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Photo Credit: UF/IFAS
Article Contributed by: Kim Rothwell, Master Gardener
The cloudless sulphur, Phoebis sennae(Linnaeus), is one of our most common and attractive Florida butterflies and is particularly prominent during its fall southward migration. Its genus name is derived from Phoebe the sister of Apollo, a god of Greek and Roman mythology.
The cloudless sulphur is widspread in the southern United States, and it strays northward to Colorado, Nebraska, Iowa, Illinois, Indiana and New Jersey, and even into Canada. It is also found southward through South America to Argentina and in the West Indies. It is the most widespread large Sulphur in the state of Florida.
Wing spans range from 1.9 to 2.6 in. Adults are usually bright yellow, but some summer form females are pale yellow or white. Females have a narrow black border on the wings and a dark spot in the middle of the front wing. Males are larger with darker markings.
At night, on dark, cloudy days, and during storms, adult cloudless sulphurs settle on leaves. Tthey are very choosy of just the right place. An adult preparing to settle makes an erratic flight around a potential tree or shrub, settling briefly at times, then flying about some more, and typically selecting a yellow or reddish leaf within other leaves on which to finally stop. This behavior may help prevent attacks from predators, such as birds, that may also be perching nearby and watching the activity. Although the adults are brightly colored when flying, they seem to disappear against similarly colored leaves in the shade. The site they choose to settle may be low to the ground in shrubs with lots of foliage or high up in the leaves of trees.
Eggs are laid singly on the host plant. Larvae live exposed (no shelter) and feed on foliage, buds and flowers. The eggs are cream colored when laid but later turn to orange.
The larvae are green with yellow lines and blue patches and transverse bands of tiny blue spots. Larvae that feed predominantly on flowers are yellow with black bands.
The pupae hang vertically attached to a silk pad. Pupae may be either green or pink with yellow lines.
Cloudless sulphurs may be found in all habitats when migrating, but breed in disturbed open areas where their caterpillar host plants and nectar plants are found. They have relatively long tongues and can reach the nectar of some tubular flowers that some other butterflies cannot. Red flowers are preferred. In Florida, they frequently nectar at the red morning-glories, scarlet creeper and cypressvine, and also at scarlet sage, Salvia coccinea. Males sometimes drink from mud.
The fall migration of cloudless sulphurs is the easiest to observe butterfly migration in the southeastern United States. In the Southeast during the fall, any butterfly watcher driving an east-west road through open country will likely see these bright yellow butterflies crossing the road and can confirm that they are crossing much more frequently from north to south than from south to north. (Monarchs are migrating at the same time, but they generally fly too high to see and are heading for Mexico and hence may miss the Southeast.) During fall, the numbers of cloudless sulphurs crossing an east-west line bisecting the Florida peninsula at the latitude of Gainesville may approach the numbers of monarchs overwintering in clusters at highly localized sites in Mexico.
There was a sharp decline of the fall migrations of cloudless through Gainesville between 1984 and 2000. Reduced planting of soybeans and more use of herbicides to control sicklepod in soybean fields may have caused, or at least contributed to, the decline.
Native species host plants: Florida Keys sensitive pea; Maryland wild sensitive plant; narrowpod sensitivepea; partridge pea; privet wild sensitive plant; sensitive pea; Chapman's wild sensitive plant; Africa wild sensitive plant; candlestick plant; coffeeweed (sicklepod); glossy shower; septicweed; and valamuerto.
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