"mole-cricket" is the most extraordinary. This animal is the largest of all the insects with which we are acquainted in this country, being two inches and a half in length, and three-quarters of an inch in breadth. The colour is of a dusky brown, and at the extremity of the colour of the tail of a mouse. The body consists of eight scaly joints or separate folds, is brown on the upper part, the more deeply tinged below. The wings are long, narrow, and terminate in a sharp point, each having a blackish line running down it; however, when they are extended they appear to be much broader than could at first sight be supposed. The shield of the breast is of a firm texture, of a blackish colour and hairy; it generally, however, runs backward; but it is commonly under-ground, where it burrows even faster than a mole. It is thought also to be amphibious, and capable of living under water as well as under ground. Of all insects this is the most detested by gardeners, as it chiefly resides in that ground which lies light, and where it finds sufficient plenty under the surface. Thus, in a single night's time it will run along a furrow which has been newly sown and rob it of all its contents. Its legs are formed in such a manner that it can penetrate the earth in every direction-before, behind, and above it. At night it ventures from its underground habitation, and, like the cricket, has its chirping call. When the female is fecundated she makes a cell of clammy earth, the inside of which is large enough to hold two hazle-nuts; and in this she lays her eggs. The whole nest is about the size of a common hen's-egg, closed up on every side, and well defended from the smallest breath of air. The eggs generally amount to the number of a hundred and fifty, being white, and about the size of a carraway-comfit. They are thus carefully covered, as well to defend them from the injuries of the weather as from the attacks of the black-beetle, which, being itself an underground inhabitant, would but for this precaution devour or destroy them. To prevent this the female mole-cricket is often posted as a centinel near the nest, and when the black invader plunges in to seize its prey, the guardian insect seizes him behind, and instantly bites him in two.

Nothing can exceed the care and assiduity which these animals exhibit in the preservation of their young. Wherever the nest is placed there seems to be a fortification, avenues, and entrenchments drawn round it; there are numberless winding ways that lead to it, and a ditch drawn about it, which few of its insect enemies are able to pass. But their care is not confined to this only; for at the approach of winter they carry their nest entirely away, and sink it deeper in the ground, so that the frost can have no influence in retarding the young brood from coming to maturity. As the weather grows milder they raise their magazine in proportion; till at last they bring it as near the surface as they can to receive the genial influence of the sun, without wholly exposing it to view; yet should the frost unexpectedly return they sink it again as before.

CHAP. V.

limbs bursts behind, like a woman's stays, and gives freedom to a set of wings, with which the animal expa tiates, and flies in pursuit of its mate.

Of all this class of insects the earwig undergoes the smallest change. This animal is so common that it scarce needs a description: its swiftness in the reptile state is not less remarkable than its indefatigable velocity when upon the wing. That it must be very prolific appears from its numbers; and that it is very harmless every one's experience can readily testify. It is provided with six feet and two feelers; the tail is forked, and with this it often attempts to defend itself against every assailant. But its attempts are only the threats of impotence; they draw down the resentment of powerful animals, and no way serve to defend it. The deformity of its figure and slender make have also subjected it to an imputation, which, though entirely founded in prejudice, has more than once procured its destruction. It is supposed, as the name imports, that it often enters into the ears of people sleeping-thus causing madness from the intolerable pain, and soon after death itself. Indeed, the French name, which signifies the ear-piercer, urges the calumny against this harmless insect in very plain terms; yet nothing can be more unjust the ear is already filled with a substance which prevents any insect from entering; and besides, it is well lined with membranes, which would keep out any little animal, even though the ear-wax were away. These reproaches, therefore, are entirely groundless; but it were well if the accusations which gardeners bring against the earwig were as slightly founded. There is nothing more certain than that it lives among flowers, and destroys them. When fruit also has been wounded by flies, the earwig generally comes in for a second feast, and sucks those juices which they first began to broach. Still, however, this insect is not so noxious as it would seem, and seldom is found but where the mischief has been originally begun by others. Like all of this class, the earwig is hatched from an egg. As there are various kinds of animals, so they choose different places to breed in: in general, however, they lay their eggs under the bark of plants, or in the clefts of trees when beginning to decay. They proceed from the egg in that reptile state in which they are most commonly seen, and as they grow larger the wings bound under the skin begin to appear. It is amazing how very little room four large wings take up before they are protruded; for no person could ever conceive such an expansion of natural drapery could be rolled up in so small a packet. The sheath in which they are enveloped folds and covers them so neatly, that the animal seems quite destitute of wings; and even when they are burst from their confinement the animal, by the power of the muscles and joints which it has in the middle of its wings, can closely fold them into a very narrow compass. When the earwig has become a winged insect it flies in pursuit of the female, ceasing to feed, and is wholly employed in the business of propa gation. It lives in its winged state but a few days; and having taken care for the continuance of posterity, dries up, and dies to all appearance consumptive.

