OF THE EGGS OF INSECTS.

[83]The remarks made by the late Mr. Hunter on the experiments of Messrs. Schirach and Debraw, in my opinion, merit the attention of the reader; they are contained in his “Observations on Bees,” comprizing a variety of information respecting the history and œconomy of those curious insects. This ingenious and interesting account is inserted in the Philosophical Transactions for the year 1792, page 128-195. I cannot altogether subscribe to his opinion relative to the minuteness and prolixity of Swammerdam.Edit.

The eggs are contained and arranged in the body of the insect, in vessels which vary in number and figure in different species; the same variety is found in the eggs themselves: some are round, others oval, some cylindrical, and others nearly square; the shells of some are hard and smooth, while others are soft and flexible. It is a general rule, that eggs do not increase in size after they are laid; among insects, we find however an exception to this; the eggs of the tenthredo of Linnæus increase after they are laid, but their shell is soft and membranaceous. The eggs of insects differ in their colours; some may be found of almost every shade, of yellow, green, brown, and even black. The eggs of the lion puceron,[84]hemerobius, Lin. are very singular objects, and cannot have escaped the eye of any person who is conversant among the insects which live on trees; though of the many who have seen them, few, if any, have found what they really were. It is common to see on the leaves and pedicles of the leaves of the plumb-tree, and several other trees, as also on their young branches, a number of long and slender filaments, running out to about an inch in length; ten or twelve of these are usually seen placed near one another, and a vast number of these clusters are found on the same tree; each of these filaments is terminated by a sort of swelling or tubercle of the shape of an egg. They have generally been supposed to be of vegetable origin, and that they were a sort of parasitical plant growing out of others. There is a time when these egg-like balls are found open at the ends; in this state they very much resemble flowers, and have been figured as such by some authors, though they are only theshells of the eggs out of which the young animals have escaped after being hatched. If these eggs be examined by a microscope, a worm may be discovered in them; or they may be put into a box, in which, in due time, they will produce an insect, which, when viewed with a microscope, will be found to be the true lion puceron.

[84]Reaumur Hist. de Insectes, vol. xi. p. 142.

Divine Providence instructs the insects, by a lower species of perception, to deposit their eggs not only in safety from their numerous enemies, but also in situations where a sufficient quantity of food is on the spot to support and nourish the larva immediately on breaking the shell. Some deposit their eggs in the oak leaf, producing there the red gall; others choose the leaf of the poplar, which swells into a red node or bladder; to a similar cause we must attribute the red knob which is often seen on the willow leaf, and the three pointed protuberances upon the termination of the juniper branches. The leaves of the veronica and cerastium are drawn into a globular head by the eggs of an insect lodged therein. The phalæna neustria glues its eggs with great symmetry and propriety round the smaller branches of trees. Fig. 1.Plate X.represents a magnified view of the nest of eggs taken off the tree after the caterpillar had eaten its way through them; the strong ground-work of gum, by which they are connected and bound together, is very visible in many places; they strengthen this connection further, by filling up all the intervening space between the eggs with a very tenacious substance. These eggs are crustaceous, and similar to those of the hen; Fig. 2 represents the natural size. Fig. 3 is a magnified vertical section of the eggs, shewing their oval shape; Fig. 4 the natural size. Fig. 5 is an horizontal section through the middle of the egg, and Fig. 6 the same not magnified. It is not easy to describe the beauty of these objects, when viewed in the lucernal microscope; the regularity with which they are placed, the delicacyof their texture, the beautiful and ever-varying colours which they present to the eye, give the spectator a high degree of rational delight.

In the Lapland Alps there is a fly covered with a downy hair, called the rhen-deer gad-fly, oestrus tarandi, Linn. it hovers all day over these animals, whose legs tremble under them; they prick up their ears, and flee to the mountains covered with ice and snow to escape from a little hovering fly, but generally in vain, for the insect but too soon finds an opportunity to lodge its egg in the back of the deer; the worm hatched from this egg perforates the skin, and remains under it during the whole winter: in the following year it becomes a fly. The oestrus bovis is an equal terror to oxen; the hippobosca equina, to horses; oestrus ovis,[85]to the sheep, &c.

[85]Oestrus ovis in naso sive sinu frontis animalium rumenantium. Linn.

