Limenitis [Basilarchia] weidemeyerii
Weidemeyer’s Admiral

Family Description:
Alternate Common Name:
Western Admiral.
Caterpillar: The humpbacked caterpillars vary in color, but generally are grayish, mottled with white, and lined with white on the sides. The head is red to brown and the back has a white patch.
Adult: The butterfly is large, with a wingspan of 2 to 3 inches. It is black on the upperside, with a white band on either side of the body running diagonally across both the fore- and hindwing, and meeting at the tip of the abdomen. The edges of the wings have a single row of white dots, and the black portion of the forewing closest to the body has a single white spot. Underneath, the butterfly is largely white, marked with brown to black lines and a curved, vertical row of orange on the outer edge of the hindwings.

It ranges from southern Alberta south through the intermountain west down to Arizona and New Mexico, and east to portions of the Dakotas and Nebraska. In Idaho it can be found in the central and southern portions of the state.

These butterflies are found along streams, in woodlands, in aspen groves, on mountainsides, in canyons, and in town.


Caterpillar: Caterpillars eat the leaves of willows (Salix spp.), cottonwoods and poplars (Populus spp.), ocean-spray (Holodiscus spp.) and serviceberry (Amelanchier spp.).
Adult: Butterflies feed on flower nectar, tree sap, and carrion.

Young caterpillars overwinter in a physiological state called diapause, immerging in the spring to feed, molt, and eventually pupate. A "sleeping bag", called a hibernaculum, is constructed for overwintering from a rolled leaf tied with silk. In the northern parts of its range there is typically one generation each year. There may be two in the southern parts of its range, in which case only the caterpillars of the second generation overwinter. Adults generally fly from June to September. They may hybridize with another Limenitis species, Limenitis lorquini, where the ranges of the two species overlap. The butterflies actively defend territories.

Males generally perch to wait for receptive females and very seldom patrol. Females lay eggs singly on the topside of the tips of leaves on host plants.

Idaho Status: Unprotected nongame species.
Global Rank:

G5; populations are widespread, abundant, and secure.

Ferris, C. D. and F. M. Brown. (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies.  Second Edition.  Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.