Metabolic-physiology
Guides
Colias eurytheme
Orange Sulphur, Alfalfa Butterfly, Alfalfa Caterpillar
Colias eurytheme, the orange sulphur or alfalfa butterfly, is a widespread North American pierid butterfly found from southern Canada to Mexico. The species is highly variable in coloration, with both orange and white morphs present, and exhibits complex thermal biology and sexual selection dynamics. Larvae are significant agricultural pests of alfalfa and other legumes, while adults are known for mass emigration events when host crops are harvested. The species has been extensively studied for its metabolic responses to temperature, costs of mating in females, and disruptive sexual selection patterns.