California Tortoiseshell (Nymphalis californica [Boisduval])
Wing span: 1 1/4 - 2 3/4 inches (3.2 - 7 cm).
Identification: Upperside is orange-brown with large black spots and dark wing borders. Underside looks like a dead leaf and is dark mottled brown with darker wing bases; hindwing does not have a centered silver spot.
Life history: Males perch in the late afternoon to look for females. Eggs are laid in bunches on the host plant; caterpillars eat leaves and feed together when young. Adults hibernate.
Flight: One brood: Adults emerge in June and fly until fall, then overwinter. They fly the following spring until April or May, mating and laying eggs for the next brood.
Caterpillar hosts: Various species of wild lilac (Ceanothus).
Adult food: Flower nectar.
Habitat: Chaparral, woodland, brush areas, forest clearings and edges.
Range: British Columbia south along the Pacific Coast to Baja California Norte, east to Montana, Wyoming, Colorado, and New Mexico. Rare migrants to Michigan, Pennsylvania, New York, and Vermont after periodic population explosions in Mexico.
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:
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.