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Alexandra Sulphur
Butterfly.--Larger than C. philodice. The male is pale canary-yellow, with much narrower black borders than the preceding species. The is pale yellow or white, without black borders, or, at most, faint traces of them at the apex of the primaries. On the under side the wings are silvery-gray, yellow only at the base and on the inner margin of the primaries. The discal spot on the hind wings is white. Expanse, male, 1.85 inch; female, 2.10-2.30 inches.
Early Stages.--The caterpillar is uniformly yellowish-green, with a white band on each side, broken with orange-red dashes running through it. The chrysalis, which resembles that of C. philodice in form, is yellowish-green, darkest on the dorsal side, and adorned with three small red dots on the ventral side of the abdomen near the wing-cases. The caterpillar eats Astragalus, Thermopsis, and white clover. Expanse, male, 1.90-2.15 inches; female, 2.00-2.30 inches.
The species is found in Colorado and the mountain regions to the north and west of that State.