Synonyms and other taxonomic changes
Dysstroma formosa (Hulst, 1896)
Size
Forewing length 15-16 mm.
(1)Identification
Adult [gray form]: forewing pale brownish-gray with darker gray median area; basal area with fairly straight dark gray band beginning at inner margin and stopping short of the costa (the band is diffuse and does not extend to the AM line); AM and PM lines jagged, irregular; short black streak in median area is slightly closer to PM line than AM line; ST line broken in middle and consisting of a series of arcs filled with gray or brown; short black diagonal streak at apex
Adult [orange form]: as above, except median area mostly brownish-orange, dark gray band in basal area edged with orange distally, and PM line with deep V-shaped cleft near costa
There is also an intermediate form with a gray median area but brownish basal and subterminal areas
hindwing of all forms uniformly-colored but varying from pale yellowish-gray to almost white
Larva: light green with whitish tint and white subdorsal longitudinal lines
Range
In Canada, reported from Newfoundland and New Brunswick in the east, and Saskatchwan to BC and Yukon in the west. Presumably occurs in adjacent areas of United States, including Alaska [records were found on the web from New York, Utah, and California]. - Note: There is no BOLD data from eastern NA and Chris Schmidt reports that this strictly a western species - Steve Nanz, 7/24/2020.
The similar D. hersiliata occurs coast to coast in southern Canada and presumably northern United States.
Food
larvae feed on leaves of currant and gooseberry (Ribes spp.)
See Also
The gray form of Dysstroma hersiliata (Orange-barred Carpet) is most similar to the gray form of D. formosa, but has these differences:
- distinct white line bordering the PM, AM, and basal lines
- dark gray band in basal area less diffuse and extending to AM line
- short black streak in median area slightly closer to AM line than PM line
Compare images of gray form of both species
Both of the above species have orange forms but the variation in color and pattern among individuals is greater than the difference between species. In areas where their ranges overlap, identification from photos is questionable.
Compare images of orange form of both species
Print References
Powell, J. A. & P. A. Opler, Moths of Western North America, Pl. 31.35f, 31.36f; p. 223.
(1)Internet References
pinned adult images of orange form and gray form (CBIF)