The gnat, the ephemera, the phryganea, the libellula, hover over the water all day to drop their eggs, which are hatched in the water, and continue there all the time they are in the larva form. The mass formed by the gnat resembles a little vessel set afloat by the insect; each egg is in the form of a keel, these are curiously connected together. The gnat lays but one egg at a time, which she deposits on the water in a very ingenious and simple manner; she stretches her legs out, and crosses them, thus forming an angle to receive and hold the first egg; a second egg is soon placed next the first; then a third, and so on, till the base is capable of supporting itself; these, as they come to maturity, sink deeper. The spawn of this insect is sometimes above an inch long, and one-eighth of an inch in diameter, and tied by a little stem or stalk to some stick or stone. Sometimes they are laid in a single, sometimes in a double spiral line; sometimestransversely. Many moths cover their offspring with a thick bed of hair, which they gather from their own body; while others cover them with a glutinous composition, which, when hard, protects them from moisture, rain, and cold. The gall-flies, it has been observed, know how to open the nerves of the leaves, to deposit thus their eggs in a place which afterwards serves them for a lodging and a magazine of food. The solitary bees and wasps prepare an habitation for their little ones in the earth, placing there a proper quantity of food for them, when they proceed from the egg. The voracious and cruel spider is attentive and careful of its eggs; the wolf spider carries them on its back in a little bag formed of its silk, it cannot be separated from them but by violence, and exhibits the most marked signs of uneasiness when deprived of them: a circumstance the more remarkable, as they love to destroy each other, and even carry on their courtships with a diffidence and caution unknown in any other species of animals. The history of bees and wasps, and their care and attention to their offspring, is so well known, that I may with propriety pass it over here, and proceed just to notice the industrious ant, whose paternal affection and care is not so well known. They are not satisfied with placing their eggs in situations made on purpose, and to raise or rear them till they come to the nymph or pupa state, but they even extend their care to the pupæ themselves, removing them from their nest to the surface of the earth, whenever the weather is fine, that they may receive the benignant influence of the sun, carrying them back again as soon as the air begins to grow cold. If any accident disturb their nest, and disperse the pupæ, they manifest the greatest signs of distress, seeking those which are lost and scattered, placing them in some sheltered place while they repair the nest, when they again transport them to it.[86]Manyother curious particulars might be related relative to this industrious insect; as their uniting together in scooping out earth, the conveyance of materials for the construction of their nests, and the curious structure of the nest itself, which, though it appears piled up at random, will be found, on stricter examination, to be a work of art and design, with other circumstances which are too long to be enumerated here.

[86]Lessers Theologie des Insectes, tom. 1, p. 143.

The fecundity of insects exceeds in an astonishing degree that of all the productions of nature; the vegetables which cover the surface of the earth bear no proportion to their multitudes, every plant supporting a number often of scarce perceptible creatures: of the fatal effects of their prodigious multiplication, our fruit trees, &c. are too frequently a deplorable testimony. On the continent whole provinces sometimes languish in consequence of the dreadful havoc made by them.

Reaumur calculated the fecundity of the queen bee as follows: he found that she laid in the two months of March and April 12,000 eggs, so that the swarm which left the hive in May consisted of near 12,000 bees, all produced from one mother: but this calculation falls short of that which was made by Leeuwenhoek on a fly, whose larva feeds on flesh, putrid carcases, &c. which multiply prodigiously, and that in a short space of time. One of these laid 144 eggs, from which he got as many flies in the first month; so that, supposing one-half of these to be females, in the third month we shall have 746,496, all produced in three months from one fly.

The following is an experiment of M. Lyonet on the generation of a moth which comes from the chenille a brosse: out of a brood of 350 eggs, produced by a single moth of this kind, he took 80, from which he obtained, when they were arrived attheir perfect state, 15 females; from whence he deduces the following consequence: if 80 eggs give 15 females, the whole brood of 350 would have produced 65; these 65, supposing them as fertile as their mother, would have produced 22,750 caterpillars, among which there would have been at least 4265 females, who would have produced for the third generation 1,492,750 caterpillars. This number would have been much larger, if the number of females among those which were selected by M. Lyonet had been greater. M. de Geer counted in the belly of a moth 480 eggs; reducing these to 400, if supposing one-fourth only of these to be females and as fruitful as their mother, they will give birth to 40,000 caterpillars for the second generation; and for the third, supposing all things equal, four millions of caterpillars. It is not surprizing, therefore, that they are found so numerous in years that are favourable to their propagation. But the Creator of all things has for our sakes limited this abundant multiplication, and wisely ordained, that those species which are the most numerous shall have the greatest number of enemies, who, though constantly employed on the destruction of individuals, are unable to effect that of the species; by which means an equilibrium is preserved, and no one species preponderates. Few insects live long after their last transformation, but their species are continued by their amazing fecundity; their growth is completed, and their parts hardened sooner than those of larger animals, and the duration of their existence is proportionably limited. There are, however some species of flies which lie in a torpid state during the winter, and revive with the returning warmth of spring.

There are few, if any, productions either of the animal or vegetable kingdoms, which do not supply some kind of insect with food. They may, therefore, be considered under two heads, thosewhich live on vegetables, and those which are supported by animal food; each insect knows that which is proper to sustain its life, where to seek it, and how to procure it. I have already observed, that several insects, when arrived at a state of perfection, feed after their transformation upon food totally different from that which nourished them in their larva state.

