Compton tortoiseshell (Nymphalis vaualbum [Denis & Schiffermüller])
Wing span: 2 1/2 - 3 1/16 inches (6.4 - 7.8 cm).
Identification: Upperside is orange-brown with darker wing bases and black spots; a single white spot on leading edge of each wing. Underside is mottled gray and brown, with dark bases and borders; hindwing with small white V at outer end of cell.
Life history: Eggs are laid in clumps on the host plant, and caterpillars feed together. Adults hibernate, sometimes in groups.
Flight: One brood: Overwintered adults emerge in May to mate and lay eggs of the next generation, which flies from July-November before hibernating.
Caterpillar hosts: Aspen and cottonwood (Populus), willows (Salix), gray birch (Betula populifolia), and paper birch (B. papyrifera).
Adult food: Sap, rotting fruit, nectar of willow flowers.
Habitat: Upland deciduous or coniferous forests.
Range: Southeast Alaska and Canada south in the mountains to Montana and Wyoming; east across southern Canada and the northern United States to New England; south to North Carolina and Missouri. Rare migrants to Newfoundland, Nebraska, and Florida. This species is also found in temperate Eurasia.
Conservation: Not usually required.
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:
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.