c< ^ i^'^'^^ ^' f y- .^^r^i^cf^ :^ LIBRARY OF 1885-1056 'u Ay* ali ^ "mh S T \^ '>G^ANB- WILEY 4 PUT. ^ai; i.j iuiLy» - .'■i.ij>'jji ^,» O'o -Kx -^v ©KlA[IiftL[IS "^A[P3 [BrC!F3Ti}{]afl~/®[r,Ri,:, IPSIDRITEIS. AGRICULTURE N E W - Y 0 R K : coMPKISI^•^, AN ACCOUNT OF THE CLASSIFICATION, COMPOSITION AND DISTRIBUTION OF THE SOILS AND ROCKS, AND OF THE CLIMATE AND AGRICULTURAL rRODUCTIONS OF THE STATE ; TOGETHER WITH DESCRIPTIONS OP THE MOKE COMMON AND INJURIOUS SPECIES OF INSECTS. BY E. EMMONS, M.D. VOLUME V. ALBANY : PRINTED BY C. VAN BENTHUYSEN. 1854. TO T. ROMEYN BECK, M.D.. LL.D. SIR There is more than one reason why the conckiding divisions of the present work, undertaken to explore and ilkistrate the natural history of the State of New- York, and conducted under legislative patronage, should be dedicated to you. You were among the first to foster the enterprise, and remained its consistent advocate in times when adverse circumstances seemed to jeopardize its continuance : much more than this, your whole life has been assiduously engaged in promoting the advance of science and the spread of popular education, and the published results of your scientific and literary labors may be referred to as reflecting an honor upon your native State. Would that the merits of the present volume were such as to render it more worthy its dedication. THE AUTHOR. [Agricultural Report — Vol. v.] PREFACE. 1 HAVE not attempted, in the preparation of this work, to place before my readers an account of all the rare and newly discovered insects of New- York and New-England, but have confined myself to those which are most common and widely distributed. The rare and the local possess an interest in the eyes of the learned ; but those which gre daily met with in the fields and in our walks, are the ones oiu- interests demand us to know : the former do neither harm nor good ; but a familiar acquaintance with the forms and habits of the common and widely spread, is an indispensable preliminary towards enabling the husbandman to take advantage of the services they may be made to render him, or to protect his premises and the fruits of his labor from the depredations of noxious broods. This view has mainly con- trolled our undertaking : as the Avork is designed for those who are supposed to be mere beginners in entomology, and perhaps intend to prosecute the study no farther than practical results will warrant, it was thought fit to restrict the field of investigation to such insects as are sufliciently numerous to interfere in some way with the prosperity or comforts of the dwellers in this northern portion of our country. One part of my labor has been to collect materials in the field, and an- other to collect them from the researches of others, the latter item con- stituting doubtlessly the largest and most valuable portion of the entire work ; but it is confidently believed that naturalists and authors who have contributed largely to the common stock of entomological knowledge, and thereby earned and received a high and enduring reputation, will not be disposed to object to the diffusion of information fraught with such great consequence to the welfare of community. These distinguished investigators are honored by their discoveries ; bvit their discoveries require to be made known to all the world, to the end that their results may redound to the common good of the human family. After saying thus much in general, it is scarcely necessary to add that this work is designed to disseminate the information collected from various periodicals in which it was first gathered, and from expensive books of the day in which a large amount is almost inaccessibly stored up, but is not expected to add much to the materials of knowledge already accumulated. "We have been poorly supplied with the means of promoting the study of entomology in this country, notwithstanding we have among us such men as the Leconte's elder and younger, who both stand in the first rank of entomologists ; but it is unfortunate that their classical works are mostly confined to the libraries of the learned. I have made the freest use of Dr. Harris's excellent and practical Avorks ; and have also been very much assisted by our distinguished entomologist. Dr. Asa Fitch of Salem, Washington county, N. Y. I have occasion also to acknowledge a further indebtedness to Mr. Hal- DEMAN of Columbia (Pennsylvania), who enjoys a European reputation as a naturalist, for several valuable notes on various insects ; and could his as- sistance have been still farther procured, the value of my work would un- doubtedly have been greatly enhanced. I have figured such insects as I have seen, and know to belong to New- York and NeAv-England ; but I have not seen them in all their states, and am therefore frequently indebted to others for the figures given of the larva and pupa stages. Some are copied from Abbott & Smith's work on the in- sects of Georgia, and some from other Avorks of like kind. I have figured very few foreign species, and these have had some special purpose in view. The figures have been drawn from specimens of the insects themselves, by E. Emmons junior, and are faithful and accurate portraits of the indivi- duals from which they Avere taken. It is difficult, howcA'er, to secure a finished and uniform coloring, especially for so large an edition as three thousand copies. I do not deem it necessary to point out the faults of this volume ; for the keen-sighted, and those Avho are disposed to look after them, Avill find them Avith little trouble. I am persuaded, however, that the general reader, as well as the student, will find in it many valuable records. E. EMMONS. Albany, -July 25, 1854. TABLE OF CONTENTS. CHAPTER I. General Considerations . . 1-7 CHAPTER n. SKETCH OF THE ANATOMY AND PHYSIOLOGY OF INSECTS. Function of digestion — Circulation — Nervous system — Senses of Anatomical description of parts touch, hearing, smell, sight and taste Circulation - ■ Muscular motion — Function of propagation, pp. 7 Appendix to Chapter II, embracing references to Plates A, B and E pp.25 24 28 CHAPTER III. Remarks on the classification of insects pp. 29, 30 CHAPTERS IV TO XL ORDER I. COLEOPTERA PI ). 31 - I3S ClCINDELlD^ . p. 32 Carabid^ 38 DyTICIDjE 55 NiTIDULIDiE 58 Engid^ 59 STAPHTLINID.ffi 61 Byrrhid^ 66 HlSTERID^ 66 LUCANID^ 66; Geotrupid^ . . 6T SCARAB^ID^ . . 68 Troqid^ 70 DrNASTiD.a: 71 MELOLONTHIDiB 71 BUPRESTID^ . . 83 Elaterid^ 86 Lampyrid^ . . 89 [Agricultural Report — Vol. v.] b CONTENTS. Telephorid^ . . . . . . . . . . . . p. 90 Clerid^ . . . . . . . , . . . . . . 91 PtinidjE . . . . . . . . . . . . . . 92 Ltmexylonid^ . . , . . . . . . . . . 92 bostrichidje 93 PYROCIIROIDiE . . . . . . . . . . . . 96 CantharidjB .. .. .. .. .. .. 96 CiSTELIDiE . . . . . . . . . . . . . . 97 DiAPERIDiE , . . . . . . . . . . . . . 97 Helopid^ . . . . . . . . . . . . . . 98 Tenebrionid^ . . . . . . . . . . . . 98 BlapsidjE . . . . . . . . . . . . . . 98 PlMELIID^ . . . ^ 98 Bruchid^ .. ., .. .. .. .. .. 100 Attelabid^e . . , , . . . . . . . . . . 106 curculionid^ . . . . . . . . . . . . 107 ScOLYTIDiE ., .. .. .. .. .. .. 112 Prionid^ .. .. .. .. .. .. .. 115 Cerambycid^ . . . . . . . . . . . . 116 Lepturid^ . . . . . . . . . , . . . . 125 Criocerid^ . . . . . . . . . . . . . . 129 Cassidid^ . . . . . . . , . . . . . . 130 Chrysomelid^ . . , . . . . . , . . . 130 GALERUCIDiE . . . . . . . . . . . . . . 133 COCCINELLID^ 136 CHAPTER XII. ORDEK II. EUPLEXOPTERA p. 139 CHAPTER XIII. OEDER III. ORTHOPTERA pp BtiATTIDiE Mantid^ Phasmid^ aciietid^ Gryllid.5; LoCtJSTID^ CHAPTER XIV. ORDER IV. APHANIPTERA p. 148 140 -14 • P 141 142 142 143 144 145 CONTENTS. CHAPTER XV. ORDER V. HOMOPTERA ClCADID^ Membracid^ Aphidid^ . . COCCID^ pp 149 166 p. 149 153 168 162 CHAPTER XVI. ORDER VI. HETEROPTERA . . HyDROMETRIDjB Reduviid^ . . Lygjeid^ Cimicid;e COREID^ ScuTELLARIDjE CHAPTER XVII. ORDER VII. DIPTERA . . TiPULIDjE MusciD^ Tabanid^ . . Xtlophagid^ Sykphid^ pp . 166 - 171 . p. 167 168 169 169 170 171 pp 172-18S p. 173 181 182 183 183 CHAPTER XVIII. ORDER VIII. NEUROPTERA . . LlBELLULID^ Myrmeleonid^ EpHEMERIDjE pp. 184 - 18 , , p. 184 185 187 CHAPTER XIX. ORDERpx. TRICHOPTERA .. p. 188 CONTENTS. CHAPTER XX. ORDER X. HYMENOPTERA pp. 189 - 197 Tenthredinid^ p. 190 Ukocerid^ 191 ICHNEUMONID^ 193 Sphegidje 195 EVANIID^ . . 196 SCOLIID^ 197 CHAPTERS XXI & XXH. ORDER XI. LEPIDOPTEEA pp. 198 - 256 Papilionid^ p. 199 Heliconiid^ 202 NTMPHALIDiE 206 Lyc^nid^ . , 214 Hesperid^ . . 215 Sphingid^ . . 216 ^GEEIDjE 222 LlTHOSIID^ . . 224 Arctiid^ 225 LiPARIDiE 230 Saturn lAD^ 231 Lasiocampad^ 234 Hepialid^ 241 NOTODONTID^ 241 Nonagriad^ 243 Agrotid^ . . 243 NOCTUID^ 244 Geojietrid^ . . ... 