BELONGING TO THE SECOND ORDER OF INSECTS.

We should still keep in memory that all insects of the second order, though not produced quite perfect from the egg, yet want very little of their perfection, and require but a very small change to arrive at that state which fits them for flight and generation. The natural functions in these are never suspended; from the instant they leave the egg they continue to eat, to move, to leap, and pursue their prey; a slight change ensues; a skin that enclosed a part of their body and

an oblong, obtuse body, and a large head with small eyes. The external wings, for it has four, are of a dusky brown, marked with two white spots; the head is black. The spume in which it is found wallowing is all of its own formation, and very much resembles frothy spittle. It proceeds from the vent of the animal and other parts of the body; and if it be wiped away a new quantity will be instantly seen ejected from the animal's body. Within this spume it is seen in time to acquire four tubercles on its back, wherein the wings are enclosed; these bursting, from a reptile it becomes a

winged animal; and thus rendered perfect, it flies to meet its mate and propagate its kind.

The water-tipula also belongs to this class. It has an oblong slender body, with four feet fixed upon the breast and four feelers near the mouth. It has four weak wings, which do not at all.seem proper for flying, but for leaping only. But what this insect chiefly demands our attention for is the wonderful lightness wherewith it runs on the surface of the water, so as scarce to put it in motion. It is sometimes seen in rivers and on their banks, especially under shady trees, and generally in swarms of several together.

The common water fly also breeds in the same manner with those above-mentioned. This animal is by some called notonecta," because it does not swim in the usual manner upon its belly, but on its back; nor can we help admiring that fitness in the insect for its situation, as it feeds on the under-side of plants which grow on the surface of the water; and therefore it is thus formed with its mouth upwards to take its food with greater convenience and ease.

We may also add the water-scorpion, which is a large insect, being near an inch in length and about half an inch in breadth. Its body is nearly oval, but very flat and thin, aud its tail long and pointed. The head is small; and the feelers appear like legs, resembling the claws of a scorpion, but without sharp points. This insect is generally found in ponds, and is of all others the most tyrannical and rapacious. It destroys, like a wolf among sheep, twenty times as many as its hunger requires. One of these, when put into a basin of water in which were thirty or forty worms of the libellula kind, each as large as itself, destroyed them all iu a few minutes-getting on their backs, and piercing with its trunk through their body. These animals, however, though so formidable to others, are nevertheless themselves greatly over-run with a small kind of louse, about the size of a nit, which very probably repays the injury which the water-scorpion inflicts upon others.

The water-scorpions live in the water by day, out of which they rise in the dusk of the evening into the air, and so flying from place to place, often betake themselves in quest of food to other waters. The insect, before its wings are grown, remains in the place where it was produced; but when come to its state of perfection sallies forth in search of a companion of the other sex, in order to continue its noxious posterity.

The last insect we shall add to this second order is the ephemera, which, though not strictly belonging to it, yet seems more properly referred to this rank than any other. Indeed, we must not attend to the rigour of method in a history where Nature seems to take delight to sport in variety.

That there should be a tribe of flies whose duration extends but to a day seems at first surprising; but the wonder will increase when we are told that some of this kind seem to be born to die in the space of a single hour. The reptile, however, from which they are bred is by no means so short lived, but is sometimes seen to live two years, and often three years together.

All ephemeras, of which there are various kinds, are produced from the eggs in the form of worms, from whence they change into a more perfect form, namely, that of aurelias, which is a kind of middle state between a worm and a fly; and from thence they take their last mutation, which is into a beautiful fly, of longer or shorter duration according to its kind.

