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and moths. In the last sort of transformation, the insect, after having arrived at the nymph state, like those before mentioned, does not divest itself of its skin in order to enter into that state, but assumes the'form of a nymph under its ikin, where it continues ihut up, till quitting two skins at once, it comes forth in its persect state. This is the metamorphosis which flies, Ichneumons, EsV, undergo.
Besides these c^anges, insects several times cast; their skins; but this does not happen to them all at the fame time or in the fame way. Some, as spiders, change their skins only once a-year; others as grasshoppers, and the cabbage caterpillars change it four times; and others-even six times. The greater part quit it entirely, but some retain it attached to the extremity of the abdomen, and carry it over their head to desend them from bad weather, or other insects their enemies. This is the case, as Frisch observes, with the Cassida nebulosa. The manner in which they divest themselves of it, varies aiso according to the diversity of specie.0. In some it is rent near the top of the head, and the insect puts it off as one draws off a stocking. In others it is sirst torn under the belly, and they throw it over their head as one does a start. The spoils of many insects preserve exactly the sigure of the animal, which is particularly remarkable in those of spiders. Some of these cast skins, are lined internally with a white membrane much more delicate than the outer one. When thrown off, they are sometimes so contracted as not to retain a third of their former length; at othe' rimes they appear swollen, and discover nothing b the hole through which the insect made its exit, in
When the insect has thrown off its last skiy the pears in the state of'a nymph or chiysali.- reach
1 method • , of are only covers under which the animal is formes and which it preserves till it has taken its natural shape. These nymphs are soft at full,and contain some liquid matter which m time evaporates, and they acquire more consilience j but in general they are very thin and fragile^
. Infects in this state may be divided into two classes. There are some of a conical shape, almost of the figure of a date: others of an angulated form, with (harp corners at the rings and anterior part, and littie elevations at these corners. There is a great diversity in their figure. Without mentioning those that are of the form of a date, some have the appearance of a child in swaddling cloaths laid in a cradle; other* have the face of a man. Others resemble the head of a dog, a cat, a bird, a mouse with its tail, andevenot the Insect itself which is to- proceed from it.
The limbs of insects are not folded with less art in chryfalids and nymphs than they are in the egg. it is wonderful to fee the artifice with which they are disposed, and the wisdom which has-contrived to* lodge in so small a space, so many different members without hurting them, or producing the least confusion. In some we may perceive externally all the limbs of the animal it encloses; others are so transparent that the insect is easily discoverable upon looking through it: but others must be opened before we ean judge of the insect they contain.
u. Great variety is remarkable, in the colour of* chrytheilids. Brown, yellow, red, green, white, violet and rindeck are the chief; but it must be observed that nymph colours appear in various degrees, and that the lupe different sliades of them may be perceived in state, wnt forts of chryfalids, and in some mingled includes Lmuch art, that the eye is astonished in view-. The ancients imagined that the beauty of
the colours in a chrysalis was a proof of the beauty of the infect it contained; but nothing is more dert ceitful; we might as well fay that the beauty of a cradle was an indication of the beauty 4>f the child that slept in it. Besides, experience teaches us that a plain insect very often issues from a gilded chrysalis, while another with a less specious appearance often produces a very gaudy one.
No motion is perceived in some of those insects while they continue in this stage of transformation; but as this incapacity of moving themselves might expose them to be devoured by their enemies, they fhelxer themselves under a stone, a root, or a piece of wood. 'This is not all, they, make that side which is exposed, so round and tense, that worms cannot lay hold of them. They are not however all motionless. Some spontaneously agitate themselves, and others do not move except they are touched. These last, on such occasions move their abdomen and shake their heads as if to defend themselves, and intimidate their enemv. There are likewise some (as the Dytiscus latiflimus) which when turned upon their back, instantly replace themselves, in their first situation. Others, (as the Coccinella septempunctata,) turn themselves round for some time. Others though they are in general motionless, is they are taken into the hand, seem to be revived by the heat which puts their humours in circulation, and makes them perform various contorsions. But neither the one nor the other take the least nourishment during the time they continue in the pupa stare.
The precaution of choosing a convenient place in order to preserve themselves from injuries, does not always appear to them sufficient; they fortify the place they have chosen with a kind of entrenchwent against attacks from without. The method of sone is to suspend themselves by the tail to threads which they draw from their own bodies, and thus they are safe from the attacks of creeping in/ sects, and they hold so firmly by these threads that they are not easily detached.' Others weave around them a web with large meshes, nearly resembling a fisher's net: this keeps at a distance from the centre such insects as might injure them, and prevents their being hurt by the fall of any body. These two precautions are peculiar to those only which have skins sufficiently thick to resist the inclemencies of the wearher. Thole which have not the fame advantage cover themselves with a particular" sort of web. Some spin cones of fi!k, others discharge from the pores of their body a sort of long wool which covers them during al! the time they remain in the nymph state. Many sortify thele cones with their fairs, which they divest themselves of, (as the Phalæna Caja ;) and thole that have no 'hairs* and also want silk, gnaw pieces of wood, and employ the small bits in fortifying the inside and outside of their mansion, as is the practice of jhe Phalseria aceris. Some of these cones ate so hard and lo well constructed that they are with difficulty torn; they may be properly compared to parchment. To connect the threads together, they moisten them with a sort of gum which issues from their bodies, and which gives their work the necessary degree of hardness. The cones are not all of the fame figure. The greater part are oval * or spheroidal, but there are some that represent an egg cut longitudinally. They are attached by the flat side to something solid which may contribute to their safe y. The precautions of some ave not confined solely to mis external one: in order the better to shelter themselves against the inclemency of the weather, they cover it widi a leaf, or many leaves gathered together: others enttr into the earth and hide themselves there, but for fear of its falling, they either plaster the
walls of their residence with a sort of viscid substance or line them with silk. . •
The period of their change into chrysalids or nymphs is sixed. Some change in May, some in June; others in July, August and September. The time of emerging srOm this state is also regulated* Some remain in it only twelve days, while others continue sifteen, sixteen or twenty. Some do not get free from their prison so soon, but are detained there three weeks or a month ; others even two months, others six, oihers nine, ten, and even some a whole year; as the Phakena Absynthii. It is easy then to conceive that insects must issue from their cones in different months of the year. We sind them appearing in the months of February, March, April, May, June, July, and August, and even in November and December. Some insects have this remarkable property, that they produce two broods that issue from their prison at two different seasons of the year, and present themselves on the theatre of the world; for it deserves particular attention, that they never come forth, but at the time when there are plants and leaves sufficient to furnish them with food. "Without this wise ordination of the providence of God, these little creatures would perifli at their birth.
May I not now be allowed to ask if ihese transformations can be the tffect of chance? If they were, is it possible that there could be so much regularity and. order in the different particulars neceffary to operate such wonderful metamorphoses? Whatever is the effect of chance is subject to no sixed, no determinate order. To day it operates in 6f£ way, to morrow in another, but here all is /Sgular without the shadow of variation. Who k. it then who has taught these insects to accomplish what is necessary,