248 TortricidjE 250 Yponomeutidje 252 Tineid^e 252 INSECTS OF lEW-YORK. CHAPTER 1. GENERAL CONSIDERATIONS. The common idea of an insect is, probably, sufficiently exact for all practical purposes ; yet it seems proper that the scientific idea should be expressed : indeed it is always im- portant to define clearly the limits of all departments of Natural History, by stating in determinate language the boundaries which confine them. Insects, then, are animals whose bodies are covered with a coriaceous integument ; and they are divided into three distinct segments or sections, the 'head, thorax, and abdomen. The head is provided with two an- tennae ; the thorax, with six articulated legs ; and the abdomen with many rings, and contains the digestive organs : the sexes are distinct. They have a respiratory, circulatory and nervous apparatus : the first permeates the whole body ; the second consists mainly of a long vessel extending through the body, and is called a dorsal vessel, from the position it occupies ; the third is a symmetrical arrangement of nervous threads in two lines, placed upon the abdominal face, and connect3d by knots or ganglia at every ring of the body. The breathing is performed through small openings along the sides of the ab- domen, at every ring : the air admitted permeates the whole system, and acts upon the fluids as in all animals. The most interesting peculiarities, however, consist in the changes which the insect imdergoes dimng its stages of growth, which, although the developments are not more remarkable than in other departments of the animal kingdom, yet difier from the higher in being stationary for certain periods, during which it performs the functions of a perfect animal, except indeed that which belongs to the exercise of the sexual ojk- gans. These changes are called metamorphoses, and consist of three stages, the toonn or larva, the pupa, and the perfect insect. [AcRICnLTUBAL RePOET — VoL. V.] 1 2 GENERAL CONSIDERATIONS. Insects, as defined in the foregoing paragraph, are still very closely related to other classes of aniilbls : thus they resemble the Myriapodes in the annular or jointed structure, and in the possession of two anteunse, but diifer from them by the division of their bodies into three segments, while the Myriapodes are composed of many rings, to each of which there is provided a pair of legs, as in the family of animals called Centipedes. They re- semble the spiders, or Arachnidse, somewhat in the division of the body, but the head in spiders is soldered to the thorax : they are also destitute of antennse ; the nervous system is condensed into fewer central ganglia, and sometimes their respiration is analogous to the pulmonary, the air being received into sacs or bags. They resemble the Crustacea in a few points, but differ essentially from them in the character of the respiratory apparatus, inasmuch as the Crustacea are provided with organs analogous to the gills of fishes. The resemblance which insects bear to the worms, Annelides, is the annulated structure : those worms have neither antennae nor feet, and, as to sex, they are mostly hermaphrodites. In addition to the foregoing, I may add, none of the classes have wings but insects, and their metamorphoses are of a different character, consisting mainly of a casting of the integu- ments as in the crab an4 lobster. All insects are oviparous, or spring from an egg laid before the birth of the individual. A few examples are known where the egg is retained in the b^dy, and there hatched. These eggs are often carefully concealed, and hence are discovered with difficulty : it is owing to this circumstance that they multiply to an injui-ious extent, and are often capable of devastating extensive territories. They are, however, generally laid upon the bodies which are to provide the food for the young : those which subsist upon herbaceous plants, are found upon or near the foliage ; those which feed upon wood are deposited in holes, or in cracks and crevices of trees, into which the young animal immediately begins to penetrate ; or, which is equally bad, the egg is deposited in the rudiments of the fruit, and will be ready to devoui- it when it is mature. Insects are extremely prolific, but the difl'erent species vary exceedingly. According to a statement in the Naturalist's Library, a certain large fly {Mese7nbri7ia 7ne)-idiana) lays only ■ two eggs ; while the female white ant lays probably not fewer than forty or fifty millions in a year, which are extruded at the rate of sixty in a minute when engaged in the act*. This statement embraces the extremes. Others are known to lay, as the queen bee for example, fifty thousand ; female wasp, thirty thousand, though generally only from two to three thousand. The eggs of the wheat fly are not very numerous, and probably less than one hundred ; yet even in that small number the increase will be sufficient to secure the destruction of the wheatfields in a large district. But many insects produce several broods in a season, and some of the most prolific produce several generations of young, consisting mainly of females, which are capable of laying eggs as soon as they have reached a stage • Naturalist's Library, Introduction, pp. 72, 73. GENERAL CONSIDERATIONS. 3 of full development. But the law of increase seems to rest upon the supply of food : where this is sure and constant, the increase is much greater than where it is precarious or un- certain ; thus those insects which subsist on animal food are comparatively limited, while the vegetable feeders are more numerous : this is in keeping with the harmony of nature, and the original arrangements of the Creator. The eggs of insects are made up, essentially, of the same parts as the egg of vertebrated animals. It consists of a yolk, with its germinal disc and gel-minal spot, which seem really to be nothing else than a cell with its nucleolus. The yolk is enveloped in a proper mem- brane ; and in order to defend and protect it, it is supplied with a hard outside envelope, analogous to the eggshell of the common fowl ; but the shell, the white, and its tough membrane, are not essential parts in the constitution of the egg. The eggs of insects, like all other eggs, obey the law of temperature. The young are hatched at an earlier day if the temperature is increased, and the hatching is retarded in a medium of low temperature. It therefore happens that man is often a gainer in consequence of the warmth of spring, which brings forward insect life at an early day, only to perish by the frosts which soon succeed. The eggs of insects are endued with the power to resist, or rather withstand, wide variations of temperatiu-e. It is evident that they sustain all the ordinary changes of the climate, and that it often happens that they are exposed to a temperature equal to 20" below zero. The ability to withstand either extreme of tempera- tiu-e depends upon the conditions of the egg : if it has progressed considerably towards the development of an embryo, its power to withstand those extreme changes is diminished. The pupa resists but feebly those changes when it first assumes this state ; but when it has nearly reached the period of completing its metamorphosis, it is surprising that it can resist a high degree of heat. I exposed the pupa3 of numerous silkworms, enclosed in a bottle, to 212^, without injuring them. I was surprised to find, not many days afterwards, that hundreds of millers of both sexes had escaped from their cocoons. The warmth of the sun, together with its light, is suiUcient to destroy the vitality of the pupa when it first assiunes that state ; but the eggs of insects require air, or oxygen, as much as the perfect animal : when enclosed in a vacuum, they lose their vitality. Oxygen is essential to the development of the embryo, and hence the outer covering must admit its passage. The eggs of some insects seem to grow : they increase in size, probal>ly by the absorption of moisture from the atmosphere, or from the surface upon which they are laid. The covering of eggs varies exceedingly : in some it is beautifully sculptured ; in others it is smooth and shining. These diiferent characters, if they could be fully delineated, would constitute important marks for the discrimination of species, for it is probable that they differ in the species to which they belong. The most remarkable fact in the history of insects, is their metamorphosis. The egg, as has been observed already, is similar to the eggs produced by oilier classes of animals ; but it never gives birth to a perfect insect, the immediate product of the egg being really as 4 GENERAL CONSIDERATIONS, unlike the perfect insect as possible ; for what can be more unlike than the caterpillar and butterfly 1 How disgusting the one, as it crawls like a reptile ; and how beautiful the other, as it flits in the air like a bird ! From the egg, the first state in which the insect appears is the larva. This stage of existence is characterized by the vermiform shape and construction of their bodies ; and it is a stage which attracts our attention more frequently than that of the perfect insect, and it is one in which it usually commits a greater amount of injury than in the perfect stage : it is, too, in this stage that the agriculturist can more effectually exterminate these his foes. The term larva is applied generally to the immature butterfly or caterpillar. Grubs are white, soft-bodied animals, which are immatiu-e beetles^ while maggots are immature flies, or belong to the dipterous order of insects. All, however, are the analogous re- presentatives of the different orders in the same stage of development, or that stage during which the insect grows and frequently casts its integuments : it devoiu-s immense quanti- ties of food, and is often very destructive to the foliage of vegetables. When it has reached its development for the larva stage, it ceases to eat, wraps itself in a mantle, simulates death, but is really luidergoing internal changes preparatory to a higher stage of develop- ment. In its mantle it casts its old skin, which it presses down into the lower part of its envelope, and soon appears in a livery peculiar to the pupa stage. The time during which it is confined to this stage varies with every insect : in some it is brief ; in others, it is long. Insects are composed of thirteen segments, including the head ; but an obscurity often arises . from the consolidation of segments, and often produces thereby a disproportionate development of certain parts. The three segments immediately behind the head correspond to the prothorax, mesothorax, and metathorax of the insect ; and these bear the three pair of legs, provided the larva possesses legs. These are persistent, and hence are called true legs, to distinguish them from the abdominal legs, prolegs or props, which are caducous, or are never transmitted to the perfect insect : they are peculiar to the larva. The mouth-pieces or oral organs frequently differ in the diffierent stages also. These are sometimes designed for suction in the larva, while the perfect insect is provided with jaws for mastication ; hence, in such cases, the natirre of the food is changed : in other cases the provisions for taking food are the same in both stages. The larvae grow rapidly, as a general fact, insomuch that the whole structure of the animal indicates provisions subservient to this result : they are provided with strong and efficient organs of manducation ; their digestive organs are very large and capacious ; the function of digestion is rapidly effected, and the consiunption of food is immense in pro- portion to the weight of the body. It is stated that flesh-flies increase two hundred times their weight in twenty-four hours. Count Dandolo remarks that the weight of the silk- worm, when first hatched, is about one-hundredth of a grain, or it requires one hundred of them to weigh a grain : after the first moulting, one hundred weigh 15 grains ; after the second, the same number weigh 94 grains ; after the third, their weight is 400 grains ; GENERAL CONSIDERATIONS. 