This is a variable species. The fore-wings are often much clouded with rich brown, and in some specimens scarcely a trace of the original purplish colour remains; the central straight transverse line is often absent, and the other lines are frequently very indistinct, except on the costa; the dots on the hind-wings are also often absent, and occasionally specimens are met with in which all the wings are almost white.
The larva is rather elongate, dull yellowish-brown or greenish-brown; there is a very broad dark brown dorsal line, and several wavy lateral lines; the prolegs are black, the spiracles are also black; there is a slight hump on the posterior edge of each of the last six segments, the hump on the penultimate segment being considerably larger than the others. The length of the caterpillar when full grown is about 1 inch.
{ 90}It feeds on _Pteris incisa_, a beautiful pale green fern, attaining a height of four feet or more, and growing in open situations in the forest. This fern is especially abundant on old decaying logs situated amongst light brushwood. When disturbed these larvæ immediately drop to the ground and coil themselves up. In this situation they are very inconspicuous, as their colouring so closely resembles that of the faded fronds or stems of the fern.
The pupa is buried in the earth about two inches below the surface, the insect remaining in this state during the winter months.
The moth first appears about September, and continues in great abundance until the end of March or beginning of April. It frequents forest, and is noticed most commonly in the neighbourhood of its food-plant. There are probably several broods in the course of a year.
This species has occasionally occurred in the neighbourhood of Wellington. I have no records of its capture elsewhere, but expect it will be found to be generally distributed.
The expansion of the wings is about 1¼ inches. _The fore-wings are bright orange-red_; there is a very faint transverse line near the base, darker on the costa; a dark red oblong mark on the costa near the middle; and a faint transverse line beyond the middle, also darker on the costa. The hind-wings are bright ochreous-yellow, with the cilia orange.