Synonyms and other taxonomic changes
Semiothisa arubrescens McDunnough 1939
Digrammia arubrescens
Semiothisa decorata
described in 1907 by Grossbeck, who originally placed it in genus Semiothisa
Size
wingspan 22-32 mm, based on several Internet photos
Identification
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
Range
Manitoba to British Columbia, south to Colorado, Arizona, and California
Habitat
prairie badlands (in Alberta), scrublands and riparian areas where foodplant grows
Season
adults fly from March to September in California; May to August in Alberta
Food
larvae feed on leaves of willow (Salix spp.)
Life Cycle
probably two generations per year
See Also
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
Digrammia fieldi has a more southern range and the PM line is straighter