Sonoran Blue (Philotes sonorensis [Felder & Felder])
Wing span: 7/8 - 1 inch (2.2 - 2.5 cm).
Identification: Our only blue with red spots on forewing. Upperside silvery blue; forewing of both sexes with red spots at outer margin; hindwing of female also with red spots.
Life history: Males patrol with a weak flight near the host plant for females. Eggs are laid singly on the leaves, and caterpillars bore into them to feed. Chrysalids hibernate under stones.
Flight: One flight from February-March.
Caterpillar hosts: Stonecrop (Dudleya species) in the Crassulaceae family.
Adult food: Not reported.
Habitat: Rocky washes, outcrops, and cliffs in desert.
Range: Very local. Placer County, California west to Santa Clara County; along coast through southern California to Baja California.
Conservation: Subspecies extinctis occurred in the upper San Gabriel river wash in southern California, but has been extinct since 1968 when its habitat was destroyed.
The Nature Conservancy Global Rank: G3 - Very rare or local throughout its range or found locally in a restricted range (21 to 100 occurrences). (Threatened throughout its range).
Management needs: Protect colonies from habitat modification.
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.