The fore-wings vary from pale yellowish-brown to rich chocolate-brown; there are two curved transverse lines near the base, generally enclosing a paler stripe between them; next a broad dark central area; then a wavy paler transverse line, usually followed by a very much paler irregular band, generally formed by two partially disconnected patches, one on the costa and one on the dorsum; there is a jagged, whitish, transverse line near the termen, _always broken in the middle_, and often shaded with black towards the base of the wing. The hind-wings are ochreous, speckled with brown towards the dorsum; there is usually a brown central dot. This is an extremely variable insect. In some specimens there are very extensive white patches on the wings, whilst in others the colouring is almost uniform rich brown, and the characteristic markings can only be detected with difficulty. It may, however, be distinguished from the allied species by the _interrupted pale jagged transverse line near the termen and by the absence of greenish colouring_. The eggs are oval with the surface honeycombed; they are pale green in colour. The young larva, when first hatched, is much attenuated, light reddish-brown with a broad pale lateral stripe, and a few bristles. The full-grown larva measures about 1½ inches in length; it is rather slender and has a large hump on the sixth segment. Its colour is dark reddish-brown, mottled and striped with dull white and greenish. It feeds on the white rata (_Metrosideros scandens_). During the day it firmly grasps a stem of its food-plant with its prolegs, holding the rest of its body out from the branch in a perfectly straight and rigid position. When in this attitude it so exactly resembles a twig, that, even in the case of captive specimens, it is often a matter of the greatest difficulty to find a caterpillar amongst the branches. Several times I have even caught hold of a larva, thinking it to be a twig, so perfect is the resemblance. At night these larvæ become much more active, and by the aid of a lantern they may then be seen busily walking about and feeding. The pupa is enclosed in a slight cocoon about two inches below the surface of the earth. The larvæ of the autumnal brood remain in this condition during the winter, but in the case of the spring and summer broods the pupa state only occupies a few weeks. The moth appears from November till May. It is very common in forest regions, and may be observed resting on the trunks of the trees, its pale yellow hind-wings being completely concealed by the mottled brown fore-wings. In this position the insect is almost invisible, and the protection afforded by its colouring is at once apparent. In the autumn evenings it is often very abundant at the blossoms of the white rata. {85}SELIDOSEMA ARISTARCHA, Meyr. (_Selidosema aristarcha_, Meyr., Trans. N. Z. Inst. xxiv. 216.) (Plate IX., fig. 17 [M], 18 [F]; Plate III., fig. 17, larva.)