Satyrium californica
California Hairstreak

Family Description:
Alternate Common Name:
Western Hairstreak.

Caterpillar: The caterpillar is beige on top, greenish white on the underside, and black on the back of the head. It is marked with white triangle-shaped spots along the side and large gray spots along the back. It reaches an average, full-grown length of inch.
Adult: The butterfly is fairly small, with a wingspan of 1 to 1 inches. The upperside is brown and marked along the edge of the forewing and rear of the hindwing with yellowish orange patches or spots. Underneath is brownish gray and marked with a row of small black spots followed towards the outside with a row of orange "<"-shaped spots. The spots are larger on the hindwing than the forewing. There is a single silvery blue spot at the rear of the hindwing, from where a long, thin tail extends.

This species ranges from southern British Columbia south to southern California, and east to Idaho and central Wyoming and Colorado.

It occurs in dry habitats such as chaparral, open woodlands, shrubby areas, and canyons of lower elevations.


Caterpillar: Caterpillars eat the leaves of a variety of species, including buck brush (Ceanothus spp.), oaks (Quercus spp.), mountain mahogany (Cercocarpus spp.), chokecherry (Prunus virginiana), and serviceberry (Amelanchier alnifolia).
Adult: Butterflies drink flower nectar, often from milkweed (Asclepias spp.),wild buckwheat (Eriogonum spp.), and buck brush (Ceanothus spp.).

Eggs are laid in the fall, overwinter, and hatch in the spring. There is only one generation of caterpillars each year. The caterpillar is equipped with a honey gland, also known as a dorsal nectary organ, which emits a sugary solution agreeable to ants. The ants feed on the solution and in turn protect the caterpillar from predators. Each caterpillar undergoes four stages of growth, called instars. Adults generally fly from June to early August. The tails of the hindwings of the butterfly resemble antennae and can act to fool predators into biting the wrong end of the butterfly, allowing it to escape.

Males perch in the tops of trees most commonly at the tops of hills to wait for receptive females, and sometimes actively patrol for them. This behavior is called "hill topping". Eggs are laid in the hollow portions of the bark of host plants, typically in clusters of two to four which are then cemented together by the female.

Idaho Status: Unprotected nongame species.
Global Rank: G4; population levels are secure, but may be of concern in the future.

Ballmer, G. R. and G. F. Pratt. 1988. A survey of the last instar larvae of the Lycaenidae of California. Journal of Research on the Lepidoptera 27:1-81.

Ferris, C. D. and F. M. Brown. (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies.    Second Edition.  Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.