Mythimna yuconensis (Hampson, 1911)

93-2934

Identification

Adults

Mythimna yuconensis is a small (FW length 13 mm) longitudinally streaked fawn-colored moth with a dark gray hindwing that flies in northern British Columbia in our region. The forewing veins are straw-colored, thickest and palest on the cubital vein. Each interspace contains two light and three dark lines, with the central gray line slightly darker and grayer than the others. The costa is pale, similar to the cubital vein. A small dark spot is present at the posterior end of the cell abutting the cubital vein near its terminal branches. The postmedial line is comprised of two small black spots, one at vein M1 and the other at CuA2. The terminal line is a series of tiny black dots between the veins. The fringe is fawn-colored. No other traces of the lines or spots are present. The hindwing is even dark gray. The hindwing fringe is light tan with a slightly darker base. The head and thorax are even slightly gray-tan, lacking transverse barring on the collar. Fine hairs cover the surface of the eyes. The male antenna is weakly biserrate.

This species is unlikely to be confused with other members of the tribe Leucaniini due to its dark wing color and northerly distribution. It is similar to Hypocoena basistriga, a member of the tribe Apameini with which it occurs in the far north. This species lacks hairs on the eyes, unlike Mythimna and other Leucaniini species. It has a different pattern of spots, lacking the pattern of two dots along the course of the postmedial line that is typical of M. yuconensis.

Mythimna yuconensis is similar M. oxygala and might prove to be a dark northern form of it.

Habitat

The habitat of this species in Atlin, British Columbia is wetlands at low elevations.

Distribution

Pacific Northwest

This species is known from Atlin in far northern British Columbia and Terrace in the west-central province.  It might be more widespread near the border with Yukon Territory.

Global

As expected from the name, this species occurs in Yukon Territory.  It is also known from Alaska.

Life History

Larvae

The larva of this species is unknown. It probably feeds on grasses (Poaceae) and sedges (Cyperaceae) based on the known preferences of related species and its habitat preference.

Adults

The adults fly during the summer and have been collected from late June until August. The normal-size eye suggests that it might be predominantly nocturnal, although at least some specimens have been collected during the day.

Economic Importance

None.

Literature

Moth Photographers Group