The expansion of the wings of the male is 4 inches, of the female sometimes fully 5½ inches. The fore-wings of the male are _bright green, with a series of paler ring-shaped markings between the veins; an irregular row of white spots crosses the wing near the middle_, and a small white spot is situated on the costa at the base. The hind-wings are very pale yellowish-brown near the body, becoming pure white in the middle, and pale green on the termen. The head and thorax are green, the abdomen is white, tinged with green at the apex. The female has all the wings of a relatively more attenuated shape; _the fore-wings are green, mottled with black_; the hind-wings are pale reddish-brown, shaded with green near the termen; the abdomen is also reddish-brown, becoming green at the extremity. The species is rather variable in both sexes. In the male the white spots on the fore-wings vary considerably in size, and there are occasionally several additional spots near the body. In the female the black markings of the fore-wings are sometimes much more extensive than the green ground colour. This dark form of the female was described by Butler as a distinct species, under the name of _Charagia hectori_. In both sexes the green colouring is occasionally entirely absent, a dull orange-brown taking its place. I formerly attributed this peculiarity to the effects of fading, but Mr. Norris has shown me a very perfect specimen of this variety, which he bred from the pupa, he having noticed the orange-brown colouring immediately after the insect emerged. The transformations of this insect are very interesting. The female lays an enormous number of very small, round, yellowish eggs, which she seems to deposit quite indiscriminately. The young larvæ consequently have to find their way along the ground to the stems of their food-plant, a large percentage no doubt perishing before they succeed in doing so, and this circumstance probably accounts for the great number of eggs produced. The food-plants of this species are numerous; the following are a few of them: "wineberry" or "currant" (_Aristotelia racemosa_), apparently the favourite; "manuka" (_Leptospermum ericoides_); "ki-ki" (_Astelia solandri_); "black maire" (_Olea apetela_); titoki (_Alectryon excelsum_); and _Melicope_. The larva tunnels the stems of these trees, feeding entirely on the wood, which it bites off with its strong mandibles.