sects, especially Cynthia cardui, appear constantly in some parts, and periodically in others." But the most extraordinary fact recorded of this kind is one related by this author, respecting the white W. hairstreak butterfly (Thecla W. album of Hubner, which was at first regarded by Mr. Stephens as the Thecla pruni of Linnæus). Previous to 1827 this butterfly had never been observed by him in the vicinity of Ripley, where he had for several seasons been in the habit of collecting, as we, who have had the pleasure of accompanying him in some of his excursions near that town, can testify. But in the month of July in that year, "the boundless profusion with which the hedges for miles were enlivened by the myriads that hovered over every flower and bramble blossom, exceeded any thing of the kind I have ever witnessed; some notion of the numbers may be formed when I mention that I captured, without moving from the spot, nearly two hundred specimens in less than half an hour, as they successively approached the bramble-bush where I had taken up my position." It will be observed that the insects were not confined to a single spot, but extended for miles; their numbers must consequently have been incalculable, and this is the more remarkable since Mr. Stephens adds, "that the hedges to the north and northwest of the village were perfectly free, although the brambles, &c., were in plenty."

CHAPTER III.

THE NATURAL HISTORY OF VARIOUS INSECTS WHICH FORM COCOONS.

Conical Chrysalides produce Moths, and are enclosed in CocoonsSupposed Causes of the Difference between Butterflies and Moths in this respect-Distribution of Colours in Insects-Cocoons of pure Silk-Slender Silken Cocoons guarded by Leaves-Mode of Spinning Cocoons-Gum and Paste introduced into the Substance of Cocoons-Processionary Caterpillars form Cocoons in Company, in which Hairs are mixed with Silk-The Great Eggar Moth Cocoon-Assembling of Moths-Palisade Cocoon of Hair and Silk-Strength of Cocoons not indicative of the Duration of the Chrysalis State-Rough Cocoons formed of Earth and Silk-Elongate Tongue-case of Chrysalides-Polished Earthen Cocoon-Cocoons formed of Chips of Wood, and of Leaves, Twigs, and Moss-Extraction of the Moth from the CocoonContrivance of the Larva to allow the more easy Extrication of the Moth-Regularity in the Time of Appearance of InsectsExtrication of the Chrysalis from the Cocoon-Extrication of Perfect Insects from the Caterpillar Case.

In a former chapter we have stated that, with very few exceptions, butterflies are produced from angulated chrysalides, while those of moths are of a conical shape. In addition to this, we may notice that the chrysalides of butterflies are, for the most part, naked and exposed, while those of moths are generally enclosed in a case or cocoon, formed by the larva previous to undergoing its change. The cause of this additional variation appears to us to result from the preceding, since it is evident that the projections and points which arm the chrysalis of a butterfly would very much annoy the inhabitant of a dwelling in which it can scarcely turn itself, while no form could be better adapted to the inhabitant of a cocoon than the conical, the base of the

cone being rounded; and this appears to be still more satisfactorily illustrated by the circumstance that the slight motions of the pupa are entirely produced by the twisting about of the apex of the cone, which part encloses the segments of the abdomen of the insect.

We shall now proceed to notice the peculiarities observable in these conical chrysalides, and in the cocoons which are thus dependant upon the forms of their bodies.

Respecting the form of these chrysalides, but little need be said. They are of a cylindric shape, the head is rounded, and the tail produced into a conical point; the wings, legs, and antennæ, are disposed as in the pupa of butterflies. It is the coverings constructed by the caterpillars, in which these chrysalides pass their inactive and almost lifeless state, which more particularly merit our attention. And here we may observe, that it appears to be a remarkable provision of nature, that while the chrysalis state of the delicate butterfly is undergone in a naked and exposed manner, the robust moths and sphinxes are buried in cocoons beneath the earth or in the midst of leaves. May not this circumstance be intended to represent the difference in the habits of the future insect; preparing it, as it were, for its coming mode of life? The butterfly passing its life in the sunbeams, we may suppose that in its exposed chrysalis state it is becoming fitted for the glare of light in which it is to live; while the moth, appearing only in the dusk, passes its inactive state within the darkened chamber of its cocoon.

This leads us to notice another beautiful provision of nature, in which, although we observe her everywhere lavishing her bounties with the utmost prodigality, we find them constantly applied where they will neither be lost nor misplaced. We allude to the illustration afforded by the various tribes of butterflies and moths of the distribution of colours in

the works of the creation, from which we may perhaps obtain another reason why the chrysalides of the butterflies should be naked and exposed, and those of the moths incased in a dark cocoon.

The butterflies being day-fliers, and exposed to the sun, are far more splendidly adorned with colours than any other of the Lepidoptera, while the dusk and night-flying moths, especially the Noctua, which are eminently nocturnal, are almost invariably of dingy teints. Those Noctua, however, which depart from the character of the family by becoming partial day-fliers, such as Noctua, Chrysites, &c., have their wings clothed with splendid scales, whence some of them are known by the English names of the Burnished Brass Moth, the Gold Spangle, &c. This economy is however even carried to a more singular extent; since in those moths whose upper wings do not cover the lower, the latter are equally variegated with the former, while in those which rest with the upper wings meeting together and covering the lower, the latter are of a uniform dirty brown colour, without markings. In like manner, we find in the moths produced from the geometric or looper caterpillars, a greater variety of teints than are exhibited in the other tribes of moths; and we consequently find them sporting by day, and forming a portion of a section which Mr. Stephens has, from this circumstance, termed Pomeridiana, with the remark that they fly early in the afternoon, and in the evening or in the twilight, though some few may be found throughout the night. But the typical species fly in the full blaze of sunshine, and when they alight elevate their wings after the manner of the Papilionida.

The indefatigable French naturalist Reaumur, to whose remarks we and other authors have been so

much indebted, has given two chapters upon the construction of cocoons-his twelfth memoir of the first volume, comprising such as are of a rounded form, VOL. II.-E

composed of materials furnished by the caterpillar itself, being either entirely of silk, or of silk mingled with the hairs of the caterpillar; and his thirteenth memoir, comprising cocoons of an irregular form, in which other matters besides silk are employed. As these memoirs would occupy at least one hundred and fifty of our pages, we can give but an imperfect idea of the various objects treated upon. In the subsequent pages of this chapter we have, however, endeavoured to introduce an account of the chief peculiarities of structure, with some additional information and remarks.

Among those insects which form their cocoons of pure silk, the silkworm stands far pre-eminent; for, as Reaumur observes, if the luxury of silk were taken away, where could wool sufficient to supply its place be found? The poor, he adds, would be obliged to go unclad, unless, indeed, he should discover some method of employing the silken cocoons of other insects, which are sufficiently common, and equally prolific, and which seem to be well adapted for such an experiment: indeed, Reaumur endeavoured to rear a tubercled species of caterpillar, found in the pear, for that purpose, but he did not succeed, except in one instance, in which the cocoon weighed as much as three of those of the silk

worm.

Some species of caterpillars being probably unprovided with a sufficient supply of silk, content themselves with spinning a cocoon of so flimsy a construction as to resemble network, allowing the chrysalis to be perceived without difficulty, and seeming formed merely as a support rather than as a defence to the enclosed animal. Of this description is one noticed by Messrs. Kirby and Spence, somewhat resembling an air balloon, the meshes of which are large and perfectly square. The pupa hangs in the centre, fixed by some few slight threads, which diverge from it to all parts of the cocoon, so