Colias alexandra
Queen Alexandra’s Sulphur

Family Description:
Note: This species has both yellow and orange morphs, or types; however, the orange morphs occur only in northern and central Canada and parts of the Midwest so are not described here.
Caterpillar: The caterpillar is yellowish green and marked with tiny black dots and white side stripes.
Adult: This is a medium-sized butterfly, with a wingspan of 1 to 2 inches. The adult male and female of this species look slightly different from one another. Males are bright yellow on the upperside, the forewing pointed at the tip and marked with a small black spot. The fore- and hindwings are edged with a brown to black border, which may be thicker on the forewing. The male butterflies reflect ultraviolet light from the outer portions of their wings. Females are yellow to white on the upperside and may have a faint border on the forewing or no border at all. Underneath, both sexes are yellowish on the forewing and grayish green on the hindwing, which is marked with a white spot.

The yellow morphs of this species occur in British Columbia and Alberta, south to eastern California and northern Arizona and New Mexico. They occur through much of Idaho.

This species prefers open habitats, including fields, meadows, sagebrush steppe, and forest openings.


Caterpillar: Caterpillars eat the leaves of plants of the pea family (Fabaceae), such as milk vetch (Astragalus spp.) and lupines (Lupinus spp.).
Adult: Butterflies drink flower nectar.

There is only one generation of caterpillars each year. The caterpillars overwinter in a physiological state called diapause, and emerge in the spring to pupate. Adults generally fly from mid-may to September. Large numbers of adult males can frequently be observed congregating at muddy sites where they obtain salt, a behavior called puddling.

Males actively patrol in search of receptive females. Females lay yellowish eggs singly on the topsides of host plant leaves.

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.