Milbert's Tortoiseshell (Nymphalis milberti [Godart])
Wing span: 1 5/8 - 2 1/2 inches (4.2 - 6.3 cm).
Identification: Forewing tip squared-off. Upperside is black with a wide orange submarginal band which grades to yellow at the inner edge of band. Narrow black marginal border on both wings; the hindwing border may contain some blue spots.
Life history: In the afternoon, males perch on hillsides, banks of gulches, logs, or behind bushes to watch for females. Eggs are laid in large batches of up to 900 on the underside of host plant leaves. Young caterpillars feed together in a web, while older ones feed alone and make shelters of folded leaves tied with silk. Adults hibernate, sometimes in small groups.
Flight: Two broods from May-October.
Caterpillar hosts: Nettles (Urtica dioica and U. procera).
Adult food: Usually flowers, such as thistles, goldenrods, and lilacs; probably also sap and rotting fruit.
Habitat: Wet areas near woodlands, moist pastures, marshes.
Range: Boreal North America south of the taiga. Southern Alaska south to California, Nevada, and New Mexico; east to Newfoundland and West Virginia.
Conservation: Not required.
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:
Elrod, M.J. 1906. The Butterflies of Montana. Bulletin of the University of Montana 30: 1-174. 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.