Dunedin Owlet

Philpott described the species as follows:

♂. 37 mm. Head, palpi, and thorax reddish-brown. Antennae reddish-brown, bipectinated, apex simple, pectinations 3+1⁄2. Abdomen greyish-brown, lateral and anal tufts reddish-ochreous. Legs reddish-brown, tarsi obscurely annulated with paler. Forewings moderate, costa slightly sinuate, termen evenly rounded, oblique; dark reddish-brown; an obscure basal fascia mixed with blackish; stigmata ringed with ochreous-white, faintly margined with black; orbicular circular, well defined; claviform sub-circular, obscure; reniform upright, regular; subterminal line parallel with termen, thin, slightly and irregularly serrate, ochreous-white, suffusedly margined anteriorly with brownish-black : cilia uniform reddish-brown. Hindwings and cilia pale reddish-fuscous, tips of cilia whitish.The male of this species has a wingspan of between 36 and 42 mm and the female of the species has a wingspan of between 43 and 47 mm. I. fenwicki is distinctive in appearance and its large size, the brown-red shade of ground colour as well as the dark markings on its forewings ensure it is unlikely to be confused with closely related species.

This species is endemic to New Zealand. It is only found in the southern parts of the South Island and on Stewart Island. It occurs locality in such places as Swampy Summit and Mt Cargill in Dunedin and at Tautuku Peninsula and Purakaunui Bay in The Catlins.

Adults of this species are on the wing from September to November. This species is attracted to light.