Plains Skipper (Hesperia assiniboia) (Lyman, 1892)

Diagnosis: This skipper is similar in size (wingspan: 21 to 30 mm) and upperside pattern to Hesperia comma, though it is usually slightly paler. The underside of the hindwing is pale green or pale greenish-grey and the band of spots is usually broken into two or three separate groups of spots, which are frequently very small and sometimes virtually absent; the spots may be white or pale yellow. Females are larger and darker.

Range: This species occurs in prairie and aspen parkland from central Alberta, Saskatchewan, and Manitoba southward into the northern Great Plains states.

Similar Species: Most likely to be confused with the Common Branded Skipper (Hesperia comma), but can be distinguished by its pale greenish coloration on the hindwing beneath and the reduced spot band. [compare images]

Early Stages: The larvae of assiniboia are reported to feed on grasses associated with native prairie: needlegrass (Stipa spp.), June Grass (Koeleria cristata), and Blue Grama (Bouteloua gracilis).

Abundance: Fairly common, but becoming more localized as native prairie habitat disappears.

Flight Season: Generally flies from mid-July to early September, with a few records as early as late June.

Habits: Native short-grass prairie is the habitat of assiniboia.

Remarks: This species was treated as a subspecies of Hesperia comma, but Bird et al. (1995) suggested that there are sufficient differences in appearance, habitat preference, and flight season that it should probably be recognized as a distinct species. Specimens of assiniboia from the aspen parkland of the three Prairie Provinces are darker than those from farther south and might be confused with comma. Specimens from these northern localities, however, are the form with yellow spots on the underside and are thus easily distinguished from comma; the two species occur together in central Saskatchewan and near The Pas, Manitoba.

© 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.