5 after the fourth, their conjoint weight is 1628 grains ; and after the fifth, when they have attained a length of three inches, they weigh 9500 grains. These changes of skin, called moulHngs, seem designed to accommodate the development of the body to its outer enve- lope : it is a critical period ; and if any accident happens which interferes with its proper performance, the animal either perishes, or is left in an enfeebled state, and is unable to assume the form of the perfect insect. The number of moultings varies with the species, but is always alike in the same species : the same changes are repeated in each respective- ly. All these changes are best observed in the silkworm, in which their number is five, and require thirty days for their complete performance. In some insects the number of moult- ings extends to nine or ten, while in others it does not exceed three or foui-. The larva ceases to eat when it is undergoing this process : an internal change takes place, however, whidi greatly favors the casting of its envelope ; it is the absorption of the fat beneath the outer skin, which becomes shrivelled, while at the same time it gives opportunity for the expansion of the internal parts. The motions are strange during this period : their bodies are curiously shaken and contorted, with jerkings of the head and posterior parts of the abdomen ; these are designed to break up the attachments of the outer skin, and finally to detach it from the new skin beneath, which is bright, fresh, and moist. A rent is finally made in the old skin along the back, through which the animal now forces its way, in which process it is assisted by attaching itself to some point of support : this is managed so adroitly that the 6ld skin remains whole, except the rent along the back, and so perfect that it might be mistaken for the perfect larva. The change is not confined to the outer envelope : the organs of respiration, though extremely delicate, as well as those of diges- tion, cast off also their membranes, which are ultimately expelled from the body. It is no wonder, then, that the moul|;ing stage is one of great danger to the larva. This becomes still more hazardous to the silkworm which is placed in an artificial state, and which is increased by the numbers that are crowded into a small area. The last change is attended with circumstances somewhat peculiar. They first seek a suitable retreat, adapted to the natui-e of the insect itself ; a crevice in the bark of trees, a shelter under the roof of a building, or a hole in the ground, in which they construct a sort of chamber, which they line and otherwise prepare in a mode suitable to their necessities. They form habitations with much skill, and the bestowment of much care, to defend their bodies from the ex- tremes of temperature, or as a defence from their enemies. Sometimes, as in the dipterous insects, the old skin is converted into a pupa case, after becoming more rigid and stilF : in other instances a beautiful case is made, and a robe of silk is laboriously woven from a single thread, which is formed and spun from the juices of the body. The silkworm is an admirable example to illustrate the instinctive powers of insects in perfecting their stages of development. We admire the skill by which it suspends itself in its case, and the beautiful manoeuvres by which it manages to place the band of silk around 6 GENERAL CONSIDERATIONS. its body. The habitation of the pupa is usually called its cocoon ; which term, however, is more commonly applied to those silken cases or envelopes of which I have been speaking, and of which we have an example in the silkworm. This is so closely woven that it ex- cludes water, and is often stiffened by a glutinous matter, by which it preserves its original form even after the perfect animal has escaped : it is also farther strengthened by leaves and pieces of wood, which undoubtedly serve as a better protection from' its enemies. Thus this helpless state is guarded and protected by a system of means which are calculated to secure the existence of the animal in its utterly helpless state ; a state which simulates death, and which, in its ultimate triumph, resembles the resiu-rection of the body from the grave of real death. All insects do not imdergo the same changes ; neither are they alike in analogous states. Thus the caterpillar of our butterilies wraps itself in its mantle, where it silently under- goes its change ; but the grasshopper comes from the egg an immature insect, but with the general form of the perfect animal, and hops about with the rudiments of wings upon its back. As it grows rapidly, it outgrows its skin, which it frequently casts, like the larva of the butterfly : its wings continue to grow, and the body to increase ; the partial wings keep pace with these changes, till at last they are perfected, and the animal has reached its perfect state Avithout having lost its activity during its period of growth. The grass- hopper, then, never passes into the inactive pupa state ; and in this its metamorphosis is similar to bugs, and dissimilar to beetles and caterpillars. There is another difference in the history of insect life, which is interesting : it is not the inhabitant of the same medium through life. It may begin its career in the water, and end it in the air : the musquito is an example. Who has not observed the wiggler in stagnant water, and in our cisterns 1 It is the musquito enjoying its water-life to the full. When the time arrives for its change, it rises to the surface, bui-sts its mantle, thrusts up its head and spreads its wings, while with its feet it rests still upon its cast-oif mantle, then rises buoyant from its sinking bark, and flies away in triumph from the element whicli gave it birth. Equally remarkable are the appetites of the insect in its larva and in its perfect state. Thus the larva, or, as it is usually called, the maggot, sports and feeds upon the putrid mass ; but the fly, which springs from its mantle, seeks the honey of our table : so various are the forms and manners of insect life. The caterpillar, grub and maggot go through the three stages, or undergo a complete metamorjjhosis ; passing through the three periods which are known as the caterpillar, pupa, and imago or perfect stage. The last is the only period which is given them to continue their kind and generations : in many it is transient as the fleeting day, and seems designed only for fulfilling the law of increase ; which, when fulfilled, the insect dies. CHAPTER II. SKETCH OF THE ANATOMY AND PHYSIOLOGY OF INSECTS. The parts of the insect which are employed in description are the antennae, the segments, the wings and nervures, the eyes, the parts forming the mouth, etc. ; and these it will be necessary to describe somewhat at length. The tlu-ee divisions of the body are marked by deep incisions, by which the head, thorax and abdomen, or hind-body as it is sometimes called, are always distinct in the perfect insect ; but in the larva there are only two divi- sions, the head and body. The middle, or thorax, supports the head and wings. The head is armed with jaws or mandibles and palpi, and ornamented or sm'mounted by the anteunse, which, in some insects, are muc'li larger than their bodies, and are made up of many joints gradually tapering to a point. The wings of beetles are composed of dissimilar pieces, lying, when at rest, one above the other. The upper or outer wing is thick, and shaped to the parietes of the abdomen, being convex above and concave below : it protects the true wing, which is delicate and studiously folded, and 'is only elevated in flight, in order to give play to the true wings. The upper wings ai-e called elytra, to distinguish them from the reticulated wing ; they are also denominated wing-covers or cases, and are often finely sculptured, punctured or ornamented : to these the insect frequently owes its beauty ; upon these, too, the fine colors are impressed, which are often of a splendent hue or lustre. In other orders of in- sects the four wings are entu-ely reticulated, or composed of a fine network ti-aversed longitudinally and obliquely by nerviues which branch in the same species in a certain manner, which, from their constancy, have been employed by systematists to aid in clas- sifying, and as characteristics of genera. The wings are still farther modified in the Le- pidoptera ; the network is more compact and close, and is covered with fine scales but slightly attached, which appear to the unassisted eye like meal of a pearly hue. Butterflies and moths are provided with this peculiar wing, which, though extremely delicate and always injured when slightly touched wfth the finger, yet always appears perfect when first captured ; showing thereby their jwwer and ability to perform the natural functions for which they were designed, without sustaining the loss of this delicate substance. 