Cloudless Sulphur

How to identify it

• Adults span about 1.9 to 2.6 inches and are usually bright yellow; females have a thin black border and spots on the forewing, some summer females are pale yellow or white.^[1][2]
• Caterpillars are yellowish green with black dots and a yellow line along each side.^[2]

Where it lives

Common in Florida and migrating through Missouri and much of the eastern United States in fall.^[1][2]

US map: public records from 30 states since 1990 (GBIF). View the map

Biology and life cycle

Its long tongue lets it feed on tubular flowers such as trumpet vine, petunias, four o'clocks, morning glories and phlox.^[2]

Damage and signs

• Caterpillars feed on legumes such as partridge pea and wild senna; feeding is not a concern.^[1][2]

Health risk

None to people or pets.^[1][2]

Control

Prevention

No control is needed.^[1][2]

Common questions

What is the big yellow butterfly flying south in fall?

Likely a cloudless sulphur on its southward migration.^[1][2]

What do the caterpillars eat?

Senna, partridge pea and other legumes.^[1][2]

Which flowers attract it?

Long tubular flowers like trumpet vine, petunias and phlox.^[2]

Sources

1. University of Florida IFAS Extension (EDIS, Featured Creatures), “Cloudless Sulphur, Phoebis sennae (EENY-524/IN929).” ask.ifas.ufl.edu/publication/IN929 (accessed 2026-10-15)
2. Missouri Department of Conservation, “Cloudless Sulphur (Field Guide).” mdc.mo.gov/discover-nature/field-guide/cloudless-sulphur (accessed 2026-10-15)
3. iNaturalist, “Phoebis sennae taxon page (order and family).” www.inaturalist.org/taxa/48550 (accessed 2026-10-06)