Eggs are laid in the summer or autumn and larvae feed during winter and spring.

The adults of this species appear reluctant to be attracted to light although they do come more frequently to the brighter mercury vapour traps.

[3] The male lectotype specimen is held at the Natural History Museum, London.

[4] In 2019 Robert Hoare undertook a major review of New Zealand Noctuidae species.

The dorsal and subdorsal lines are very narrow but fairly well marked; dull white in colour faintly edged with red or reddish brown.

The lateral line is often edged with small brown blotches situated above the spiracles, and on the anterior segments these blotches are sometimes joined to form a broad, faintly marked upward edging to the lateral line.

Abdomen pale greyish-ochreous with fine black specks, densely hairy towards base.

Forewings light - brownish, with scattered black specks, towards base and costa suffused with light greyish-ochreous; first line represented by two or three black dots, second line by a series on veins; two white dots longitudinally placed about lower angle of cell, connected by grey suffusion; a terminal series of black dots between veins : cilia light brownish-ochreous.

Hindwings fuscous, paler and tinged with pale greyish-ochreous towards base; cilia whitish-ochreous, tips whitish.

[2] The colour of adults of this species can range from pale to pink ochreous up to a deep brown.

[2] There are specimens that have been collected at Ōkārito in Westland that are regarded as a dwarf form of I. epiastra as they are very similar both in appearance and in genitalia but are smaller than the typical I.

[2] This species lives in open habitats such as wetlands, dunes and forest clearings.

[2] Eggs of this species are laid in summer or autumn and larvae feed during winter and spring.