Description: This species has predominantly bright yellow wings with black-borders above. On females these borders are interrupted with several yellowish spots. Females are often white, making them difficult to distinguish from white females of the Alfalfa Butterfly, from which it differs by being smaller with narrower black bands.

Distribution and habitat: Abundant species statewide, where it occurs in a variety of native and disturbed open habitats.

Natural History: Larvae feed on a variety of native and naturalized legumes, but are particularly fond of clovers. Population sizes can vary by as much as a factor of ten on the same sites in consecutive years (Olsen 1990). Currently the Clouded Sulphur is less abundant than the Alfalfa Butterfly, but when clover was the major hay source several decades ago, this pattern was reversed. Natural hybridization occurs in Iowa between C. philodice and C. eurytheme, often complicating the identification of a given individual. While courtship differences ordinarily keep these two species genetically isolated, such mechanisms begin to break down when host plants are cultivated side by side.