Among those which feed on vegetables, some sink themselves in the earth, and by destroying the roots of the plants, do considerable injuries to our gardens. The food of others is dry and hard; they pierce the wood, reduce it to powder, and then feed on it; some, as the cossus, attack and destroy the trees, while the food of others more delicate is the leaves. The leaf is eaten in a different manner by different insects; some eat the whole substance, while others feed only on the parenchymous parts, which are contained between its superficial membranes, forming withinside the leaf paths and galleries. These insects are not always content with the leaf, but attack the flower also: even this food is too gross for many; the bee, the butterfly, the moth, as well as several species of flies, feed only on the honey, or finer juices, which they collect from flowers. We are continually finding the larva of some insect in pears, plumbs, peaches, and other fruit; these unwelcome intruders on the produce of human industry divide fruits, grain, and corn with us, often depriving us of large quantities. There is, indeed, no part of a plant which does not serve as food to different insects; some have one kind of plant marked out for them to inhabit and feed on, others have another assigned to them, on which, and no other, they will feed; each has its appropriate food, and though the parent animal eats not at all, or lives upon food entirely different, yet she is guided, as has before been observed, to deposit her eggs on that peculiar shrub or plant that will be food for her young; while some, more voracious than the rest, feed upon all with equal avidity; but incountries less cultivated than our own, their annoyance and devastations are terrible. The gryllus migratorius, a few years since, poured out of Tartary in such quantities, as to lay waste a great part of Europe, producing almost unequalled calamities, swarming in such multitudes as to cloud the air and cover the ground, mocking human power and craft; wherever they settled, all verdure disappeared, and the summer fruitfulness was turned into winter desolation; in Sweden the cattle perished with hunger, and the men were forced to abandon their country, and fly to the neighbouring regions.[87]The far greater part feed only, however, on one species of plant, or at most on those which are similar to it, and the same species may always be found on the same plant. Reaumur says, that the caterpillar which infests and feeds upon the cabbage, destroys in twenty-four hours more than twice its weight. If larger animals required a proportionable quantity, the earth would not afford sufficient nourishment for its inhabitants.

[87]Select Dissertations from the Amœnitates Academicæ, vol. I, p. 398.

A great number of insects reject vegetable, and live on animal food; some seeking that which is beginning to putrefy, while others delight in food entirely putrid; others again are nourished by the most filthy puddles, and disgusting excrements; some attack and feed on man himself, while others are nourished by his provision, his cloaths, his furniture: some prey upon insects of another species; others, again, attack their own, and harrass each other with perpetual carnage. Reaumur informs us, that those insects which feed upon dead carcases never attack living animals; the flesh-fly deposits her eggs in the bodies of dead animals, where her progeny receive that nourishment best adapted for them; but this fly never attempts to lay her eggs in the flesh of sound and living animals.

Every animal has its appropriate lice, which feed on and infest it. M. Rhedi has given an accurate account of a great number of these little noxious creatures accompanied with figures; but, as if it were not sufficient that these creatures should dwell and live on the external part of the body, and suck the blood of the animal that they infest, we find another species of insects seeking their food in the more vital parts, and feeding on the flesh of the animal, while full of life and health. Reaumur has given an history of a fly, oestrus bovis, the larva of which lives upon the backs, and feeds on the flesh of young oxen and cows, where it produces a kind of tumor. The fly lodges its eggs in the flesh, by making a number of little wounds, in each of which it deposits eggs, so that every wound becomes a nest, the eggs of which are hatched by the heat of the animal. Here the larvæ find abundant food, at the same time that they are protected from the changes of the weather; and here they stay till they are fit for transformation. The parts they inhabit are often easy to be discovered by a kind of lump or tumor, which they form by their ravages; this tumor suppurates, and is filled with matter; on this disgusting substance the larvæ feed, and their heads are always found plunged in it.[88]

