It is difficult for us, who are able to see in one direction only, to STKUCrURK AND CLASSIFICATION. 43 imagine the sort of picture an insect perceives, and we are by no means certain how well or iiow poorly it really does see. We know only that larval forms and low types, provided with ocelli only, see very feebly and indefinitely, and can do little more than dis- criminate between light and darkness. Many insects have no eyes at all, living under such circumstances as to make them useless. That insects hear follows almost inevitably from the fact that many of them "sing," — that is, produce some sort of noise. What those organs of hearing are is not so certain in all cases, nor where they are situated, since we cannot confine our search for ears to the head alone. In the Orthoptera they have been located with a reasonable degree of certainty : in the grasshopper the ears are on each side of the basal segment of the abdomen, while in the locusts and crickets they are on the anterior tibiae. Essentially, these ears consist of a tense membrane stretched over a cavity, and connected by means of little processes, correspond- ing somewhat to the bones of the human ear, with a bulb-like vesicle and a large auditory nerve. In most other orders no similar structures are found, and the sense of hearing is located in the antenna^, or feelers, of which more will be said later on. Insects are able to discriminate as between foods, and the sense of taste is undoubtedly developed to some extent ; but the taste which seems agreeable to their sense would be to us, in many instances, the vilest conceivable. No true tongue, as this organ e.xists in the vertebrates, is found among insects ; but on the up- per side of the lower lip there is often a finely papillate surface, set with little fleshy pegs and processes communicating with nerve fibres, and this represents the nearest approach to the tongue of the higher animals. It is called the hypopharynx , and is not always present. Beneath the labrum, or upper lip, we often find a separate, flat, similar piece, and this is the epipharynx, corresponding in function to the palate of the higher animals. Nothing resembling a nose is found among insects, and yet the sense of smell seems very highly developed. Insects often discover their food with unerring certainty, even when concealed from sight. Among the nocturnal species, where sight can play but a small part at best, the sense of smell seems most highly developed, and usually more in the male than in the female. This is due to the fact that the males, as a rule, seek their mates, 44 AN ECONOMIC ENTOMOLOGY. and so keen is this sense that they discover the presence of the female, even when confined in a breeding-cage, if a window be left open. Sometimes male wood-borers will sit around a spot on the bark for a considerable time awaiting the emergence of a female, which their keen sense tells them is fully developed and ready to make her way out. Carrion feeders discover their food when con- cealed from sight, and almost before decay has set in. So far as we have been able to ascertain, the olfactory organs are situated in the antennae, and form small pits or depressions, from which usually arise specialized hairs, bristles, or pegs, as the case may be. Fig. 23. Sensory organs of insects.—^, sensory pittings in plant-louse antenna;; B, organ of smell in May-beetle; C, same in wasp; />, sensory organs in Termes flavipes ; E, F, organs of taste in a wasp ; G, organ of smell in grasshopper ; //, sensory depressions on the tibia of Te>-mes ; /, terminal joint of antenna of an ant ; K, section through the antenna of a honey-bee, showing supposed olfactory organs. All greatly enlarged. The sense of touch is located popularly, and I think correctly, in the antennae ; but it is quite certain that tactile hairs exist all over the body of the insect, more developed in some than in others, and most, perhaps, in larval forms. These structures always consist of specialized hairs or bristles, and end in a nerve cell. S'/'RLVrrA'E AXD CLASS /J- /CAT/ OX. 45 It is probable that in the antennae we have a sense of percep- tion which is able to discriminate between atmospheric vibrations, and in this way the same or similar structures may serve as organs of hearing, smell, and touch. That is to say, it is probable that there is no such sense in insects as the power to discriminate between smells, but that each is able to recognize certain definite kinds of odors which do produce an effect upon it. So it is also likely that only sounds of certain descriptions are recognized, and these sounds may even be such as the human ear is not capable of perceiving. We are far from understanding the senses of insects, but the above outline is all that is necessary for our present purpose. CHAPTER VII. THE REPRODUCTIVE SYSTEM. The rate of increase among insects is often very great. It is nothing unusual to hear a farmer say that on one day his plants were free from insects, or nearly so, while a week thereafter everything seemed to be swarming. As a matter of fact, this is frequently due to a failure to observe the insects in the first place, either in the stage in which they then existed or on account of their small numbers ; but it remains true, nevertheless, that in- sects are often exceedingly prolific. The number of eggs laid by a female often runs up to one thousand, or even more, while the number of eggs within the power of a Termite queen is be- yond all calculation. If it were not for their natural checks, in- sects would soon overrun the world. In one year not one green thing would be left on the face of the earth, and not one living being other than insects would exist. These natural checks con- sist largely in sudden changes or abnormally high or low tem- perature, in unusual moisture or drought, or in a combination of two or more of these factors. Diseases often attack insects, and genuine epidemics occur, sweeping off millions in one stage or the other. The natural enemies are legion ; many vertebrates are largely dependent for their food upon insects, and this is especially true of birds and reptiles, some of which subsist upon insects exclusively. A large proportion of the insects themselves 46 AN ECONOMIC ENTOMOLOGY. Fig. are predaceous, and live upon others of their kind ; great num- bers are parasites, their prey being other insects of all orders, and in this way forms that depend upon plant life for their sub- sistence are kept within definite bounds. These bounds, though they may vary from year to year, never change much except where man interferes. This subject will be touched upon in an- other place more fully. Except in rare instances insects are of two sexes, male and female, and we nowhere find among them true hermaphrodites. In the plant-lice and gall-wasps we have apparent exceptions ; but these are only apparent. In the female the most prominent sexual organs are the ovaries. These consist of two sets of tubes, one in each side of the abdo- men, usually below the digestive system, united at their base into one larger tube called the oviduct ; the two oviducts unite, just before opening outwardly, into a single chamber called the vagina. The vagina opens out- wardly at the end of the body, sometimes with- out special modification, sometimes by means of a flexible or extensile tube, sometimes as a long, rigid cylinder, and occasionally in the form of a sting. These structures, be they rigid or otherwise, are always called ovipositors, and their function is to place the &^^ into the position necessary for its best development. Associated with this system are a number of glands, the use of which is either to give a sticky coating to the &%^, enabling it to adhere to the leaf or other point at which it is laid, or to supply a poisonous secretion, where such is of development, with Hcccssary lor dciencc or lor stupefymg prey. nutritive cells, WW, be- There is also a little sac, attached by a slender cIpTade^orovi'duct^; ^uct to the vagiua, at about the point where the two oviducts unite. This is the seminal receptacle, and in this is received the seminal from it the eggs are fertilized as they pass from the oviduct into the vagina on their way through the ovipositor. In some insects these receptacles are very large, especially where Ovarian tubes of one side, in Polistes, show- ing eggs in all stages vag, vagina. fluid of the male STUrCTlRE AXD CLASSI/-7CAT/0A. 47 copulation takes place in the fall, and the female, living through the winter, does not begin to lay eggs until some time in spring. The eggs have at one end small openings termed niicropyles^ and through these the spermatozoa find their way into the ^^^ to fertilize it. In the ovarian tubes a variable number of cells are developed, and these grow rapidly, each cell eventually forming an egg. The number of tubes and the number of cells in the tubes vary within wide limits in the different species. In some they are rigidly limited, and the insects are able to lay only a definite number of eggs ; in others the cells are so numerous that a definite number seems unlikely. Before the female has been impregnated the ovarian tubes are \ery slender and occupy only a little space in the abdomen. When the eggs develop, however, the ovaries increase in size until, finally, the abdomen is almost entirely occupied by them, and is often enormously distended. In the male the ovaries are replaced by the testes, which also are more or less coiled tubular structures, and these tubes, like the ovaries, unite to- gether on each side into ^^^- ^5- a larger tube, which in turn are combined into a single organ, usually more or less horny in structure, — the penis. Reproduction among insects is, therefore, in its essentials, like that of the higher animals. The only difference is that as the life period is shorter, the eggs must all be laid within a defi- nite time, and they are v&ry much greater in number. It further proves that we have a definite development in insects as in higher animals, and that with them also, like pro- duces Uke,— that is to say, the product of the €:gg when fully de- Male organs of May-beetle. — One side only beyond the ductus ejaculatorius, duct, ejac; glni., mucus glands; ves. sem.,s^ram2X vesicles; vas. de/., vasa deferentia. 48 .'LV ECONOMIC ENTOMOLOGY. veloped will be like the parent that laid it, and never anything else. Insects are as a rule unable to reproduce until they have reached the adult stage, and the few apparent exceptions may not be real when all the factors are understood. An insect, when once adult, never changes into one of a different kind ; so a beetle can never change into a cricket, nor a small fly into a larger one. CHAPTER VIII. GROWTH AND METAMORPHOSIS. Insects grow only in the larval stage, and moult, or change their skin, every time there is an increase in size. As has been stated, the insect crust is rigid and inelastic, and extension is possible only by the expansion of the membrane between the rings. When a growing insect reaches the extent of the elasticity in its covering, a new skin forms beneath the old one, and the latter splits, allowing the newly-clad and much larger specimen to crawl out of it. In this respect insects resemble crabs, lobsters, and other crustaceans. The terms larva, pupa, and adult have been several times used in the previous chapters, and need more explanation. Most insects undergo, in the course of their life, a series of changes or transformations, in which their form, appearance, and habits are often so diverse that the different stages could not be recognized as belonging to one species without definite, continued observa- tion. These changes are termed metamorphoses, and they include the egg, larval, pupal, and adult stages. With few apparent exceptions, all insects begin in an egg stage, and the method in which this egg is developed has been already described. In this stage, whether it be long or short, the creature is unde- veloped and quiescent, except for the changes going on within, and which do not result in outward movement. In rare cases the eggs are not extruded from the body of the insect, but fertili- zation takes place in the ovary, the larvae hatching within the abdomen of the mother. From this egg comes in due time a larva, a minute creature STRUCTURE AND CLASSIFICATION. 