Greenish Blue
Plebejus saepiolus (Boisduval, 1852)

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Diagnosis: The upperside in the male is a pale metallic blue, with narrow black borders and a row of dark spots near the margin of the hindwing. In the female the forewing is dark brown with a blue sheen, particularly near the base of the wings, and there is a row of faint orange-capped black spots on the hindwing margin. In both sexes there is a black spot at the end of the forewing cell and often a smaller black one on the hindwing. The underside in the male is silvery grey, bluish near the base of the wings; in the female it is darker grey to pale tan. There are two rows of small black spots on both wings. In the hindwing below, there is a partial third row on the wing margin with a trace of orange shading between the second and third rows; one spot in the third row near the anal angle is larger and corresponds to the "thecla" spot in hairstreaks; the spots on the underside tend to be larger and more distinct in females. Wingspan: 21 to 28 mm.

Subspecies: There are seven subspecies but only two occur in Canada. Subspecies insulanus flies on Vancouver Island, and subspecies arnica is found throughout the remainder of the Canadian range.

Range: Plebejus saepiolus is found from southern Nova Scotia (one record) to Vancouver Island, Yukon, and the Northwest Territories; in the west its range extends southward in the mountains to Arizona and California. It is absent from Newfoundland, Prince Edward Island, and southern Ontario.

Similar Species: The Arrowhead and Silvery Blues (Glaucopsyche piasus and G. lygdamus). Boisduval's Blue (Icaricia icarioides) males have at most a trace of dark discal spots on the upperside; on the underside of both sexes of Boisduval's Blue the outer row of spots is reduced and vague, without a marginal third row and without a larger "thecla" spot. [compare images]

Early Stages: The eggs are laid singly among flowers and the larvae eat flowers and fruits. There are two colour forms, green and reddish brown. They eat many species of clovers; in the east White Clover (Trifolium repens) and and Alsike Clover (T. hybridum), but not Red Clover (T. pratense).

Abundance: The Greenish Blue is often abundant, especially where it is expanding its range at roadside clover patches, but it is uncommon to rare in the east and near the northern limits of its range.

Flight Season: The Greenish Blue flies from mid-May to mid-July in the south, late June to mid-August farther north; there is one generation per year.

Habits: Plebejus saepiolus is usually seen in open areas where there are clovers, such as moist meadows, bog edges, prairies, and roadsides.

© 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.