Speyeria egleis
Great Basin Fritillary

Family Description:
Alternate Common Name:
Egleis Fritillary.
Caterpillar: The caterpillar is grayish brown, marked with yellow and black along the back, and has a black head. The body is covered with bristly spines, colored yellow or white at the base and black at the tip.
Adult: The Fritillaries as a group are very similar in appearance, and the differences between individual species are often minor and difficult to see. Positive identification to the species level is difficult and requires detailed examination. This is a small to medium-sized Fritillary, with a wingspan of 1 1/2 to 2 3/8 inches. Its appearance varies between regions. Generally, the upperside is orangish brown, or brown with a wide band of yellow along the outer half of the wings. It is marked with black: along the leading edge with four or five short, wavy, nearly parallel lines; a vertical, wavy and winding band across the center; a row of spots, followed by a row of inverted "v"-shaped marks along the outside edge; and two thin lines on the border. The hindwing is similarly marked. Underneath has a distinctive smoky or hazy appearance. The underside of the forewing is pale yellow to brownish yellow, possibly tinged with orange at the base. It is marked as above and also with several small silver or white spots at the tip and along the upper half of the edge. The underside of the hindwing is golden brown but may be tinged with reddish brown or grayish green. It is marked with several silver or white spots near the base, followed by a vertical, curved row of white spots across the center, followed by a band of yellow, and finally with a curved row of white flattened or triangular spots, capped with greenish brown, along the outside edge.

This species ranges from Washington south to California, and from Idaho and western Montana south to northeastern Nevada, central Utah, and northern Colorado.

It occurs in forest openings and on open, rocky ridges.


Caterpillar: Caterpillars feed on the leaves of several species of violets (Viola spp.).
Adult: Butterflies drink flower nectar.

There is one new generation of caterpillars each year. Eggs hatch in the fall; the newly emerged caterpillars, having not yet fed, enter a physiological state called diapause to overwinter. In the spring the young caterpillars feed on the new leaves of host plants. Adults generally fly from the first of June to October. Butterflies often congregate on hilltops and at mud puddles. Fritillaries are long-lived for a butterfly, surviving several weeks to months.

Males actively patrol low to the ground in search of receptive females. pheromones, chemicals used to locate and attract the opposite sex, are produced by both male and female Fritillaries. These chemicals are believed to play an important role in assisting these butterflies to find and recognize other members of their own species. Eggs are laid singly near host plants. In cases where the violet plant has already withered and blown away, females are still able to lay their eggs near to where the host plant will reappear the next spring. This is possible, it is believed, because females are able to locate violet roots by smell!

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.