Bog Fritillary (Boloria eunomia) (Esper, [1800])

Diagnosis: The lesser fritillaries all tend to look very similar on the upper surface of the wings with black markings on an orange background. The Bog Fritillary is best characterized by the submarginal row of pearly spots surrounded by a black rim on the underside of the hindwing. Wingspan: 32 to 40 mm.

Subspecies: The more southern and eastern records (from Newfoundland to Alberta) are subspecies dawsoni, which is browner above than subspecies triclaris, found in arctic and alpine areas. Some populations near ice-fields in the Rocky Mountains of Alberta are very dark (subspecies nichollae), but none of these three subspecies is very distinctive. Subspecies denali, which occurs in Alaska and northern Yukon, is much more striking. It is paler above with reduced black markings, and pale and washed out below with the silver spots replaced by pale yellow.

Range: This small fritillary is circumpolar in distribution. In Canada it is found from Newfoundland to Yukon in the Boreal Zone and in alpine areas and wet tundra, and much further south in bogs. There are records north to Churchill, Manitoba, and to Aklavik, Northwest Territories. It is absent from Nova Scotia, New Brunswick, Prince Edward Island, the Prairies, the high Arctic, and western British Columbia. Where recorded, it is usually highly localized to suitable bog habitat, but is frequently absent from other bogs that appear just as suitable.

Specimen collection data

Similar Species: The Silver-bordered Fritillary (B. selene) has metallic silver spots below and the submarginal row of spots, as in other lesser fritillaries, is a row of black spots rather than the white or yellow-filled circles of eunomia. [compare images]

Early Stages: The silver-grey larvae have fine white dotting above. The spines are white or flesh-coloured. Foodplants vary with location. The literature frequently records violets and willows as foodplants, but in the west they feed on Alpine Bistort (Polygonum viviparum), and near Ottawa on Small Cranberry (Vaccinium oxycoccos) and Creeping Snowberry (Gaultheria hispidula).

Abundance: Because this species is so localized, it is rarely common anywhere in its range in Canada. In Newfoundland, despite the immense number of sphagnum bogs, there are only three reported records, indicating that it is rare or has been overlooked.

Flight Season: The Bog Fritillary is reported to have an extremely short flight period in the more southerly parts of its range. It flies for about three weeks in mid-June in western Quebec near Ottawa. It is on the wing from mid-June until August in the north and in the Rocky Mountains.

Habits: As its name indicates, this species should be looked for in bogs. However, it can also be found in wet tundra and damp alpine meadows. The flight can be strong, but low to 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.