Forewings elongate, costa moderately arched, apex obtuse, termen very obliquely rounded; whitish-ochreous, with a few scattered dark-fuscous scales, in ♂ mostly suffused with brownish except on dorsal streak; a broad pale dorsal streak from base to tornus, upper edge prominent near base, where there is a tuft of scales, and about middle of dorsum; some dark-fuscous suffusion extending above this streak from base to 3⁄5 of disc, and thence upwards to costa; stigmata round, whitish-ochreous, edged with dark fuscous, plical obliquely beyond first discal; an angulated dark-fuscous line or series of dots from a of costa to tornus : cilia ochreous-whitish, in 3- irrorated with grey, basal third barred with fuscous.

[7][6][8] The larvae of this species have been recorded as emerging in the New Zealand spring and attain their full size of over 2.5 mm in length by autumn.

[10] Hudson regarded the adults of A. isogama as being sluggish and noted that the species frequented urban gardens and cultivated plants.

[6] During the day the adult moth can be found resting on tree trunks or fences, often on the underside of structures almost touching the ground.

[6] They have been observed having entered houses and have a habit of drowning in open containers filled with water.