Edwards' Fritillary (Speyeria edwardsii) (Reakirt, 1866)
Diagnosis: One of the larger (wingspan: 60 to 70 mm) of the western greater fritillaries, this butterfly is also one of the more distinctive. The outer margin of the forewing is distinctly concave. The black zigzag markings across the orange hindwing upperside almost disappear along the veins. On the underside the base of the forewing is reddish and the hindwing has a green basal colour with large, elongated silver spots.
Range: Edwards' Fritillary is mainly a butterfly of the west-central U.S. It is found sparingly in Canada in southern Alberta north to Moose Mountain, and in the Cypress Hills of southwestern Saskatchewan. It was formerly more widespread in Saskatchewan and occurred in Manitoba north to Riding Mountain National Park, but has not been seen in Manitoba since 1934 (Miniota,7 and 10 July 1934, specimens in the CNC).
Similar Species: Although most similar to the Great Spangled Fritillary (S. cybele) and the Callippe Fritillary (S. callippe), this species can confidently be identified by the characteristics given above in the diagnosis. [compare images]
Early Stages: The larva has been recorded feeding on Nuttall's Yellow Violet (Viola nuttallii), but probably feeds on other violets as well. It is yellow on the back with grey sides marked by a black stripe and mottled with yellow.
Abundance: This fritillary is considered uncommon to scarce throughout its Canadian range. It maybe extirpated from Manitoba and parts of Saskatchewan because of habitat loss.
Flight Season: It is on the wing from mid-June into July in Canada.
Habits: This is a butterfly mainly of the native prairie and Rocky Mountain foothills, where it flies in open pine forests. The butterflies visit flowers and also feed on animal dung. The lighter males usually emerge two to three weeks ahead of the females.
Remarks: Most fritillaries show great variation with many subspecies. Edwards' Fritillary is unusual in being fairly constant throughout its range with no recognized subspecies. The disappearance of this and other prairie butterflies from portions of their former range is something of a mystery because suitable relict prairie habitat exists where they once occurred. We suspect that these prairie remnants are too small in size to sustain populations of wide-ranging species like Edwards' Fritillary, because a high proportion of butterflies would wander away from the habitat and the colony would gradually decline and disappear.
© 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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