Orthosia mys (Dyar, 1903)

93-2766

Identification

Adults

Orthosia mys is an attractive medium-sized (FW length 16 - 19 mm) even dark brownish red moth with light pink hindwings that flies along the Pacific Coast in the late fall. The forewing has a pointed apex and smooth rounded outer margin. The ground color is even, very similar to madrone bark in color. Some specimens have slightly darker filled orbicular and reniform spots, but the transverse lines are completely missing in most specimens. A few individuals have a series of small spots on the veins at the position of the postmedial line. The hindwing is light pink with slightly darker pink veins and discal spot. The head and thorax are uniform and match the forewings. The thorax has a weak median crest. The eyes are covered with fine hairs. The male antenna is broadly bipectinate.

This red and pink species cannot be confused with any other fall-flying moth in our area. 

Larvae

Larva is smooth, brick red with dark brown shadings.  It blends closely with the bark of the madrone and manzanita foodplants, and is illustrated by Miller & Hammond (2003).

Habitat

This species is endemic to the West Coast in moist to dry forests with madrone and manzanita.  In the Pacific Northwest, it is moderately common in manzanita brushlands and mixed hardwood-conifer forests of the Siskiyou region, Coast Range, and along the west slope of the Cascades.  It is relatively rare at high elevations along the summit of the Cascades, but is moderately common in dry, open ponderosa pine forests along the east slope of the Cascades.

Distribution

Pacific Northwest

Orthosia mys is found west of the Cascades as far north as Vancouver Island in our area. It is most common along the immediate coast in the northern portion of its range, but is widespread in western Oregon. It also occurs along the east slope of the Cascades in Oregon.

Global

This species occurs throughout most of California. A single record from southeastern Arizona is shown on The Moth Photographers web site.

Life History

Larvae

This species is a foodplant specialist feeding on madrone (Arbutus menziesii) and manzanitas (Arctostaphylos spp.) in the Ericaceae.  It favors hairy manzanita (A. columbiana) along the west slope of the Cascades, and green manzanita (A. patula) along the east slope of the Cascades.  It also uses A. viscida in the Siskiyou Mountains of southwestern Oregon.

Adults

Adults fly in the late fall unlike all other members of the tribe Orthosiini except Orthosia arthrolita. The flight season is very late, beginning in October and extending well into November. An occasional specimen overwinters to fly in the early spring. This species is nocturnal and comes to lights.

Economic Importance

None.

Literature

BugGuide

Miller & Hammond (2003)

Moth Photographers Group

Powell & Opler (2009)