North American Butterflies and Moths List

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Butterflies of North America

Western Square-dotted Blue (Euphilotes battoides)
JPG -- species photo

Western Square-dotted Blue (Euphilotes battoides [Behr])

Wing span: 11/16 - 13/16 inches (1.6 - 1.7 cm).

Identification: Extremely variable geographically. Upperside of female brown often with orange band on outer edge of hindwing. Male blue with dark borders. Male may have orange band on outer edge of hindwing. Underside is off-white to gray with black postmedian spots ranging from square to round and from large to small, again depending on subspecies. Best identified by associated host, locality, and season.

Life history: Males patrol all day near host plants to find receptive females. Eggs are laid singly on host plant flowers; caterpillars eat flowers and fruits, and are protected by ants. Chrysalids hibernate in sand or leaf litter.

Flight: One flight; Mid-April to August depending on location and host bloom.

Caterpillar hosts: Various wild buckwheats (Eriogonum species) including coastal buckwheat and sulphur-flower.

Adult food: Flower nectar especially that from Eriogonum species.

Habitat: Varies by subspecies; includes, prairie, open woodlands, chaparral, dunes, and alpine rock gardens.

Range: Spotty distribution from Washington south to Baja California Norte, thence west to southern Colorado and New Mexico.

Conservation: Most populations are probably secure, but invasive alien weeds such as cheatgrass may threaten an unknown proportion.

The Nature Conservancy Global Rank: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.

The Comstock's Blue (subspecies comstocki), and an unnamed subspecies all have The Nature Conservancy rank of T1 - Critically imperiled because of extreme rarity (5 or fewer occurrences, or very few remaining individuals), or because of some factor of its biology making it especially vulnerable to extinction. (Critically endangered throughout its range).

Management needs: Maintain habitat together with host plants of all known populations.


Emmel, T.C., editor. 1998. Systematics of Western North American Butterflies. 
     Mariposa Press, Gainesville, Fla. 878 pp.

Emmel, T.C. and J.F. Emmel. 1973. The butterflies of southern California. Natural
     History Museum of Los Angeles County, Los Angeles. 148 pages.

Ferris, C.D. and F.M. Brown. 1981. Butterflies of the Rocky Mountain States. 
     University of Oklahoma Press, Norman. 442 pages.

Garth, J.S. and J.W. Tilden. 1986.California Butterflies. University of California 
     Press, Berkeley and Los Angeles. 246 pp, 24 plates.

Layberry, R.A., P.W. Hall, and J.D. Lafontaine. 1998. The Butterflies of Canada. 
     University of Toronto Press, Toronto. 282 pages, 32 color plates.

Matthews, J. R., editor. 1990. The official World Wildlife Fund guide to endangered 
     species of North America, Vol. 2. Beacham Publishing, Inc., Washington, D. C. 
     636 pages.

Opler, P.A. 1999. A field guide to western butterflies.  Houghton-Mifflin Co., 
     Boston, Mass. 540 pages, 44 color plates.

Scott, J. A. 1986. The butterflies of North America. Stanford University Press, 
     Stanford, Calif. 583 pages, 64 color plates.

Stanford, R. E. and P. A. Opler. 1993. Atlas of western USA butterflies including 
     adjacent parts of Canada and Mexico. Denver and Fort Collins, CO. 

Author: Paul A. Opler

Western Square-dotted Blue (Euphilotes battoides)
distribution map
map legend

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