49 which may or may not resemble the parent that laid it. Assum- ing that it does, it is without trace of wings. It grows apace, moults as often as necessary, and at last attains very distinct wing pads. It is now in the pu[)al stage, and with the next moult the wings become fully developed. It is then adult and fitted to reproduce its kind. This sort of metamorphosis is said to be incomplete, because there is no inactive stage, and because there is always a close resemblance in all stages. The larvae are quite usually termed nymphs, and differ from the adults only in size, in the absence of wings, and in the undeveloped sexual characters. A peculiarity of this method of growth or moulting is worthy of incidental mention. When the insect moults, it is not the outer Fig. 26. Moulting of a grasshopper.— o, nymph ready to change; b, the skin split along the back and the adult emerging ; c, continues the process, and at d, the adult insect drying out. skin alone that is aftected : all the most delicate mouth parts with their hairs and processes are cast and replaced by a new cover- ing ; the lining of a large proportion of the digestive system is shed, and the inner coat or surface of the tracheal tubes is renewed, so that practically the insect gets, in part, a new diges- tive system and a new breathing apparatus, every time it increases in size. The number of these moults varies in the different orders, and even in species of the same order. There may be as few as three or four, and there may be twenty or more. We can some- times modify the normal number by changing the circumstances under which the insects live. Thus, the larva of the common Dermestid found in museum cases normally moults four times 4 5° AN ECONOMIC ENTOMOLOGY. before it is ready to change to a pupa. I have confined several larvse in vials, closed them tightly with rubber stoppers, and sup- plied a small amount of food. In these dry vials larv« have lived for months, in one case more than a year, and apparently as a mere pastime they moulted at intervals, so that in one vial there were eight or ten cast skins, more than doubling the ordi- nary number of changes. Withal the insects did not increase in size, simply because no more food was supplied. Where the metamorphosis is complete, there hatches from the Q.^% a grub, caterpillar, slug, maggot, or other crawling or wormlike creature, quite unlike the parent. Growth continues, as before, by moulting, until the full size has been attained, and then feeding ceases. The larva now seeks some retired spot, sometimes spinning a silken covering termed a cocoon, and then changes to a chrysalis or pupa. The term chrysalis is used in the butterflies, where it is free and often prettily ornamented, and the term pupa in most other cases. In this stage it is inactive and rests quietly for some time. The character of the future in- sect is usually more or less clearly defined, but occasionally it resembles neither the larva that formed it nor the adult insect which is to come from it. In due time the adult emerges as a butterfly, moth, beetle, fly, or bee, and no trace remains of the previous larval condition. Insects never grow after they reach the adult stage, but remain of exactly the same size as when first they emerged from the pupa. Thus, as has been indicated in the previous chapter, large flies are never the parents of small flies, nor do small flies ever grow to become larger flies. This cycle of change in an insect is termed its life history, which it is sometimes very difficult to work out. Scarcely two species are alike in habit during all their lives, and a complete knowledge of the full life cycle and the habits in all stages is essential to an intelligent application of remedial or preventive measures. It is often possible to reach an insect easily in one stage, or at one period, where it is naturally protected during all others. So we may, sometimes, by a little change in farm practice, or by taking advantage of some preference on the part of the insect, avoid injury. To ascertain all these facts and to suggest the treatment indicated, is the work of the economic entomologist. Watching the transformations of an insect is a delightful task, S TR L X '7'C RE AND CLASSIFICA TION. 51 and one that can be easily accomplished in most cases by any one possessing a Httle patience. In leaf- feeding insects all that is necessary is to bring in a supply of food with the larva upon it, and keep it in a box rf can-e, renewing from time to time, so that fresh food may be always available. In the bottom of the F'iG. 27. ^^ A breeding-cage of the Riley pattern. box there should be three or four inches of clean sand for the benefit of those forms that go underground to change to a pupa, and in due time the caterpillar or slug will, under the observer's very eyes, change to a butterfly, beetle, or other insect, accord- ing to the character of the larva. F>AR1^ II. THE INSECT WORLD. CHAPTER I. GENERAL CLASSIFICATION. Those structures which are of economic importance and, in- cidentally, those that are used in classification have been described in the first part. Classification is the arrangement of the insects into series which are so related to each other that a species never before seen may be recognized, and its place ascertained from certain, easily discernible, structural characters. Insects that agree in structure usually have similar habits, and by placing an example into its systematic position, the probable life cycle becomes also known, and its exact life cycle can be more easily and intelligently traced out. The divisions used are orders, families, genera, and species. The term sub- may be prefixed to either, to indicate a division not marked enough to claim full rank. A species is the ultimate division, and consists of individuals which agree with each other in appearance, structure, and life history, mating freely and producing progeny, which resemble the parents. An assemblage of such species agreeing in generaJ characters forms a genus, and this is a more or less uncertain divi-sion, depending somewhat upon the opinion of the systematic student. A series of genera agreeing in form, structure, and life history makes a family, and families are united into orders. For the division into orders, use is made of wings and mouth structures and of the transformations. For convenience in ready classification the Linnaean orders are here adopted, though some of them have been properly sub- 52 THE INSECT WORLD. 53 divided. The new orders are referred to, however, in the proper place. Lowest of all are the 77iysa intra, ineludinu;^ "bristle-tails," ' ' spring-tails, " " fish-moths, ' ' and the like. They never become winged or develop even a trace of wings. The mouth parts are small, retracted, usually formed for biting, but sometimes so undeveloped as to be almost without type. The metamorphosis is incomplete ; indeed there is only a simple increase in size, and nothing really worthy of the term development. In most cases the abdomen bears a pair or more appendages at the tip, from which some of the common names are derived. Next come the Neiiroptera, or nerve-winged insects. These have four well-developed wings, membranous, more or less transparent, and so crossed by numerous veins that they seem reticulated or netted : from which character they derive their name, which means nerve-winged. The mouth parts are man- dibulate, usually well developed, but sometimes almost obsolete. In its broadest sense the order includes " May-flies," "dragon- flies," "caddice-flies," "white ants," " stone-flies," " lace-wing flies," and the like. There are, however, two types of meta- morphosis, — one complete, the Neiiroptera proper, and the other incomplete, the Pseudo-neiiroptera. It is here that most of the new ordinal divisions have been made. A step in advance are the Orthoptera, or straight-winged insects, such as roaches, crickets, katydids, and grasshoppers. They have two pairs of well-developed wings, — the first or ante- rior usually narrow and a little thickened or parchment-like; the second or posterior broader, plaited or folded like a fap beneath the anterior pair. The mouth parts are formed for biting, and the metamorphosis is incomplete. The order Heiniptera, or "half-winged" insects, includes all the true ' ' bugs ;' ' and to members of this series only the term "bug" is properly applied, according to entomological opinion. The order is always distinguishable by the mouth structure, which is haustellate, and consists of a jointed beak, concealing two pairs of slender, pointed lancets. The metamorphosis is incomplete. The term Hemiptera, or " half-winged," is derived from the fact that in the typical series the primaries are thickened at base and thin or membranous at tip. In it we have such creatures as the 54 AN ECONOMIC ENTOMOLOGY. "chinch-bug," "squash-bug," and others of equal note. The term Homoptera, or "similar-winged," is used for that series in which the fore-wings are uniform in texture, as in the plant-lice and Cicadas. The order Coleoptera contains the beetles, and the name, mean- ing " sheath- winged," is due to the fact that the anterior wings are hard and horny, unfitted for flight, and used only as a sheath or covering for the posterior pair. The mouth parts are man- dibulate, and the metamorphosis is complete. An easily recognized order is the Lepidoptera, or "scaly- winged," including the butterflies and moths. Here wings and body are covered with minute scales, easily rubbed off and resembling colored dust. The mouth parts are haustellate, and form a coiled tongue, which is usually concealed beneath the head, but can be readily extended at the will of the insect. The metamorphosis is complete. Equally recognizable are the Diptera, or "two-winged" flies. The single pair of wings is characteristic, and with it are asso- ciated mouth parts varying much in type, but never mandibulate nor forming either a coiled tongue or jointed beak. The meta- morphosis is complete. The Hymenoptera, or "transparent winged" insects, include bees, wasps, ants, and the like, and stand at the head of the Class Insecta. They have two pairs of transparent wings, with only a few veins ; the posterior smaller than the anterior. The mouth parts are mandibulate, but the tongue is often developed as a lapping organ, and sometimes greatly enlongated. The metamorphosis is complete. To show the differences succinctly the following table may be of use : Insects which never become winged, have the mouth feebly developed and the metamorphosis incomplete Thysanura. All others are winged : With four transparent wings, which are net-veined and flat; mouth parts mandibulate and well developed ; the metamorphosis, either incomplete Pseudo-neuroptera. or complete Neuroptera. With the fore-wings narrow and somewhat thickened ; the posterior folded fan-like, or plaited ; mouth mandibulate ; transformations incomplete Orthoptera. THE INSECT WORLD. 