North American Butterflies and Moths List

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Butterflies of North America

Butterflies of Arizona

Reakirt's Blue (Hemiargus isola)
JPG -- species photo

Reakirt's Blue (Hemiargus isola [Reakirt])

Wing span: 3/4 - 1 1/8 inches (2 - 2.9 cm).

Identification: Upperside of male light blue with darker veins and dusky border; female darker. Underside of forewing with postmedian row of 5 round black spots circled with white.

Life history: Males patrol for females with an erratic flight during daytime. Females lay eggs singly on flower buds of host during midday. Caterpillars eat flowers and seedpods, sometimes leaves; and are tended by ants which presumably protect the caterpillars in return for their sugary secretions.

Flight: All year in South Texas; 3 broods from March-November in the remainder of its residential range; migrates north once each year after hibernating in the south.

Caterpillar hosts: Many plants in the pea family (Fabaceae) including yellow sweet clover (Melilotus officinalis), rattleweed (Astragalus), mesquite (Prosopis), indigo bush (Dalea), mimosa (Albizia), and indigo (Indigofera) species.

Adult food: Flower nectar from a variety of herbs including spearmint and white sweet clover.

Habitat: Grasslands, fields, desert, meadows, weedy areas, creeksides.

Range: Resident from southern California, the Southwest, and Texas through Mexico and Central America to Costa Rica. Summer migrant north and east through the Mississippi River states to Wisconsin and Ohio.

Conservation: Not required.

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

Management needs: None reported.


Opler, P. A. and G. O. Krizek. 1984. Butterflies east of the  Great Plains. Johns 
    Hopkins University Press, Baltimore. 294 pages, 54 color plates.

Opler, P. A. and V. Malikul. 1992. A field guide to eastern  butterflies. Peterson 
    field guide #4. Houghton-Mifflin Co.,  Boston. 396 pages, 48 color plates.

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

Tilden, J. W. 1986. A field guide to western butterflies.  Houghton-Mifflin Co., 
    Boston, Mass. 370 pages, 23 color plates.

Author: Jane M. Struttmann

State and Regional References:

Bailowitz, R. A. and J. P. Brock. 1991. Butterflies of Southeastern Arizona. 
     Tucson, Ariz.: Sonoran Arthropod Studies, Inc.

Garth, J.S. 1950. Butterflies of Grand Canyon National Park. Grand Canyon 
     Natural History Association, Grand Canyon, Ariz.

Opler, Paul A. 1999. Peterson Field Guide to Western Butterflies, revised 
     edition. Houghton Mifflin Co., Boston, Mass.

Stanford, R.E. and P.A. Opler. 1993. Atlas of Western USA Butterflies. 
     Privately published, Denver, Colo.

Tilden, J.W. and A.C. Smith. 1986. A Field Guide to Western Butterflies. 
     Houghton Mifflin Co., Boston, Mass.
Reakirt's Blue (Hemiargus isola)
distribution map
map legend

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