The ephemera, in its fly state, is a very beautiful

winged insect, and has a strong similitude to the butterfly, both from its shape and its wings. It is about the size of a middling butterfly; but its wings differ, in not being covered with the painted dust with which those of butterflies are adorned and rendered opaque, for they are very transparent and very thin. These insects have four wings, the uppermost of which are much the largest; when the insect is at rest it generally lays its wings one over the other on the back. The body is long, being formed of six rings, that are larger at the origin than near the extremity; and from this a tail proceeds, that is longer than all the rest of the fly, and consists sometimes of three threads of an equal length, or sometimes of two long and one short. To acquire this beautiful form the insect has been obliged to undergo several transmutations; but its glory is very short lived, for the hour of its perfection is the honr of its death; and it seems scarcely introduced to pleasure when it is obliged to part with life.

The reptile that is to become a fly, and that is granted so long a term when compared to its latter duration, is an inhabitant of the water, and bears a very strong resemblance to fishes in many particulars-having gills by which it breathes at the bottom, and also the tapering form of aquatic animals These insects have six scaly legs fixed on their corselet. Their head is triangular; the eyes are placed forward, and may be distinguished by their largeness and colour. The mouth is furnished with teeth; and the body consists of six rings, that next the corselet being largest, but growing less and less to the end; the last ring is the shortest, from which the three threads proceed, which are as long as the whole body. Thus we see that the reptile bears a very strong resemblance to the fly, and only requires wings to be very near its perfection.

As there are several kinds of this animal their aurelias are consequently of different colours-some yellow, some brown, and some cream-coloured. Some of these also bore themselves cells at the bottom of the water, from which they never stir out, but feed upon the mud composing the walls of their habitation in contented captivity; others, on the contrary, range about go from the bottom to the surface, swim between two waters, quit that element entirely to feed upon plants by the river-side, and then return to their favourite element for safety and protection.

The reptile, however, though it lives two or three years, offers but little in its long duration to excite curiosity it is hid at the bottom of the water, and feeds almost wholly within its narrow habitation. The peculiar sign whereby to know that these reptiles will change into flies in a short time consists in a protuberance of the wings on the back. About that time ne smooth and depressed form of the upper part of the body is changed into a more swoln and rounder shape, so that the wings are in some degree visible through the external sheath that covers them. As they are not natives of England, he who would see them in their greatest abundance must walk about sun-set along the banks of the Rhine or the Seine, where for about three days in the midst of summer he will be astonished at their numbers and assiduity. The thickest descent of the flakes of snow in winter seem not to equal their number; the whole air seems alive with the new-born race, and the earth itself is all covered with their remains. The aurelias or reptile insects, that are as yet beneath the surface of the water, wait only for the approach of evening to begin their transformation. The most industrious shake off their old garments about eight o'clock, and those who are the most tardy are transformed before nine.

We have already seen that the operation of change in other insects is laborious and painful; but with these nothing seems shorter, or performed with greater ease. The aurelias are scarce lifted above the surface of the

water than their old sheathing skin bursts; and through the cavity which is thus formed a fly issues, whose wings at the same instant are unfolded, and at the same time lift into the air. Millions and millions of aurelias rise in this manner to the surface, at once becoming flies, and filling every quarter with their flutterings. But all these sports are shortly to have an end; for as the little strangers live but an hour or two the whole swarm soon falls to the ground, and covers the earth like a deep snow for several hundred yards on every side of the river. Their numbers are then incredible, and every object they touch becomes fatal to them; for they instantly die if they hit against even each other.