55 With fore-wings thickened at base, thin at the tip ; mouth parts form- ing a jointed beak ; transformations incomplete • . . . Hemiptera. With the fore-wings uniform in texture ; mouth parts and transforma- tions as before Homoptera. The fore-wings are horny, and useless for flight, serving only as a cov- ering for the posterior pair ; mouth mandibulate ; metamorphosis complete Coleoptera. All the wings and the body covered with scales ; mouth parts developed into a long coiled tongue ; transformations complete Lepidoptera. The wings transparent, with only a few longitudinal veins ; mouth mandibulate, the tongue formed for lapping ; transformations com- plete Hymenoptera. Two wings only ; mouth parts haustellate ; transformations complete DiPTERA. CHAPTER II. THE THYSANURA. Spring -tails. Bristle-tails, Fish-moths, etc. Under this term are grouped a number of lowly insects which never become winged, and can hardly be said to have any real transformations. Most of them are small, soft bodied, with feebly developed mouth parts, and live in damp earth, among decaying vegetable matter. Some live under bark of dead or decaying trees, or in decaying wood, while in rare instances spe- cies are found preferring dry and warm localities. Among those that live in damp places are forms without eyes, and with no de- veloped tracheal system, the necessary oxygen being absorbed through the skin itself Compound eyes are developed in a few in.stances only, though ocelli are usually present. Peculiar to the order are certain abdominal appendages. In some cases these are in the form of rudimentary abdominal legs, indicating a relationship to the Myriapods or Centipedes ; but more often they consist of bristles or filaments attached to the anal segment. In the simplest form they consist of long, many- jointed appendages, whose function may be tactile, similar to that of the antennae. A good example of this type is the little creature known to 56 AN ECONOMIC ENTOMOLOGY. Fig. 28. house-keepers as the "fish-moth," or "silver fish." It is one of the few species tliat prefers a dry, warm locaHty, and is found in cupboards and closets, hiding in crevices, and running rapidly when disturbed. It is about one-quarter of an inch in length, oblong, a little pointed towards both ends, and has the body covered with minute, sil- very-white, glistening scales. It is one of the largest species belonging to the order, feeding upon starchy substances and food remnants. It sometimes becomes troublesome in libraries, gnawing the calendered surface of leaves and bindings and defacing them. The insect can scarcely be said to be injurious, but it is often annoying, and may be driven out by a free use of pyre- thrum dusted in corners and crev- e^ A much more common type is the spring-tail," so named from the fact that the anal appendages consist of two short, bristle-like processes, arranged to enable the insect to leap or spring. They are normally bent under the body, held in place by a catch-like organ until the insect de- sires to move suddenly, when the catch or spring is released, sending the insect forward a surprisingly long distance. When excited it progresses by a series of rapid leaps of this kind, its course being decidedly erratic because no two of the springs are made in the same direction. "Spring-tails," or Podurids, are found in moist localities, wherever decaying vegetable matter occurs. In manure beds they often occur in millions, and on warm days may come to the surface in astounding numbers. I have seen a forcing bed cov- Bristle-tail or fish-moth ; Lepisma sp. THE INSECT WORLD. 57 ered nearly half an mch in depth by a solid mass of these little creatures not one-sixteenth of an inch in length. Frequently a Fig. 29. Fig Papyrus species : showing spring curved under the body. sudden rise of water on meadow or bog land drives them out of their hiding-places, and they leap about on its surface for a time as readily as they do on land. I have seen, on cranberry bogs reflowed late in May, square rods of the surface so densely cov- ered that nothing of the water was visible. They are often found in damp cellars, on any vegetable matter stored there, and are sometimes ac- cused of promoting decay. In the fields a cut potato placed underground piay attract dozens of specimens that feed upon the juices of the raw sur- face, and they have been therefore ac- cused of producing scabby potatoes. They are of all colors, but usually slate-gray or yellowish, the markings sometimes quite pretty and distinct. As a matter of fact, these insects are never injurious. Healthy vege- table tissue is not attacked by them, and their mouth parts are adapted for feeding on soft or moist tissues only : hence a decayed or bleeding spot at- tracts them. They are sure to occur in manure and on manured land, and can be kept out to a large extent by using only mineral A Podurid, or spring-tail, found on manure beds. 58 AN ECONOMIC ENTOMOLOGY. or " commercial" fertilizers. In the manure itself they are bene- ficial rather than otherwise, hastening its decay by changing the form of the more resisting portions. It sometimes happens that, when found associated with decay or rot of stored produce, the insects are accused of causing it ; but they always follow and never precede or cause the diseased appearance. CHAPTER III. THE NEUROPTERA AND PSEUDO-NEUROPTERA. May-flies, Dragon-fiies, Stone-flies, Caddice-flies , etc. The old term Neiiroptera comprised all insects with four more or less transparent wings, reticulated or netted with numerous longitudinal and transverse veins, and the mouth parts formed for biting. As thus defined the order was easy of recognition, and, practically, the division is convenient here, for nowhere in this series are any species injurious to field crops. We find troublesome species among the parasites, and the Termites, or " white ants," are injurious under some circumstances ; but, as a broad statement, subject to a few exceptions, it is correct to say that no Neuroptera are injurious to field crops, and no appre- hension need be felt whatever the numbers in which they may appear. It was early found that under this term insects quite different in life habits were included, some having complete and some in- complete metamorphoses. The order was then divided, the term Fsezido-neiiroptera being applied to those forms in which the transformations are incomplete. The division is a good one ; but, as there is nothing in the adult to indicate to the tyro the nature of the changes it undergoes, it was not always easy to de- cide to which order a given insect belonged. More recently the series has been yet further divided, and we have now somewhat compact groups of net-veined insects which may be recognized without much trouble. These will be referred to in order under their modern names. THE INSECT WORLD. 59 Fig. 31. Order EPHEMEROPTERA. This order inckules what are known as "May-" or "day- flies," the names indicating either the time at which they first appear or the brief period of their adult Hfe. "May-flies" occur most abundantly during spring or early summer, in the vicinity of lakes, ponds, and rivers. They are readily recognized by their fragile body, terminated by two or three long, thread-like appendages, and by their large, frail wings, the posterior much smaller than the anterior. They fly at night, and are readily attracted to light, dozens being often seen hov- ering around a single street lamp. I have seen bushels of them at the base of electric lights on the banks of the Ohio, and the shores of the Great Lakes are sometimes covered with heaps six inches or more in depth, so that the stench from the decaying bodies becomes nearly insupportable. The head is large, the eyes are round and prominent, and the forelegs are conspicuously long and stout ; but the feelers are reduced to mere rudiments, and the mouth parts are atrophied and utterly useless for feeding purposes. In the May-flies we have the survival of an ancient type, their generalized structure indicating a low place in the scale of -devel- opment. The eggs are laid on the surface of the water and sink gradually to the bottom. From them hatch narrow, elongate- oval, more or less flattened larvae, furnished laterally and some- times at the end of the body with gill-tufts, living in the mud ooze of river and lake bottoms, under stones, or among aquatic plants. They feed on all sorts of minute animal life, and prob- ably also upon the low forms of vegetation on submerged stones or sticks. They grow slowly, moult frequently, and live from Mav-flv and its larva. 6o AN ECONOMIC ENTOMOLOGY. one to three years in this condition. Wing-pads gradually appear, and eventually the adults emerge and fly away, only to shed their skins once more in the very act of flight. I have seen their delicate, pure- white exuviae float about over the Ohio River in such numbers as to resemble a fall of snow. This moulting of the adult is peculiar to the Ephemerids, who mate soon after it occurs, deposit their eggs, and before morning perish, — their life-work accomplished. Not all forms are so short-lived, however, some requiring sev- eral days to complete oviposition ; but their inability to feed indicates a brief existence at best. The number of species is large, and the number of specimens immense, indicating an active, aquatic insect life at least as great as that found in the air or on the dry land. While the larvae feed on smaller creatures, they are in turn devoured by fishes, who find in them an important article of food, and in this view only are they of any economic importance. Order ODONATA. Under this head come the dragon-flies, or, as they are often termed, "devil's darning-needles," "spindles," or "snake- doctors." Many superstitious beliefs are connected with these insects, and there is a general indisposition to handle them, be- cause of their supposed ability to sting. The insects are common about ponds and streams, flying rapidly over the surface of the water, occasionally darting down to touch its surface, and delight- ing always in the bright sunshine. The body is long and slender, fitted with an enormous head principally occupied by the eyes, and with two pairs of long nar- row wings, which are similar in size and appearance. In some species there are leaf-like appendages at the end of the abdomen, and these are erroneously supposed to be weapons of offence. The legs are stout, clothed with spines and spurs, as well as with long claws at the tip. The mouth is formed for biting, the man- dibles and maxillae being greatly developed and sharp-toothed, for tearing their prey. They are, as has been indicated, predaceous, and capture their food during flight, their powerful wings and legs enabling them to overtake and grasp any creature that comes within the range of their huge eyes. Flies and mosquitoes are the usual victims, and THE INSECT WORLD. 6i hence the term "mosquito hawk" has also been apphed to them. It has been suggested that dragon-flies might be artificially propagated to lessen the mosquito pest ; but this is not feasible, because they fly only during the day, while the mosquito is decidedly more a creature of the night. No dragon-fly volun- tarily remains in woods, except along streams and in open glades, yet here mosquitoes lurk by the million. The proposition looks well at first sight, but is not practical. KiG. 32. Draguii-fly arnl its ile\ clopment. — Lar\a ami pupa feeding at i and 3; 2, nymph ready to change ; 4, a pupa skin from which 5, the adult, has emerged. The early stages are passed under water, and the larvae are ugly creatures, somewhat resembling the adults, but without wings. They move sluggishly among the aquatic vegetation, or on the mud of the bottom, strongly resembling the latter in color. They do not swim readily, but some are able to propel themselves by drawing into the posterior part of the digestive tract a quantity of water and then expelling it forcibly. This process really answers a double purpose, for this same tract is supplied with numerous fine tracheal tubes through which oxygen is drawn from the water : two functions, respiration and locomo- tion, being thus curiously combined. Respiration is also carried on by means of leaf-like anal appendages, in which trachea ramify in all directions, forming gill-like structures. As the larvae grow, wing-pads appear, and when these are fully developed the pupal stage has been reached ; the insects continuing active, however. 62 AN ECONOMIC ENTOMOLOGY. until ready for the change to the adult. Then they crawl up the stem of some water plant, or upon a projecting stone, and soon the skin splits and the imagos_emerge. A few minutes suffice to harden and dry the newly-developed adults, then with spread wings they sail away on a new career, in a new medium. In habit the larvae are as predaceous and voracious as the adults, and their prey consists of any aquatic forms which they can cap- ture, — mosquito larvae forming quite a staple article of diet. It has been already indicated that they are not very active' creatures, and prey is captured by simply waiting in the mud or on a mossy stone until it comes within reach. Their color renders them almost invisible under such conditions, and nature has furnished a remarkably extensile mouth structure, by means of which they are able to reach out some distance and seize whatever creature may be passing near. It is the labium, or lower lip, that is modified for this purpose, and is supplied with a double hinge which can be straightened out rapidly to bring into play a pair of large, slender, and pointed jaws at its tip. When this structure is retracted it is invisible, covering the other mouth parts entirely and hiding them. The term ' ' mask' ' has therefore been applied to it. Oviposition varies with the species, and is interesting. The sexes pair during flight. The male has the organs of copula- tion at the base of the ab- ^^' domen, while the opening of the testes is at the tip. Before pairing he fills the seminal pouch at the base of the abdomen, then grasps the female by the neck with a pair of anal claspers, and she curves up the tip of her abdomen into contact with the opening to the seminal duct of the male. As the eggs are fertilized the pair descend to the surface of the water, the female drops a little mass upon the surface, and copulation is resumed, the process being repeated until all the eggs are laid. A species of v4^r/o« and its larva; the latter with anal gill-tufts. THE INSECT WORLD. 