Orange Sulphur
Colias eurytheme
[b]Alfalfa Butterfly
Description
1 5/8-2 3/8" (41-60 mm). Male and female above bright gold-orange with pink blush and black borders (broken by yellow spots of female); black spot in FW cell, red-orange spot in HW cell. Below, orange, yellow, or greenish-yellow with single or double red-rimmed silvery spot in HW cell and brown submarginal row of spots. Both wings have pink fringe. Spring individuals may be yellow above with orange cell flush.
Similar Species
Clouded Sulphur is normally yellow. Orange form Queen Alexandra's Sulphur and Arctic Sulphur are smaller, paler, and lack prominent row of brown spots below.
Life Cycle
Egg whitish, long and pitcher-shaped; laid singly on top or bottom of leaves. Caterpillar dark grass-green with pink stripes low on sides, white stripes higher, and covered with tiny white hair. Chrysalis green, dashed with yellow and black; overwinters.
Host plants include great array of herbaceous legumes; alfalfa (Medicago sativa) and white clover (Trifolium repens) are preferred.
Flight
Overlapping broods; March-December, shorter period farther north.
Habitat
Nearly any open space, particularly alfalfa fields.
Range
Almost ubiquitous in North America; rarer north of Canadian border, in subtropical Florida, and in coastal Northwest.
Discussion
Like the Clouded Sulphur, this species breeds with enormous success on native and naturalized legumes. These food preferences, along with strong and probing flight habits, allow the Orange and Clouded Sulphurs to colonize disturbed and cultivated areas as well as natural habitats. When these 2 sulphur species are superabundant in an alfalfa field, they often hybridize and produce many part-orange, part-yellow butterflies that are difficult to classify. However, the species have not merged; they breed true where density is lower.
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