Family: Pieridae, Whites and Sulphurs view all from this family

Description 1 1/2-1 7/8" (38-48 mm). Male clear, lemon-yellow above, FW pointed and yellow-fringed with small black spot near end of FW cell; brighter yellow spot in HW cell; narrow black FW and HW border. Female yellow or white with fainter cell spots and suggestion of dusky, interrupted border on FW above. Below, FW yellow; HW granular, lime- to olive-green with silvery, unrimmed cell spot. Some northern populations are orange.

Similar Species Western Sulphur is dusky yellowish below with pink-rimmed cell spot. Pink-edged Sulphur has rounder wings with bright pink edge. Clouded Sulphur has row of brown spots below. Scudder's, Pelidne, and Giant Sulphurs have pink fringes. Orange form Hecla Sulphur is rounder, smaller, and darker at base of wings above. Orange Sulphur has row of brown spots below.

Life Cycle Eggs pale yellowish, pitcher-shaped; laid singly on golden banner (Thermopsis) and many other legumes, including some species of milkvetch (Astragalus), wild pea (Lathyrus), and locoweed (Oxytropis); lupine (Lupinus) may also be used. Caterpillar green with lighter and darker lengthwise stripes; overwinters in 3rd instar after aestivating through drier part of summer.

Flight 1 brood; June-July.

Habitat Clearings, meadows, roadsides, and other openings, and edges in mountainous ponderosa pine and true fir forests; also sagelands.

Range British Columbia and Alberta south to Nevada and New Mexico in mountains and Great Basin (yellow populations); Northwest Territories, Manitoba, and South Dakota (orange populations), with mixtures in between.

Discussion When these butterflies congregate by the score at damp earth following a Colorado mountain shower, the stationary green triangles and frenetic yellow blurs create a striking spectacle. This species is named for Queen Alexandra, wife of Edward VII of England, who also lent her name to the world's largest butterfly, Queen Alexandra's Birdwing (Ornithoptera alexandrae) of Papua New Guinea.