63 In some species the female when impregnated crawls under water, down the stem of some aquatic plant, and lays her eggs on stones, plants, or even in the mud. By folding the wings backward, close to the body, a film of air is gathered which keeps the insect dry and supplies it with a sufficient amount of oxygen for a temporary return to its old medium. The order contains no injurious species, because all are pre- daceous ; but, on the other hand, none are markedly beneficial, because, though they devour an enormous number of other insects, these are not usually species destructive to farm crops. Order PLECOPTERA. The ordinal term signifies "plaited wing," and is used because the hind wings are longitudinally folded or plaited beneath the Fig. 34. stone-fly, Perla bicandata. and its larva. anterior pair, which rest flat upon the back. The insects them- selves are called "stone-flies," and are loosely jointed, flattened, 64 AN ECONOMIC ENTOMOLOGY. the thoracic parts large and not closely united, the wings exceed- ing the abdomen in length. In texture they are rather soft, and the antennae are long and many-jointed. They frequent the margins of streams and running ditches, preferring damp, shady localities. The mouth parts are mandibulate, but their food habits are not well known. They are not injurious, and are economically important only as food for fishes. The eggs are laid in masses upon the surface of the water, through which they sink to the bottom. The larvae are flattened, live among and under stones, feeding upon vegetation, and probably also upon such small, soft-bodied creatures as come in their way. The legs are well developed and of nearly equal size. The antennae are long and slender. There are usually slender, hairy appendages at the end of the abdomen, and on the under side are tufts of gill- like structures serving for respiration. In some species these gills persist even in the adult, forming a remarkable exception to the general rule that adult respiration is through spiracles only. One natural family the Perlidce, comprises the entire order. Order PLATYPTERA. The ordinal term signifies "flat winged," or " broad winged," and in those forms in which wings are present the secondaries are not folded or plaited, but lie flat over the body, covered by the primaries. The mouth parts are mandibulate, the thoracic rings are loosely jointed, and as a rule the insects have a flattened appearance. In most cases the head is large and prominent, wider than the thoracic rings. Three distinct families, using that term loosely, are grouped in this order, diflering greatly from each other, all of some economic importance, and requiring more detailed consideration. Family termitid^. Termites, or "white ants," as they are called, from their appearance and habits, occur all over the United States, but are more common southward. They are separated as a distinct order under the term Isoptera, meaning similar-winged, and are interesting from their social organization, which is complicated, several forms or castes existing in each colony. All our species live in and feed upon woody or fibrous material, though extend- THE INSECT WORLD. 65 ing their galleries through the soil, often for great distances, and also inhabiting underground chambers. In woodland almost any log or decaying tree will be found swarming with these dirty yellowish-white insects, about one- fourth of an inch long, readily recognizable by their large heads and oval, obtusely- terminated abdomen. Fig. 35. They are wingless, and when exposed to light seek at once to make their way back into darkness. These are workers, and blind ; they never voluntarily come out of their gal- leries, all their wander- ing being in tunnels of enormous length run over or under ground in every direction from the main nest. If they must reach a point to which they cannot burrow, they build a covered way of earth mixed with saliva, woody and excrementitious matter. These workers are the most familiar to the casual observer, and form much the greater pro- portion of the inhabitants of a nest or colony. They have distinct, hard, brown mandibles, not excessive in size, and can be thus readily distinguished from the soldiers, which are larger, with proportionately larger heads and very largely developed mandi- bles. The soldiers form a standing army whose duty it is to protect the community ; therefore, if we disturb a colony the workers at once run away, leaving the field to the soldiers, who are impotent enough in the daylight, blindly gnashing their jaws ; but are no doubt useful in the ordinary routine of Termite life. Early in spring we find, in addition, larger, winged individuals, chestnut-brown in color, and these are the true sexed forms, male and female. On a bright, warm day, when spring is well advanced, these individuals, which by the bye are furnished 5 Ttrmes fiavipes. — a, larva; b, winged male; c, worker; d, soldier: e, female;/", pupa. 66 AN ECONOMIC ENTOMOLOGY. with eyes, leave the parent-nest in great numbers and fly about, enjoying for a few brief hours the sun and air. They are then said to be "swarming," and select their mates, returning to the surface before the setting of the sun. Out of the vast numbers leaving the nest few survive the day of flight. They have numer- ous enemies, and, even if they escape these, must depend upon being found and adopted by some vagrant workers before they are able to form a colony. The sexed individuals — king and queen — are helpless, can do nothing for themselves, and are not permitted to return to their old home. This serves to keep the insects in check, for the chances of starting a new colony are very small. Let us assume, however, that a pair is adopted and housed, the workers at once building a proper habitation for the royal pair. Reproduction begins immediately, and the female, now stripped of wings by her own act, gradually enlarges, the abdomen ultimately becoming a mere egg-sac. Such a queen becomes the mother of the colony, and she is tolerably prolific : sixty eggs a minute have been counted, making a possible output of over eighty thousand in a single day ! The workers take entire charge of the eggs and resulting young, feeding and tending them until they are able to take part in the ordinary work of the colony. Both males and females are represented among the larval forms, but it seems to depend entirely upon the nurses as to what caste is to result. They are able at will to arrest devel- opment and to produce whatever forms are needed in the com- munity. Thus workers and soldiers are each of both sexes, but the sexual organs never become developed or functional. A certain proportion are allowed to develop fully, and these furnish the annual swarms. If the queen becomes old or unable to sup- ply the colony with a sufficient number of young, the workers provide for a number of " complemental" males and females. These never become winged, reaching only the pupal stage in which the wing-pads appear, and they never leave the nest, but pair within it, the female laying fertile eggs, though never in such numbers as a perfect queen. Therefore, several of these comple- mental pairs may inhabit a colony, and there may be no real queen at all. Curiously enough, no queen of our common species has ever been found, and we are yet in ignorance of just where the royal chamber is situated. THE INSECT WORLD. 67 Termites become injurious in one of two ways : they either eat into wood-work of furniture and buildings, or they attack grow- ing plants. In the Northern and Eastern United States they confine themselves to dead wood, and we have only a single spe- cies, — Termcs flavipcs ; but in the South and Southwest they attack living plants, among them orange-trees and sugar-cane. In buildings they sometimes live in beams, weakening them to such an extent as to threaten or actu;illy cause collapse. Not many years ago some of the heavy wooden supports of the Bos- ton State House were found infested, and more recently a build- ing in Cleveland, Ohio, was invaded, requiring prompt measures to prevent accident. They also attack stored products in gen- eral, skilfully concealing their presence by leaving the outer sur- face untouched. Thus, in a pile of old records stored in a vault of the United States Department of Agriculture, a large proportion was found badly injured, though no external trace appeared. In the United States National Museum is a mass of black linen thread from a South American store-house in which the outer form of a pile of skeins is accurately preserved, while all below is a mass of hard, black galleries. These are made of the partly digested and excreted thread itself ; and so we find that in the galleries in logs or trees the walls are composed of partly digested wood-fibre. Termites are often found in decaying stumps, and sometimes in the roots and stems of weak and dying plants ; in the latter case often hastening or inducing death. In the Southern States they are more abundant and troublesome, attacking sugar-cane and also eating the bark of orange-trees at the crown. REMEDIAL MEASURES. Where the insects are found in buildings, injecting bisulphide of carbon into their galleries will destroy them. They should be traced to their outside nest, if possible, and, when found, this should be destroyed. Frequently an old stump of some large tree may be a centre from which a district becomes infested, and the bisulphide should be liberally employed wherever the insects are observed in numbers. On growing plants the bisulphide is also useful in many in- stances ; but here, too, the efitbrt should be made to discover the 68 ^A' ECONOMIC ENTOMOLOGY. central colony, rather than to protect individual trees or plants. Hot water has been recommended, but is not so effective as the bisulphide. Dead stumps and pardy dead, infested plants should be removed and burnt, to deprive the insects of congenial quarters. The true home of the Termites is in the tropics, where they are pests of the first magnitude. In Africa some of the species are mound-builders, erecting turreted structures from ten to fif- teen feet in height, made up of earth and partly digested wood and other fibre. Family psocid^. To this family belong the minute "book-lice" often found in dusty corners, under loose paper, in collections, and in other dry localities. They are always small, resembling somewhat a "Termite" in miniature, very active, running backward or for- ward with equal facility, and furnished with very long, slender antennae or feelers. The head Fig. 36. A book-louse, X 25 diameters. is very large, with small, coarsely granulated com- pound eyes. The mouth or- gans are mandibulate, but not at all prominent, and fitted for gnawing rather than biting, — whence the insects have been called Corrodentia or ' ' gnawers. ' ' They are white or dirty-yellow in color, and look just enough like true lice to be mistaken for them under some circum- stances. Occasionally con- ditions favor their increase in houses, and almost in a day it will be overrun, beds and bedding being especially favored, to the horror of the housewife, who almost invariably mistakes their true character. Several times within my experience I have received these creatures with anxious entreaties for a remedy, and equally anxious requests for secrecy. The Psocids may be always distinguished from para- THE INSECT WORLD. 