These changes of skin take place a definite number of times in the larvæ of each species. The breeders of silk-worms tell us that that precious, if not priceless, little larva, sheds its skin four times; other larvæ moult oftener than these: some five times, some seven times, some eight times, and some nine, or even ten times; others, again, only moult thrice. The ordinary number of moults appears to be about three or four. Some, however, never moult at all in the larva state. The larva of the common bee, and that of the flesh-fly, and some others, are among this number.

Whatever may be the general opinion upon the want of beauty and comeliness in insects, and particularly during the larva stage of their history, it is very certain that it is quite erroneous. We may possibly fail, unaided by the pencil and colours of the artist, in conveying even an approach to an adequate conception of the rich and glowing raiment with which it has pleased God to clothe these minute and humble beings. But a very little actual observation of a few even of the commoner larvæ or caterpillars of the butterfly and moth species, will convince the reader that few other created things have been so exquisitely adorned with magnificence of colour and apparel as the larvæ of these insects. Here will be found hues so rich and deep as to—

"Make the rose's blush of beauty pale,
And dim the rich geranium's scarlet blaze."

Here is a larva of a moth before us whose head is a delicate orange colour, whose belly and feet a pale pure green, whose sides are of primrose tint, variegated with slashes of green, and along the back there runs a beautiful band of white, the intensity of which is most agreeably relieved by a vein of lovely pink, which divides it in the middle. There is another clothed in purple, green, and white; another, the larva of the butterfly called the "Camberwell Beauty," is of a brilliant black, dotted with spots glowing like carbuncles along its back; another has a coat which seems as if set with precious stones, blazing with an intensity of colour which cannot be conveyed by description. In a word, larvæ, on the whole, can boast as varied a display of beautiful hues as can almost the whole array of flowers in our gardens. In consequence of the, unfortunately, too general feeling of loathing, to which allusion has already been made, but few persons are in reality acquainted with their beauties. Their diminutive size also renders them less attractive than they might otherwise prove, since we are generally most pleased with the beauty of an object when its size makes it so manifest to our eyes, as to render it impossible it should escape our attention.

It is a very remarkable fact, and corresponds, to a certain extent, with the influence of the same agent upon plants[G]—that light seems to be in some measure necessary in order to develop the colours of the larva. Thus it has been noticed, that those larvæ which are, by their habits, much in darkness, dwelling, perhaps, in caves of the earth, or immured in the heart of a piece of timber, or inhabiting a cell scooped out of the solid rock, are, most frequently, of a uniform whitish colour. Some experiments have shown that when these whitish larvæ have been brought out of darkness and exposed to the sunlight, their colour has turned to brown. Very probably this effect is due to precisely the same kind of change as takes place when a fair-skinned European travels into a southern clime, his face and hands becoming so brown, tanned, and dark, as to form a ludicrous contrast to the whiteness of his chest or arms, which are not exposed to the influence of the solar ray.

Larvæ resembling Twigs.

There is still something more to be said about the coats of the larva. To look at some of them, it would be difficult for a person unacquainted with entomology, to guess at the real nature of the object before him. Some look like dry twigs. Some look far more like little Cactuses than insects. Some are clothed with hairs, arranged in the most curious and eccentric manner. Some have hairs so long as to give them all the appearance of very minute shock-dogs. In some, the hairs are arranged like stars; in others, like the quills of the "fretful porcupine." The backs of other larva look just as if they were studded over with little camel-hair pencils. Madame Merian has described the larva of an insect found in Surinam as having the various divisions of its body ornamented with three blue tubercles, like turquoise beads, from each of which proceeds a long, delicate, feathery plume of a black colour. Another, described by the same lady, is splendidly adorned on each side with fifty red tubercles, shining like coral, from each of which proceed five or six long hairs. Some, again, are covered as thickly as possible with sharp processes, like thorns, sufficiently strong and sharp to pierce the skin of any one who incautiously ventures to take them up. The body of a small caterpillar brought from Brazil, is described by Kirby and Spence as possessing a body so thickly planted with spines, like the branches of a tree, as absolutely to wear the appearance of a forest or thicket in miniature! It has been stated, indeed, by some travellers, that the larva of some insects has the power of darting out, when alarmed by the approach of anything, such as the human hand, from as many knobs or protuberances in its back, eight bunches of little stings, with which it inflicts a very painful and venomous wound.