Idia immaculalis (Hulst, 1886)




Idia immaculalis is a large Idia species (FW length 16 - 21 mm) with uniformly light gray-tan ("ecru") wings with complete absence of markings. The hindwings are slightly lighter than the forewings. The forewings are relatively broad. The labial palpi are moderately long. The male antenna is bipectinate and that of the female is simple with long cilia extending from each side of each segment (biciliate).

No other Pacific Northwest has the wing shape and color of this species. The most similar species, Idia occidentalis, has dark lines across both wings.


This species is moderately common on dry sagebrush steppe and in juniper woodlands at low elevations east of the Cascades.  However, it is usually rare on rangelands heavily grazed by livestock.


Pacific Northwest

This species occurs in dry habitats in southeastern Oregon and southern Idaho in the Pacific Northwest.


This species occurs in the American West. The range is incompletely known.

Life History


No specific information is presently available for this species, but it is probably a detritivore feeding on dead leaf material, like related species.


Idia immaculalis is a summer species. Adults have been collected from mid June until early August. It is nocturnal and comes to light.

Economic Importance



Moth Photographers Group