6 * DESCRIPTION OF PARTS. The external covering of insects is quite hard : it is called integument, or crust, and supplies the place of the internal skeleton, and is the part to which the muscles are at- tached. It is somewhat horny, or corneous, but varies considerably in this respect in the different species : in certain beetles it is hard and inflexible ; while in others, it is soft and quite flexible. It resembles the true skin of animals in its divisibility into three layers, an epidermis, a rete mucosum, and a leathery tunic called the corium or dermis, the true skin. This outer integument is composed chemically of phosphate of lime and magnesia ; but, what is interesting, it is found to contain a peculiar substance, termed chitine, which is insoluble in potash. Phosphate of iron, albumen, and a peculiar coloring matter, are also among the substances composing this integument. The shape of the head is variable, but the spherical form predominates. The integument forms a kind of box, with an aperture in front, through which the organs of the mouth may be thrust. The posterior part furnishes a place and attachments for the muscles which move the head upon the thorax. The eyes are large, usually, and occupy the lateral parts of the head. The external parts of the head have received different names. The epicranium is that portion which extends from the eyes backwards. In front of the epicranium, is the forehead. The clypeus is the margin in front above the mouth. Sometimes the whole region in front of the eyes is called the face. The inferior parts of the box enclosing the head has also its spaces, which have received distinct names, as gula, or throat, which lies imme- diately behind the margin of the lower lip, and extends back to the prothorax. The cheeks are situated upon the sides of the head, from the eyes downwards to the mouth. The an- tennae are situated between the angle of the mouth and the eyes : they have a subglobose joint at the base, upon which they move, and which is placed in a kind of socket ; this is sometimes called a torulus. The mouth, as may be supposed, is constructed so as to answer the ends designed, and it is either suctorial or manducatory, masticating : if the food is fluid, it is suctorial ; if solid, it has jaws for mastication. In the mandibulate or masticating, there is perfect free- dom of motion ; in the suctorial or haustellate {haustdlata), the parts are more or less soldered together ,^ so as to form a tube for the transmission of fluids. The terms haustellata and mandibulata apply, therefore, to two great classes of insects, one of which subsists on the juices of plants and animals, which they obtain by suction ; the others, the masticating, subsist on solid substances. Animals destined to obtain food by modes so apparently distinct, furnish many distinctive characters of importance. The lubrum is the most anterior part seen from above ; it covers the mouth, and is united by a membranous hinge to the cly- peus : it is employed in retaining the food in the mouth during mastication ; it is, there- fore, a true upper lip, but of a variable form. Mastication is performed by the mandibles, which are two strong jaws that move laterally, and consist of wedge-shaped or triangular pieces more or less elongated, and placed immediately below the labrum. These organs are also called upper jaws : they move like the blades of scissors. Their inner edge is fre- DESCRIPTION OF PARTS. 9 quently dentate or toothed, the teeth being arranged so as to shut within each other. Below the upper jaw are the feeler jaws, or maxillte ; these also move horizontally : they are smaller, and, instead of notches, their inner edges are fiu-nished with bristles or hairs ; they are articulated to flie thrutterflies and .moths. In these the membrane and network, constituting the frame and ftnindation-work of the organ, are covered with a mealy substance, or what appears to the unassisted eye as such. This substance, however, is a scale of a lieautiful workmanship, of a variable form and size in different insects, and in different parts of the wing of the same insect : they are beautiful objects for the microscope. Rude handling immediately destroys the beauty of the wing, by detaching these scales, and leaving the membrane beneath naked and broken. The wing, anatomically considered, is composed of two parts : the 7>ervurcs, and mem- brane. The former are likened unto ribs, which start from tlie anterior angle, and branch in various ways as they pass to the posterior margin. They give strength to the organ, and serve an important purpose in supporting and staying the outstretched membrane. The nervures are not, as might at first be supposed, solid ribs : they are traversed internally by a spii-al vessel and nerve. The membrane is double, although extremely delicate : this delicacy, however, is no obstacle to the growth of appendages, such as hairs, etc., inasmuch as it is frequently densely covered with them. The wing, divided by the branching and anastomosing of the nervures, forms a network more or less fine. The spaces enclosed by the branches are called cells or areolefs ; and being quite constant in form and place, they are employed in the determination of groups. Tliree areas are particularly noticed, namely, the costal, intermediate, and anal areas. The wing has a base, and anterior and posterior margins : the first is the part attached to the sternum ; the two others define themselves. The apex of the wing is the part opposite to the base. Various views have been expressed by different authors on the analogical relations of the wings J many of which are certainly very fanciful. M. Atjdouin takes a rational common sense view of these relations, and regards the wings as organs sui generis, intended for the exercise of special functions. The legs. Each segment of the thorax supports a pair of legs. The joint wliich unites them with the body is called the coxa or hip : it is held in its socket by a ligament. The motions of the leg are controlled more or less by the form of the coxa. The thigh is the largest portion of the leg : its form is various ; it is cylindrical or flattened, it is straight or arched. If the insect leaps, the posterior thighs are thick and strong. The legs are also more or less spinous. The tibia is the next part of the leg, and f )rms an angle with the thigh. It is more 12 DESCRIPTION OF PARTS. slender than the thigh, and is connected with it by a joint similar to a knee-joint, called giaglimus (articulation) : it is so formed that it may be closely applied to the thigh. Spines and spurs are also found upon the tibia or shank : when the spines are short, they are regarded as teeth. The spurs are articulated with the part, and possess some motion : they are commonly arranged in pairs at the extremity of each tibia. The tibia terminates below in the tarsus, or foot : this consists of a series of pieces, more or less heart-shaped, and never exceeding five in number. The combined motion of these pieces is considerable, though it is such as belongs to the ginglimus articulation : they are never of equal length, and the first one is the longest of all. The terminal piece bears a bifid claw, often dentate or serrate on the edges ; and a spurious claw is frequently found between the branches. In addition to the forenamed parts, we often find cushions placed upon the bottom of the foot, which serv« as sucking cups, enabling the insect to support Itself in a pendant position. Hairs also clothe the sole. The forelegs often exhibit a form more or less divergent from the others, and hence serve an additional purpose in the economy of the insect : they are employed in prehension. So it is sometimes the case that the hindlegs have a form specially adapted to a particular purpose, such as the rolling of the ball in which the eggs are enclosed, etc. The third part of the body of an insect, which calls for our attention, is the abdomen : it has no appendage, and in this respect differs from the parts already noticed. Its external structure is not peculiar ; for, like the other parts, it is composed of a series of horny rings or segments, which are closely connected together. The rings do not exceed nine in num- ber : if they appear to be fewer than nine, it may arise from the overlapping of adjacent ones. A section of the abdomen exhibits a triangular outline. The abdomen itself is united to the thorax, but not always in the same way : the area of junction is sometimes, broad, or equal to that of the first segment ; in other cases the union is by a short stem, or petiole, consisting of a trumpet-shaped tube : the abdomen is sessile in the former case, and pe- tiolated in the latter. Tlie rings or segments are united to each other in two ways : by the first, the inferior and middle parts are joined or soldered together, leaving the sides and dorsal portions only free ; by the second way, there is no soldering of parts, but the rings are supported by overlapping each other, and may slide into each other like the pieces of a telescope. In the former mode, motion is restricted, while the greatest freedom exists in the latter. The segments are lined by a memlirane, but it is scarcely visible except in the case of a gravid female, when it is seen distended like a bag. The abdomen, being comparatively free, is well fitted to sustain the function of respira- tion. To this end, each segment or ring is furnished with an opening fir the transmission of air, which penetrates thence in appropriate vessels throughout the whole body. These openings are surrounded by rings, and are usually denominated spiracles. As the abdomen is devoted to digestion, and is also the cavity in which the generative organs are lodged, it DESCRIPTION OF PARTS. J3 is necessary that it should be well supplied with air or oxygen : hence each segment has a pair of spiracles, which are capable of inhaling a large amount of this essential element. The external orifices are often protected by hairs, which shut over them, and thus serve to exclude foreign matters, while the air permeates freely into the interior of the body. Besides the digestive organs, and a portion of the respiratory apparatus, the abdomen contains the genital organs, the piercer and sting of females. The piercer is a flexible jointed tube, and is used to puncture trees or other bodies for the pm-pose of depositing the eggs. It varies in length and form, and is fitted to perform its oflice according to the instinct of the animal to which it belongs. I have now described, in as few words as possible, the most essential external parts of insects ; those parts which are particularly employed in the description of genera and species, as well as those used in general classification. From these parts the student will be able to form a correct notion of the extent of this class