The expansion of the wings is from 1½ to 1¾ inches. The fore-wings of the male vary from pale yellowish-white to rich brown or dark brownish-black; there is a jagged transverse line near the base; a large black or white spot in the middle of the wing; a doubly curved transverse line beyond the middle, then a very jagged transverse line, followed by several paler markings, and an obscure line parallel with the termen. The hind-wings are paler in colour; there is a slightly curved transverse line near the base; a jagged line near the middle, and a very faint line beyond the middle. The termen of both fore- and hind-wings is slightly indented. The female varies from pale ochreous to dark slate-colour; the markings resemble those of the male, but the termen of the wings is more indented. This species is so extremely variable that a more detailed description would be useless; its numerous forms may, however, be at once recognised by the _unbroken jagged transverse lines of both fore- and hind-wings_. The larva is quite as variable as the perfect insect. When very young it is bright green, with a conspicuous white dorsal line; as age advances the caterpillar becomes dark olive-brown, sometimes striped with paler brown or green, whilst many specimens retain the green colouring throughout the whole of their lives. The favourite food-plant is the kawa-kawa (_Piper excelsum_), which the larvæ voraciously devour, thus causing the riddled appearance which the leaves of that plant almost invariably present. These larvæ often select a forked twig to rest in, where they lie curled round, with the head and tail close together. Other food-plants are _Aristotelia racemosa_ and _Myrtus bullata_. Those caterpillars found on the latter plant are strongly tinged with pink, and are consequently very inconspicuous amongst the young shoots, where they generally feed. The burrows of the larvæ of _Hepialus virescens_ are frequently utilised by the caterpillars, which feed on the _Aristotelia_, as convenient retreats during the winter. When full-grown these caterpillars descend to the ground and construct loose cocoons of silk and earth on the under sides of fallen leaves. The moth usually emerges in about a month's time, but the autumnal larvæ either hibernate or remain in the pupa state throughout the winter. The perfect insect appears from October till April. It frequents forest and is extremely common. It also occurs in great abundance on the white rata blossoms in the autumn, and specimens may be occasionally seen even in the depth of winter. Genus 2.--HYBERNIA, Latr.