Colias gigantea
Giant Sulphur

Family Description:
Alternate Common Name: Great Northern Sulphur.
Caterpillar: A detailed scientific description of the caterpillar has not been published.
Adult: This is a medium-sized butterfly, with a wingspan of 1 to 2 inches. The males are bright yellow on the upperside, with the outside edges of the wings marked with black. The females are yellow or white on the upperside and lack the solid black border but may have traces of it. The wings of both sexes are fringed in pinkish white. Underneath is white to gray, with the hindwings possibly slightly darker. The undersides of the fore- and hindwings are each marked with a small spot; the hindwing may have a second, smaller spot directly above the first.

It ranges from Alaska, south and east across the middle portion of Canada, south along the Rockies to Wyoming. It has been documented in isolated portions of northern and central Idaho.

It can be found primarily in willow bogs.


Caterpillar: Caterpillars feed on the leaves of willow (Salix spp.) and possibly blueberry (Vaccinium spp.).
Adult: Butterflies drink flower nectar.

There is only one generation of caterpillars each summer. Young caterpillars overwinter in a physiological state called diapause, and emerge in spring to continue feeding, molting, and eventually to pupate. Adults generally fly from early June to early August.

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

Idaho Status: Unprotected nongame species.
Global Rank:

G4; population levels are secure, but may be of concern in the future.

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.