of animals ; but there are yet other portions, occupying the interior of the insect's body, which are important for us to study, inasmuch as they will yield information in regard to the economy of this interesting class whieli will be of essential service. I z-efer to the digestive, circulatory, and nervous systems. If the external forms of insects are curious and interesting, the student will find that the apparatus for carrying on the foregoing functions is still more so. There is espe- cially one curious fact particularly worthy of notice in relation to the digestive apparatus : it is this, that the secretory organs are reduced to t^ie simplest form, that of tubes ; from which we learn that nature requires no special fonn of instrument for the performance of a given function. All the essentials of a digestive apparatus, which belong to the higher classes of animals, are found in the insect. Some interesting differences, it is true, exist ; still when it is con- sidered that the food of insects does not really differ from that of other animals, we may ' of course expect to find the digestive organs essentially the same in kind. As insects subsist upon various kinds of food, some upon vegetables, others upon the elaborated juices of animals or upon flesh, so we find similar variations in the form and proportion of the organs as exist among the higher animals. The vegetable feeder has a larger and more capacious digestive apparatus than the carnivorous insect, nature always adapting her means to the end. The function of digestion in insects, as in all other animals, is performed through the instrumentality of an alimentary canal. Our first object will be to describe this apparatus. The function itself involves the existence of two kinds of apparatus : the parts through which the food must pass ; and the parts which supply the special fluids essential to eflect certain changes in the food before it can become aliment or nutrient matter. Beginning with the description of the first kind of apparatus, namely, the organ or organs through which the food passes during the process of digestion, we may regard this apparatus as a 14 DESCRIPTFON OF PARTS. oanal open at each extremity, with an enlargement or dilatation more or less in its central portion ; whence it is diminished, and becomes tubular and folded repeatedly vipon itself, increasing thereby in length until in some instances it is many times the length of the body. Different portions of this canal have received different appellations, as is highly proper, from the fact that certain of its parts perform functions of a modified character, although all contributing to one general result. In this division of parts, comparative anatomists have employed the same names that have long been in use in the anatomy of the higher animals, as the following enumeration will show, to wit : the pharynx, oesophagus, crop, gizzard, stomach or chylific ventricle, small intestines, csecum and rectum. The pharynx is the anterior portion or beginning of the canal. The cavity of the mouth opens into it, and it is an aperture more or less enlarged : it is, however, better developed in those insects which masticate their food, the mandibulated class. Indeed it is regarded as having no existence except in this class ; for in the suctorial insect, the next part, or esophagus, is in direct continuity with the haustella or sucking tube, which is connected with it by two distinct tubes. The esophagus, commonly known as the gullet, is a tube connecting the pharynx witli the crop, or first enlargement of the intestinal canal. It passes directly through the thorax and constricted part of the insect, terminating in the abdomen in the crop. It is variable in length : it may form one-half the length of the canal, while in other instances it is less than one-sixth of such length. It has a peculiarity which has already been alluded to : its bifurcation anteriorly in the lepidoptera, eacli spiral sucking tube extending its branch to it just behind the head. The esophagus is connected in the first place with the crop, an enlargement having a close analogy in position and form with the crop of a bird. It is also called a stomach by ' some writers on entomology. It is sometimes placed on a line with the esophagus, when it appears as a simple enlargement of the tube ; in otlier instances it is placed on one side, and then appears more like a sac connected with the esophagus by a short canal, and serving as a kind of reservoir ; or, in other words, more analogous to the crop of birds*. In certain beetles, as the Cicindela, the organ is provided with a glandular apparatus, which secretes an abundant and active juice to soften and otherwise change the food deposited in it. In the hemiptera it is remarkably modified in function : it loses its importance as a depository of food, and becomes a part of a pumping apparatus ; whence it has been called a sucking stomach. The insect in this case has the power of distending the sac, and thereby • It is proper in this place to notice the fact, 'that while there are numerous variations in the form and length of the alimentary canal of insects, there are two modifications that shonld be particularly spoken of, namely : the bot-fly has no opening at all answering to the mouth and pharynx, and hence can take no nourishment ; and in the larva of the wasp and bee, the rectum is closed, and hence their economy does not require the evacuation of cx- erementitious matter. 'iis»- DESCRIPTION OF PARTS, 15 raiifying the air in its interior ; in consequence of which, fluids rise in it as in a pump. We have in this case an instance of a modification of an organ of the simplest kind, by which, however, the entire function is changed ; passing from a digestive function to a transferring one, or one more immediately subservient to the mouth. XJie gizzai-d is the next organ, and may be distinguished from the crop by its peculiar apparatus for mastication : its internal surface is studded " with teeth or spines, or horny ridges ; " the organ, therefore, is eminently fitted for performing a perfect comminution of the matters received into it. It completes, in this respect, what has been performed but imperfectly. It performs a function somewhat analogous to that of rumination in the herbivora. All the insects which feed upon hard substances, those which might be regarded as nearly indigestible, are provided with a strong muscular gizzard, furnished with a masticating apparatus. The stomach, or that part in which we first observe the food reduced to a pulpy mass, and first exhibiting a chylous appearance, is bounded above by the gizzard, and below by a constricted portion of the canal, which receives a bundle of vessels that give it an ana- logy to the liver of vertebrated animals, and in fact it is strictly the hepatic organ of in- sects. The stomach is of an oval shape, or an elongated oval : it has been denominated the chylific ventricle by M. Leon Dufour. Its capacity is considerable : its surface is lined by a mucous membrane, and it is sometimes studded over with little mucous cysts or bags, which secrete a solvent fluid similar in composition and use to the gastric fluid of the higher animals. Tlie organ, in order to increase the extent of surface, is frequently con- stricted, and also twisted upon itself, so as to form many circumvolutions, and hence it is quite variable in shape in the different orders of insects : its inner sm-face, however, is always villous. From the stomach outwards or downward, the canal becomes narrower, or passes along with a diminished calibre ; but as there are still enlargements or dilatations in its course, anatomists speak of a duodenum, ileum, csecum, colon and rectum. But this is regarded by many as an unnecessary multiplication of names, inasmuch as it is extremely difficult to recognize the parts which are thus designated. The beginning of this part of the canal, however, is indicated by a constriction and the existence of a sphincter muscle, as well aa by the junction below of the hepatic vessels. The tube is generally short, rarely exceeding the length of the body : sometimes it is inflated into an ovoid sac ratlier abruptly. In following out the distinction of parts in the intestinal canal, we may recognize the existence of a colon, or what corresponds to the large intestines of the higher animals, by the character of the alimentary ball ; for the food, after having passed the stomach and through the narrowed part of the canal posterior to the stomach, loses its viscidity, and becomes more or less dry and compacted into the form of an excrement, showing by its condition that the nutrient matter has been extracted from it- Here is also a valve to guard 16 FUNCTION OF DIGESTION. the passage of the canal , which it closes to prevent the backward movement of the digf sted mass. The segment recognized as the cacum is short, and in direct communication with the anterior tube ; but in some cases it seems as if joined laterally to it, and then it has the appearance of a pouch. Fluids are supposed to be secreted by warty excrescences situated upon the mucous face of this intestine, designed to aid in the digestive process. , . The rectum is that part of the large intestines which terminates the alimentary canal below : it is always short, and is furnished with a sphincter at its extremity. It is mus- cular, has thicker walls than the ceecum, and gives shape and form to the excrements. The function of digestion requires, in addition to the formal tube .through which the parent matter must pass, a supply of certain fluids which shall possess a solvent power upon the contained mass ; and more than one kind of fluid seems to be necessary. Though these different fluids agree in use and effect with analogous ones found in the higher ani- mals, the organs which secrete them have a very different form : indeed, the difference is so great, that a student whose views of the function of digestion have been obtained solely from the observation of the organs of a vertebrate animal would not at first recognize the parts which perform similar functions in insects. The