Colorado Hairstreak (Hypaurotis crysalus [W. H. Edwards])
Wing span: 1 1/4 - 1 1/2 inches (3.2 - 3.8 cm).
Identification: Hindwing has slender tail. Upperside dark purple with wide dark border and orange spots at lower outer edge of each wing.
Life history: Adults rest in Gambel oaks, and males patrol there for receptive females. Eggs are laid singly on twigs of the host tree, then hibernate. Caterpillars eat young leaves in spring.
Flight: One flight from June-August.
Caterpillar hosts: Leaves of oaks, particularly Gambel oak (Quercus gambelii) in the beech family (Fagaceae).
Adult food: Tree sap, raindrops, probably honeydew from aphids and other insects.
Habitat: Oak scrub and oak woodlands.
Range: Utah, Colorado, Arizona, and New Mexico; north into southern Wyoming, west into eastern Nevada.
Comments: The official State Butterfly of Colorado.
Conservation: Not usually required.
The Nature Conservancy Global Rank: G4 - Apparently secure globally, though it might be quite rare in parts of its range, especially at the periphery.
Management needs: None reported.
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.