When the caterpillar increases in length, it takes care to add to the length of its house, by working in fresh hairs at either end; and if it be shifted to stuffs of different colours, it may be made to construct a party-coloured tissue, like a Scotch plaid. Réaumur cut off with scissors a portion at each end, to compel the insect to make up the deficiency. But the caterpillar increases in thickness as well as in length, so that, its first house becoming too narrow, it must either enlarge it, or build a new one. It prefers the former as less troublesome, and accomplishes its purpose "as dexterously," says Bonnet, "as any tailor, and sets to work precisely as we should do, slitting the case on the two opposite sides, and then adroitly inserting between them two pieces of the requisite size. It does not, however, cut open the case from one end to the other at once; the sides would separate too far asunder, and the insect be left naked. It therefore first cuts each side about half-way down, beginning sometimes at the centre and sometimes at the end (Fig. _c_), and then, after having filled up the fissure, proceeds to cut the remaining half; so that, in fact, four enlargements are made, and four separate pieces inserted. The colour of the case is always the same as that of the stuff from which it is taken. Thus, if its original colour be blue, and the insect, previously to enlarging it, be put upon red cloth, the circles at the end, and two stripes down the middle, will be red."[BV] Réaumur found that they cut these enlargements in no precise order, but sometimes continuously, and sometimes opposite each other, indifferently. The same naturalist says he never knew one leave its old dwelling in order to build a new; though, when once ejected by force from its house, it would never enter it again, as some other species of caterpillars will do, but always preferred building another. We, on the contrary, have more than once seen them leave an old habitation. The very caterpillar, indeed, whose history we have above given, first took up its abode in a specimen of the ghost-moth (_Hepialus humuli_), where, finding few suitable materials for building, it had recourse to the cork of the drawer, with the chips of which it made a structure almost as warm as it would have done from wool. Whether it took offence at our disturbing it one day, or whether it did not find sufficient food in the body of the ghost-moth, we know not; but it left its cork house, and travelled about eighteen inches, selected "the old lady," one of the largest insects in the drawer, and built a new apartment, composed partly of cork as before, and partly of bits clipt out of the moth's wings. (J. R.)