Pacific Northwest Moths

Identification

Adults

This small (FW length 8 mm) sexually dimorphic moth with white and black males and dark females and dark hindwings has been recorded from Oregon, although we have no bona fide records for it in the Pacific Northwest Moths database. Males resemble most other Tarache species in having a white forewing with a pattern of gray brown and olive. The basal half of the posterior forewing is solid dark brown, occasionally with purple tint. The distal third of the wing is mottled with dark gray, brown, and olive, mostly as the components of the incomplete postmedial and subterminal lines, the terminal line is a series of black dots, and the apex and fringe are dark. Dark marks on the costa at the medial, postmedial, and subterminal lines. The reniform spot is a dark circle filled with white. The orbicular spot is absent or at most a black spot. Females are darker than the males with most of the white pattern elements replaced by gray. A patch of nearly white scales persists near the anal angle. The head, thorax, and hindwing of both sexes are even smoky gray except for a white edge of the hindwing fringe. The male antenna is filiform.

Tarache acerba is unlike other species in the genus with white forewing ground color in having a uniform dark hindwing. The only other Pacific Northwest Tarache with white on the forewing and a dark hindwing is Tarache knowltoni. It differes from T. acerba in several respects: white patches on the forewing are present along the posterior margin near the wing base, white pattern elements are nearly absent on the distal forewing, and the central part of the hindwing is pale with contrasting dark veins.

Habitat

The most likely habitat for this moth is dry open forest based on its distribution in North America. The precise habitat in our region is unknown. 

Distribution

Pacific Northwest

A single record of this moth from west-central Oregon is given by Robert Poole on Nearctica.com. No further details are known. This record is plausible given the distribution in California (see below). It should be sought west of the Cascades, especially in the Siskiyou Mountain region, as well as in the south-central part of the state.

Global

This species occurs in central California, both along the coast near San Francisco Bay (Nearctica.com) and in the northern Sierra Nevada (Moth Photographer's Group).

Life History

Larvae

Nothing is known of the early stages, although it is likely that it feeds on plants in the mallow family (Malvaceae) based on foodplants of other Tarache species.

Adults

Nothing is known of the flight period of this moth in the Pacific Northwest, but Poole gives a range of dates from April to June. It is not known whether it is nocturnal or diurnal.

Economic Importance

None.

Literature

Moth Photographers Group

Nearctica.com