Orange sulphur -female - Colias eurytheme - with what appears to be a beak mark imprinted on the underside of the hindwing. Widespread, larvae feed on a variety of native and introduced legumes including alfalfa. Does not overwinter in eastern Kansas but migrates into Kansas each spring from Texas. The species is polymorphic in that the sexes have different wing patterns and the females have two color forms, one orange like the male and the other white.
A sister species, the common sulphur, Colias philodice, has a place in the history of genetics in that the inheritance of the white form was the first sex-limited trait to be described in detail. This work was done by J. H. Gerould in 1911.