Acmon Blue (Plebeius acmon [Westwood & Hewitson])
Wing span: 3/4 - 1 1/8 inches (2 - 2.9 cm).
Identification: Upperside of males blue with dark narrow border; female brown. Underside white with black spot pattern. Hindwing above and below with red-orange submarginal band.
Life history: Males patrol near hosts for females. Eggs are laid singly on leaves or flowers of host plants. Caterpillars feed on leaves, flowers, and developing seeds, and are tended by ants. Second-stage caterpillars hibernate.
Flight: Many flights from March-October.
Caterpillar hosts: Various species of buckwheats (Eriogonum nudum), lupines (Lupinus), trefoils (lotus), and milkvetches (Astragalus).
Adult food: Flower nectar.
Habitat: Desert, fields, prairie hills, weedy areas, road edges.
Range: Primarily California west of Sierra Nevada-Cascade Divide south to northern Baja California. Precise limits in neighboring Oregon and Nevada not ascertained.
Conservation: Not usually of conservation concern.
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.