[88]The obscure and singular habitations of the British oestri are the stomach and intestines of the horse, the frontal and maxillary sinuses of sheep, and beneath the skin of the backs of horned cattle. In other parts of the world they inhabit various other animals.The larva of the oestrus bovis lives beneath the skin of horned cattle, between it and the cellular membrane, in a proper sack or abcess, which is rather larger than the insect, and by narrowing upwards opens externally to the air by a small aperture. When arrived at its full growth, it effects its escape from the abcess by pressing against the external opening; when the opening has thus obtained the size of a small pea, the larva writhes itself through, and falls from the back of the animal to the ground; and, seeking a convenient retreat, becomes a chrysalis, in which state it continues from about the latter end of June to about the middle of August; the perfect insect, on leaving the chrysalis, forces open a very remarkable marginated triangular lid or operculum. The oestrus in its perfect or fly state is the largest of the European species of this genus, and is very beautiful. Although its effects on the cattle have been so often remarked, yet the fly itself is rarely seen or taken, as the attempt would be attended with considerable danger. The pain it inflicts in depositing its egg is much more severe than in any of the other species: when one of the cattle is attacked by this fly, it is easily known by the extreme terror and agitation of the whole herd; the unfortunate object of the attack runs bellowing from among them to some distant part of the heath, or the nearest water, while the tail, from the severity of the pain, is held with a tremulous motion straight from the body, in the direction of the spine, and the head and neck are also stretched out to the utmost. The rest, from fear, generally follow to the water, and disperse to different parts of the field. The larvæ of this insect are mostly known among the country people by the name of wornuls, wormuls, or warbles, or more properly bots.The larva of the oestrus equi is very commonly found in the stomach of horses. These larvæ attach themselves to every part of the stomach, but are generally most numerous about the pylorus; and are sometimes found in the intestines. They hang most commonly in clusters, being fixed by the small end to the inner membrane of the stomach, to which they adhere by two small hooks or tentacula. The larvæ having attained their full growth in about a month, on dropping to the ground find some convenient retreat, change to the chrysalis, and in about six or seven weeks the fly appears.The larva of the oestrus hæmorrhoidalis resembles in almost every respect that of the oestrus equi, and occupies the same situation in the stomach of the horse. When it is ripe, and has passed through the intestines and the sphincter ani it assumes the chrysalis state in about two days, and in about two months the fly appears.The generally received opinion has been that the female fly enters the anus of the horse to deposit its eggs, and Reaumur relates this circumstance on the authority of Dr. Gaspari; from the account of its getting beneath the tail, it is probable that the fly he saw was the hippobosca equina, which frequently does this: its getting within the rectum appears to have been additional. That a fly might deposit its eggs on the verge of the anus is not impossible, but we know no instance of it: the fact is, that the part chosen by the oestrus hæmorrhoidalis for this purpose is the lips of the horse, which is very distressing to the animal from the excessive titillation it occasions; for he immediately after rubs his mouth against the ground, his fore legs, or sometimes against a tree, or if two are standing together, they often rub themselves against each other. At the sight of this fly, the horse appears much agitated, and moves its head backward and forward in the air to baulk its touch, and prevent its darting on the lips; but the fly, watching for a favourable opportunity, continues to repeat the operation; till at length, the enraged animal endeavours to avoid it by galloping away to a distant part of the field. If still pursued, its last resource is in the water, where the oestrus is never observed to follow him.The oestrus veterinus is by Linnæus called nasalis, from an idea of its entering the nostrils of the horse to deposit its eggs, which it could not well do without destroying its wings, and is therefore probably as much a fable as the “mire per anum intrans” of the oestrus hæmorrhoidalis.The oestrus ovis is mostly found in the horns and frontal sinuses of the sheep, though it has been remarked that the membranes lining these cavities were hardly at all inflamed, while those of the maxillary sinuses were highly so; from which it is suspected that they inhabit the maxillary sinuses, and crawl, on the death of the animal, into these situations in the horns and frontal sinuses. When the larvæ are full-grown they fall through the nostrils, and change to the pupa state, lying on the earth, or adhering by the side to a blade of grass. The fly bursts the shell of the pupa in about two months.The above concise account of the different oestri is extracted from the excellent paper on the subject by Mr. B. Clark, F. L. S. For his more ample description, accompanied with coloured figures of the several British species, see Transactions of the Linnean Society, vol. iii. page 283-329, just published.Edit.

The larva of the oestrus bovis lives beneath the skin of horned cattle, between it and the cellular membrane, in a proper sack or abcess, which is rather larger than the insect, and by narrowing upwards opens externally to the air by a small aperture. When arrived at its full growth, it effects its escape from the abcess by pressing against the external opening; when the opening has thus obtained the size of a small pea, the larva writhes itself through, and falls from the back of the animal to the ground; and, seeking a convenient retreat, becomes a chrysalis, in which state it continues from about the latter end of June to about the middle of August; the perfect insect, on leaving the chrysalis, forces open a very remarkable marginated triangular lid or operculum. The oestrus in its perfect or fly state is the largest of the European species of this genus, and is very beautiful. Although its effects on the cattle have been so often remarked, yet the fly itself is rarely seen or taken, as the attempt would be attended with considerable danger. The pain it inflicts in depositing its egg is much more severe than in any of the other species: when one of the cattle is attacked by this fly, it is easily known by the extreme terror and agitation of the whole herd; the unfortunate object of the attack runs bellowing from among them to some distant part of the heath, or the nearest water, while the tail, from the severity of the pain, is held with a tremulous motion straight from the body, in the direction of the spine, and the head and neck are also stretched out to the utmost. The rest, from fear, generally follow to the water, and disperse to different parts of the field. The larvæ of this insect are mostly known among the country people by the name of wornuls, wormuls, or warbles, or more properly bots.

The larva of the oestrus equi is very commonly found in the stomach of horses. These larvæ attach themselves to every part of the stomach, but are generally most numerous about the pylorus; and are sometimes found in the intestines. They hang most commonly in clusters, being fixed by the small end to the inner membrane of the stomach, to which they adhere by two small hooks or tentacula. The larvæ having attained their full growth in about a month, on dropping to the ground find some convenient retreat, change to the chrysalis, and in about six or seven weeks the fly appears.

The larva of the oestrus hæmorrhoidalis resembles in almost every respect that of the oestrus equi, and occupies the same situation in the stomach of the horse. When it is ripe, and has passed through the intestines and the sphincter ani it assumes the chrysalis state in about two days, and in about two months the fly appears.

