Giant Sulphur (Colias gigantea Strecker)
Wing span: 2 - 2 3/4 inches (5.1 - 7 cm).
Identification: Upper surface of male yellow with narrow black borders; lower surface without submarginal black spots. Female with 2 forms, yellow or white; both may have black border reduced or lacking.
Life history: Third-stage caterpillars overwinter.
Flight: One flight from June-July.
Caterpillar hosts: Dwarf willow (Salix reticulata).
Adult food: Flower nectar.
Habitat: Willow bogs.
Range: Alaska south along Rocky Mountains to Wyoming.
Conservation: Not usually required.
Management needs: Not reported.
The Nature Conservancy Global Rank: G4 - Apparently secure globally, though it might be quite rare in parts of its range, especially at the periphery.
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. Tilden, J. W. 1986. A field guide to western butterflies. Houghton-Mifflin Co., Boston, Mass. 370 pages, 23 color plates.
Author: Jane M. Struttmann