69 sites by -their very rapid motions and their long antennae or feelers. Their food is starch, where they can get it, or dry ani- mal or vegetable matters, and they can be driven out by a free use of naphthaline crystals. Their injury in libraries is done by eating the starched surface of bindings, plates, and pages, and so disfiguring them. The forms just described are all wingless throughout their en- tire life, Atropos [^Clothilla) divinatoria and A. pulsatoria being common species. In some mysterious way the term "death- watch" has been applied to these creatures, and they have been credited with making the ticking sound often heard at night in old houses, and which is supposed to give warning of a death to come. But there are some winged forms, and these somewhat resem- FiG. 37. Psociis lineatus, much enlarged. ble overgrown plant lice, differing, of course, by the mandibulate mouth. These winged Psocids sometimes occur in great num- bers on the bark of trees, in my experience most often on cherry and orange, where they feed upon lichens and other dry vege- table matter. They sometimes create alarm when great numbers are noticed by the farmer ; but none of them are in the least in- jurious. They are more cylindrical in appearance than the wing- less forms, and the thoracic parts are better developed and larger than the head, which bears the same coarsely granulated eyes and long antennae. When a group of specimens is disturbed they run in every direction, and often drop to the ground rather than use their wings in flight. Altogether, this family 70 AN ECONOMIC ENTOMOLOGY. contains insects that simulate injurious forms, while doing little or no actual damage themselves. Family mallophagid^. The literal meaning of this term is "wool eater," and it ap- propriately expresses the habits of some of the species. All members of this family are parasitic, and are known as biting lice ; never sucking blood, but feeding upon young hair, feathers, skin-scales, clots of blood, and scabby or other scurfy material found on the skin or among hair and feathers. They infest warm-blooded animals only, and principally birds, whence the term "bird-lice" has been erroneously applied to the entire group. All the common farm animals except the pig are infested Fig. 38. Biting-lice.— (I, clog-louse, Trichodectus latus ; b, sheep-louse, Trichodectiis sphcero- cephaliis ; <-, turkey-louse, Goniodes siylifer. by some species of this family, and all the poultry or fowls are troubled to a greater or less extent. The insects are all small, flattened, with large, prominent head, often bulging eyes, and short antennae or feelers. The legs are short and stout, fitted for holding to and moving among hair or feathers, and the abdomen is oval. No trace of wings is ever developed. The eggs are fastened to the hair or feathers of the host, and in a few days the young emerge, not differing from their parents except in size and sexual immaturity. The entire life is thus tup: insect world. 71 passed on the host, and the insects usually spread from one animal to tlic other on occasions of contact, or through litter into which some specimens may crawl or be thrown. They also crawl upon the wood-work of coops and stables, and thence upon such animals as may rest against it. The only way to reach these insects is by means of poisons acting through the respiratory system, and this is not difficult, because the spiracles are not well protected. Barn-yard fowls will keep themselves tolerably free if furnished with plenty of fine dust. The finer it is the more effective, and the birds will so thoroughly powder themselves that few of the parasites can escape. Cleanliness on the roosts and in hen-houses is impera- tive, and a liberal use of whitewash and occasionally of kerosene on all the wood-work is useful. A badly infected house may be cleaned by shutting it up tight for twenty-four hours, and evap- orating in a shallow dish a few ounces of bisulphide of carbon. This kills all, save eggs, and the treatment should, therefore, be renewed a week later to reach such as may have hatched since that previously made. It has also been recommended to hang small open vials of bisulphide below the perches, and this, it is asserted, kills the parasites without discommoding the fowls. On farm animals greasy mixtures may be successfully employed, or carbolic or tobacco washes or dips. For larger animals — horses, cows, or mules — a thorough grooming with comb and brush, dipping the brush into a kerosene emulsion diluted five times so as to moisten all parts of the body, is decidedly the best method. This must be duplicated a week later to reach any that may have hatched from eggs since the previous treatment. On large herds, badly infested, the kerosene emulsion, diluted nine times, is simply sprayed on the animals as they pass through a narrow opening, the application renewed at intervals of a week, until no more lice appear. With so considerable a range of remedial and preventive measures no serious trouble from these parasites need be appre- hended, and it remains only to urge again the utmost cleanliness everywhere as the best of all preventive measures. All the neuropterous orders heretofore treated have had the metamorphosis incomplete, and are therefore classed as pseudo- 72 AN ECONOMIC ENTOMOLOGY. or false-neuroptera. While they are not directly followed in the classification by the true neuropterous series, yet for convenience they may be so arranged here, and not entirely without reason, because they are descendants of the same stock. Order NEUROPTERA. As this term is now limited it includes only those nerve- or net-winged forms with complete metamorphosis in which the biting mouth parts are well developed and not prolonged. The thoracic parts are large, frequently the prothorax is dis- tinctly separated and square, and the entire insect is somewhat flattened. Of this type are the large forms like Corydalns and Chaicliodes, and the peculiar Raphidia found on the western coast, members of the family Sialidce. The head is large and broad, the mandi- bles well or, as in the male Corydalus, even enormously developed, the antennae long and many jointed ; in Chauliodes pectinated. The prothorax is always distinct, square or oblong, in Raphidia very long and narrow, the other thoracic segments well developed and loosely held together. The abdomen is soft in texture, and as a whole the forms appear loosely jointed. The broad wings lie nearly flat on the back and much exceed the tip of the ab- domen, the hind pair being partially folded at rest. The eggs of Corydalns are laid in masses on leaves or sticks, coated with a water-proof secretion, and from them hatch flattened six-footed larvae, which live under stones or other shelter on the bottom of running streams. They are furnished with gill tufts, through which they obtain oxygen, and prey on whatever insects or larvae may come within their reach. In turn they are preyed upon by fishes, and the larvae of the Corydalns cornntns, or "dobson," make excellent bait, being locally known as " hellgrammites." When full-grown they come to the edge of the stream and, under stones or other shelter, change to quiescent pupae, in which all of the limbs are free and the form of the future adult is fully shown. The species of this family are interesting, but of no sort of economic importance. Not so the next family, the Hemerobiidcs ,w\\\ch. contains numer- ous species of interest, all of them predaceous and beneficial to THE IXSECT WORLD. • Fig. 39. 73 The " hellgrammite" or " dobson" in all its stages. — Upper series : a, the larva ; b, the pupa ; c, the male adult ; (/, the head of the female : in the lower series the leaf bears egg masses at aa, enlarged at be ; d, the larva just hatched, with details from e toj. 74 AN ECONOMIC ENTOMOLOGY. the farmer. There are several sub-famUie.s, which together are termed "lace-winged flies," from their delicate, finely-reticulated or netted wings, which lie flat and are not folded. The insects are slight, and in the species allied to Hcmerobiiis the colors are brownish or smoky. They are less common than the forms allied to Chrysopa^ which are green, with long antennae and prominent, bright, yellowish-brown eyes, which have given them the name "golden-eyed flies" in some localities. They are commonly found in fields or along the edges of woods, and emit, when handled, a peculiarly sickening odor which is quite unmis- takable when once known. In the adult stage the insects feed little or not at all ; but the larvae, known as " aphis lions," feed almost constantly, their prey being small, soft-bodied insects of all kinds, aphids or plant-lice ranking as special favorites. Fig. 40. A lace-wiiiged Hy, Ckrysopa oculata. — a, the ejfgs ; b, the larva ; d, same, feeding on a pear-psylla ; e, cocoon, from which /, the adult, has escaped ; g, head of adult in front, enlarged. The entire life history of the insects is interesting. The female in ovipositing touches the end of the abdomen to the surface, — usually a leaf, — upon which the eggs are to be laid, and then elevates her body about a quarter of an inch, emitting at the same time a viscid thread which hardens on exposure to the air. At the tip of this the q%% is fastened, and we get thus a little THE INSECT WORLD. 75 grove ol eggs on stilts. This is supposed to insure their safety from wandering predaceous forms that might otherwise feed upon them. Wlien the larva hatches it climbs down the slender thread, and attacks and feeils upon the hrst suitable specimen it can find, — usually a young plant-louse. Now, here is another peculiarity : it does not chew or tear its prey, but holds it firmly, sucking the juices by means of grooves on the inner side of the large mandibles, which are closed by the slender maxillae. The larva grows rapidly, becoming rather more than a quarter of an inch in length, narrow, spindle-shaped, pointed at the anal ex- tremity, the head distinct and with prominent sickle-shaped mandibles. When full-grown it spins, by means of anal glands, a perfectly spherical, white, silken cocoon of very dense texture, and small in proportion to the lar\a. It resembles a moderate sized pearl in form and appearance, and when the adult is ready to emerge, a circular lid is lifted off to give the matured pupa exit. Comparing the fully developed insect with the cocoon from which it issued, the marvel is great that it was ever packed away in so small a space. These insects are really of much practical value, frequenting, as many of them do, tilled fields and orchards, feeding upon larvae, plant-lice, and similar creatures. They become injurious, however, in some parts of California, where they attack and destroy coccinellid or lady-bird larvae. Somewhat closely allied in all stages to the Hemerobiidcz are the Myy-melconidcE^ or "ant-lions," but they are larger, with longer and narrower wings, and clubbed antennae. As before, the adults are graceful, harmless creatures, which fly mostly at night, while the larvae are predatory, resembling the "aphis- lions" in structure, save that they are broader and chunkier in appearance. They are also peculiar in that many of them capture their prey in pits or traps. In constructing its trap, the larva usually selects a spot of mod- erately compact, fine sand, and excavates a funnel-shaped pit with the sides as steep as the sand will lie. It remains buried and invisible in a little gallery at one side of the bottom, in wait for any unlucky creature that may come within reach. Ants are the most frequent victims, from their wandering habits and their tendency to investigate, a pause at the brink resulting in a slip of 76 AN ECONOMIC ENTOMOLOGY. sand and a tumble into the jaws of the enemy. Should the ant recover a footing before reaching the bottom, a shower of sand, sent by the vigilant Fig. 41. 1 u 1 larva below, over- whelms and brings it down to its death. When the juices are exhausted, the empty shell is thrown out and the pit is repaired for other victims. Sometimes pits are made in saw-dust or friable leaf mold and some make no pits at all. The adults are of two rather dis- tinct series : the first with short antennae which thicken rather gradually toward the tip, including Myrmeleo ; the second with long, slender antennae, enlarging suddenly into a flattened club. The head is larger and the body more robust, covered with stiff bristly hair, giving the insects a fierce appear- ance. The most common genus is Asca/aphus, and the larval habits are not known, though it is probable, from what we learn of foreign species, that they do not build pits or traps. Though interesting, the family is of no economic importance. An odd family is the Mantispidtr, so named from the peculiar resemblance which they bear to the Orthopterous genus Mantis. The species are not common, and are easily recognized by the enormously developed forelegs, which are fitted for grasping, and are inserted into a long and slender prothorax. They are pre- daceous, while their larvae are parasitic in the egg-sacs of spiders. The eggs are laid on stalks, as with the "lace-wings," and the slender larvae that hatch from them live through the winter with- out food, becoming active again in spring, when they seek the Myrmeleo species. — The adult above; the larva in its pit, which is shown in section. THE INSECT llOKLD. 