The generally received opinion has been that the female fly enters the anus of the horse to deposit its eggs, and Reaumur relates this circumstance on the authority of Dr. Gaspari; from the account of its getting beneath the tail, it is probable that the fly he saw was the hippobosca equina, which frequently does this: its getting within the rectum appears to have been additional. That a fly might deposit its eggs on the verge of the anus is not impossible, but we know no instance of it: the fact is, that the part chosen by the oestrus hæmorrhoidalis for this purpose is the lips of the horse, which is very distressing to the animal from the excessive titillation it occasions; for he immediately after rubs his mouth against the ground, his fore legs, or sometimes against a tree, or if two are standing together, they often rub themselves against each other. At the sight of this fly, the horse appears much agitated, and moves its head backward and forward in the air to baulk its touch, and prevent its darting on the lips; but the fly, watching for a favourable opportunity, continues to repeat the operation; till at length, the enraged animal endeavours to avoid it by galloping away to a distant part of the field. If still pursued, its last resource is in the water, where the oestrus is never observed to follow him.

The oestrus veterinus is by Linnæus called nasalis, from an idea of its entering the nostrils of the horse to deposit its eggs, which it could not well do without destroying its wings, and is therefore probably as much a fable as the “mire per anum intrans” of the oestrus hæmorrhoidalis.

The oestrus ovis is mostly found in the horns and frontal sinuses of the sheep, though it has been remarked that the membranes lining these cavities were hardly at all inflamed, while those of the maxillary sinuses were highly so; from which it is suspected that they inhabit the maxillary sinuses, and crawl, on the death of the animal, into these situations in the horns and frontal sinuses. When the larvæ are full-grown they fall through the nostrils, and change to the pupa state, lying on the earth, or adhering by the side to a blade of grass. The fly bursts the shell of the pupa in about two months.

The above concise account of the different oestri is extracted from the excellent paper on the subject by Mr. B. Clark, F. L. S. For his more ample description, accompanied with coloured figures of the several British species, see Transactions of the Linnean Society, vol. iii. page 283-329, just published.Edit.

Neither the larva, pupa, or even the egg-state of some insects are exempt from the attacks of others, who deposit their eggs in them; these, after having passed through the usual transformations, become what is termed the ichneumon fly. The following are the curious observations of an ingenious naturalist on this fly. “As I was observing,” says he, “one day some caterpillars which were feeding voluptuously on a cabbage leaf, my attention was attracted to part of the plant, about which a little fly was buzzing on its wing, as if deliberating where to settle: I was surprized to see the herd of caterpillars, creatures of twenty times its size, endeavouring in an uncouth manner, by various contortionsof the body to get out of its way, and more so whenever the fly poised on the wing as if going to drop; at length the creature made its choice, and seated itself on the back of one of the largest and fairest of the cluster; it was in vain the unhappy reptile endeavoured to dislodge the enemy. If the caterpillar had shewn terror on the approach of the fly, its anguish at intervals now seemed intolerable, and I soon found that it was in consequence of the strokes or wounds given by the fly. At every wound the poor caterpillar wreathed and twisted its whole frame, endeavouring to disengage itself, by shaking off the enemy, sometimes aiming its mouth towards the place; but it was all invain; its little, but cruel tormentor kept its place. When it had inflicted thirty or forty of these wounds, it took its flight with a visible triumph; in each of these wounds the little fly had deposited an egg. I took the caterpillar home with me, to observe the progress of the eggs which were thus placed in its body, taking care to give it a fresh supply of leaves from time to time; it recovered to all appearance in a few hours from the wounds it had received, and from that time, for the space of four or five days, seemed to feed with its usual avidity. The eggs were all hatched into small oblong voracious worms, which fed from the moment of their appearance on the flesh of the caterpillar, in whose body they were inclosed, and seemingly without wounding the organs of respiration or digestion; and when they had arrived at their full growth, they eat their way out of the sides of the animal, at the same time destroying it. The caterpillar thus attacked by the larva of the ichneumon never escapes, its destruction is infallible; but then its life is not taken away at once; the larva, while it is feeding thereon, knows how to spare the parts which are essential to its life, because its own is at that time tied up in that of the caterpillar. No butterfly is produced from it; the worms that feed on the wretched creature, are no sooner out of its body, than every one spins its own web, and under this they pass the state of rest necessary to introduce them to their winged form.”[89]To treat of each species of the ichneumon would alone fill a volume; Linnæus enumerates no less than seventy-seven of them.[90]

[89]Inspector, No. 64.[90]“The genus of insects called ichneumon derive their support and nourishment from other insects, some depositing their eggs in the larva, others again in the pupa, and some even in the ovum or egg itself, the contents of which, minute as they are, are sufficient to support the young larvæ until their change into their pupa state. Some deposit only one egg in a place, as the ichneumon ovulorum, and others again a great number, as ichneumon puparum, &c. but whether the egg be placed in the pupa, larva, or ovum, the destruction of the foster parent is inevitable. The larvæ of large moths or butterflies that have been wounded by an ichneumon, live and feed, though with evident marks of disease, until those parasites are full fed, and able to change into their second or pupa state.” See Observations on the Œconomy of the Ichneumon Manifestator, in the Transactions of the Linnean Society, vol. 3, p. 23 & seq. by T. Marsham, Esq. Sec. L. S.Edit.

[89]Inspector, No. 64.

