This species varies considerably in the size and shape of the black markings on the fore-wings, which are often slightly different on the opposite sides, in the same specimen. The eggs of this moth are oval in shape, slightly roughened on the surface and light blue in colour. They are deposited towards the end of October. The young larva escapes by gnawing a hole out of the side. When first hatched it is dull brownish-black, with creamy-white lateral lines and prolegs; the head is reddish. It feeds on _Panax arborea_. After the first moult the lateral lines become much wider, especially towards the head. After the second moult the two dorsal tubercles are fully developed, the thoracic segments much swollen and flattened above, the latter bearing traces of the black markings of the full-grown larva. After the third moult the larva becomes a dark brownish colour inclining to chocolate on the dorsal surface. The characteristic markings on the penultimate and anal segments of the adult larva now appear, and the dorsal tubercles are yellowish in colour; the extra prolegs are very small, and are visible as wart-like appendages on the lower surface of the tenth segment. The full-grown caterpillar is a remarkable-looking animal. The head is very small; the first three segments of the body are enormously swollen and flattened above, the flattened portions being white, with several small black ring-shaped markings; there is a pair of large yellowish tubercles on the dorsal surface of the seventh segment, and two smaller ones on the tenth and eleventh segments; the larva is much stouter towards the posterior extremity, especially behind the ninth segment; the penultimate segment is furnished with a large creamy-white ridge, starting on the back and proceeding downwards and forwards; the extra pair of prolegs is small and only occasionally used in walking. The general colour of the larva is brownish- or blackish-green; the tenth and eleventh segments are generally darker, and there are many fine parallel lines of darker colouring on the central portions of the larva; the whole insect is also speckled with black; the spiracles are red. The larva varies a good deal in colour, but its peculiar structure will at once distinguish it from any other. These larvæ often coil themselves up when at rest, clinging firmly with their large prolegs to their food-plant. Whilst thus engaged they have a very remarkable appearance. I have not yet ascertained the precise object of the peculiar shape and coloration of this caterpillar. It appears to resemble very closely a lichen-covered twig, but I suspect in this case there is something more special aimed at.