Abagrotis baueri McDunnough, 1949

93-3677

Identification

Adults

Abagrotis baueri is a rare medium size Abagrotis (FW length 15 - 16 mm) with orange-brown ground color sprinkled with black scales and dark-filled orbicular and reniform spots that occurs in dry oak forests in the western part of our region. Most specimens of this species have a similar rich orange-brown color, but the degree and pattern of black suffusion varies considerably between individuals. Some are nearly even orange-brown while others are nearly black with the lighter ground color showing as filling of the lines and spot. The lines are dark gray, double, and are filled with the ground color. The antemedial line is slightly irregular in shape and is slightly obliqued toward the anal angle from anterior to posterior. The postmedial line is smooth with weak scalloping of its medial component. It is nearly perpendicular to the wing with slight slant toward the base posterior to the reniform spot. The light subterminal line is well-defined and slightly irregular. A gray shade precedes it in light-colored specimens, darkest near the costa. A series of gray spots between the veins forms the terminal line. The orbicular and reniform spots are pale with uniform dark gray-brown filling, even in light specimens. The orbicular spot is round or slightly oval and the reniform spot is medium-sized with a slight figure-eight shape. The claviform spot is absent. The hindwing is medium brown-gray with darker gray margin, spot, and veins. The fringe is two-toned with a gray base and whitish margin. The head and thorax match the forewing. The male antenna is filiform.

This species is similar to a number of other Abagrotis species as well as Parabagrotis cupidissima. It is easily told from the later species because it has an orbicular spot that opens toward the costa, complete in A. baueri. It can be distinguished from other Abagrotis species by the powdery orange-brown color and dark-filled spots. Heavily suffused specimens are unlikely to be confused with other species. The most similar species is Abagrotis orbis which usually is light brown with a sprinkling of dark scales. It is larger, usually with a forewing greater than 16 mm, and typically has dark in the reniform confined to the lower end. Some specimens of Abagrotis forbesi, a variable species, can also resemble A. baueri. Its orbicular spot is filled with the ground color, not dark, and the rest of the wing usually lacks the scattered black scales that are present in A. baueri. Some specimens of Abagrotis trigona, particularly females, are also very similar to A. baueri and can have dark-filled spots. The superficial differences are slight but include a narrower wing shape, smoother wing color with fewer black scales, a wider and less bar-shaped reniform spot, and smoother forewing lines that usually lack black dots along the lateral postmedial line in A. baueri. The tips of the male valves are expanded and flattened like small paddles unlike the thin tapering valves of A. nefascia. The expanded tips are smaller than the foot-shaped processes of A. orbis.

Habitat

This species occurs in forests along the West Coast.  In the Pacific Northwest, it is common in oak savanna, oak woodlands, and mixed hardwood forests with oaks at low elevations west of the Cascades.  It also occurs in mixed hardwood-conifer forests with golden chinquapin at middle elevations along the west slope of the Cascades and Siskiyou Mountains.

Distribution

Pacific Northwest

Abagrotis baueri is found in dry oak forests from Vancouver Island and western Whatcom County, Washington south through western Oregon. It also occurs in association with oaks in Klickitat County, Washington. Populations found near Agassiz, British Columbia and near Ross Lake in eastern Whatcom County, Washington are not associated with oaks.

Global

This species is found to the north of Los Angeles, California as far east as the foothills of the Sierra Nevada.

Life History

Larvae

This species is strongly suspected to be a foodplant specialist feeding on Fagaceae based upon the habitat associations, and Oregon white oak (Quercus garryana) and golden chinquapin (Castanopsis chrysophylla) may be the primary larval foodplants.

Adults

Adults of this species have a long flight period from late June to early October. They are nocturnal and come to lights.

Economic Importance

None.

Literature

Lafontaine (1998)

Moth Photographers Group