Larvae feed on tussock grasses such as Chionochloa pallens and species in the genus Poa.

Adult moths are on the wing from November to February and are attracted to both sugar and light traps.

This species was first described by Francis Walker in 1856 using specimens collected at Waikouaiti by Percy Earl.

[4] George Hudson discussed and illustrated this species under the name Leucania unica both in his 1898 book New Zealand moths and butterflies (Macro-lepidoptera),[5] and his 1928 publication The Butterflies and Moths of New Zealand.

[7][4] In 2019 Robert Hoare undertook a major review of New Zealand Noctuidae species.

Forewings moderately dilated, costa almost straight, apex obtuse, hindmargin waved, somewhat oblique, rounded beneath; whitish-ochreous, slightly brownish-tinged, sometimes with a few scattered black scales; first Iine represented by three pairs of obscure black dots; a posterior curved series of black dots : cilia whitish-ochreous.

[6] It is also similar in appearance to I. toroneura but can be distinguished as the black vein markings are more patchy on the I. unica forewings.