Nymphalis californica
California Tortoiseshell

Family Description:
Alternate Common Name:
Western Tortoiseshell.
Caterpillar: The caterpillar is black, dotted with white, and striped lengthwise with yellow. The body has several rows of black and yellowish branching spines.
Adult: The butterfly has a wingspan of 1 to 2 inches. The edges of the wings appear jagged or scalloped. The upperside is orange-brown, with dark, brownish black borders and brownish shading on the wings close to the body. The forewing has several large patches of black near the forward edge, and one to several black spots. Underneath is grayish brown and mottled with varying shades of brown, resembling bark. Near the edge is an irregular, broken, thin line of blue.

This species normally ranges from southern British Columbia south to southern California, and east to western Montana south to northern Mexico. It may also migrate into the Midwest and parts of the northeastern U.S. In Idaho, it occurs throughout most of the state.

It utilizes a variety of habitats, including woodlands, chaparral, and forest clearings and edges.


Caterpillar: Caterpillars feed on buck brush (Ceanothus spp.).
Adult: Butterflies drink flower nectar.

There is generally one generation of caterpillars each year in the northern part of its range, and up to three in the south. Adults overwinter in a physiological state called diapause. In spring, they emerge to mate and lay eggs. In those areas with multiple generations each year, as in central California, adults from the first generation often migrate east and reproduce; their adult offspring return in the fall to overwinter. Adult migration may also be triggered by high Tortoiseshell densities and other environmental factors. Adults generally fly from April to October.

Males perch to wait for receptive females. Females lay groups of eggs on buck brush (Ceanothus spp.).

Idaho Status: Unprotected nongame species.
Global Rank:

G5; populations are widespread, abundant, and secure.

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. http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm (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.