77 egg-sacs of Lycosid or running spiders. The larva, that succeeds, enters the sac and begins feeding upon the eggs, gradually losing its active form and becoming clumsy and grub-like. The pupa forms within the larval skin, and after midsummer the adult appears. Very curious creatures are the Panorpidcc, or ' ' scorpion- flies," usually ranked as an order under the term Mccoptera. They have netted wings similar to but more robust than the " lace-wings," but have the mouth prolonged into a beak, at the end of which the biting parts are situated. In the genus Pmi- orpa the males have a pair of huge anal forceps, curved up some- FiG. 43. Manlisf'a species. — Showing the legs and body from the side. A Panorpa, or scorpion-fly, and its larva. what like the sting of a scorpion, and from this the common name is derived. As a matter of fact, the insects are entirely harmless save to others of their kind, for they are predaceous. The genus Bittacus is narrower winged, with unusually long legs, looking somewhat like a crane-fly at first sight. Species belonging to the genus Boreus occur on the snow in very early spring. The larvae, so far as we know them, are predaceous and resemble caterpillars in appearance ; they have eight pairs of fleshy prolegs, however, while no true caterpillar ever has more than five. None of the species are common and none are of practical importance to the farmer. The " caddice-flies" have also been elevated to ordinal rank under the name Trichoptera, or "hairy-winged." The adults have moderately developed bodies, with large wings, which are more or less densely clothed with hair, the first pair often thicker 78 AN ECONOMIC ENTOAIOLOGY. than the second, which are folded beneath them. Both wings have numerous longitudinal veins connected by only a few cross- veins, losing the reticulated appearance of the more typical Neu- roptera, and resembling more closely some of the lower moths, for which, indeed, some of the smaller forms may be easily mis- taken. The mouth parts, however, though rudimentary, are mandibulate in type, and there is no approach to the coiled tongue of the Lepidoptera. The antennae are very long and slender, resembling hairs rather than jointed organs. The species are found frequently in great numbers along the banks of streams, ponds, or ditches, in which the larval life is passed. The larvae are caterpillar-like, with three pairs of unusu- ally well-developed legs, and live in cases which they make of bits of sticks, moss, leaves, stones, shells, or other material, held together by silken threads with which the entire inside of the habitation is lined. Frequently the cases are roughly and irreg- ularly constructed ; but as often they are marvels of skilled work- manship. Small Fig. 44. stones are fitted so carefully that no break as large as a needle-point oc- curs, and some- times they mimic shells so closely that conchologists have been deceived into believing them such. In these cases the larvae live, and from them they obtain their com- mon name " caddice " or case-flies. Whatever the form of the case, the insect lives in and carries it about everywhere through- out the larval life, crawling about under water by means of the large legs and keeping the soft, white, hind body constantly pro- tected. Some live in ponds or sluggish streams, others in rapid brooks and torrents ; some are vegetarians, some are predatory, feeding on other larvae or even on small fish. Some forms con- A caddice-fly, Limnophilus rkombicus, its larva, and at a the larval case. THE INSECT WORLD. 79 Struct effective nets in which very young fish become entangled and fall easy victims to the insect fishermen. Streams in which these kinds of caddice-flies are abundant are not easily stocked with fish unless the fry is so well grown as to be out of danger from this source. Practically, the insects are of no importance to the agriculturist. CHAPTER IV. THE ORTHOPTERA. Grasshoppers, Crickets, Katydids, etc. The order Orthoptera, or ' ' straight-winged' ' insects, includes those forms with biting mouth parts and an incomplete meta- morphosis, commonly known as "earwigs," "grasshoppers," "locusts," "crickets," and "roaches." The distinctive characters, aside from those just mentioned, are that the fore-wings are firmer in texture than the secondaries, and that the latter are folded fan-like, or plaited, when at rest. They are then covered by the primaries, which are usually nar- row and of little use in flight, resembling in this respect the wing- covers of the beetles, and here termed "tegmina." With few unimportant exceptions the insects belonging to this order are herbivorous, and among them are some of the most destructive pests to agriculture, such as the migratory locusts or grasshop- pers, which have been known and dreaded since the dawn of history, and the "Rocky Mountain locust," of evil repute in our own country. First come the Forficiilidce , or ear-wigs, generally accepted as forming a separate order under the name Dermaptera (skin- wing) or Euplexoptera (well-folded wing). They differ from all the other Orthoptera by having a pair of anal forceps and by their resemblance to the Staphylinidce, a family of half-winged beetles. The wing-covers are short and thick, not extending to the middle of the flattened abdomen, and the large hind wings are first plaited fan-like around a point near the middle of the anterior margin, and are then transversely folded into a neat little 8o AN ECONOMIC ENTOMOLOGY. packet, which is tucked away under the fore-wings by means of the anal forceps. Some of the species, however, lack the wings entirely, in which case the peculiar anal forceps and the beetle- like form distinguish them quite readily. Fig. 45. Cases or caddices, made by the larvae of Trichoptera, illustrating differences of shape as well as varieties of material used. Except in the South, ear-wigs are rare in the United States, and not injurious. In parts of Europe and in sub-tropical and tropical countries they are sometimes abundant and frequently annoying, eating at night into flowers in which they hide during the day. In vine- and flower-covered houses or arbors they are sometimes a nuisance, and their long, slender form and nocturnal habits have given rise to the unfounded belief that they crawl into the ears of sleepers and kill them. The female lays a small number of eggs only, and broods over or watches them until some little time after they are hatched. The more typical Orthoptera may be conveniently divided into series by their leg structure and method of locomotion, as follows : THE INSECT WORLD. 8i 1. The Cursoria, or "'runners," with stout, long legs fitted for rapid motion, — like the roaches. 2. The Raptoria, or "graspers," in which the forelegs are developed into grasping organs and the insects are predaceous, — in strong contrast to all the others of the order. 3. The Ambidatoria, or "walkers," in which the legs are long and slender, useful for deliberate progress only. 4. The Saltatoria, or "jumpers," which have the hind legs unusually long and well developed, fitted for leaping, — like grass- hoppers and crickets. KiG. 46. Ear-wig.— I, mature male ; 2, nymph ; 3, the wing, showing the radiate type of pleating. The Oirsoria, or "runners," belong to the family Blattida, or roaches. They are flattened, rather soft, repulsive creatures, with long, powerful, spiny legs ; long, slender, filiform antennae, and the head bent under the body so as to locate the mouth parts between the front legs. They are brown or yellow in color, are nocturnal in habit, and live under bark or in crevices, for which their flattened form suits them peculiarly well. Roaches eat almost anything, or are practically omnivorous. They are among the most ancient type of insects, and are yet disgustingly common in the tropics, their numbers decreasing northwardly until only a few cosmopolitan forms are found do- mesticated in houses. A peculiar feature in the life history is the method of oviposi- tion. The eggs mature at about the same time, and are closely packed into a somewhat bean-shaped case, which the female car- ries about with her, partially protruding from the end of the ab- domen, for several days. It is then deposited intact in some 6 82 AN ECONOMIC ENTOMOLOGY. Fig. 47. convenient crevice, and very soon thereafter the young issue. Modifications of this habit occur, and in some cases the eggs act- ually hatch within the body of the mother, who thus becomes viviparous. I am not aware that roaches ever become injurious to growing crops in our country ; but two species are certainly great nuisances in houses, — the " Croton bug," Phyllo- dromia germanica, and the ' ' black beetle, ' ' Periplaneta orientalis. Both are introduced and almost cosmopolitan forms. The former is small, averaging about half an inch in length, and is winged in both sexes. The latter is larger, varying between three- fourths and one and one-fourth inches, with short wings in the male and mere rudiments in the female. The most satisfactory way of dealing with these insects is by means of a phosphorus paste, spread upon bits of soft bread and placed near their haunts, all other food particles being care- fully put out of reach. A short period of such treatment will usually prove effective. Almost as good is a mixture of equal Fig. 48. Forjicula tcsniata, and female. male The Croton bug, Phyllodromia geynnanica. — a, first stage; b, second stage; c, third stage ; rf, fourth stage ; e, adult ; f, adult female with egg-case ; g, egg-case, enlarged ; h, adult with wings spread. All natural size except^. parts of finely powdered chocolate and borax, dusted into the crevices where the insects hide. The mixture should be inti- mate, and is best made in a mortar, so that with each part of THE INSECT JVORLD. 83 chocolate, of which the roaches are very fond, they will get also a particle of borax, which is poisonous to them. This mixture has proved successful in many instances within my own experi- ence, and has the advantage of being cheap as well as non-poi- sonous to man. The Raptor ia, or "graspers," form one family, the Mantidcs, as odd in appearance as their habits are unusual. They are clumsy, heavy-bodied insects, with short, broad wings, the middle and hind-legs rather weak, but with an unusually long and slender prothorax, to which is attached a pair of huge forelegs, armed with sharp spurs and spines. The head is usu- ally much broader than the prothorax, with prominent, often globular eyes, short antennae, and so set as to be capable of lat- eral motion. It is, in fact, the only type capable of turning its head ! The insects are, as a rule, sluggish, those occurring with us incapable of rapid motion, depending entirely upon such prey as Fig. 49. The Oriental roach, Periplaneta oricntalis. — a, the male; b, the female; r, egg-case. comes within easy reach, and securing this through their often remarkable resemblance to the vegetation among which they lurk. In other countries there are some more active species, capable of pursuing and capturing their prey. Their colors are green or yellowish, like leaves, or brownish, like bark ; the wing- covers sometimes mottled and roughened to mimic an irregu- larity or o\ergrown injury on a trunk or branch. Thus con- 84 AN ECONOMIC ENTOMOLOGY. cealed, they rest, body close to the surface, prothorax elevated, and forelegs held in the attitude of prayer, whence the term "praying mantes," Mantis religiosa, which is applied to a for- FiG. 50. Stagmomantis Carolina.— a, the female ; b, tlie male. eign species. But prayer is far from the object in view, as any small insect that happens within reach learns to its cost. A sud- den clasp wounds and crushes it into helplessness, and the Mantis then leisurely devours its victim, the forelegs serving admirably as hands in the operation. The eggs are laid in a mass on twigs or branches, held to- gether by a peculiar silken fibre which encases and protects each ^%^ as well as the entire cluster. The predaceous habit excludes these insects from the category of injurious forms ; but they are not sufficiently common in our country to be of any practical advantage. They are southern in geographical range, and only one species, Stagmomantis Caro- lina, is rarely found north of New Jersey on the Atlantic coast. The Ambulatoria, or "walkers," include a series of very curious species, popularly known as "walking-sticks" and "walking-leaves," represented in our fauna by a few species belonging to the family Phas^uidcs. The true home of these THE INSECT WORLD. 