secretory organs, and those which are subservient to digestion, are always tubular in insects : the gland or parenchyma present in quadrupeds being entirely absent in in- sects, these organs are redviced to their simplest form. The kinds of tubes taking their names according to the natiu-e of the fluid secreted, are the salivary, biliary, and urinary. The salivary apparatus is quite complicated : it consists of tubes, single and double, and even triple, situated around the esophagus and mouth, and provided with bags that serve as reservoirs. The tubes open into the mouth or esophagus by two or more excretory orifices. The salivary apparatus is most perfect in the haustellata or sucking insects ; the tubes ascending into the abovenamed cavities in a meandering coui-se, whereby the extent of secreting surface is much increased. The operation of salivation is an important preliminary to digestion : mixed with the food, the saliva serves to soften its consistence, while it also carries along with it much air which appears to be necessary for some purpose in the econom)'. The bile is a still more important fluid than the saliva : it is secreted in long capillary tubes, more or less flexuose and folded upon themselves, which connect with the alimentary tube below the stomach, or just behind the pylorus ; though they sometimes continue farther down, and enter near the csecum. These tubes vary in number : there are usually two, especially in coleoptera, hemiptera and diptera ; but in these orders they are not absolutely uniform, as in the cerambycidse there are three, and foiu' in some diptera, while in neuroptera there are six, and in certain neuropterous gi-oups as many as eight. Where the number of the tubes varies, however, it operates as a compensation for their length : for example, if the simple tubes are each five or six times the length of the body, their number is less ; but when FUNCTION OF DIGESTION. 17 they are short, their number is proportionally increased. Although these hepatic tubes are generally quite uniform in diameter, there are some deviations from the rule ; but it is perhaps unnecessary to describe particularly the few modifications that are known to occur. The function of these tubes, as has been intimated, is to secrete or prepare a fluid analogous to bile. They may be recognized in the caterpillar, when the abdomen is opened, by their position, and by their white vermiform appearance : they float apparently loosely in the cavity of the abdomen. Among the secretions mentioned is the urinary, which seems to be far less constant than those already described. When the urinary organs are present, they terminate in the rec- tum-: they have been found in certain carnivorous coleoptera. The fluid which has been called the urine in insects, is caustic and odorous : it is often discharged by the carabici, on handling them, in jets, which, when falling upon the skin, occasion a transitory burning. In connection with this secretion, may be noticed that peculiar to the bombardiers, which is discharged in explosive jets, and is supposed to be intended as a means of defence. The name of the genus possessing the power of producing explosive jets of fluid, is Brachinus. I am not aware of the fact, if it has been ascertained, that this fluid is similar in composi- tion to that of the higher animals, or that it contains ui-ea. In concluding our remarks on digestion in insects, we may observe that the function is performed in ways quite as numerous as in the higher orders of animals, though there is no departui'e from the general principles which prevail in the vertebrate and molluscous types. There is always an apparatus for trituration, or mechanical separation of the food into fine parts : it is thereby prepared for the action of the several fluids which concur in the digestive process, and which exercise some peculiar chemical influence that serves to separate the nutrient matter from the useless portion of the food. These fluids are more or less acrid in their natui-e : thus the saliva injected into the wound made by a flea or a fly, for example, by the tabanus, occasions inflammation and itching ; and this irritation is designed to favor the insect, inasmuch as it produces a flow of blood to the wounded part. An effect of saliva is seen upon leaves attacked by the caterpillar, which very soon suffer a loss of color ; and as the moi-sel swallowed passes along from one receptacle to another, it is constantly undergoing changes : it is softened in the crop ; in the gizzard, it becomes pulpy ; and in the true stomach the chyle is formed, and is at once recognized by the globules it contains. A controversy has been long maintained respecting the oflice of those tubes which have been called hepatic or biliary. Some eminent physiologists have regarded them as urinary, inasmuch as uric acid is sometimes found in them ; but as this is not always the case, a compromise seems to have been made by regarding them as both biliary and urinary, and' giving them a corresponding denomination urino-biliary. The circumstance that the same tubes which have since been found sometimes to contain urine were regarded as biliary [Agricultural Report — Vol. v.] 3- 18 CIRCULATORY SYSTEM. tubes by the older anatomists and physiologists, is accordant with known facts in the economy of the lower animals, among Avhich it is common for an organ to perform a double function. The food in the alimentary canal of insects is moved along by a peristaltic motion : the canal, therefore, is supplied with a muscular apparatus. Indeed, from the phenomena exhibited, we might infer that the apparatus has a construction and parts such as have place in quadrupeds : thus the coats of the alimentary canal are three, a mucous, a cellu- lar, and a muscular coat ; the first being the internal one, the muscular the outside, and the cellular in the middle. The mucous coat is thin, often transparent, and difiicult to detect. The muscular coat is perfectly developed : its fibres are both longitudinal and circular ; and where the constrictions peculiar to the tube exist, there it is more perfectly developed, or in greater force. These muscles serve partly as sphincters, and also to keep up a continual movement. Circulation. Insects are furnished with a circulatory apparatus : it consists of a dorsal vessel, which, as its name indicates, is a tube running beneath the dorsal face of the ex- ternal covering. This is the central organ, and is equivalent to the heart in the higher orders of animals ; and the circulation is continued from the dorsal vessel, in channels excavated in the tissues. Tlie structure of the dorsal vessel permits the blood to flow from the posterior to the anterior part of the animal, by means of a series of valves opening forwards. The blood is transmitted to the thorax and head, the wings and legs, and returns through certain channels denominated veins, which open into the dorsal at different points through the valves ; but the larger portion of the returned fluid collects in the posterior chamber, and passes the whole length of the vessel. The vessel has been, and still is, re- garded by some physiologists as analogous to the heart : others, however, consider it as more analogous to the aorta of quadrupeds. It does not seem to be a matter of much importance whether we regard the so-called dorsal vessel a heart, an aorta, or an organ compounded of both, the posterior segment taking more especially the form and function of an aortic vessel. Its visible contractions, as seen through the transparent covering of many insects, furnish ostensibly valid reasons for regarding it a heart. The fluids which circulate in the vascular system of insects are usually white, carrying along distinct corpuscules having forms like those which are found in the higher and more perfect animals. In connection with the foregoing facts, it should also be stated that the circulation in insects is carried on in vessels having close proximity with those of another kind, namely, the air-vessels, or trachea. The two classes are easily distinguished from each other by the structure of the latter ; for in order that air may traverse the insect system, it is necessary CIRCULATORY AND NERVOUS SYSTEMS. » 19 that its conducting vessels be maintained in a tubular form : this is effected by means of a spiral elastic thread wound closely upon itself. By this means the vessels are prevented from collapsing, the air enters freely at the sides of the insect, and permeates perfectly the whole system. The air, then, is constantly in contact with the thin membrane intervening between the trachea and those vessels which transmit the blood to the different parts of the insect's body and extremities. Recent observations prove, in regard to the relations of blood and air, that the former moves through the space between the outer and inner membranes, in which a spiral filament winds, so as to bathe the exterior of the air-tubes themselves*. It would therefore seem that there is in insects a most complex system of spiral vessels or air-tubes, in connection and close relation with the vascular system, both being dis- tributed with the greatest minuteness throughout the whole body. There is still another provision for keeping up a supply of air especially in those insects whose flight is rapid, and requires to be long sustained : it is found in the air-sacs that are distributed in dif- ferent parts of the body; they serve not only to retain a due supply of air, but also to buoy up the body and render it lighter. The pulmonary system, by a combination of elastic tubes and sacs, receives an extraordinary development, so as to compensate in the most perfect manner for the deficiencies resulting from a less perfect form of circulation ; for powerful muscular motion requires a rich supply of oxygen, rather than food, in order to give energy and activity to the muscular system. From these facts, it appears that insects occupy no mean place in the scale of being, when they are ranked according to the development of their circulatory apparatus and the accompanying tracheal system. This combination, so