Its first process is to select a suitable leaf or twig, upon which it weaves a sort of little mound of silk of the shape of a button. This done, it examines it carefully to ascertain its strength, and satisfied therewith, it then proceeds to thrust its two hind legs in amongst the threads of which the button is composed, and in so doing it causes the hook-like processes which fringe these legs to become securely entangled in them. It then is safe as to the issue, and now lets its body drop down, fearless of the most violent rockings to which even a tempest might expose it.
Another way of suspending themselves is almost equally singular with this. It may be witnessed by the reader if he will take the pains to collect the larvæ of the common white butterfly, found in abundance upon our cabbage rows; and by properly attending to, feeding and watching them, this curious proceeding may generally be observed, in a few at least of the number, supposing that the others may have hung themselves up without being seen in the very act. If we were to set a mountebank to the task this larva has to perform, it may well be doubted whether with the richest reward before him he could manage to effect it. First, he would have to tie both his feet fast to a branch, so that he would swing head downwards; then, in order to hang himself in the horizontal posture, he must bend his body up, fasten a cord round the branch in a proper place, so as to form a loop, and then put his head and body into it, so that it would support him comfortably just under the arms. Probably the most supple-jointed gentleman would find himself discomfited in the attempt. The caterpillar in question, however, does all this, and more; for it has _to spin the ropes_ with which it is to be suspended. Fixing its hinder part, in the manner just described, to the little button of silk, which it first forms, it then spins the girth, in which it intends to trust its safety, by the apparatus of the mouth. Sometimes larvæ tie themselves in an upright position, as martyrs to a post; but the most common method is the horizontal one, giving the insect the resemblance of a sailor swinging in his hammock.
[Illustration: _Perpendicular Suspension._]