Dorcas Copper
Lycaena dorcas W. Kirby, 1837

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Diagnosis: A small, mainly brown butterfly with a purplish iridescence on the upperside in the male. Both sexes have small black spots scattered on the upperside. There is little orange on the upper surface except for a few spots near the anal angle of the hindwing. The underside is yellow orange on the forewing and orange brown on the hindwing. Wingspan: 19 to 27 mm.

Subspecies: Four subspecies are found in Canada: the nominate subspecies dorcas occurs in eastern and central Canada as far north as southern Northwest Territories; subspecies florus occurs in Alberta and British Columbia north in the MacKenzie Mountains to the Arctic Ocean; subspecies arcticus is in western Yukon and Alaska; and subspecies claytoni occurs in Maine, extending into Canada only in a small area of western New Brunswick.

Range: This has long been considered a mainly western species, with isolated populations in the east. However, the opening of the James Bay and Trans-Labrador Highways has shown that it is equally widespread in the east, occurring south of the tundra from Yukon to the Avalon Peninsula in Newfoundland. It is absent from the Prairies and from eastern Ontario.

Similar Species: The Purplish Copper (L. helloides) has an orange band along the edge of the hindwing and the females have more extensive orange shading than the females of the Dorcas Copper (see also Remarks below). The Bog Copper (L. epixanthe) has the underside yellowish or silvery grey, never orange. The Maritime Copper (L. dospassosi) is larger, has much larger black spots on the wings above and below, and is pale yellow buff on the underside. [compare images]

Early Stages: The larvae are usually reported to feed on Shrubby Cinquefoil (Potentilla fruticosa), but in Alberta they also use Marsh Cinquefoil (Potentilla palustris) (Norbert Kondla, pers. comm.). They are pale green with brownish mottling. They have short white hairs, white oblique dashes on each segment, and a green mid-dorsal line. The head is tan.

Abundance: It can be locally abundant where its foodplant is found, but does not wander far from its foodplant.

Flight Season: Single brooded, Dorcas Coppers appear in some localities in late June and can be on the wing until late August.

Habits: This is usually a butterfly of wet areas, such as moist meadows, bogs, and streamsides. However, along the James Bay Highway, dorcas is seen in almost all habitats, anywhere there are flowers. In Manitoba, it is usually restricted to acid bogs.

Remarks: Although this species is generally considered to replace the Purplish Copper in the east and north, work still needs to be done to more accurately determine the status of some western populations. Subspecies florus has been treated as a dorcas-looking form of helloides by many workers and other populations in British Columbia and Yukon appear intermediate between dorcas and helloides. We follow Ferris (1977) in treating arctic and alpine single-brooded populations associated with Potentilla fruticosa as dorcas and lowland multi-brooded populations in the Prairie Provinces and British Columbia associated with Polygonum and Rumex as helloides. The two species can be difficult to distinguish in western Canada by appearance alone. Lycaena dospassosi, formerly treated as a subspecies of dorcas, is treated as a full species.

© 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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