Western Tailed Blue (Everes amyntula) (Boisduval, 1852)

Diagnosis: The upperside is purplish blue with dark margins and white fringes in the male and usually dark brown in the female, but in many spring specimens females are blue with expanded dark brown margins. There are one or two very small black spots near the single hair-like hindwing tail. The underside is whitish, with indistinct black spots on both wings, usually with a single orange-capped black spot near the tail. Wingspan: 17 to 27 mm.

Subspecies: Two subspecies occur in Canada. Subspecies albrighti is found throughout most of the range and subspecies maritima on the east coast. This eastern population was only recently described as a new subspecies. See Remarks below.

Range: Everes amyntula is found in the western U.S. and in Canada from northeastern Quebec to Vancouver Island, Yukon, and the Northwest Territories, with a single record from Nunavut at Coppermine. An isolated population occurs in the Gaspé Peninsula of Quebec and in northern New Brunswick.

Similar Species: The Eastern Tailed Blue (E. comyntas). [compare images]

Description of this image follows.
Western Tailed Blue (Everes amyntula albrighti). Churchill, Man. J.T. Troubridge

Early Stages: Eggs are laid singly on flowers or young seed pods and larvae eat both, burrowing inside more mature pods. They are often attended by ants and hibernate as mature larvae. They are variable in colour, from yellowish to green with a dark green or reddish dorsal line, pink or red diagonal stripes, and a pink lateral line. They eat a variety of herb Fabaceae, and are usually seen around wildpea (Lathyrus sp.) in Manitoba.

Abundance: The Western Tailed Blue is common to abundant on the Prairies, uncommon and local farther east.

Flight Season: Adults fly from mid-May to late August, with two generations per year in the south, one in the north.

Habits: Everes amyntula is usually found around forest edges, clearings, and shrubby areas; it only rarely occurs in disturbed areas.

Remarks: The name Everes amyntula maritima Leblanc, 1985 was validated in the book Les Lycénidés (Lepidoptera: Lycaenidae) du Québec, Fabreries (Supplement 4), p. 45. The situation was discussed and a type specimen was designated by Landry (1994).

© 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.