Pacific Northwest Moths

Identification

Adults

Anarta columbica is a mottled dull gray-brown small to medium-sized moth (FW length 14 - 15 mm) that flies in dry forests and steppe during late spring and summer. It has a dark reniform spot and a two-toned light gray-tan and dark gray hindwing. The forewing color is slightly darker and grayer in the terminal area. The basal, antemedial, and postmedial lines are gray to dark gray, double with filling of slightly lighter brown than the ground. The basal and antemedial lines are moderately irregular. The latter line is slightly slanted away from the base and slightly incurved at the posterior margin. The median line is dark gray, but usually faint except on the costa. The postmedial line is faint, weakly to moderately scalloped, sometimes with thin pale lines on the veins near the tips of the teeth, drawn toward the base on the costa, gently and broadly excurved around the reniform spot, and bent to join the posterior margin at near a right angle. The subterminal line is pale ochre-brown, irregular with an offset toward the base below the costa and a strong W-mark on M3 and CuA1 to the outer margin. The line is preceded by dark gray to black marks on the costa and near the W-mark, usually a series of wedges. The terminal line is a series of gray spots between veins. The fringe is gray-brown, sometimes weakly checkered. The orbicular and reniform spots are outlined in thin black. The orbicular spot is round, filled with the ground or slightly lighter brown and usually with a darker central ocellus. The reniform spot is moderately large, broadly kidney-shaped, filled with the ground color anteriorly and smudgy purplish gray elsewhere. The claviform spot is small to moderate in size, black, filled with the ground color or dark gray. The hindwing is pale gray-tan with a moderately well-defined dark gray marginal band, a discal lunule, and veins. The hindwing fringe is whitish gray-tan with a tan base. The head and thorax match the forewing, often with gray transverse bands on the collar. The eye is covered with fine hairs. The male antenna is bead-like.

This species is closely similar to other brown and gray-brown Anarta species in our area. It tends to be smaller than Anarta oregonica and Anarta hamata, the closest in superficial appearance. Anarta oregonica is more common in conifer forests and does not occur in sage habitats, but these species occur together in parts of southern British Columbia. Anarta columbica is slightly smaller in size, grayer in color, and flies earlier in the year. Anarta hamata flies in sage like A. columbica, but is usually larger and lighter tan in color. Males of A. hamata have a curved tip on the clasper of the left valve which is visible after brushing the scales from the tips of the valves. That of A. columbica is straight.

Habitat

This species occurs in dry ponderosa pine forests and open sagebrush steppe at middle to low elevations east of the Cascades, particularly in the Columbia Basin and southeastern Oregon

Distribution

Pacific Northwest

Anarta columbica is found in central British Columbia, the Columbia Basin in Washington, and the deserts of southeastern Oregon in our region.

Global

This species is distributed south into eastern California.

Life History

Larvae

No information is presently available regarding larval foodplants of this species.

Adults

Anarta columbica flies during late spring and summer, beginning as early as late April and last to early August. The peak flight in most parts of our region is during June, earlier than that of A. oregonica. It is nocturnal and comes to lights.

Economic Importance

None.

Literature

Moth Photographers Group