Adult: upperside of male wings lemon yellow or pale greenish-yellow with no markings; female forewing with small dark spot, usually a narrow blackish outer margin, and a few vague dark dots near tip. Underside of hindwing with two silver black-rimmed spots in both sexes.
Caterpillar: usually pale green and marked by a yellow stripe on each side and black spots in rows across each abdominal segment. (1) Above and below the yellow stripe there are usually small areas marked with blue.
There is also a yellow form that occurs when it feeds on yellow flowers of its host plants. The later instars of the yellow form have a dark transverse band across each segment (see image).
Range
Southern United States; often migrates north in late summer/fall, sometimes reaching northern states and southern Ontario (see US distribution map).
Permanent resident in the tropics, occurring south to the tip of South America.
Habitat
Tropical forests and areas of regrowth with woody members of the pea family (1)(2). Disturbed open areas including parks, yards, gardens, beaches, road edges, abandoned fields, scrub.
Season
Adults fly throughout the year in the south; northern migrants fly late summer-fall. (1)
Food
Caterpillar feeds most commonly on Cassia and some other woody and herbaceous legumes (1). Species of Cassia now in genus Senna(3)? [No; Cassia and Senna are two distinct and different genera. RM]
Life Cycle
Breeds continuously in the tropics; usually two generations per year in the southern United States. (1)
See Also
Usually in Texas, Florida:
Large Orange Sulphur (Phoebis agarithe) male is bright orange above with no markings, and female is either pinkish-white or yellowish-orange above (see images)
Orange-barred Sulphur (Phoebis philea) male is bright yellowish-orange above with reddish-orange bar on forewing, and reddish-orange outer margin on hindwing; female is either off-white or pale yellowish-orange above with submarginal row of broken dark smudges (see images)
Butterflies and Moths of North America; USGS (live adult image of male by Paul Opler, plus description, biology, food plants, flight season, habitat, distribution, status, references, US range map)
