Labrador Sulphur (Colias nastes Boisduval)
Wing span: 1 1/4 - 1 3/4 inches (3.1 - 4.5 cm).
Identification: Upperside of both sexes dirty white or dirty green-yellow; black border contains white or greenish spots. Underside of hindwing has submarginal rows of black spots.
Life history: Overwinter as mature caterpillars.
Flight: One flight from late June-early August.
Caterpillar hosts: Plants of the pea family (Fabaceae) including milk vetch (Astragalus alpinus) and white clover (Trifolium repens).
Adult food: Flower nectar.
Habitat: Arctic and alpine tundra.
Range: Alaska south in Rocky Mountains to north-central Washington and northwest Montana.
Conservation: Not usually required.
Management needs: Not reported.
The Nature Conservancy Global Rank: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
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:
Brown, F.M., Eff, J.D., and B. Rotger. 1957. Colorado Butterflies. Denver Museum of Natural History, Denver. Ferris, C.D. and F.M. Brown. 1980. Butterflies of the Rocky Mountain States. University of Oklahoma Press. Norman. Layberry, R.A., Hall, P.W. & Lafontaine, D.J., 1998. The Butterflies of Canada. University of Toronto Press, Toronto, ON. 280 pp. 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.