Lasionycta uniformis (Smith, 1893)

93-2999

Identification

Adults

Lasionycta uniformis is a variable medium-sized noctuid moth (FW length 14 - 17 mm) with uniform dark gray to mottled greenish-gray or blue-gray dorsal forewing and pale ventral hindwing with a geographically variable pattern that flies commonly near timberline in the Cascade Mountains in Washington and throughout British Columbia. The forewings have a somewhat pointed shape. The ground color is slate gray to blackish gray, but the number of ochre and white scales is variable producing great variation in the color and pattern, especially in southwestern British Columbia. The ground color varies from slate and black to predominantly dull green-gray, yellow-green, and blue-gray. Lighter areas of different color are most prominent at the wing base and margin. The lines are dark gray, with an irregular antemedial line and dentate postmedial line. The median line is usually present but is variable, dark gray to nearly absent. The pale irregular subterminal line is usually preceded by a darker shade, limited to a faint patch at the costa in plainly marked populations. The fringe is checkered with gray and the lightest color on the wing and is plain gray in plain populations. The outlines of the orbicular and reniform spots are dark. The orbicular spot is usually filled with the color of the paler areas on the wing and usually has a dark ocellus. The reniform spot also contains pale and dark scales but is less prominent. Both spots are barely evident in plain populations. The dorsal hindwing is dark gray with lighter scales along the costal margin, near the discal spot, and between the dark postmedial line and the marginal band. The fringe is pale whitish gray or yellowish. The ventral hindwing is pale ochre with a triangular or chevron-shaped discal spot, prominent postmedial line that is close to the discal spot and a pale patchy marginal line in most of our populations; paler whitish gray with a thinner discal spot, nearly absent postmedial line, and darker and wider marginal band in populations from the Rocky Mountains of British Columbia and Alberta. The head and thorax match the forewings, often with a broad band on the collar and dark area on the thorax posterior to the collar. The eye is covered with fine hairs. The male antenna is biserrate.

This species can be confused with many other Lasionycta species with which it flies near timberline. Blue-gray specimens from southwestern British Columbia resemble Lasionycta caesia and Lasionycta gelida. Both of these species have whiter ventral hindwings with solid dark gray to black marginal bands unlike the yellowish hindwing with an interrupted marginal band in L. uniformis. Plains populations of L. uniformis from eastern British Columbia resemble Lasionycta brunnea and Lasionycta promulsa, both plain olive-gray to brown-gray species. The ventral hindwing again holds the key to correct identification. That of L. brunnea has a distinct postmedial line and weak marginal band while L. uniformis in this region has the opposite pattern with virtually no postmedial line and a dark marginal band. Lasionycta promulsa has a more uniform light yellow-brown ventral hindwing with a small nearly round discal spot and very weak marginal band unlike those of L. uniformis.

The North American populations of L. uniformis are arranged in five subspecies, two of which are known to occur in the Pacific Northwest on one that is possible in our area. The appropriately named nominate subspecies L. u. uniformis is very plainly marked slate gray dorsally and has a pale ventral hindwing with dark marginal band but faint or absent postmedial line. It occurs in eastern and northern British Columbia. Subspecies L. u. multicolor is named for the multiple forms described above. Its ventral hindwing is pale yellow off-white with a prominent discal spot, prominent postmedial line, and interrupted marginal band. It is found in western British Columbia and Washington. These subspecies intergrade in northern British Columbia and Yukon Territory. A third subspecies, L. u. fusca flies in the Rocky Mountains in western Wyoming and norther Utah. It is browner and duskier than our other populations and should be sought in eastern Idaho.

The type locality of Lasionycta uniformis multicolor is Canada, British Columbia, Gott Peak, 7100', 50° 21' N 122° 08' W. 

Larvae

The early stages are unknown.

Habitat

This species is common and widely distributed in high elevation montane habitats throughout much of western North America.  It is most common on rocky alpine tundra above timberline, but also occurs in subalpine meadows around timberline.

Distribution

Pacific Northwest

Lasionycta uniformis is found throughout the Cascade Range in Washington. It is more widespread in British Columbia. Subspecies L. u. uniformis has been found throughout the eastern part of the province, while L. u. multicolor is widespread in the west.

Global

This species occurs to southern Yukon Territory just north of the border with British Columbia. The range extends south through the Rocky Mountains in Alberta. Central Rocky Mountain populations are found from the Beartooth Plateau on the Montana-Wyoming border to Colorado and northern Utah. Isolated populations are found on Mt. Shasta in northern California and on Mt. Albert on the Gaspe´ Peninsula, Quebec.

Life History

Larvae

Larval foodplants for this species are not certainly known, but an unknown species of Lasionycta was observed feeding on Polemonium elegans in the Polemoniaceae on rocky alpine tundra above timberline on Mt. Rainier in Washington (Crumb, 1956) that was likely this species.

Adults

This species is single-brooded and flies during the summer, usually in July and August. It is predominantly nocturnal and comes to lights, although it also flies during the day. Females are more likely to be collected during the day, often while taking nectar at flowers such as moss campion (Silene acaulis).

Economic Importance

None.

Literature

Crabo & Lafontaine (2009)

Crumb (1956)

Moth Photographers Group