[90]“The genus of insects called ichneumon derive their support and nourishment from other insects, some depositing their eggs in the larva, others again in the pupa, and some even in the ovum or egg itself, the contents of which, minute as they are, are sufficient to support the young larvæ until their change into their pupa state. Some deposit only one egg in a place, as the ichneumon ovulorum, and others again a great number, as ichneumon puparum, &c. but whether the egg be placed in the pupa, larva, or ovum, the destruction of the foster parent is inevitable. The larvæ of large moths or butterflies that have been wounded by an ichneumon, live and feed, though with evident marks of disease, until those parasites are full fed, and able to change into their second or pupa state.” See Observations on the Œconomy of the Ichneumon Manifestator, in the Transactions of the Linnean Society, vol. 3, p. 23 & seq. by T. Marsham, Esq. Sec. L. S.Edit.

Of this strange scene it is difficult for us to form a proper judgment; we are unacquainted with the organs of the caterpillar,ignorant of the nature of its sensations, and therefore we cannot be assured what may be the effects of that which we see it suffer. “It is wisdom to suppose we are ignorant, while we know the Creator cannot be cruel.” From revelation we learn, that man is the mean through which life is conveyed to the creatures of this lower world; that by sinking into error, and fostering evil, he perverts his own life, and corrupts all that which proceeds from him: so that the effects are the same on the orders beneath him, as would arise to the world if a continual cloud was placed between us and the sun, depriving us at once of the salutary effects of its invigorating heat and cheering light. Hence there is in this degraded world an obscure and melancholy shade cast over all the beauties of creation.

Lastly, the number of insects which feed upon others, nay, some even upon their own species, is very great: it is among these that we find the traces of the greatest art and cunning, as well in attack as defence; some indeed use main force alone. Most persons are acquainted with the dexterous arts of the spider, the curious construction of the web he spins, and the central position he takes, in order to watch more effectually the least motion that may be communicated to its tender net. Those who wish to pursue this subject further, will find ample satisfaction by consulting the works of Reaumur and De Geer.

Insects may be divided, with respect to their habitations, into two classes, aquatic and terrestrial.

Stagnant waters are generally filled with insects, who live therein in different manners. These are, 1. Aquatic insects which remain always on the superficies of the water, or which at least plunge themselves therein but rarely. 2. Others that live only in the water, and cannot subsist out of it. 3. Many, after having lived in the water while in the larva and pupa state, quit it afterwards with wings, and become entirely terrestrial. 4. Some undergo all their transformations in the water, and then become amphibious. 5. Others again are born and grow in the water, but undergo their pupa state on dry land, and after they are arrived at their perfect state, live equally in air and water; and 6. There are some who live at the same time part in the water and part on land, but after their transformation cease to be aquatic.

Among the insects which remain on the superficies of the water, are some spiders, which run with great address and agility, without moistening their feet or their body; when they repose themselves, they extend their feet as much as possible. There are also aquatic bugs, which swim, or rather run on the water with great velocity, and by troops; another bug walks very slowly on the water; the gyrinus moves very swiftly, and in circles. There is a species of podura[91]which live in society, and are often accumulated together in little black lumps. Those insects which always live in the water are generally born with thefigure which they retain during their whole lives, as the monoculi, crabs, several kinds of water mites, &c.

[91]De Geer Discours sur les Insectes, tom. 2, p. 103.

Those insects which, after having lived in the water, leave it when in a winged state, are very numerous: among these we may reckon the libellula, the ephemera, the phryganea, culices, tipulæ, and some species of muscæ. All these, when in the larva and pupa state, live in the water; but when they have assumed their perfect form, are entirely terrestrial, and would perish in their former element.

The notonecta, the nepa or aquatic scorpion, &c. never quit the water till they have passed through all their transformations, when they become amphibious, generally quitting it in the evening.

The water-beetles, of which there are many species, remain in the water all day, but toward evening come upon the ground and fly about, then plunge themselves again in the water at the approach of the rising sun. The larvæ of these insects are entirely aquatic, but when the time of their pupa state arrives, they take to the earth, where they make a spherical case; so that these insects are aquatic in the larva, terrestrial in the pupa, and amphibious in the imago state.

We find an instance of an insect that lives at the same time in the water and the air, in the singular larva described by Reaumur, Memoires de l’Acad. in 1714, p. 203. It has the head and tail in the water, while the rest of the body is continually kept above the surface. In order to support itself in this singular position, it bends the body, bringing the head near the tail, raising the rest above the water, and supporting itself against some fixed object, as a plant, or against the borders of the pond; or, if it be placedin a glass vessel, against the sides of the vessel; and if the glass be inclined gently, so that the water may nearly cover the larva, it immediately changes its position, in order that part of the body may be kept dry.

At the baths of Abano, a small town in the Venetian state, there is a multitude of springs, strongly impregnated with sulphur, and of a boiling heat. In the midst of these boiling springs, within three feet of four or five of them, there is a tepid one about blood-warm. In this water, not only the common potamogetons and confervas, or pond-weeds and water-mosses are found growing in an healthy state, but numbers of small black water beetles are seen swimming about, which die on being taken out and plunged suddenly into cold water.[92]

[92]Jones’s Physiological Disquisitions, p. 171.

