The wingspan of the alfalfa butterfly is about one and three-fourth to two and one-half inches. The upperside of the wings of the male is orange-yellow with a solid black border. The upperside of the wings of the female is either orange-yellow or cream-colored with a black border that contains spots of the same shade as the main section of the wing. The underside of the wings is either orange-yellow or cream, matching the main coloration of the upperside of the wing. Coloration varies by season.
This species is found statewide in Illinois in open areas. Adults are active from March through November. Adults feed on nectar and are often seen congregating in clusters around puddles on the ground. The larvae eat alfalfa (Medicago sativa) and other legumes. The overwintering stage is the chrysalis.