Mountain Fritillary
Boloria napaea (Hoffmansegg, 1804)

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Diagnosis: This butterfly is orange above, with small black markings and dusky black shading closerto the body. It is unique among look-alike species in the shape of the hindwing, which angles outward towards the middle of the margin. The hindwing underside is orange with a lighter band running across it. There is a bright-white crescent at the base of the hindwing cell along the upper margin of the yellow transverse band. Females are larger than males and have a dirty-yellow ground colour above with heavier black markings. Wingspan: 28 to 38 mm.

Subspecies: There are three subspecies in western North America, two in Canada. Subspecies alaskensis is found throughout most of the Canadian range. The darker, more contrastingly coloured subspecies nearctica is found in the northernmost part of the range, including Victoria Island.

Range: The Mountain Fritillary is found in Eurasia and in North America from Alaska to Wyoming in scattered colonies. In Canada, it is found mostly in the western Arctic as far east as Austin Island, near Arviat (Eskimo Point), Nunavut. It also lives in scattered colonies south to the most northerly part of the Rocky Mountains in northern British Columbia and Alberta.

Similar Species: The other dark lesser fritillaries generally look similar, but lack the white crescent and the angled hindwing.

Early Stages: The larval foodplants of the Mountain Fritillary in Canada are not entirely known, but it has been recorded in British Columbia on Alpine Bistort (Polygonum viviparum) (Scott, 1986).

Abundance: This butterfly is fairly common in the western Arctic, but is rare and local in the northern Rocky Mountains.

Flight Season: There is a single generation that flies in late June and July.

Habits: The males are fast flyers staying close to the ground. They search continually for the slower-flying females, only stopping occasionally to sip nectar at flowers.

Remarks: Crosson du Cormier (1977), in a study of the Boloria napaea group, suggested that alaskensis is not a subspecies of Boloria napaea but is a separate species that occurs in northern Eurasia and in North America, with Boloria napaea occurring in Europe and the mountains of central Asia. He bases this mainly on details of the wing pattern. There is so much variation in pattern in the North American, Russian, and Swedish material we examined that we feel the issue will remain unresolved until more extensive fieldwork has been carried out in Russia.

© 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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