At this time the males and females are very differently employed. The males, quite inactive and apparently without desires, seem only born to die: no way like the males of other insects, they neither follow the opposite sex nor bear any enmity to each other; after fluttering for an hour or two, they drop upon land without seeming to receive wings for scarce any other purpose but to satisfy an idle curiosity. It is otherwise with the females; they are scarce risen from the surface of the water and dried their wings but they hasten to drop their eggs back again. If they happen also to flutter upon land, they deposit their burthen in the place where they drop. But then it may be demanded, Where and in what manner are these eggs fecundated, as no copulation whatever appears between the sexes in their transitory visits in air? Swammerdam is of opinion that they are impregnated, in the manner of fish-spawn, by the male after being ejected by the female; but, beside that this doctrine is exploded even from the history of fishes, it is certain that the males have not time for this operation, as the eggs drop to the bottom the instant they are laid on the water. Reaumur is of opinion that they copulate, but that the act bears a proportion in shortness to the small duration of their lives, and, consequently, must be soon performed as to be scarcely visible. This, however, is at best forcing a theory; and it is probable that as there are many insects known to breed without any impregnation from the male-as we have already seen in muscles and oysters, and shall hereafter see in the gnat and a species of the beetle-so the ephemera may be of this number. Be this as it may, the females are in such haste to deposit their eggs that multitudes of them fall to the ground, but the greatest part are laid in the water. As they flutter upon the surface, two clusters are seen issuing from the extremity of their body, each containing about three hundred and fifty eggs, which make seven hundred in all. Thus, of all insects this appears to be the most prolific; and it would seem that there was a necessity for such a supply, as, in its reptile state, it is the favourite food of every kind of fresh-water fish. It is in vain that these little animals form galleries at the bottom of the river, from whence they seldom remove; many kinds of fish break in upon their retreats, and thin their numbers. For this reason fishermen are careful to provide themselves with these insects as the most grateful bait, and thus turn the fish's rapacity to its own destruction.

But though the usual date of these flies is two or three hours at farthest, there are some kinds that live several days; and one kind in particular, after quitting the water, has another case or skin to get rid of. These are often seen in the fields and woods distant from the water; but they are more frequently found in its vicinity. They are often found sticking upon walls and trees, and frequently with the head downwards, without changing place or having any sensible motion. They are then waiting for the moment when they shall be divested of their last incommodious garment, which sometimes does not happen for two or three days together.

BOOK III.-CHAP. 1.

OF INSECTS OF THE THIRD ORDER.

OF CATERPILLARS.

If we take a cursory view of insects in general, caterpillars alone, and the butterflies and moths they give birth to, will make a third part of the number. Wherever we move, wherever we turn, these insects, in one shape or another, present themselves to our view. Some in every state offer the most entertaining spectacle; others are beautiful only in their winged form. Many persons, of which number I am one, have an invincible aversion to caterpillars and worms' of every species; there is something disagreeable in their slow, crawling motion, for which the variety of their colouring can never compensate. But others feel no repugnance at observing, and even handling them with the most attentive application. There is nothing in the butterfly state so beautiful or splendid as these insects. They serve, not less than the birds themselves, to banish solitudes from our walks, and to fill up our idle intervals with the most pleasing speculations. The butterfly makes one of the principal ornaments of oriental poetry; but in those countries the insect is larger and more beautiful than with ns.

The beauties of the fly may therefore very well excite our curiosity to examine the reptile. But we are still more strongly attached to this tribe from the usefulness of one of the number. The silk-worm is, perhaps, the most serviceable of all other animals-since from its labours and the manufacture attending it near a third part of the world are clothed, adorned, and supported.

Caterpillars may be easily distinguished from worms or maggots by the number of their feet, and by their producing butterflies or moths. When the sun calls up vegetation, and vivifies the various eggs of insects, the caterpillars are the first that are seen upon almost every vegetable and tree, eating its leaves, and preparing for a

state of greater perfection. They have feet both before and behind, which not only enable them to move forward by a sort of steps made by their fore and hinder parts, but also to climb up vegetables and to stretch themselves out from the boughs and stalks to reach their food at a distance. All of this class have from eight feet, at the least, to sixteen; and this may serve to distinguish them from the worm tribe, that never have so many. The animal into which they are converted is always a butterfly or a moth; and these are always distinguished from other flies by having their wings covered over with a painted dust, which gives them such various beauty. The wings of flies are transparent, as we see in the common flesh-fly, while those of beetles are hard, like horn; from such the wing of a butterfly may be easily distinguished, and words would obscure their differences.

