Pontia sisymbrii
Spring White
Family:Pieridae
Family Description:
Alternate Common Names:California White, Sisymbrium White.
Note: This species is referred to by the older genus name Pieris by some sources.
Description:
Caterpillar: The caterpillar is brightly marked with horizontal stripes: thin white and black, thick and wavy black, and thick yellow. The head is black and marked with white.
Adult: The butterfly is medium-sized, with a wingspan of 1 ¼ to 1 ¾ inches. The upperside is white to yellowish white. The forewing is marked with a black or gray spot in the center, and black or gray marks at the tip and along the edge. Underneath is white to beige. The underside of the hindwing is marked along the veins with brown to blackish brown, which may be dusted with off-white in freshly emerged individuals. The forewing tip or the entire forewing may have brownish veins on the underside as well.

Range:
This species ranges from the Yukon and western Northwest Territories south to southern California and Mexico, extending east as far as central Alberta, western Montana, western South Dakota, and central Colorado. It occurs through much of Idaho.

Habitat:
 It can be found in coniferous forests, dry slopes and canyons, deserts, and in alpine areas of west coast mountains.

Diet:

Caterpillar: Caterpillars feed on the leaves and flowers of members of the mustard family (Brassicaceae), such as hedge mustards (Sisymbrium spp.), rock cresses (Arabis spp.), and jewel flower (Streptanthus spp.).
Adult: Butterflies drink flower nectar.

Ecology:
There is one generation of caterpillars each year. Pupae overwinter in a physiological state called diapause, and butterflies emerge in the spring, often very early. Adults generally fly from February to June.

Reproduction:
Males actively patrol in search of receptive females. Females lay yellow eggs singly on all parts of host plants.

Conservation:
Idaho Status: Unprotected nongame species.
Global Rank:

G5; populations are widespread, abundant, and secure.

References:
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.