85 Fig. forms is in the tropics, where we find excellent examples of pro- tective mimicry in the development of wings so colored and veined that the insects cannot be easily distinguished from the foliage upon which they feed. Our own species have mere rudi- ments of wings only ; but have very long, slender bodies, an- tennae, and legs. When at rest, with long legs fully stretched out, the resemblance to a bare twig or a torn leaf is perfect. The insects move slowly and awkwardly, feeding on the foliage of a variety of forest trees, and are occasionally quite destructive. They do not extend north of the Middle States on the Atlantic Coast, but occur everywhere in the Central and Southern States, reaching northwardly in the Mississippi Valley much further than in the East. So far as I am aware, they never attack field or orchard crops, and are not strictly injurious to agriculture, though they may be to forestry. Unlike the families previously mentioned, they take no care of their eggs, but the females drop them at random upon the ground. It has been said that in a badly- infested piece of woodland the pattering of the eggs as they fall from the trees sounds like rain. Thoroughly and carefully burning over in- fested woodland during some favorable period in winter will prove effective in case remedial measures become necessary ; spraying with arsenites can be resorted to for the protection of single or small groups of trees. In the Saltatoria, or "junipers," we find the most destructive species, and they separate readily into three families : the Acridiidce, or "short-horned grasshoppers ;" the Locustidce, or "long-horned grasshoppers" and "katy- dids ;" and the GryllidiB, or " crickets," which have long horns or antennae like the Locustidce, but cylindrical instead of flat, sword-like ovipositors. The Acridiidce, or short-horned grasshoppers, are among the most common and best known of our insects, flying up or jump- ing out of the way, however one turns, among grass or low herb- Egg masses ol Stagmoniantis Car- olina, from above and from side. 86 ajv economic entomology. Fig. 52. Walking-sticks, Diapheromerafenwrata. — a and b, the eggs, enlarged, from the eage and side; c, young just hatching ; d, the male, and e the female adult. THE INSECT WORLD. 87 age in roads, fields, or meadows, but not favoring dark woods. Tiiey have no external ovipositor, but the female is furnished with four horny valves, between which the eggs pass, and which are also useful in making the hole, in soil or wood, into which the eggs are laid. The term "short-horned," as applied to these insects, is relative, and means that the antenna; are moderately stout, the joints well marked, and the whole member not as long as the entire insect, — in fact, rarely even half as long. A curious Fig. 53. Rocky Mountain locust ovipositing. — a, a, females with abdomen inserted in the soil ; b, an egg-pod broken open and lying on the surface ; c, a few scattered eggs ; d, section of soil removed to show eggs being put in place ; e, an egg-pod completed ; /, an egg- pod sealed over. character is a pair of ears situated one on each side of the basal segment of the abdomen, and we therefore expect and do find that most of the species are capable of making some kind of song or noise, though this ability is confined to the male. A series of species characterized by a very receding front, meeting the vertex of the head in an acute angle, is referred to the sub-family TryxalincB, of which there are many species throughout our country, none of them abundant enough to be injurious. They are partial to low, sedgy land or meadows, es- pecially on sandy soil, and I have met with the species most abundantly near the sea, or on the sandy plains not far inland. Some species are common on or near cranberry bogs, but are not injurious. Quite a series of species is referred to the sub-family CEdipodin(e, 88 AN ECONOMIC ENTOMOLOGY. Chortophaga viridifascia — a, larva ; b, adult. and these differ from the preceding in that the front meets the top of the head in an even, obtuse curve. The species are usually long-winged, and the thorax is either crested or rough and tuberculate, with somewhat prominent and sharp angles. Quite usually the hind wings are brilliantly red or yellow and black, sometimes blue, and frequently contrasting in color. To this sub-family belong those species that fly early in spring and have wintered in Fig. 55. an immature stage, ready for the trans- formation to the adult form as soon as the weather per- mits. Good ex- amples of such species are the green-striped locust {Ckoi'tophaga viridifascia), which occurs over a large part of the United States, and has the hind wings without strong contrasts ; and the large, red-winged Hippiscus discoideiis, which is more southern in its range, not extending north of New Jersey. Species of this kind are most frequent in barren, sandy, or partly desert regions, and few ever become injurious. Among the troublesome forms are the " Carolina locust," Dis- sosteria Carolina, and the long-winged locust, Dissosteria longi- pennis ; the first found throughout the United States, and easily recognized by its large size and the ample, black, yellow-bordered hind wings ; the latter a similar but somewhat longer-winged western species, usually confined to the Rocky Mountain region, but sometimes migrating for considerable distances from their normal breeding-places. These species deposit their eggs in the ground in the fall and the young hatch in the spring. The "Carolina locust" is often met with in late fall, clinging fast to the tops of plants, killed by a fungous disease which ordinarily keeps the species within bounds. It is further con- spicuous by its habit of poising a few feet from the surface, and making a continuous " whirring" or rasping sound. The sub-family Acridiince is one of great extent, containing those grasshoppers that have become famous by their evil deeds, Fii;. 5.S. Fig. 54, Syrbtua adiiiirabilU. ric;. 56, Hippisnts diM-i-idnii. ]-"ig. 57, Vissosfrira carn/hia. Fig. 5S, Schistocerca americatia. Fig. 59, MiiauDplus sfiretiis. Fig. 60, Mcla- noplus allanis. THE INSECT WORLD. 89 and it dififers from the precedint; in havino^ the breast between the anterior legs produced into an obvious tubercle or pointed pro- cess. The prothorax is usually smooth and (luitc even, rarely ridged or crested or even angulated, and the hind wings are not often contrastingly colored. The typical genus Acridium of older authors contained the long-winged forms, which, hatching in great numbers in their natural haunts, sometimes find food insufficient, and are seized with a migratory mania that impels them to rise, by what seems common consent, and fly to fresh fields and pastures new. Such swarms may number uncounted millions of specimens, and they leave a wake of devastation which only those who have seen can appreciate. The species described in biblical history is the Schistocerca peregrbuim, or true migratory locust, and is strongly resembled, except in size, by the Schistocerca americana of the Eastern United States, which is common and sometimes destructive in the South, but becomes more rare northwardly, until in Central New Jersey it is but occasionally seen. In all the species oi Acridium the wings are longer than the abdomen, and in the males the tip of the abdomen is not swollen. The sexes in these insects are easily distinguished, because the female abdomen terminates in four pointed, horny valves, or pieces, no trace of which is found in the males. Perhaps this is a convenient place to describe the life history of grasshoppers, or Acridiidce, in general. The eggs are most frequently laid in the ground, though sometimes in partly de- cayed wood, the horny valves already mentioned serving to make the holes. The species that oviposit in the ground select a moderately hard or compact soil where obtainable, not too densely covered with vegetation, and then force the abdomen into it as deeply as possible. When this is accomplished the eggs are laid, each coated with a gummy secretion which causes it to adhere to its neighbor and to form a pod, extending almost to the surface. The hole is then closed, and becomes indis- tinguishable except on close examination. In this state they remain through the winter, the young hatching during the fol- lowing spring or early summer. The term nymph rather than larva is employed for these young, unfledged grasshoppers, and 90 AN ECONOMIC ENTOMOLOGY. in this stage their traveUing powers are hmited, though their appetite is not. Yet even now they are able to cover consider- able distances if a short food supply makes it necessary. The wing- pads, which become visible early in the nymphal life, increase in size until the insect is ready for its final change, and when this occurs its powers for destruction are multiplied by the new facility in travelling. In some species the wings never become devel- oped even in the adult ; but these are easily distinguished from the immature stages of winged forms, because in the latter the rudiments of the hind wings always cover those of the fore- wings, while in adults, even when the wings are mere stumps, the secondaries are always overlaid or covered by the others. Our best-known migrating forms belong to the genus Melan- oplus, in which the anal extremity of the males is enlarged and swollen. Here we find the Melanoplus sprehcs, or ' ' Rocky Mountain locust, ' ' which in years past has caused ruin in many States west of the Mississippi, and even yet does much injury and periodically threatens disaster. The home of this species, about which volumes have been written, is on the high, dry, eastern slopes of the Rocky Mountains, and in some regions west of these mountains in Idaho and Utah. There it breeds abundantly each year, frequently extending into the adjacent regions to obtain food and maintaining itself for some time. As a result of any unusual increase in numbers with a corresponding failure of food-supply, emigration may become necessary, and the long, broad wings of the species suffice to carry it even to the Mississippi River, ranging north and south from Minnesota to Texas. But in these moist eastern regions the insect cannot thrive, and from millions of eggs laid only a small proportion of weakly larvae appear, which usually die before they mature. An allied but shorter-winged form is the Melanoplus atlanis, or "lesser locust," which occurs commonly over all the more northern United States, while the M. fenuir-riibrian, or "red- legged locust," is much the most common eastern species, some- times doing considerable injury to crops. Among the more common short-winged forms we have in the East species of Paroxya, in which the males are smaller and ready fliers, the females much larger, with wings covering half the abdomen, and used rather as aids in leaping than as organs THE INSECT WORLD. 91 of actual flight. The species of Pezotettix and aUied genera are short-winged in both sexes, are of medium or small size, and prefer cool or shady spots on mountain sides, among rocks, at the edges of woods, or in similar localities, hence never become economically important. The species are most numerous in the West and South. F'iG. 61. Lubber grasslioppers. — a, Dictyophorus rcticiilatis : b, />'/ iu/iys/o/u iiiagim. Two very large and clumsy species occur, both known as "lubbers;" one in Florida, short-winged, yellow and black, is Dictyophorus retiadatis, — the other, a Western plains species, dirty-brown in color, and with mere rudiments of wings, also known as the ' ' Buffalo grasshopper, ' ' is Brachystola viagna. Last to be mentioned in this series are the "grouse locusts," or TettigincB. These remarkable little creatures have the pro- 92 AN ECONOMIC ENTOMOLOGY. thorax very much developed and extended backward so as to cover a large part or even all of the abdomen. They frequent banks of streams and moist places, resembling in color Fig. 62. j-j^g dead leaves or muddy flats where they often occur, and they are powerful leapers. Many of the species are found as adults early in spring, while I have found others in September. None of them are known to be injurious. REMEDIES. The question of remedies against the ' ' locust, ' ' or Tettix. short-horned grasshopper, is an important one, not always easy of solution. As the country is brought into more complete cultivation the ' ' grasshopper' ' pest will natu- rally decrease, injury from the migrating forms only remaining to be dreaded. In the general life history it was said that a large proportion of the eggs are laid in fall, remaining unhatched during the winter. The young nymph, or larva, is a feeble insect, able to dig to the surface through the way opened by the pod, or through loose soil, but scarcely otherwise. Fall-plowing the infested land is therefore a most effective remedy. If the pods are deeply cov- ered, the young die attempting to get to the surface ; if lightly covered or exposed, their natural enemies find them easily ; and when the pods are broken, rain and sunshine induce decay or disease, and the eggs never hatch. Where grasshoppers other than the migratory forms are troublesome, systematic fall-plowing will effect a prompt reduction in their numbers. Special or lim- ited localities,! like cranberry bogs, are sometimes infested, and in such cases turkeys are effective. They prefer grasshoppers to almost any other food, and, if allowed to run where such abound, will eat nothing else. In some cases the arsenites may be used to protect crops which are easily sprayed, and occasionally " driving" will answer for the fledged insects. Larval forms in grass or short vegetation can be collected in large pans or "hopper-dozers," drawn by men or horses, and coated with coal-tar, crude petroleum, or other sticky substance, and of all these the crude petroleum is to be preferred. As against the migratory forms in their permanent breeding grounds, I have no suggestion to make here. The subject has THE INSECT WORLD. 