Colias

Colias is a genus of butterflies in the family Pieridae. They are often called clouded yellows in the Palearctic and sulphurs (a name also used for other coliadine genera) in North America. The closest living relative is the genus Zerene, which is sometimes included in Colias.

thumb|upright|Wing venation This genus occurs throughout the Holarctic, including the arctic regions. They are also found in South America, Africa, China and India. Their caterpillars feed on certain Fabaceae, for example vetches (Vicia). The adults forage for nectar. most are thus beneficial by keeping weeds at bay, some occasionally become nuisance pests on crops like alfalfa. In some species, the wings of males have brilliant ultraviolet reflection, while those of females do not. Adults of both sexes have various colour forms. Males are particularly conservative based on their genitalia structures. These structures are difficult to identify making it difficult to classify the Colias.