Identification
The smallest of the Arches (Drasteria) moths. In Alberta, it is the only species in the genus with black lines along the veins of the ventral forewing margin. The mountain populations (ssp. athabasca) tend to be slightly larger and have a more yellow-tan cast to the hindwing compared to the prairie populations (ssp. crokeri). Prairie individuals can be strikingly different with their blue-grey and white colouration, and Barnes and Benjamin (1924) thought these differences may be indicative of a separate species; Individuals from the Calgary and Lethbridge region seem to be intermediate between the two forms, but more work is needed to clarify this situation.
Range
A western species, found from the Yukon and NWT south to New Mexico in the Rockies, east to Manitoba (Lafontaine & Wood 1997).
Habitat
Sparsely vegetated, open habitats, including alpine and montane meadows and prairie grasslands.
Season
Adult flight peaks between mid May and mid July, earlier at lower elevations.
Food
The larvae feed on Hedysarum (Lafontaine & Wood 1997). Adults take nectar at flowers, including mint in Utah (Richards 1939).
Life Cycle
Adults are diurnal and do not come to light. They can be difficult to detect and observe with their rapid flight and contrasting black and white coloration.
