Pacific Northwest Moths

Identification

Adults

Catocala meskei is a large moth but a medium-sized underwing moth (FW length 32–35 mm) with two distinct forms. Both forms are powdery dull gray, lightest in the anterior medial area, particularly medial to the reniform spot. Form (or subspecies) orion is darker along the posterior wing, particularly in the fold. The basal, antemedial, postmedial, and subterminal lines are crisp and distinct, double, dark, with lighter filling. The antemedial line is strongly zig-zagged, slanted laterally from anterior to posterior. The postmedial line is bicuspid at the end of the cell, forms a hairpin loop to form the subreniform spot on the mid-wing, and has a horizontal dark black segment in the fold. The postmedial line is evenly zigzag across the wing, slightly excurved. The medial line is limited to a dark smudge at the anterior margin. The black terminal line is thin, black, slightly scalloped. The orbicular spot is poorly defined. The reniform spot is double, black, filled with the light gray of the adjacent medial area. The hindwing is relatively light, nearly salmon colored, with black typical black medial and marginal bands. The medial band ends without reaching the medial margin.

The form of C. meskei with darker posterior hindwing is unlikely to be confused with other Catocala species. The evenly gray morph is more nondescript but can usually be recognized by its powdery gray forewing without brown tints and relatively light salmon-colored hindwing. It most closely resembles Catocala unijuga and Catocala semirelicta in our region. Catocala meskei tends to be smaller than C. unijuga, has a much lighter hindwing, and has a thinner hindwing medial band that ends before the medial margin. The forewing of C. meskei is more uniform than that of C. semirelicta, lacking black suffusion in and around the reniform spot and along the posterior margin of the postmedial line. The horizontal black mark along the posterior postmedial line is thin and well-defined in C. meskei, thick and ill-defined in C. semirelicta.

The relationship between the two forms of this moth are currently being investigated (L. Gall, pers. comm.)

Habitat

This species is associated with riparian forest.

Distribution

Pacific Northwest

Catocala meskei has only been found once in the Pacific Northwest in Missoula, Montana.

Global

This species is found in a relatively narrow north-south distribution across central and eastern North America. The distribution is bandlike from Montana and southern Alberta across the northern Plains states and the southern Great Lakes regions to New England and the southern Maritime Provinces.

Life History

Larvae

The larva feeds on plants in the Salicaceae, particularly long-leaved willows (Salix spp.) (L. Gall, pers. comm.)

Adults

Adults of C. meskei fly during late summer and early fall. The only Pacific Northwest specimen was found in late August.

Economic Importance

None.

Literature

BugGuide

Moth Photographers Group

Sargent TD. 1976. Legion of night. The underwing moths. University of Massachusetts Press. Amherst. 222 pp.