Male. © Peter J. Bryant.

Orange Sulphur (Alfalfa butterfly)

Colias eurytheme

Lepidoptera: Pieridae

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Female. © Peter J. Bryant.

Alba Variant. © Peter J. Bryant.

Male. © Peter J. Bryant.

Female. © Peter J. Bryant.

Irvine Park, Orange, Orange County, CA. 10-24-06. © Ron Hemberger

Irvine Park, Orange, Orange County, CA. 10-24-06. © Ron Hemberger

Mating pair. San Mateo campground, San Clemente, Orange County, CA.5/13/12. © Robert Gorman

Characteristics: Male -- yellow or orange with dark marginal border around dorsal forewing and hindwing. Female -- yellow, orange, or less commonly, white (albino) with incomplete dark border on dorsal wings. Forewing length: 20-30 mm.

Similar Species: In the suburbs, this species could be confused with the urban Eurema nicippe, which is more orange in color than eurytheme.

Habitats, Behavior: This is a rather rapid flyer, often associated with alfalfa fields, where it swarms in numbers. B. Kerr (1918) recorded it as "very common in alfalfa fields throughout the county".

Distribution: The Alfalfa Caterpillar Butterfly primarily inhabits the lowland areas of Orange County. It is occasionally found in the canyons (low elevations) of the Santa Ana Mountains. The species is most likely to be encountered in large vacant lots and other semi-disturbed areas, although it is rarely common, due to the lack of extensive alfalfa cultivation in the county today.

Flight Period: This butterfly probably flies every month of the year in Orange County; multiple brooded.

Larval Foodplants: Many species of legumes (family Leguminosae) are utilized, primarily Alfalfa (Medicago sativa); also clovers (Trifolium spp.) and perhaps Deerweed (Lotus scoparius) at Upper Newport Bay and in the foothills. Lotus crassifolius is commonly utilized in the Mt. Pinos region (Kern Co.) and may be utilized in the Santa Ana Mountains as well.

Other Remarks: Many seasonal color varieties of this species exist and there are many old names referring to these forms (e.g. form "alba" for the albino female form). See Emmel and Emmel ( 1973) and Comstock (1927) for further information on these forms.

From Orsak, L. J. (1977). The Butterflies of Orange County, California. Center for Pathobiology Miscellaneous Publication #3. University of California Press, New York. 349pp.

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