Pacific Northwest Moths

Identification

Adults

Clostera multnoma is a small (FW length 12–14 mm) mottled dark blue-gray Clostera that is widely distributed in the Northwest but is never common.  Like other Clostera species it has pale transverse lines, and the postmedial line forms a white mark at the costa that is surrounded by red-brown scales.  The hindwing is blackish gray without spots or lines. The head and thorax are black and the rest of the body is dark gray.  The antennae are bipectinate and the tip of the male abdomen is tufted.

This species can be distinguished from most of our other gray Clostera species by the orientation of the pale lines in the medial area.  The antemedial and medial lines do not touch in C. multnoma.  In Clostera "apicalis" and Clostera strigosa the lines are partially fused producing and oblique line from the medial third of the costa to the distal third of the posterior margin. Clostera multnoma is closely similar in patterning to C. brucei, and was until recently considered to be conspecific with it (Miller et al. 2018). Clostera brucei is only definitively known from south-eastern British Columbia in the Pacific Northwest. Clostera multnoma has more red-brown on the anterior forewing and tends to be the smaller and darker of the two species. The hindwing of C. multnoma lacks markings while that of C. brucei has a visible pale postmedial line.

Larvae

The larva is finely mottled with white and gray and has two prominent rows of large yellow spots along each side, a short row of black spots on each side behind the head, and dorsal black spots on top on the anterior and posterior abdomen. It is depicted in Miller et al. (2018).

Habitat

This species appears to be most common in association with quaking aspens.  It occurs rarely in conifer forests at low to middle elevations in the Northwest.

Distribution

Pacific Northwest

In the Pacific Northwest Clostera multnoma is found most commonly in central and southern British Columbia as well as in adjacent northern Washington and Idaho. Scattered records from west of the Cascades extend south to west-central Oregon. This moth has also been found in southeastern Idaho.

Global

This moth occurs from central British Columbia to southern California, with a disjunct population in northwest Wyoming near the southeast Idaho populations in our region. It essentially replaces C. brucei west of the Rocky Mountains and the desert Southwest.

Life History

Larvae

Larvae of this species feed on woody plants in the family Salicaceae, and may prefer quaking aspen (Populus tremuloides).

Adults

Adults have been found from late spring to summer in our region, with most records from June and July.  The moth is nocturnal and comes to light.

Economic Importance

None.

Literature

Miller et al. (2018)

Moth Photographers Group