Wing span: 1 3/4 - 2 1/4 inches (4.5 - 5.8 cm).

Identification: Upperside of wings white; forewing with black tip. Two submarginal black spots in female, one in male. Underside of hindwing and forewing apex evenly yellow-green or gray-green. Spring and fall short-day form is smaller, less yellow, with reduced black areas.

Life history: Males patrol for females. Females lay single eggs on undersides of host leaves. Chrysalids hibernate.

Flight: Two to three in northern part of range; 7-8 in the south. It is usually the first butterfly to emerge in spring.

Caterpillar hosts: Many plants in the mustard (Brassicaceae) family and occasionally some in the caper family (Capparidaceae).

Adult food: Flower nectar from a very wide array of plants including mustards, dandelion, red clover, asters, and mints.

Habitat: Almost any type of open space including weedy areas, gardens, roadsides, cities, and suburbs.

Range: From central Canada south through the United States (except Florida Keys, southern Louisiana, and South Texas) to northwest Mexico.