Clostera brucei (Edwards, 1885)

93-0008

Identification

Adults

Clostera brucei is a small to medium-size (FW length 15–17 mm) mottled blue-gray Clostera that has a limited distribution in the extreme eastern part of the Pacific Northwest.  The forewing is blotchy pale blue-gray and darker gray to blue-gray, with the lightest patches in most of the medial area and near the anal angle. Like other Clostera species it has pale transverse lines, with the postmedial line widened to form a white mark at the costa with adjacent dark red-brown scales in the postmedial area.  The head, thorax are abdomen are dark gray.  The antennae are bipectinate and the tip of the male abdomen is tufted.

Clostera brucei is closely similar to Clostera multnoma and can be difficult to distinguish from it in the Pacific Northwest, especially from photographs. Both species have slightly wavy antemedial and medial lines that remain separate across the wing.  In the similar species Clostera "apicalis" and Clostera strigosa the lines are partially fused. Also, the red-brown scales near the anterior postmedial line are less prominent in C. brucei. In general, C. brucei is larger and less dark than C. multnoma. In spread specimens the hindwing postmedial line is visible in C. brucei but not in C. multnoma. If C. brucei is eventually found in extreme south-eastern Idaho it would overlap the range of Clostera paraphora, a slightly larger species that occurs there. The postmedial line is nearly straight in C. brucei but sinuous in C. paraphora.

Larvae

The larva is illustrated in Miller et al. (2018). It is smoky to charcoal gray with black dorsal warts on segments A1 and A8 and scattered small orange spots laterally. It is covered sparsely by short fine hairs.

Habitat

This species is associated with aspen forest throughout its range. No specific habitat requirements are known in the Pacific Northwest.

Distribution

Pacific Northwest

Clostera brucei is only known to occur in south-eastern British Columbia and western Montana in our region, but the true distribution is uncertain due to recent confusion of this species with C. multnoma. It could potentially occur in other parts of the Pacific Northwest, particularly in eastern Idaho and northeastern British Columbia.

Global

This is a species of the boreal forest and Rocky Mountains. It has a large range in North America, occurring from Alaska to eastern Quebec and northern New England in the East and Arizona and New Mexico to the south. It is replaced by C. multnoma west of the Rocky Mountains, Utah, and New Mexico.

Life History

Larvae

The larvae feeds on trembling aspen (Populus tremuloides) and willows (Salix spp.) in the Salicaceae (Miller et al. 2018).

Adults

The adults typically fly during early summer (mid-June to mid-July), but can be found earlier or later in the year depending on elevation.

Economic Importance

None.

Literature

Miller JS, Wagner DL, Opler PA, Lafontaine JD, Gill JD. (2018) Drepanoidea, Doidae, and Noctuoidea, Notodontidae (part): Pygaerinae, Notodontinae, Cerurinae, Phalerinae, Periergosinae, Dudusinae, Hemiceratinae. In Lafontaine, J. D. et al., The moths of North America, Fascicle 22.1A. Lawrence, Kansas. 348 pp.