Colias behrii, the Behr's sulphur or Sierra green sulfur, is a butterfly in the family Pieridae. It is endemic to California's Sierra Nevada from Tuolumne County south to Tulare County. The wingspan is 35–42 mm (1.4–1.7 in). The upper surface of the males is dull green with a dark border and with a pale hindwing cell spot. Females are greenish-yellow with a dark diffuse border. The underside of both sexes is green. Adults are on wing from July to August. They feed on flower nectar. The larvae feed on Vaccinium species and Gentiana newberryi.