Species Digrammia decorata - Decorated Granite - Hodges#6389

6389

Semiothisa arubrescens McDunnough 1939

Digrammia arubrescens

Semiothisa decorata

described in 1907 by Grossbeck, who originally placed it in genus Semiothisa

wingspan 22-32 mm, based on several Internet photos

Adult: forewing medium gray or brownish-gray with black AM and PM lines, and distinct dark discal spot; lower portion of AM line bold/conspicuous but upper portion faint/absent; PM line strongly curved, S-shaped, interrupted by short space near costa, and edged distally by diffuse band of grayish=brown shading; hindwing PM line slightly concave and visible only in lower half (does not extend across wing)

In some specimens (such as these 2 labelled arubrescens and Jim Vargo's arubrescens photo at MPG) lower portion of PM line is almost straight, not S-shaped. Perhaps "arubrescens" is a recognizable form (?)

Specimen identified by DNA analysis:

Larva: body green with paler lines and yellow lateral stripe

Manitoba to British Columbia, south to Colorado, Arizona, and California

prairie badlands (in Alberta), scrublands and riparian areas where foodplant grows

adults fly from March to September in California; May to August in Alberta

larvae feed on leaves of willow (Salix spp.)

probably two generations per year

Signate Digrammia (Digrammia s-signata) is smaller, forewing is paler, more yellowish, AM line is faint or absent, discal spot is smaller or absent, hindwing PM line is almost straight and completely crosses wing

Mesquite Looper (D. cyda) forewing has extensive dark transverse streaks, PM line is interrupted by yellowish-orange blob near costa, AM and median lines are blackish and conspicuous

D. subminiata forewing PM line is straighter, forming a very shallow S-shape, and is usually thicker than in decorata

D. rippertaria

Digrammia fieldi has a more southern range and the PM line is straighter

Moth Photographers Group