Sylvan Hairstreak (Satyrium sylvinus [Boisduval])
Wing span: 1 - 1 3/8 inches (2.5 - 3.5 cm).
Identification: With or without tails. Upperside gray-brown or reddish with blue sheen; hindwing with small orange patch at lower edge. Female with yellowish tinge. Underside pale gray to white. Postmarginal band of small black dots; some individuals may have only a few spots. Yellow to red spot at hindwing lower edge.
Life history: Males perch on low vegetation near host plants to watch for females. Eggs are laid singly on stems of host plants where they hibernate until spring. Caterpillars feed on leaves.
Flight: One flight from May-August.
Caterpillar hosts: Various willow (Salix) species.
Adult food: Nectar from flowers including milkweed and Indian hemp.
Habitat: Willow thickets, open woodlands, streams, oases.
Range: British Columbia southeast to Wyoming, Colorado, New Mexico; south through California to Baja California Norte.
Conservation: Not usually required.
The Nature Conservancy Global Rank: G4 - Apparently secure globally, though it might be quite rare in parts of its range, especially at the periphery.
Management needs: None reported.
Brown, J. W., H. G. Real, and D. K. Faulkner. Butterflies of Baja California. 1992. Lepidoptera Research Foundation, Inc., Beverly Hills, CA. 129 pages, 8 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.