Alpine Casemoth

Butler described the casing of this moth as follows:

The case of P. unicolor is fusiform, truncated and open at the apex, through which (after the exclusion of the moth) the dark mahogany-brown pupa-skin projects; it is composed of short pieces of grass-stalks placed longitudinally, the largest being at the base, the smallest (mixed with small chips and silk) at the apex. Butler described this adult moth of this species as follows:

Uniformly grey, the primaries of a slightly more brownish tint than the secondaries, and with a blackish costal edge; the secondaries subhyaline: body clothed with long woolly hair. Expanse of wings 1 inch. Only the male metamorphoses into a recognisable moth. The adult female never leaves the bag and has no wings. Its case is covered with layers of short (up to 10 mm) lengths of tussock, laid longitudinally and overlapping, so that it looks like a bundle of twigs. The case averages 34 mm long and can reach 40 mm. The male is a hairy grey moth with translucent wings and a short abdomen and a 26.5 mm wingspan.

This species is endemic to New Zealand and is restricted to dry areas of the South Island.

The larvae of this species commences making its bag as soon as it comes out of its egg. Like other bagmoths the larvae of O. unicolor pupates inside its bag with females remaining inside the bag as adults and males emerging as grown moths. The male adults are on the wing from September until December and are attracted to light.

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