From hence it appears that caterpillars, whether in the reptile state or advanced to their last state of perfection into butterflies, may easily be distinguished from all other insects, being animals peculiarly formed, and also of a peculiar nature. The transmutations they undergo are also more numerous than those of any insect hitherto mentioned, and in consequence they have been placed in the third order of changes by Swammerdam, who has thrown such lights on this part of natural history. In the second order of changes, mentioned before, we saw the grasshopper and the earwig when excluded from the egg assume a form very like that which they were after to preserve, and seemed arrived at a state of perfection in all respects, except in not having wings, which did not bud forth until they came to maturity. But the insects of this third order, which we are now about to describe, go through a much greater variety of transformations; for when they are excluded from the egg they assume the form of a small caterpillar,

which feeds and grows larger every day, often changing its skin, but still preserving its form. When the animal has come to a certain magnitude in this state it discontinues eating, makes itself a covering or husk, in which it remains wrapped up seemingly without life or motion; and after having for some time continued in this state, it once more bursts its confinement, and comes forth a butterfly. Thus we see this animal put on no less than three different appearances from the time it is first excluded from the egg. It appears a crawling caterpillar; then an insensible aurelia, as it is called, without life or motion; and lastly, a beautiful butterfly, variously painted according to its different kind. Having thus distinguished this class of insects from all others, we will first survey their history in general, and then enter particularly into the manners and nature of a few of them.

CHAP. II.

In general, caterpillars of this kind are found in great numbers together, enclosed in one common web that covers them all, and serves to protect them from the injuries of the air.

Lastly, there are some of the caterpillar kind whose butterflies live all the winter, and who, having fluttered about for some part of the latter end of autumn, seek for some retreat during the winter, in order to answer the ends of propagation at the approach of spring. These are often found lifeless and motionless in the hollows of trees or the clefts of timber; but on being brought to the fire they recover life and activity, and seem to anticipate the desires of the spring.

In general, however-whether the animal has subsisted in an egg state during the winter, or whether as a butterfly bred from an aurelia in the beginning of spring; or a butterfly that has subsisted during the winter, and lays eggs as soon as the leaves of plants are shot forwardthe whole swarm of caterpillars are in motion to share the banquet that Nature has provided. There is scarce a plant that has not its own peculiar insects; and some are known to support several of different kinds. Of these many are

CORRESPONDING BUTTERFLY OR MOTH FORM.

When winter has disrobed the trees of their leaves, Nature then seems to have lost her insects. There are thousands of different kiuds with and without wings, though swarming at other seasons, then entirely disappear. Our fields are re-peopled when the leaves begin to bud by the genial influence of spring, and caterpillars of various sorts are seen feeding upon the promise of the year, even before the leaves are unfolded. Those caterpillars which we then see may serve to give us a view of the general means which Nature employs to preserve such a number of insects during that season, when they can no longer find subsistence. It is known by united experience that all these animals are hatched from the eggs of butterflies; and those who observe them more closely will find the fly very careful in de positing its eggs in those places where they are likely to be hatched with the greatest safety and success. During winter, therefore, the greatest number of caterpillars are in an egg state, and in this lifeless situation brave all the rigours and the humidity of the climate, and though often exposed to all its changes, still preserve the latent principles of life, which is more fully exerted at the approach of spring. That same Power which pushes forth the budding leaf and the opening flower impels the insect into animation, and Nature at once seems to furnish a guest and the banquet. When the insect has found force to break its shell it always finds its favourite aliment provided in abundance before it.

But all caterpillars are not sent off from the egg in the beginning of spring; for many of them have subsisted during the winter in their aurelia state, in which, as we have briefly observed above, the animal is seemingly deprived of life and motion. In this state of insensibility many of these insects continue during the rigours of winter-some enclosed in a kind of shell, which they have spun themselves at the end of autumn -some concealed under the bark of trees-others in the chinks of old walls and many buried under ground. From all these a variety of butterflies are seen to issue in the beginning of spring, and adorn the earliest part of the year with their painted flutterings.

Some caterpillars do not make any change whatsoever at the approach of winter, but continue to live in their reptile state through all the severity of the season. These choose themselves some retreat, where they may remain undisturbed for some months together; and there they remain quite motionless, and as insensible as if they were actually dead. Their constitution is such, that food at that time would be useless; and the cold prevents their making those dissipations which require restoration.

up to its leaves for subsistence; the eggs of others have been glued by the parent butterfly to the leaves; and they are no sooner excluded from the shell but they find themselves in the midst of plenty.

