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.
In connection with this subject, it is noteworthy that the flattened extremities of the elytra of the beetle, _Ectopsis ferrugalis_, closely resemble in both shape and colour the remarkable anterior segments of the larva of _D. atronivea_. As both insects feed on the same plant, and thus exist under very similar conditions, it is highly probable that the peculiarities have been independently acquired in each species for similar purposes.
The pupa is enclosed in a light cocoon amongst dead leaves, &c, on the surface of the ground.
{ 96}The perfect insect appears in February and March, and may sometimes be taken at blossoms in the evening. It is also attracted by light, and has been found occasionally, in the daytime, resting on tree-trunks. It hibernates during the winter, coming abroad again the following spring to lay its eggs. I have observed that a good many pupæ from the autumnal brood do not emerge until September or October, so that the insect evidently spends the winter both as a pupa and as an imago.
(_Chlenias egregia_, Feld. cxxxi. 24; Fereday, Trans. N. Z. Inst. xii. 268, pl. ix. 2. _Detunda egregia_, Meyr., ib. xvi. 101.)
This very handsome insect has occurred in the South Island at Nelson, Christchurch, Akaroa and the Otira Gorge.
The expansion of the wings is about 1¾ inches. _The fore-wings are creamy-white; there is a small dark brown mark at the base, a broad transverse wavy brown band before the middle, a very large four-cornered irregular brown mark beyond the middle, one of its corners touching the apex and the other the tornus_; the termen is shaded with pale grey, and there is a series of faint brown marks on the costa and dorsum. The hind-wings are dull white, darker towards the termen; there are two very faint transverse lines.
The perfect insect appears from November till February. It is a very rare species.