Euphilotes battoides
Square-Spotted Blue

Family Description:
Alternate Common Name:
Buckwheat Blue.
Note: There are many subspecies of E. battoides, the distinctions being based primarily on differences in the species of host plants. Each subspecies utilizes a specific variety of buckwheat (Eriogonum spp.).

Caterpillar: The appearance of the caterpillar varies, and it usually matches the flowers of the host plant. Caterpillars can be bluish green, green, yellow, brownish, or pink. They may be marked with brown spots or stripes. The average length is inch.
Adult: The appearance of the butterfly varies widely as well. It is a small butterfly, with a wingspan of to 1 inches. Typically, males are blue on the upperside, edged in black, and possibly with a row of orange spots or an orange patch just inside the edge of the hindwing. Females are brown to blue on the upperside and marked similarly. Underneath, both sexes are white to gray and marked with either square or round black spots of different sizes. The underside of the hindwing is marked with orange just in from the edge.

It ranges from southern British Columbia south to Mexico, and east to western Montana and central Colorado and New Mexico. In Idaho, it occurs primarily in the central and southwestern portions of the state.

A species of drier habitats, it can be found in deserts, chaparral, open woodlands, and dunes.


Caterpillar: Caterpillars feed on the flowers and fruits of various species of wild buckwheat (Eriogonum spp.).
Adult: Butterflies drink nectar, most often from host plant flowers.

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 one generation of caterpillars each growing season. Each caterpillar undergoes four stages of growth, called instars. Pupae overwinter in a physiological state called diapause; chrysalises are often in the soil or leaf litter below host plants. Adults generally fly from mid-April to August, primarily when the host plants in the area are in bloom.

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

Idaho Status: Unprotected nongame species.
Global Rank: Varies with subspecies. Several subspecies are listed as T1, which means each is critically imperiled because of extreme rarity and is imminently vulnerable to extinction. This includes the El Segundo Blue (Euphilotes battoides allyni) of California, which is listed as an Endangered Species.

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.