When the caterpillar first bursts from the egg it is small and feeble; its appetites are in proportion to its size, and it seems to make no great consumption; but as it increases in magnitude it improves in its appetites-so that in its adult caterpillar state it is the most ravenous of all animals whatsoever. A single caterpillar will eat double its own weight of leaves in a day, and yet seems no way disordered by the meal. What would mankind do if their oxen or their horses were so voracious?

These voracious habits, with its slow crawling motion, but still more a stinging like that of nettles which follows upon handling the greatest number of them, make these insects not the most agreeable objects of human curiosity. However, there are many philosophers who have spent years in their contemplation, and who have not only attended to their habits and labours, but minutely examined their structure and internal conformation.

The body of the caterpillar when anatomically considered is found composed of rings, whose circumference is pretty near circular or oval. They are generally twelve in number, and are all membraneous-by which caterpillars may be distinguished from many other insects that nearly resemble them in form. The head of the caterpillar is connected to the first ring by the neck, which is generally so short and contracted that it is scarce visible. All the covering of the head in caterpillars seems to consist of a shell; and they have neither upper nor under jaw, for they are both placed rather vertically, and each jaw armed with a large thick tooth, which is singly equal to a great number. With these the animals devour their food in amazing quantities, and with these some of the kind defend themselves against their enemies. Though the mouth be kept shut the teeth are always kept uncovered; and while the insect is in health they are seldom without employment. Whatever the caterpillar devours these teeth serve to chop it into small pieces, and render the parts of the leaf fit for swallowing. Many kinds while they are yet young eat only the succulent part of the leaf, and leave all the fibres untouched: others, however, attack the whole leafe, and eat it clean away. One may be amused for a time in observing the avidity with which they are seen to feed; some are seen eating the whole day, others have their hours of repast; some choose the night, and others the day. When the caterpillar attacks a leaf it places its body in such a manner that the edge of the leaf shall fall between its feet, which keeps it steady while the teeth are employed in cutting it; these fall upon the leaf somewhat in the

manner of a pair of gardener's sheers, and every morsel is swallowed as soon as cut. Soms caterpillars feed upon leaves so very narrow, that they are not broader than their mouths: in this case the animal is seen to devour it from the point as we would eat a raddish.

As there are various kinds of caterpillars, the number of their feet are various; some having eight, and some sixteen. Of these feet the six foremost are covered with a sort of shining gristle, and are therefore called the shelly-legs. The hindmost feet, whatever be their number, are soft and flexible, and are called membraneous. Caterpillars also, with regard to their external figure, are smooth or hairy. The skin of the first kind is soft to the touch, or hard like shagreen; the skin of the latter is hairy, and, as it were, thorny; and generally, if handled, stings like nettles. Some of them even cause this stinging pain if but approached too nearly. Caterpillars in general have six small black spots placed on the circumference of the fore ring, and a little to the side of the head. Three of these are larger than the rest, and are convex and transparent; these Reau mur takes to be the eyes of the caterpillar; however, most of these reptiles have very little occasion for sight, and seem only to be directed by their feeling.

But the parts of the caterpillar's body which most justly demand our attention are the stigmata, as they are called, or those holes on the sides of its body through which the animal is supposed to breathe. All along this insect's body on each side these holes are easily discoverable. They are eighteen in number, nine on a side, rather nearer the belly than the back; there is a hole for every ring of which the animal's body is composed, except the second, the third, and the last. These oval openings may be considered as so many mouths, through which the insect breathes; but with this difference, that as we have but one pair of lungs, the caterpillar has no less than eighteen. It requires no great anatomical dexterity to discover these lungs in the larger kind of caterpillars; they appear at first view to be hollow cartilaginous tubes, and of the colour of mother-ofpearl. These tubes are often seen to unite with each other; some are perceived to open into the intestines, and some go to different parts of the surface of the body. That these vessels serve to convey the air appears evidently from the famous experiment of Malpighi; who, by stopping up the mouths of the stigmata with oil, quickly suffocated the animal, which was seen to die convulsed the instant after. In order to ascertain his theory he rubbed oil upon other parts of the insect's body, leaving the stigmata free; and this seemed to have no effect on the animal's health, but it continued to move and eat as usual; he rubbed oil on the stigmata of one side, and the animal underwent a partial convulsion, but recovered soon after. However, it ought to be observed that air is not so necessary to these as to the nobler ranks of animals, since caterpillars will live in an exhausted receiver for several days together; and though they seem dead at the bottom, yet, when taken out, recover, and resume their former vivacity.

