Western Tailed-Blue (Everes amyntula [Boisduval])
Wing span: 7/8 - 1 1/8 inches (2.2 - 2.9 cm).
Identification: Narrow tail on hindwing. Upperside of male blue, female brown with blue at wing base. Underside white with black spots indistinct or lacking; single small orange spot near tail.
Life history: Males patrol and perch during the day. Females lay eggs on flowers or young seedpods of host plant. Caterpillars eat young seeds inside the pod, where they overwinter and pupate.
Flight: March-July. Several broods in southern California, a partial second brood in the southern Rocky Mountains, and one brood elsewhere.
Caterpillar hosts: Legumes with inflated pods including false lupine (Thermopsis), milkvetch (Astragalus), crazyweed (Oxytropis), and vetches (Vicia and Lathyrus).
Adult food: Flower nectar.
Habitat: Open - usually native - areas with low shrubs including chaparral, meadows, and open woodland.
Range: Alaska south through western North America and all western mountains to northern Baja California, east across Canada's prairie provinces to northern Michigan, Ontario, and the Gaspé Peninsula.
Conservation: Not usually required.
The Nature Conservancy Global Rank: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
Management needs: None reported.
Opler, P. A. and G. O. Krizek. 1984. Butterflies east of the Great Plains. Johns Hopkins University Press, Baltimore. 294 pages, 54 color plates. Opler, P. A. and V. Malikul. 1992. A field guide to eastern butterflies. Peterson field guide #4. Houghton-Mifflin Co., Boston. 396 pages, 48 color plates. Scott, J. A. 1986. The butterflies of North America. Stanford University Press, Stanford, Calif. 583 pages, 64 color plates. Tilden, J. W. 1986. A field guide to western butterflies. Houghton-Mifflin Co., Boston, Mass. 370 pages, 23 color plates.
Author: Jane M. Struttmann
State and Regional References:
Elrod, M.J. 1906. The Butterflies of Montana. Bulletin of the University of Montana 30: 1-174. Ferris, C.D. and F.M. Brown. 1980. Butterflies of the Rocky Mountain States. University of Oklahoma Press. Norman. Layberry, R.A., Hall, P.W. & Lafontaine, D.J., 1998. The Butterflies of Canada. University of Toronto Press, Toronto, ON. 280 pp. Opler, Paul A. 1999. Peterson Field Guide to Western Butterflies, revised edition. Houghton Mifflin Co., Boston, Mass. Stanford, R.E. and P.A. Opler. 1993. Atlas of Western USA Butterflies. Privately published, Denver, Colo. Tilden, J.W. and A.C. Smith. 1986. A Field Guide to Western Butterflies. Houghton Mifflin Co., Boston, Mass.