Plebejus saepiolus
Greenish Blue

Family Description:
Alternate Common Name:
Greenish Clover Blue.

Caterpillar: The caterpillar varies in color, from greenish, to greenish white tinged with purplish at the ends, to reddish. It has a bumpy appearance, with each individual segment appearing fat. It reaches an average, full-grown length of inch.
Adult: The butterflies vary greatly in appearance between populations, the sexes, and even from individual to individual. They are fairly small, each with a wingspan of 1 to 1 inches. Males: Typically, the male is silvery blue on the upperside, possibly tinged with green. The borders of the wings are black and fringed with white. The forewing may have a dark spot near the middle, and the hindwing may have a faint row of blackish dots at the rear. Underneath is grayish white to gray, possibly bluish where the wings meet the body. Both the fore- and hindwings are dotted with black underneath; the hindwing may have one large spot and/or several small, orange spots. Females: The female is brownish on the upperside, possibly with orange near the edge of the wings, or brownish with blue shading, sometimes extensive, where the wings attach to the body. The forewing may have a dark spot near the middle. The edges are black and fringed with white. Underneath is beige and marked similarly to the male.

This species ranges from central Alaska south to the mountains of southern California and northern Arizona and New Mexico, extending east as far as western Montana and Wyoming; it also extends east across central and southern Canada and the Great Lakes states to New England and Nova Scotia. It occurs through most of Idaho.

It can be found in moist areas such as bogs, meadows, grassy fields, open forests, and along streams. Most commonly, it occurs above 6,000 feet elevation.


Caterpillar: Caterpillars feed on the flowers and fruits of clovers (Trifolium spp.).
Adult: Butterflies drink flower nectar, often from clovers. Males are often found "puddling" at muddy seeps where they gather salts and nutrients by sipping moisture.

The caterpillar is equipped with a honey gland, also known as a dorsal nectary organ, which emits a sugary solution agreeable to ants. The ants feed on the solution and in turn protect the caterpillar from predators. Also for protection, the caterpillar bears a pair of everscible tubercles or tentacles on the eighth segment. These tubercles are usually housed within the body, but when the caterpillar feels threatened by the approach of a potential predator, they can be pushed out to release a chemical which mimics an ant alarm pheromone. This scent causes the ants to become frenzied and aggressive, and the potential predator takes leave or is eaten by the ants. There is usually only one generation of caterpillars each summer. They feed all summer and then overwinter in a physiological state called diapause until spring. In spring they emerge to continue feeding and molting and eventually to pupate. Each caterpillar undergoes four stages of growth, called instars. Adults generally fly from mid-May to mid-August. Butterflies tend to remain near clovers.

Males actively patrol in search of receptive females. Females lay eggs singly in the buds and young flowers of clovers.

Idaho Status: Unprotected nongame species.
Global Rank: G5; most populations are widespread, abundant, and secure. However, one subspecies from southern California, the San Gabriel Blue, is now extinct due to destruction of its habitat.

Ballmer, G. R. and G. F. Pratt. 1988. A survey of the last instar larvae of the Lycaenidae of California. Journal of Research on the Lepidoptera 27:1-81.

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.