|scientific name Drasteria adumbrata |
common name Shadowy Arches
Dry montane woodlands and sandy, open woods in the southern boreal and parkland region.
Adults occur most commonly in June.
Forewing mottled light and dark brown, with the basal area, antemedian band, orbicular patch and wing margin paler. Hindwing creamy-ochre to orange with a black margin and postmedian band, the latter joined to a black discal crescent. Similar to D. hudsonica, but the forewing ground colour is brown not grey, and the hindwing tends to be more orange rather than pale cream.
Subspecies saxea inhabits montane habitats from the Crowsnest region south- and westward, subspecies alleni is eastern in distribution, ranging as far west as the Athabasca sand dunes and Lloydminster area. Differences in the appearance and ecology (see below) between alleni and saxea, and the large range disjunction, are highly suggestive of two separate species involved under the nominal taxon adumbrata.
A rapid-flying, day active species that is usually rare or uncommon. Subspecies saxea also comes to light regularly in southern BC (unpubl. data), compared to subspecies alleni which is very rarely attracted to light (Handfield 1999).
D. a. saxea has a slower flight and is easier to approach than the extremely wary alleni; flushed individuals often fly a short distance before alighting on the ground, where the mottled forewings (which hide the bright hindwings) afford excellent camouflage.
Ssp. saxea is not of concern. Ssp. alleni is a rare and local species in the province.
Larvae feed on Lowbush Blueberry ( Vaccinium angustifolium) in Quebec (Handfield 1999). Although V. angustifolium does not occur in Alberta, other Vaccinium species are likely used. A population at Dilberry Lake Provincial Park in east-central Alberta is associated with Bearberry (Arctostaphylus uva-ursi).
Alleni ranges from eastern Alberta to New York and Nova Scotia. The western populations occur from southern BC and southwest Alberta south through California and Colorado (Richards 1939, Forbes 1954).
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