Many insects that live under the surface of the earth crawl out on certain occasions, as the julus, scolopendra, and the oniscus; they are often also to be found under stones, or pieces of rotten wood. Some insects remain under ground part of their life, but quit that situation after their change; as do some caterpillars, many of the coleoptera class, &c. There are some species of spiders, which form habitations in sand; one of which makes a hole in the sand, lining it with a kind of silk, to prevent its crumbling away; this spider generally keeps on the watch near the mouth of the hole, and, if a fly approach, runs at it with such velocity, as seldom to fail in its attempt of seizing the little animal, which is immediately conveyed to the den of the spider. The formica-leo, or ant-lion, also inhabits sand.[93]

[93]The art and dexterity with which the formica-leo entraps ants, as well as other insects, merits notice; he makes a pit in fine dry sand, shaped like a funnel or an inverted cone, at the point or reverted apex of which he takes his station, concealing every part of his body except the tips of his two horns; these are expanded to the two sides of the pit. When an insect treads on the edge of this precipice, it perhaps slides into it; if not, its steps remove a little of the sand, which of course descends down the sides, and gives the enemy notice of his prey. He then throws up the sand with which his head is covered, to involve the insect, and bring it to the bottom with the returning force of the sand: this, by repeated efforts he is sure to effect, as all the attempts of the unfortunate victim to escape, when once within the verge of the pit, are in vain. One species of the formica-leo forms no pit to entrap its prey, but seizes it by main force.Edit.

Another spider, discovered by M. l’Abbe Sauvage,[94]burrows in the earth like a rabbit, making a hole one or two feet deep, of a regular diameter, and sufficiently large to move itself with ease. It lines the whole of it, either to keep the ground from tumbling in, or in order to perceive more regularly at the bottom what happens at the mouth, at which it forms a kind of door, made of different layers of earth, connected together by threads and covered with a strong web of a close texture; the threads are prolonged on one side, and fixed to the ground, so as to form a strong joint; the door is hung in such a manner, as always to fall by its own gravity. One of these cases or nests is in her Majesty’s cabinet at Kew.

[94]Histoire de l’Acad. 1758, p. 26.

The several parts of trees and plants afford a variety of habitations for insects, where they find an abundance of food. They dwell, l. in the roots; 2. in the wood; 3. in the leaves, and in the galls which grow upon them and the branches; 4. in the flowers; 5. in the fruits and grains. To enumerate the various species of these inhabitants would be endless; many particulars have been already noticed; it has also appeared that some inhabit the most fœtid substances they can find, while others dwell with and live on the larger animals; so that it only remains just tomention some of those in whom industry and art is more strongly marked to our eyes than in others.

Among the solitary bees there are so many curious circumstances to be described, that a single volume would not suffice to contain the particulars; we shall here only relate such as concern their habitations. One of these forms its nest under ground, which is composed of several cells artfully let into each other, but not covered with a common inclosure; each cell consists of two or three membranes, inexpressibly fine, and placed over each other. The cavity, in which the nest is placed, is smeared over with a layer of matter, like that of which the cells are formed, and apparently similar to the viscous humour which snails spread in their passage from one place to another, and it is probable that they are formed of the same materials; this substance, though of so delicate a nature, gives them such a degree of consistency, that they may be handled without altering their form. An egg is deposited at the bottom of each cell, where, after it is hatched, the worm finds itself in the midst of a plentiful stock of provision; for in each cell there is placed a quantity of paste, or a kind of wax, which is to serve as food for the worm, and support the wall of the cell. The worm is also instructed so to conduct itself, and eat this food, as to leave sufficient props for supporting the walls of its apartment. Many species of these bees content themselves with penetrating into the earth, scooping out hollow cavities therein, polishing the walls, then depositing an egg and a sufficient quantity of provisions.

There is another species, that forms its nest under ground with remarkable industry; this bee generally makes a perpendicular hole in the earth about three inches deep, and cylindrical, till within about three-fourths of an inch of the bottom, when it begins to enlarge; as soon as the bee has given it the suitableproportions, it proceeds to line not only the whole inside of its dwelling, but round the entrance; the substance with which it is lined is of a crimson colour, and looks like satin. From this circumstance Reaumur[95]terms it the tapestry bee. This tapestry or lining is formed of fragments of the flowers of the wild poppy, which she cuts out curiously, and then seizing them with her legs, conveys them to her nest. If the pieces are wrinkled, she first straightens and then affixes them to her walls with wonderous art; she generally applies two layers of these fragments one over the other. If the piece she has cut and transported be too large for the place she intends it for, she clips off the superfluous parts and conveys the shreds out of the apartment. After the bee has lined her cell, she fills it nearly half an inch deep with a paste proper to nourish the larva when hatched from the egg; when the bee has amassed a sufficient quantity of paste, she then takes her tapestry, and folds it over the paste and egg, which are by these means inclosed as it were in a bag of paste; this done, she fills up with earth the empty space that is above the bag. There is another bee which does the same with rose-leaves, and in the substance of a thick post. A friend of mine had a piece of wood cut from a strong post that supported the roof of a cart-house, full of these cells or round holes, three-eighths of an inch in diameter, and about three-fourths deep, each of which was filled with these rose-leaf cases finely covered in at top and bottom.