93 been treated at great length in the reports of the U. S. Entomo- logical Commission and of the U. S. Department of Agriculture, and these must be consulted : the methods discussed and recom- mended are too numerous for reference here. In the invaded regions foil plowing to destroy the eggs and the use of the "hopper-dozers" on the young arc indicated. Under some circumstances, when the number of grasshoppers is not too great, they may be destroyed, or a large measure of protection may be secured, by tempting them with poisoned bran, of which they seem to be rather fond. It should be com- posed of bran and Paris green, at the rate of one part of Paris green to fifty by weight of bran, thoroughly moistened with sugar water. Cabbage patches can often be protected in this w^ay against grasshoppers that come from uncultivated land, and there are other cases where such a measure is of value. Indi- vidual judgment must determine those cases. The LoaistidcB are "long-horned grasshoppers," "meadow grasshoppers," and "katydids," distinguished at once by very long, slender antennae, rarely shorter than, and usually much exceeding, the body. They are green in color as a rule, with slender legs and thin wings, and we find them a vast array of mu- sicians, — always the males only, — the sound-producing structure occupying a triangular area at the base of the fore-wings, where they overlap. Here one or more of the veins is elevated and ridged on each wing, and by rubbing these ridged surfaces to- gether a strident sound is produced, in- tensified by a membrane tightly stretched between them. The pitch and volume of the ' ' song' ' are regulated by the develop- ment of veins and membrane as well as of the tegmina, no two species being alike in this respect. Special students of the family soon learn to recognize the sounds made by the different species as certainly as or- nithologists know birds by their song. The ears through which the songs appeal to the courted females and competing males are situated on the fore tibiae, and are essentially like the same organs found on the abdomen of the Acridiida. Fig. 63. Overlapping portion of the base of the wing in Cono- cephalus ,s\\o\\\t\p, the ridged veins and sound-producing organ. 94 AN ECONOMIC ENTOMOLOGY. Another feature peculiar to this family is the exserted, promi- nent, blade-like ovipositor of the female, which indicates an es- sentially lifferent method of oviposition. This, in fact, exists, for the eggs are mostly laid in plant tissue, — usually in the stems of reeds and grasses, among which some forms abound, — some- times in woody tissue ; rarely in leaves, the edges being split to receive them ; and only occasionally are they laid externally. Certain cricket-like species are exceptions, and oviposit in the ground. The most prominent, from their large size, are the species loosely termed "katydids," — insects which are familiar by their song, but are not always personal acquaintances, because they are most active and noisy in the evening, and prefer trees and shrubs to more modest plants. The true ' ' katydid' ' is Cyr- tophylliim concavHJU, much the heaviest in build of all our spe- cies, with very broad concave wing-covers and an unusually developed sound-producing structure. In fact, the entire fore- wings are immense sounding-boards, enabling the insect to make itself heard at great distances. It produces its characteristic note three or four times in succession, with slight intervals only, bear- ing thus a semblance to " Ka-ty-did" or " Ka-ty-did-n't :" oc- casionally it merely rasps out ' ' Ka-ty. ' ' This species lays its ovate, slightly convex eggs into the twigs or trunks of trees late in fall, and the young appear during the early summer following. One of the most common of the large species, found over a great part of the Northern United States, is the Microcentruni retinervis, replaced in the South by the allied M. laurifolium, which lay their large eggs externally in regular rows on the edges of leaves, on twigs, or on any sort of likely or unlikely place, — e.g. , the pulley-strap of a sewing-machine. The Southern spe- cies is the more common, and in Florida becomes injurious to young orange-trees by eating the foliage. They can be kept in check on such trees by collecting and destroying the eggs during winter, by collecting the insects themselves, or by spraying the foliage with one of the arsenites. The genus Scudderia contains smaller, narrower-winged spe- cies, in which the tegmina are not expanded in the middle and the ovipositor is curved sharply upward. They frequent shrubs P'lG. 65. The Southern katydid, Microcentrum /auri/oliitni. — i, the female adult; la, eggs laid on leaves and twigs of orange ; lb, the young katydids ; 2 and 2a, female and male Eitpflmus mirabilis : parasites on the eggs at 2h. 95 96 A.V ECONOMIC ENTOMOLOGY. and low vegetation, often near marshy or boggy land in sandy districts. The eggs are sometimes laid in the edges of leaves, singly, between the upper and under surfaces, and are so 'tKin that they can be perceived with difficulty only. They swell, however, very considerably before hatching. In New Jersey species of this genus sometimes do great injury on cranberry bogs, eating out the seed-capsule of the berries and rejecting the pulp. A single specimen may eat, at one meal, the seed-capsules of five or six berries, and in a week half a peck may be destroyed or rendered unmarketable. Turkeys exercise a good effect here also, the insects recog- nizing the presence of an enemy in a very short time and leaving the bogs. A good method of lessening the injury is to burn over the ground around the infested district to destroy the eggs. Nature itself does much to check increase, the number of speci- mens averaging about the same from year to year ; so any in- telligent interference by man must be to his advantage, and a destruction of the dropped leaves, especially of oak, which may contain eggs, will be a gain. Next in size and musical ability are the "cone-nosed grass- hoppers," Conocephaliis, with very long antennae, very long hind legs, very long and narrow fore-wings, and a pointed, conically- projecting head. In the female the ovipositor is as long as or longer than the rest of the body. These insects may be quite common, yet rarely seen, because of their resemblance to the reeds, grasses, and other vegetation among which they live. They do not become active until late in the afternoon, and may be located by their loud, shrill, long-sustained song. Then, quietly waiting until it is resumed, the male may be seen with wings rapidly vibrating and usually near his mate, for whose benefit all this concert is produced. The eggs are laid in the stalks of the reeds and grasses among which the insects live ; hence late mowing of infested meadows, or burning over, during the winter, swampy or marshy spots in which they breed will keep them in check when they become troublesome. Close relatives of the above are the smaller, green meadow grasshoppers, largely members of the genera Oi'chelimuni and Xiphidium, — the former with curved, the latter with a straight ovipositor in the female. These species all prefer moist lands V\G. 68. I'lc. 64. Fig. 66. Fig. 67. Fig. 04. the- katydid, Cyrtopliyllum coiicavum. Fig. 66, Oiclulimum vulgare, male. Fig. 67, Orchrlmmm vulgare, female, from side. Fig. 68, Mormon cricket, Ancbrui simplex : a, female ; b, c. anal parts of the male. THE IXSECT WORLD. 97 with rank vegetation abounding in reedy grasses, in which they lay their eggs, and among which they sport and sing, except during midday. They are especially fond of eating the seeds of grasses, and sometimes become troublesome from this habit. The late mowing and burning suggested for Conocephahis will answer in this case as well. We find quite a departure from the normal type in a series of wingless or short-winged species erroneously called "crickets," and, more correctly, "shield-backed grasshoppers." In the Eastern United States these are rare, found under stones or rub- bish in woods, sometimes in caves. Some are blind, and others have equally interesting structures, but are of little or no economic importance. From their peculiar humped shape some are known as "camel crickets." In the West these species become more abundant, and, at the base of the Rocky Mountains, extending up into the foot-hills, they find their true home. Here the ' ' Mormon cricket, ' ' Anabnis simplex, occasionally multiplies so greatly that it migrates to the plains below, destroying everything in its path. As the insects are wingless they move but slowly, and may be often checked by ditching in their path. They are very pugnacious, with cannibalistic tendencies, falling upon and devouring any injured comrade, and indulging in free fights when driven into a corner. A plowed field in their course forms a barrier difficult for them to pass, and in such an army of the insects can be materially reduced or exterminated by means of heavy rollers. Yet more cricket-like are the clumsy, large-headed species of Stenopalmatus , known on the Pacific Coast, where they occur, as "sand-crickets." They are sometimes quite plentiful, but have not been known as injurious, since they are partly carniv- orous in their food-habit. The crickets belong to the family Gryllidcr, and differ from the Lociistid(B in that they have the wings laid flat on the back, the fore-wings abruptly bent down at the sides, and, in the female, have the ovipositor cylindrical or needle-like, instead of flattened or sword-like. This ovipositor usually has a little enlargement, somewhat resembling a spear-head, just before the tip, which facilitates placing the ^%'g. The males are even greater musicians than the Locustidce, the entire wing-covers being modified into a 7 98 AN ECONOMIC ENTOMOLOGY. stridulating- organ. Here the sound is produced by the ridged edge of one wing-cover scraping over the ridged veins of the other, setting into vibration the membraneous spaces in both wings. The ear is situated on the fore-tibia, as in the LocustidcB. Fig. 69. A sand-cricket, Stenopalmatus species. The mole-crickets are curious, subterranean creatures, with small heads and powerful forelegs, developed somewhat like the corresponding organs in the mole. The larger, more common species belong to the genus Gryllotalpa, and are more frequent Mole-crickets, Gryllotalpa species. in the South and Southwest, where they occasionally injure field crops. They are strictly nocturnal in habit, and remain during the day in their burrows, in which a chamber is excavated to contain the eggs. THE II^SECT WORLD. 99 When they are sufficiently numerous to be troublesome, the insects may be attracted to the sweetened and poisoned bran mixture heretofore mentioned, and this will usually check injury. The field-crickets, species of Grylhts, well known to all, are found nearly everywhere, even in houses. They are usually dark- brown or blackish in color, with large, broad heads, and rather short though power- ful hind legs. They ^''^''- '2 are very active, and jump about so errat ically that it is not u | a Fig A field-cricket, Gryllm species. The tree-cricket, fif