Erynnis icelus
Dreamy Duskywing

Family Description:
Alternate Common Name: Aspen Duskywing.

The caterpillar is light green, dotted with white, and covered with short hairs. The body is marked lengthwise with a dark line along the back and a white stripe along the side. The head is black and may be marked with red, orange, or yellow.
Adult: This is a medium-sized skipper, with a wingspan of 1 to 1 inches. It is dark brown on the upperside. The forewing is marked with gray to brown hazy spots that form a band, outlined in black; the wing appears dusted with gray or silver. The hindwing is slightly lighter in color and has two rows of hazy white dots along the outside edge. Underneath is similarly marked but paler in color. Males have a small fold (called a costal fold) on the front inside edge of the forewing, which covers yellow scent scales. Males also possess long "hairs" called tibial tufts on the upper sections of the hind legs. They are used to direct pheromones towards a female during courtship. The head has two noticeable, furry appendages (called palpi) that project straight ahead.

This species ranges in Canada from northern Alberta south and east to Nova Scotia. In the U.S., its range extends through the Pacific Northwest south into eastern California and patchily in the southwest, east across Montana and North Dakota, and throughout the eastern third of the U.S. as far south as northern Georgia. It occurs through much of Idaho.

It occurs in open areas such as sagebrush steppe, mountain meadows, and forest edges and openings.

Caterpillars eat the leaves of willows (Salix spp.), poplars (Populus spp.), birches (Betula spp.), and locusts (Robinia spp.).

Adult: Butterflies drink flower nectar from a variety of preferred species, including hawkweed (Hieracium spp.), blueberry (Vaccinium spp.), dogbane (Apocynum spp.), and lupine (Lupinus spp.).

Caterpillars make nests of leaves and silk. There is usually only one generation of caterpillars each summer, but there may be two in the southeastern parts of its range. Older caterpillars overwinter in a physiological state called diapause. Adults fly from April to early July.

Males perch to wait for receptive females, and may occasionally actively patrol for them. Females lay green eggs singly on the new leaves of young host plants. The eggs become pink before hatching.

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.