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:
Brown, J.W., Real, H.G., and D.K. Faulkner. 1992. Butterflies of Baja California. Lepidoptera Research Foundation, Beverly Hills, Calif. Comstock, J.A. 1927. Butterflies of California. Privately published, Los Angeles, Calif. [Facsimile available from Entomological Reprint Specialists, Los Angeles, Calif.] Dameron, W. 1997. Searching for butterflies in southern California. Flutterby Press, Los Angeles, Calif. Emmel, T.C. Editor. 1998. Systematics of western North American butterflies. Mariposa Press, Gainesville, Florida. Emmel, T. C. and J. F. Emmel. 1973. The Butterflies of Southern California. Natural History Museum of Los Angeles County Science Series No. 26. Garth, J.S. and J.W. Tilden. 1986. California Butterflies. California Natural History Guide 51. University of California Press, Berkeley and Los Angeles. Langston, R.L. 1981. The Rhopalocera of Santa Cruz Island, California. Journal of Research on the Lepidoptera 18: 24-35. Miller, Scott E. 1985. Butterflies of the Califorenia Channel Islands. Journal of the Research on the Lepidoptera 23: 282-296. Opler, Paul A. 1999. Peterson Field Guide to Western Butterflies, revised edition. Houghton Mifflin Co., Boston, Mass. Orsak, L.J. 1977. The Butterflies of Orange County, California. Museum of Systematic Biology, University of california, Irvine. Stanford, R.E. and P.A. Opler. 1993. Atlas of Western USA Butterflies. Privately published, Denver, Colo. Steiner, J. 1990. Bay Area Butterflies: The Distribution and Natural History of San Francisco Region Rhopalocera. Hayward, Calif.: Hayward State University, Masters Thesis. Tilden, J.W. and A.C. Smith. 1986. A Field Guide to Western Butterflies. Houghton Mifflin Co., Boston, Mass. Tilden, J.W. 1965. Butterflies of the San Francisco Bay Region. California Natural History Guide 12. University of California Press, Berkeley and Los Angeles.