Green Carpet Owlet

George Hudson describes the larva of this species as follows:

The larva ... is about 1+1⁄2 inches in length, of fairly uniform thickness, slightly attenuated towards the head and thickened posteriorly. Its general colour is pale pinkish-brown becoming pale green on the ventral surface; there is an obscure wavy blackish lateral line, stronger near the middle of each segment; a wavy blackish subdorsal line stronger near the middle of the posterior segments and appearing from above as a series of very slightly oblique blackish marks. Walker described the male adult of the species as follows:

Male. Green, cinereous beneath. Palpi hardly extending beyond the head; second joint densely pilose; third conical, less than one-fourth of the length of the second. Antennae rather long, slightly pectinated, except towards the tips. Abdomen brown, extending rather beyond the hind wings; apical tuft of moderate size. Femora and tibiae densely pilose; tarsi with black bands. Fore wings partly black-shaded, with several denticulated transverse black lines; orbicular and reniform marks large, pale green, black-bordered, slightly tinged with red, of the usual form; some pale cinereous points on the exterior part of the costa; marginal points black. Hind wings brown; fringe cinereous, interlined with brown; under side with a brown discal spot. …

I. plena is endemic to New Zealand. It is widespread throughout the North, South and Stewart Islands.

Adults of this species are on the wing from late August to May. They are attracted to light and have been collected via a mercury vapour light trap.