Cercyonis pegala
Common Wood-Nymph

Family Description:
Alternate Common Names:
Large Wood-Nymph, Blue-Eyed Grayling.
Caterpillar: The caterpillar is bright green and covered with hair, making it appear fuzzy. The head is green, the length of the body is marked with four yellow or white stripes, and there are two reddish "tails."
Adult: The butterfly is medium to large, with a wingspan of 1 to 3 inches. Its appearance is variable, but generally it is light to dark brown on the upperside, and light brown underneath. The upperside typically has two large eyespots outlined in yellow on the forewing, which may be lying in a yellowish band. The hindwing may have two or more similar but smaller spots. Underneath may be striped, particularly toward the interior of the wings, and marked with eyespots as above.


This species is found throughout the southern half of Canada and the entire continental U.S., except for parts of the southwest and Texas. It occurs commonly throughout Idaho.


It is found in open, grassy areas such as fields, meadows, prairies, and open woodlands.


Caterpillar: Caterpillars eat the leaves of various grasses (Poaceae), such as purpletop (Tridens flavus).
Adult: Butterflies use flower nectar, often from alfalfa (Medicago spp.) and spiraea (Spiraea spp.). They are also known to use rotting fruit and tree sap for food.


There is generally one generation of caterpillars each year, with possibly two or more in the southern part of its range. The caterpillars hatch close to the end of the growing season and do not feed; instead, they enter a physiological state called diapause and overwinter until spring. Upon emergence, they feed, molt, and eventually pupate. Adults generally fly from late May to mid-September.

Males actively patrol in search of receptive females. Females lay off-white, barrel-shaped eggs typically on the leaves of 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. http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm (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.