Wing span: 2.2 to 2.6 cm.

Flight time: First migrants appear from late May through June. These individuals found a series of overlapping later broods that fly from late July to frost.

Status: Spring-early summer southern stray; mid-summer to fall resident.

Distinguishing features: This is the smallest pierid in the state. It is typically yellow above with black apices and a black bar on both wings where they meet. Color variability is present with some females being white or orange. Males have a very apparent sex-patch on the dorsal hind wing, which may vary in color from red to yellow (Clench, 1976). This color may fade in preserved specimens.

Distribution and habitat: Scattered throughout the southwestern 2/3 of Iowa, where it occurs in various open, mesic, disturbed habitats.

Natural History: Unlike other small sulfurs, larvae of this species consume members of the aster family, especially tickseed (Bidens spp.). However, its range of host plants may be wider, as Lulu Berry (1934) reared larvae on chickweed in Benton County. The species flies rather close to the ground, with sporadic stops at low-growing flowers.