far as the power of muscular motion is concerned in- the estimate, serves to elevate the insect to a rank but little below that of the vertebrate class. Nervous system.. The nervous system consists of a pair of chords extending through the insect, upon the interior abdominal face, and connected at each segment by a ganglion. Thus disposed along the ventral face of the body, the nervous system forms a symmetrical whole. The ganglionic masses of the head, however, are more largely developed than those of the trunk : this is necessary, from the condition of the eyes and the perfection of the masticating apparatus. The cephalic centres are placed also above the esophagus.. So the nervous centres which supply the wings and legs are larger than those of the abdomen. We see here again a provision for the locomotive apparatus, by which a due supply of nervous power or foi-ce is secured. There are probably but few instances in the animal kingdom, that exhibit such minute • See Carpenter, p. 382 of his General and Comparative Plysiology, ^^ 20 • NERVOUS SYSTEM ; SENSE OF TOUCH. subdivisions of matter as certain portions of tlie nervous system do. Thus when it is stated for the first time in our hearing, that the eye of the common house-fly is compounded of no less than 4000 single eyes, it seems impossible that a nerve, originally microscopic, can be subdivided into threads or fibres sufficiently fine to furnish a nerve to each simple eye ; and when we are further informed that the eye of the dragon-fly has (24,000) six times as many subdivisions as that of the house-fly, our faith is still more severely taxed ; but to suppose that a filament is wanting in an eye, is to suppose that the eye is made in vain ; for the eye depends upon its nervous filament, however slender that may be, for its power of vision. The sympathetic system of nerves in insects has been known from the days of Swam- MERDAM, who first discovcrcd it in the rhinoceros beetle. While this system is found more or less perfect in all articulated animals, it is specially perfected in insects. The imperfec- tion of the nervous apparatus consists in the absence of the cerebral masses, or of all that portion concerned in the formation of ideas. Nothing appears in the nervous system of the articulata, higher or above the ganglionic centres which connect together the double ventral chord. The ganglia of this system which are more particularly devoted to the purely animal functions, undergo a slight change during the passage fi-om the larval state to that of the perfect insect ; the change consisting chiefiy in a concentration of nervous matter upon those ganglia which are subservient to the function of locomotion. The sym- pathetic system, however, undergoes no change : it is equally perfect in the larva as in the mature animal, and reaches its full development in this early stage of existence, there- by showing that it presides over the functions of vegetative life. It is scarcely necessary to speak more particularly of the functions of the nervous system. It may, however, be observed, that it is upon this system that sensation depends, and the nervous fibrils are the channels through which the properties of external bodies become known to the individual. If we may judge of causes by effects, we are warranted in believing that impressions are received by insects from without, in the same manner as is the case with the higher animals ; and that they possess all those special senses which belong to the latter, and some of them in much greater perfection. Touch. The sense of touch in insects, in consequence of the hard covering of their bodies, must be confined to certain parts. Those who have watched their motions are fully convinced that the palpi are the organs in which this sense is concentrated, or in which it exists in its greatest perfection. These organs are constantly applied by the insect, after •the manner oi feeler s^ to the external bodies with which it comes in proximity ; and they are well adapted by their structure to fulfil such a purpose, being flexible, and furnished with a soft and delicate integument. FUNCTIONS OF HEARING, TASTING, SMELLING, AND SEEING. 21 Hearing. The plienomeua wliich indicate tlie existence of the sense of hearing are perhaps more equivocal than those of touch. Still attentive observers have noticed that insects seem to place themselves in an attitude of listening", when loud sounds are emitted from any quarter in their vicinity : they erect their antennae, and remain motionless for the time being ; and when the distm-bance has ceased to excite them, they resume their ordinaiy movements. From the position of the antennae, then, under the circumstances alluded to, it is inferred tliat they are connected directly with the function of hearing. Beneath them is a nei-ve connected with a soft membrane, which seems to be adapted to this special end. The antennaj in themselves extending outwardly, must become sensible of the vibrations in the air, and transmit them to this delicate auditory apparatus lying immediately beneatli. The organs are often long-branched, or plumose, so as to increase the extent of surface. This view of the office of the antennae does not conflict with the one often entertained, namely, that they may also be useful and employed as organs of touch. Taste. The existence of this sense rests more upon analogy, than upon well determined facts to support and prove its existence. Smell. Insects are attracted to odorous bodies from a distance : hence there can be no doubt that they are possessed of the sense of smell in great perfection, although its precise location is a matter of great uncertainty. Several different parts of the insect's body have been conjecturally assumed as the seat of this sense ; and it has often been assigned to parts that are variable, evanescent, or of occasional existence only. If analogical reasoning were to be our guide in this case, we should point to certain inward parts of the body that are in direct relation with the external air. In the mammalia, though the organ of smell is located in the head, yet its distinguishing characteristic is its immediate communication with the atmosphere, and the sense itself is exercised only when the air is inhaled. It i« not necessary to infer, that because in the higher animal it holds this intimate relation to the head, that it must occupy the same place in the insect : it is more consistent to suppose that its closest relation is with the respiratory organs. It is highly probable, therefore, that the trachea and spiral vessels, which conduct the air inwards, constitute the channels by which this sense is furnished with the odorous particles on which the sensuous nerve is to operate. Accordingly this view is looked upon with favor by Cuvier and many other dis- tinguished physiologists. Sight. Of all tlie senses, that of sight seems to be the most perfect in insects. The organ is compound, or, in other words, consists of many eyes comparted together, each of which is perfect in itself, being furnished with the proper humors and lenses essential to the exercise of vision. In addition to the compound eye, which often occupies the largest portion of the head, they are often furnished with simple eyes upon the forehead : these 22 FUNCTION OF VISION. have received the names of ocelli and stemmata, and are generally three in number, and arranged in the form of a triangle ; but there may be but two, or only one. Their structure qualifies them for viewing such objects only as are close at hand. The compound eye presents a reticulated appearance under the microscope : the surface is convex or globular ; but the organ is immovable, except by the motion of the head. The reticulated appearance is produced by the lines that mark the boundary of each eye or lens : these are hexagonal, and their number is almost incredibly great in some species. They vary in tliis respect from 50 in the ant, to 25,000 in a species of Mordella : the butterfly has 17,000, and the dragonfly 12,544. Each eye is furnished with an apparatus sufficiently perfect for the exercise of vision in its sphere :; it has its lens for refraction, its choroid for the correction of aberration, and its retina for the reception of the images of external objects. Each single eye, however, must embrace an extremely limited field of vision, and there is no doubt that it requires the use of many of these eyes to see a single object ; for only those rays of light that fall perpendicularly upon the eye can reach the optic nerve. The eyes of predaceous insects, such as the dragonfly, are large, prominent and globular : hence they enjoy,, altogether, a large field of vision. In those insects, on the other hand, which are confined in their range, or ai-e parasitic, the field of view is diminished by a reverse of circumstances. The nerve of each eye terminates in a common nerve : this must be regarded as the sensorium commune, the nervous plane upon which the image of an object is spread. Some- times the eye is pedunculated, or placed upon a footstalk : sometimes it is semicircular, in consequence of the implantation of the antennse, and indeed this implantation may be such as to give the semblance of four eyes. In other instances the size of the eye is a sexual mark. We are too much in the habit of looking vaguely upon the insect tribes. While we recoo-nize the movements of the vertebrated class as resulting from distinct acts of the will, and as controlled by internal feelings, we are little disposed to entertain the view that the apparatus of a fly or a beetle indicates similar internal motives for action ; or, in other words, we do not possess so lively a sense of the perfection of the being of the insect, as of the beiiag of the higher order.. We see, however, that insects have eyes to see, cars to hear, and orgajis of smell ; a highly developed nervous apparatus, and an active circula- tion : in fine, the insect moves in a world of its own, which takes no part in the sphere belonging to the mollusca or vertebrata. Its senses and organs of animal life, however, give it a wide sphere of activity, and have prepared it for fulfilling important functions, and furnished it with a capability to affect very materially the interests of man. Being widely diffused, and their life overflowing with activity, always moving as if impelled forward by important business or engaged in errands of the most momentous character, tliey seem to FUNCTION OF MOTION. 