Red-disked Alpine (Erebia discoidalis) (W. Kirby, 1837)
Diagnosis: The upperside is blackish brown with a reddish flush over a large part of the centre of the forewing. On the underside, the forewing has a large reddish central patch and the hindwing has hoary grey shading towards the edge. There are no eye-spots. Wingspan: 35 to 44 mm.
Subspecies: There are two subspecies in North America and at least one in central Asia. The nominate subspecies discoidalis was described from Cumberland House, Saskatchewan (incorrectly recorded as Manitoba in Miller and Brown, 1981), and is found east of the Rocky Mountains; subspecies mcdunnoughi, in which the reddish forewing area is smaller, is found in western Alberta, British Columbia, and Yukon.
Range: Erebia discoidalis flies in a broad diagonal band extending from Parc-des-Laurentides, ineastern Quebec, through northern Ontario (south to Sudbury), and the northern Prairies to northernBritish Columbia, the Northwest Territories, Yukon, and Alaska. It reaches just into the northern U.S.between Michigan and Montana, and also occurs in Asia.
Early Stages: The larva is cream-coloured, with a dark diagonal stripe on most segments (Bird et al., 1995). The species has been reared by Walter Krivda at The Pas, Manitoba, on Canby's Blue Grass (Poa canbyi), and Scott (1986) records the larvae feeding on Meadow Grass (Poa alpina and Poa glauca). At Belcourt, in western Quebec, the suspected foodplant is a small sedge (F. Lessard, pers.comm.). The mature larvae spin flimsy cocoons before pupating (Kondla et al., 1994).
Abundance: Very local in the east, it is more widespread and common in the west.
Flight Season: Erebia discoidalis flies in May in the southern prairie Provinces, in late May and early June in Quebec and Ontario, and in late June to late July in the north.
Habits: The Red-disked Alpine is usually reported from moist prairie habitats and grassy areas on bog margins; in Manitoba it also occurs along forest edges and in dry meadows and sandy ridges in open Jack Pine forests; in Saskatchewan it is reported from gravelly prairie knolls. The flight is very weak and close to the ground; they usually perch on grasses or on the ground.
© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.
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