One of the larger sulfur butterfly species, wingspan of butterflies can be over 3 inches. Males are brilliant yellow above with no markings. Females have some black marginal markings. Each body segment is also marked with rows of black dots. Adults of the alfalfa caterpillar , Colias eurytheme Boisduval, are commonly seen sulfur butterflies.
Females lay eggs on host plants.
Caterpillars hatching from eggs develop through several stages before forming a smooth chrysalis suspended from a plant stem by its base and a silk thread. Broods are continuous in the eastern half of Texas. Caterpillars have chewing mouthparts. Adults have siphoning mouths. Adults are strong migratorsm, particularly in late summer when their range expands northward.