[One puss-moth larva, which I reared, made its nest in a rather curious manner. After it had ceased feeding it had been placed on a marble mantelpiece under a glass tumbler, as a temporary residence until a more appropriate dwelling could be found for it. But its instincts urged it to make its nest without delay, and it accordingly set to work, and spun itself up in a cocoon composed entirely of its own silk, neither the glass tumbler or the mantelpiece affording it any material with which to harden the walls of its dwelling.
Cell built by the Larva of the Puss-Moth.
Consequently, the texture of the cocoon was of a rather singular nature. The silken threads had been fused together so as to form a translucent cocoon, looking as if it had been made of gelatine, and being nearly equally transparent, the chrysalis being plainly visible through its walls. The cocoon was thin and elastic, as if it had been made of very thin horn; and it was so tightly fixed to the mantelpiece as well as to the tumbler, that it could not be removed without damage. The moth suffered no injury from the privation which the larva had to undergo.
The cocoons of the puss-moth are to be found upon the trunks of trees, but they are so rough, and so greatly resembling the bark, with which, indeed, their walls are strengthened, that an inexperienced eye would fail to detect them. Even when they have been pointed out to a novice in practical entomology, he has failed to find them again whenever his eye has been taken off their rugged outlines.]
A question will here suggest itself to the curious inquirer, how the moth, which is not, like the caterpillar, furnished with mandibles for gnawing, can find its way through so hard a wall. To resolve this question, it is asserted by recent naturalists (see Kirby and Spence, vol. iii. p. 15) that the moth is furnished with a peculiar acid for dissolving itself a passage. We have a specimen of the case of a puss-moth, in which, notwithstanding its strength, one of the ichneumons had contrived to deposit its eggs. In the beginning of summer, when we expected the moth to appear, and felt anxious to observe the recorded effects of the acid, we were astonished to find a large orange cuckoo-fly make its escape; while another, which attempted to follow, stuck by the way and died. On detaching the cell from the box, we found several others, which had not been able to get out, and had died in their cocoons. (J. R.)
Ichneumon (Cphion luteum), figured from the one mentioned.
Among the carpenter-grubs may be mentioned that of the purple capricorn-beetle (Callidium violaceum), of which the Rev. Mr. Kirby has given an interesting account in the fifth volume of the ‘Linnæan Transactions.’ This insect feeds principally on fir timber which has been felled some time without having had the bark stripped off; but it is often found on other wood. Though occasionally taken in this kingdom, it is supposed not to have been originally a native. The circumstance of this destructive little animal attacking only such timber as had not been stripped of its bark ought to be attended to by all persons who have any concern in this article; for the bark is a temptation not only to this, but to various other insects; and much of the injury done in timber might be prevented, if the trees were all barked as soon as they were felled. The female is furnished, at the posterior extremity of her body, with a flat retractile tube, which she inserts between the bark and the wood, to the depth of about a quarter of an inch, and there deposits a single egg. By stripping off the bark, it is easy to trace the whole progress of the grub, from the spot where it is hatched, to that where it attains its full size. It first proceeds in a serpentine direction, filling the space which it leaves with its excrement, resembling sawdust, and so stopping all ingress to enemies from without. When it has arrived at its utmost dimensions, it does not confine itself to one direction, but works in a kind of labyrinth, eating backwards and forwards, which gives the wood under the bark a very irregular surface: by this means its paths are rendered of considerable width. The bed of its paths exhibits, when closely examined, a curious appearance, occasioned by the gnawings of its jaws, which excavate an infinity of little ramified canals. When the insect is about to assume its chrysalis state, it bores down obliquely into the solid wood, to the depth sometimes of three inches, and seldom if ever less than two, forming holes nearly semi-cylindrical, and of exactly the form of the grub which inhabits them. At first sight one would wonder how so small and seemingly so weak an animal could have strength to excavate so deep a mine; but when we examine its jaws, our wonder ceases. These are large, thick, and solid sections of a cone divided longitudinally, which, in the act of chewing, apply to each other the whole of their interior plane surface, so that they grind the insect’s food like a pair of millstones. Some of the grubs are hatched in October; and it is supposed that about the beginning of March they assume their chrysalis state. At the place in the bark opposite to the hole from whence they descended into the wood, the perfect insects gnaw their way out, which generally takes place betwixt the middle of May and the middle of June. These insects are supposed only to fly in the night, but during the day they may generally be found resting on the wood from which they were disclosed. The grubs are destitute of feet, pale, folded, somewhat hairy, convex above, and divided into thirteen segments. Their head is large and convex.[BP]