If the caterpillar be cut open longitudinally along the back, its intestines will be perceived running directly in a straight line from the mouth to the anus. They resemble a number of small bags opening into each other; and strengthened on both sides by a fleshy cord by which they are united. These insects are upon many occasions seen to cast forth the internal coat of their intestines with their food, in the changes which they so frequently undergo. But the intestines take up but a small part of the animal's body, if compared to the fatty substance in which they are involved. This substance changes its colour when the insect's metamorphosis begins to approach; and from white it is usually seen to become yellow. If to these parts we add the caterpillar's implements for spinning (for all caterpillar's spin at one time or another), we shall have a rude sketch of this

animal's conformation; however, we shall reserve the description of those parts till we come to the history of the silk-worm, where the manner in which these insects spin their webs will most properly find a place.

The life of a caterpillar seems one continued succession of changes; and it is seen to throw off one skin only to assume another, which also is divested in its turn, and this for eight or ten times successively. We must not, however, confound this changing of the skin with the great metamorphosis which it is afterwards to undergo. The throwing off one skin and assuming another seems in comparison but a slight operation among these animals; this is but the work of a day-the other is the great adventure of their lives. Indeed, this faculty of changing the skin is not peculiar to caterpillars only, but is common to all the insect kind; and even to some animals that claim a higher rank in Nature. We have already seen the lobster and the crab out-growing their first shells, and then bursting from their confinement in order to assume a covering more roomy and convenient. It is probable that the louse, the flea, and the spider. change their covering from the same necessity, and, growing too large for the crust in which they have been for some time enclosed, burst it for another. This period is probably that of their growth; for as soon as their new skin is hardened round them the animal's growth is necessarily circumscribed while it remains within it. With respect to caterpillars, many of them change their skins five or six times in a season; and this covering when cast off often seems so complete, that many might mistake the empty skin for the real insect. Among the hairy caterpillars, for instance, the cast skin is covered with air; the feet, as well gristly as membraneous, remain fixed to it; even the parts which nothing but a microscope can discover are visible in it-in short, all the parts of the head, not only the skull but the teeth.

In proportion as the time approaches in which the caterpillar is to cast its old skin its colours becomes more feeble, the skin seems to wither and grow dry, and in some measure resembles a leaf when it is no longer supplied with moisture from the stock. At that time the insect begins to find itself under a necessity of changing; and it is not effected without violent labour, and perhaps pain. A day or two before the critical hour approaches the insect ceases to eat, loses its usual activity, and seems to rest immoveable. It seeks some place to remain in security, and, no longer timorous, seems regardless even of the touch. It is now and then seen to bend itself and elevate its back; again it stretches to its utmost extent; it sometimes lifts up the head, and then lets it fall again; it sometimes waves it three or four times from side to side, and then remains in quiet. At length some of the rings of its body, particularly the first and second, are seen to swell considerably, the old skin distends and bursts, till, by repeated swellings and contractions in every ring, the animal disengages itself, and creeps from its inconvenient covering.

How laborious soever this operation may be, it is per formed in the space of a minute; and the animal, having thrown off its old skin, seems to enjoy new vigour, as well as acquired colouring and beauty. Sometimes it happens that it takes a new appearance and colours very different from the old. Those that are hairy still preserve their covering, although their ancient skin seems not to have lost a single hair; every hair appears to have been drawn, like a sword from the scabbard. However, the fact is that a new crop of hair grows between the old skin and the new, and probably helps to throw off the external covering.

The caterpillar having in this manner continued for several days feeding, and at intervals casting its skin, begins at last to prepare for its change into an aurelia. It is most probable that from the beginning all the parts of the butterfly lay hid in this insect in its reptile state;