Western Green Hairstreak
Callophrys affinis (W.H. Edwards, 1862)

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Diagnosis: In the subspecies found in Canada, the upperside of the tailless wings is grey with tawny shading, particularly in the female. The underside is bright yellowish green with little or no trace of the white line that crosses the wings of most related species. Wingspan: 20 to 28 mm.

Subspecies: Subspecies washingtonia occurs in Canada.

Range: This western hairstreak is found from California to Colorado and north to Washington in the U.S. In Canada, it has only been found in the southern interior of British Columbia.

Similar Species: Sheridan's Hairstreak (C. sheridanii) has a prominent line of white dots crossing the hindwings on the underside. [compare images]

Early Stages: The larva is green or red with ridges across each segment of the body and with a white line on the back. The main foodplant is Parsnip-flowered Buckwheat (Eriogonum heracleoides, Polygonaceae) (Dennis St.-John, pers. comm.).

Abundance: This hairstreak is local and uncommon. It is considered a vulnerable species in its limited Canadian range (Guppy et al., 1994)

Flight Season: Most records are between early March and mid-June.

Habits: This butterfly tends to stick close to the foodplant in its sagebrush and meadow habitats on the tops of low hills. Males, when disturbed, often return to the same perch.

Remarks: In the western U.S., affinis is part of a complex that includes a number of similar species and subspecies that hybridize in some areas but apparently do not in other areas. The number of species recognized varies from two to seven.

© 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.

The Toronto Entomologists' Association thanks Agriculture and Agri-Food Canada for providing the content and computer code for this web page.