Ross's Alpine
Erebia rossii (Curtis, 1835)

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Diagnosis: The upperside is very dark, blackish brown. The forewing in the male has two black eyespots with white pupils, close together, which may be surrounded by a single orange ring, or two orange rings, but there is no pale patch around the eye-spots as in similar species. The male hindwing has no spots or an incomplete row of very small spots or flecks. The female has two large eye-spots and may also have a row of smaller spots or flecks on both wings. The hindwing underside has a pale-greyish median band with jagged borders. Wingspan: 31 to 44 mm.

Subspecies: There are four subspecies, of which two occur in Canada: the nominate subspecies rossii, described from the Boothia Peninsula in Nunabut, occurs through most of the Canadian range; subspecies ornata, described from Churchill, Manitoba, usually has the two upper forewing eye-spots fused.

Range: Ross's Alpine flies from Alaska and Yukon, across the mainland of the Northwest Territories and Nunavut and the southern tier of Arctic Islands to Baffin Island. Its range extends into northern British Columbia, south to Mile 108 on the Alaska Highway, and northern Manitoba. There are also records from Cape Mugford in northern Labrador, and from Kuujjuaq (Fort Chimo) in northern Quebec.

Similar Species: The Disa Alpine (E. disa) and the Taiga Alpine (E. mancinus) have two light grey patches, one in the centre and the other near the top of the hindwing underside. They have three to five eye spots on the forewing contained in a series of rings that form a diffuse orange patch. [compare images]

Early Stages: The larvae are plain or lightly striped; they overwinter in the third or fourth instar. Foodplants are sedges, Carex atrofusca and C. rariflora (Scott, 1986).

Abundance: This alpine is generally a common species.

Flight Season: It flies from early June to late July in most areas.

Habits: Erebia rossii flies in wet boggy tundra and shrub tundra where sedges abound. Farther south it occurs in wet open bogs.

© 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.

The Toronto Entomologists' Association thanks Agriculture and Agri-Food Canada for providing the content and computer code for this web page.