23 make the most of their brief and uncertain existence. Witness the energy of the dung- beetle in finishing tlie ball in which it has deposited its egg : it often dies in the act of providing for the continuance of the life of its kind. To some these actions may seem less intei-esting, because instinctive ; but surely the faculty of instinct affords matter for deep thought to the ordinaiy observer, and to the philosopher it must possess an interest next to that of reason itself. Instinct urges the individual forward to the fulfilment of its destiny, but it makes no inquiry as to the cost. Muscular motion. The insect enjoys a full development of the power of motion, especially in itsj perfect state : the two kinds of muscle, striated and non-striated, are al- ways present. Every part of the system is supplied with muscular fibres ; not only are the legs and wings largely supplied with them, but also the abdomen and various parts of the trunk, head, and thorax. The most interesting fact which appears in this connexion, is the power of the insect to sustain a long and vigorous flight : thus the dragonfly darts for- wards, backwards, or sideways, and is able to outstrip the swallow in its most rapid course ; and this it can do for hours together. Taking into consideration the diminutive size of insects, we readily see, that in proportionate locomotive power, they far excel the verte- brate animal. We have already observed that their joints usually admit of but two kinds of motion, forwards and backwards, or the ginglimus movement : when, however, this motion is exerted in extension and flexion, as in the leaping of the grasshopper or flea, we cannot fail to perceive that their powers in this respect, also as in flying, are far superior to those possessed by any other class of animals. Though the lai'val state of insects is generally sluggish, we are not without many examples where there is a great degree of activity. We often see the caterpillar hurrying along as if it were in great haste, though tlie space it is able to traverse is quite limited- We observe, in all these movements, an aim to preserve life : the life of self, however, is subordinate to that of kind or progeny. Propagation. Insects propagate their kinds from eggs laid by the female, subsequent to the act of congress with the male : the sexes are therefore distinct. Their power of multiplication is immense, especially in those insects which produce several broods in a season. But there is a remarkable exception to the foregoing rule : the aphis increases by a process of gemmation ; females being cast off at once for several generations, of which each possesses the power of multiplying its kind in the same way. Carpenter likens it to the gemmation of the polypi, " the individuals being budded off from internal stolons, instead of being developed from ova provided by the female and fertilized by the male." It has long been known, that in the aphis, this method of propagation is repeated to the seventh or ninth generation. At tlie end of the season, the perfect individuals, both male 24 FUNCTION OF PROPAGATION. and female in a winged state, are produced, by the congress of which ova are fertilized : these are preserved through the winter. It would seem from this, that although in the articulated class budding is resorted to to multiply the number of individuals, yet it is not adequate to continue the existence of the species. Calculations have been made of the numbers which an aphis may produce in a single season, provided the individuals are not destroyed by accident. According then to calculation, based upon observed facts, the whole brood in a season from a single aphis will amount to the inconceivable number of 1, 000,900,000,000,000 jOOO ! From such an ability to increase, we should at first thought be disposed to expect a result approaching the calculated numbers ; but it is gratifying to observe, that where the powers of increase are extended and multiplied as in the case of the aphis, the destructive powers are equally multiplied and active : there is therefore but little reason to fear an excessively injurious multiplication in the midst of so many enemies. The aphis is extremely feeble : the touch destroys it ; the winds, rains, and cold sweep off its numbers by hundreds of thousands. The excessive multiplication of individuals is only a means of supplying an increased number of consumers : hence instead of an approach to the enormous number indicated by calculation, their actual numbers will fall infinitely short of it. The balance of nature is always preserved ; and wherever danger seems to point, there checks are provided, which put an effectual restraint upon inordinate increase. We may conceive of what is possible; but the actual just suffices to keep up a suitable equilibrium : at most the threatening is transient, and recurs only at wide intervals. EXPLANATION OF ANATOMICAL PLATES. 25 APPENDIX TO CHAPTER II. DESCKIPTION AND REPRESENTATION OF PARTS OF SUCH INSECTS AS ARE REFERRED TO IN THE FOLLOWING TREATISE. ( Copied mostly from the Nmuralist's Library.) I. PARTS OF THE HEAD, MOUTH, &c.— PLATE A. Fig. 1. Head, upper side : a, forehead ; I, vertex ; c, occiput ; dd, temples ; ee, eyes ; /, torulus, the cavity for the insertion of the antennaj ; g, clypeus ; h, labrum. Fig. 2. Under side of the head : It, posterior orifice ; Z, neck ; m, mentum ; o, eyes ; p, mandibles ; s, labial palpi. Bigs. 3, 4, 5. Forms of the labrum. Fig. 5. Mandible of Hydnis piccus. Fig. 7. Mandible of Garius. Fig. 8. Mandible of Cahsoma sycophanta. Fig. 9. Maxilla of Necrophoms germanims : a, maxillary palpus ; b, external lobe of the maxilla ; c, internal lobe. Fig. 10. Maxilla of Cicindela : a, external maxillary palpus : b, internal ditto ; c, interior lobe, with an articulated hook at the apex d. Fig. 11. Form of the maxilla of Hydrus piceus : a, insertion or hinge ; b, dorsal piece ; c, squame- palpifers of Strauss : bed form the stalk (stipes) ; e, external lobe ; /, internal ditto. Fig. 12. Labium of Cychnts rostratus : a, mentum ; b, ligula ; c, labial palpi. Fig. 13. Labium of Carabus, inside : a, mentum ; b, lingua ; c, paraglossas. Fig. 14. Thorax of ScoliaJlavifro7is, showing in succession the prothorax, mesothorax and metathorax, also the coxaj : A, pronotum ; c, mesonotum ; F, metanotum ; nn, parapleura ; c, soutel- lura ; dd, patagia. Fig. 15. Side view of the thorax of Scolia JlatifroJis : e, mesosternum ; b, prosternum ; g, meta- sternum ; d, patagium ; c. scutellum ; a, first spiracle ; b, second ditto. Fig. 16. View of the same from beneath : bb, prosternum ; ee, mesosternum ; ao, mctasternuni. Fig. 17. Thorax of Cicada fraxini : A, pronotum ; c, mesonotum ; FF, metanotum ; c, scutellum ; dd, frenum. Fig. 18. ILm^hg oi Melolonlha vulgaris : aJ, coxa ; cf, trochanter ; e, thigh; /, tibia; h, tarsus; i, claws. Fig. 19. Pectinated claws. [Agricultural Report — Vol. v.] 4 26 EXPLANATION OF ANATOMICAL PLATES. Fig. 20. Claws of Asilus : o, central filaments ; ss, membranous expansion of the terminal joint, ad- vanced beneath the claws. Figs. 25, 26 : showing the upper and under side of the domestic cricket [Acheta aradmoidea). Fig. 27. Maxillary palpi (it) of the cricket; b, galea. Fig. 28. Lower lip of the cricket : a, uientum ; d, labium; e, additional articulations, divided into two, three, or more lobes ; cc, apparently 3-jointed palpi, yet the basal joint enveloped or concealed in the lip. Fig. 29. Mandibles of the grasshopper {Aorydium) : b, molar plate. Fig. 30. Mandibles of the cricket. Figs. 31, 32. Forms of antennas. Fig. 33. Serrated antennjc. Fig. 34. Lamelliform antenna?. Yi". 35. Pectinated antennae ; bipectinated, if it produces two long teeth, instead of one ; and flabel- late, when the branches are very long, and flattened Idee the rays of a fan. Fig. 41. Setaceous antenna; : filiform, when the antennoe are of unequal thickness ; moniliform, as in fig. 42 ; ensiform, when tapering, and angulatcd at the sides ; subulate, when short, and pointed at the tip ; fusiform, when narrowed at the two extremities and thickened in the centre, as in fig. 43 ; clavate, when they gradually thicken at the top, as in 37 and 35 ; geniculate, when bent as in 39 abc ; capitate, when terminated in a knob or head, as 36 , plumose, when the lateral filaments go oflf from a shaft, like those of a feather ; nodose, when the joints are thickened in various parts like knobs ; vorticillate, when whorls of hairs are placed at equal distances upon the joints ; fasciculate, when the hairs are gathered in bundles upon each joint; soopiferous, when a single bundle is p)laced upon one joint; palmate, when the antennsc are short, broad, and divided by deep divisions ; auriculate, when one of the basal joints is dilated into a shield or oar partially covering the rest ; fissile, when they are terminated by a cleft knob ; ramose, when several of the joints throw out branches ; furcate, when there are two branches like a fork ; aristate, when the antennae are terminated by a fine bristle, as in the order Musca ; dentate, when the joints are armed ■ with short spines ; cylindrical, when they are of equal diameter throughout ; prismatic, when they resemble a prism, or are formed of three sides. II. PARTS OF THE DIGESTIVE APPAR.ITUS.— PLATE B. Figs. 2, 3. a shows the esophagus, beginning in fig. 3 just behind the head, and terminating in an en- largement which is the crop ; or, if the crop is absent, it terminates in the gizzard d. The esophagus is a simple tube, except in the lopidoptera. Fig. 4 c represents the position and relation of what has been denominated a sucking stomach. The gizzard is shown in position, fig. 2 c. The true stomach, or, as called by some entomologists, the clujlific ventricle, is seen in figs. 2 & 3