[95]Reaumur Memoires pour l’Histoire des Insectes, edit. 8vo. tom. 6, partie 1, p. 170.

The mason bee is so called by Reaumur from the manner of its building its nest. These bees collect with their jaws small parcels of earth and sand, which they glue together with a strong cement furnished from the proboscis; and of this they form a simple but commodious habitation, which is generally placedalong walls that are exposed to the south. Each nest resembles a lump of rude earth, of about six or seven inches diameter, thrown against the wall; the labour of constructing so large an edifice must be very great, as the bee can only carry a few grains at a time. The exterior form is rude and irregular, but the construction and art exhibited in the interior parts make up for this seeming defect; it is generally divided into twelve or fifteen cells, separated from each other by a thick wall; in each of these an egg is deposited by the parent bee. The cells are not constructed all at once, for when one is finished, she places an egg therein, with a sufficient quantity of honey to nourish the larva; she then builds another. When the insect is arrived at a proper state, it penetrates through its inclosures by means of its strong jaws. When all the bees have quitted the nest, there are as many holes on the surface thereof as there are cells within. We find no neutral bees among this species, or at least we do not know of any being yet discovered.

Another species of the solitary bee (apis centuncularis, Linn.) constructs her nest in pieces of rotten wood, and has therefore been called the carpenter bee.[96]She divides it into stages, disposing them sometimes in three rows, with partitions curiously left between each; in these she deposits her eggs, with the food necessary for the young ones when hatched. They separate the wood in a very expeditious manner, by dividing its ligneous fibres or threads, till they have made a proper sized hole.

[96]Geoffroy Hist. abregee des Insectes, tom. 2, p. 401.

The art and sagacity displayed by another bee,[97]whose nest is constructed of single pieces of leaves, is truly wonderful. The nest itself is cylindrical, formed of several cells, placed one withinthe other, as thimbles are in a hard-ware shop. The cells consist of several pieces cut from one leaf, of forms and proportions proper to coincide with the place each is intended to occupy. The outer case or cover is formed with equal care and exactness. In a word, says Bonnet, there is so much exactness, symmetry, uniformity, and skill, in this little master-piece, that we should not believe it to be the work of a fly, if we did not know at what school she learnt the art of constructing it. In each cell the mother deposits an almost liquid substance, and yet so nicely are the cells formed, as not to suffer any of this substance to be lost. But for a minute account of the works of this bee, and the curious mechanism of its cells, we must refer the reader to Reaumur’s admirable history of insects.

[97]Reaumur Memoires pour l’Histoire des Insectes, tom. 6, par. 1, p. 122.

The proceedings of the mason ichneumon wasp,[98]sphex, Linn. are totally different from those of the common wasp, though equally curious. It generally begins its work in May, and continues it for the greatest part of June. The true object of her labour seems to be the digging of a hole a few inches deep in the ground; yet in the constructing of this, she forms a hollow tube above ground, the base of which is the aperture of the hole, and which is raised as high above ground as the hole is deep below; it is formed with a great deal of care, resembling a gross kind of fillagree work, consisting of the sand drawn from the hole. The sand out of which she excavates her cell, is nearly as hard as a common stone; this it readily softens with a penetrating liquor with which she is well provided; a drop or two of it is imbibed immediately by the sand on which it falls, which is instantly rendered so soft, that she can separate and knead it with her teeth and fore feet, forming it into a small ball, which she places on the edge of the hole as the foundation stone of the pillar sheis going to erect; the whole of it is formed of such balls, ranged circularly, and then placed one above the other. She leaves her work at intervals, probably in order to renew her stock of that liquor which is so necessary for her operations. These intervals are of short duration; she soon returns, and labours with so much activity and ardour, that in a few hours she will dig a hole two or three inches deep, and raise a hollow pillar two inches high. After the column has been raised a certain height perpendicular from the ground, it begins to curve a little, which curvature increases till it is finished, though the cylindrical form is maintained: she constructs several of these holes all of the same form, and for the same purpose. It is easy to see why the hole was dug in the ground; that it was destined to receive an egg; but it is not so easy to perceive why the tube of sand was formed. By attending to the labours of the wasp, one end, however, may be discovered; it will be found to serve the purpose of a scaffold, and that the balls are as useful to the wasp, as materials, &c. to the mason; and are therefore placed as much within her reach as possible. She uses them to stop and fill up the hole after she has deposited an egg therein, so that the pillar is then destroyed, and not the least remains left in the nest. The parent wasp generally leaves ten or twelve worms as provision necessary and proper for the growth of the young larva: no purveyor could take better precautions than our wasp, for she has received her instructions from HIM who provides for the necessities of all his creatures. In selecting the worms, she chooses those of a proper size, that they may be sufficient in quantity, and of an age that will not be in danger of perishing with hunger, in which case they would have been corrupted; she therefore selects them when they have their full growth. It is also observed, that if she choose a larger sort, she gives a less number of them, and so reciprocally.

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