# Cloudless sulphur (Phoebis sennae) > Large bright-yellow sulphur butterfly common in open habitats; caterpillars feed mainly on senna and related legumes. Source: https://insectscanner.com/species/cloudless-sulphur/ (updated 2026-10-10) ## Is it dangerous? **Non-toxic.** Cloudless sulphurs do not bite or sting and are not poisonous. They may land on people but cause no harm. Handle gently if necessary; adults are fragile and can lose wing scales. **Pets:** Not toxic to pets. Caterpillars feed on specific host plants and are not known to be poisonous to dogs or cats, though ingestion of large plant material could cause mild stomach upset. ## Quick facts - Scientific name: Phoebis sennae - Order: Lepidoptera (Butterflies and moths) - Family: Pieridae (Whites and sulphurs) - Size: 5.5-8.0 cm wingspan - Colours: Bright yellow, Pale yellow, Orange yellow, Brown (markings), Black (tiny spots/veins) - Habitat: Open, sunny areas: fields, roadsides, gardens, scrub and disturbed sites; also suburban plantings with host plants. - Range: Widespread from the southern United States through Central America and South America; some populations migrate northward seasonally into temperate North America. - Active: Spring through fall in temperate zones; year-round in tropical regions. Diurnal, most active in warm daylight. - Lifespan: Adults typically live 2-4 weeks; overall life cycle from egg to adult depends on temperature and food availability. - Effect on plants: Host-specific herbivore - Pest: no ## Overview Phoebis sennae, the cloudless sulphur, is a widespread butterfly of open fields, roadsides, gardens and disturbed areas across the Americas. Males are typically vivid yellow to orange-yellow and very mobile; females vary from yellow to pale white or with orange markings. The species often visits flowers for nectar and can appear in large numbers during migration or local population peaks. Larvae develop on plants in the pea family (Fabaceae), especially Senna species. Adults are harmless to people. ## How to identify it Adults are medium-large to large for 'sulphurs', with smooth, unbroken wings often uniformly yellow to orange-yellow on the upper side. Males tend to be more uniformly bright yellow or golden orange, while females show more variation: some are pale yellow or whitish with faint markings, others resemble males. The forewing may have a small dark spot or faint border; the underside is paler and may show a row of indistinct spots. The body is slender and scaled like other butterflies. Caterpillars are typically green or yellow-green, often with faint striping or small tubercles, and grow to match the length of the folded host leaves. The chrysalis is smooth and usually green, attached to leaves or stems. - Large sulphur with a 5.5-8.0 cm wingspan and uniformly bright yellow to orange upper wings in males. - Females may be paler or whitish; check underside for paler tones and faint spots. - Lacks the heavy dark border or strong spotting seen in some other sulphurs; overall smooth, unbroken wing color. - Observe host plants: larvae on Senna species strongly suggest Phoebis sennae. ## Lookalikes - **Orange sulphur** (Colias eurytheme): Colias species often have distinct dark wing borders and more pronounced underside patterning; they are generally smaller and belong to a different genus. - **Little yellow** (Eurema lisa): Eurema lisa is smaller and more lemon-yellow; cloudless sulphur is larger and often more uniformly orange-yellow on males. ## Life cycle - **Egg:** Females lay single eggs or small groups on the underside of host plant leaves (Senna and related legumes). Eggs hatch in about 4-10 days depending on temperature. - **Larva (caterpillar):** Caterpillars feed on host leaves, growing through several instars. They are typically green or yellow-green and blend with foliage. - **Pupa (chrysalis):** The chrysalis is attached to stems or leaves; pupation lasts roughly 7-14 days in warm conditions but varies with climate. - **Adult (butterfly):** Adults feed on nectar from a wide range of flowers and seek mates; they can disperse or migrate seasonally. ## Diet and predators - Young eat: Leaves of Senna and other Fabaceae (pea family) species. - Adults eat: Nectar from many flowering plants, including lantana, shepherd's needle, bougainvillea and other garden flowers. - Predators of the young: Parasitoid wasps and flies, predatory insects, birds and small spiders. - Predators of adults: Birds, dragonflies, spiders and other aerial predators; adults avoid predation by rapid flight and mobility. ## Effect on plants and gardens Larvae feed mainly on Senna species (e.g., Senna hebecarpa, Senna mexicana, Cassia spp.) and other Fabaceae. Heavy localized feeding can defoliate small plants but they are generally not a major agricultural pest. ## Where and when to find it Adults on nectar flowers in sunny gardens, fields and roadsides; eggs and caterpillars on Senna and other Fabaceae leaves; chrysalises attached to stems or underside of leaves. - Best time: Spring through fall in temperate zones; during warm daylight hours when flowers are open. - Tips: Use a long lens or stay downwind and still to photograph; approach slowly as they can be skittish. Look under leaves of Senna plants for eggs and young caterpillars. ## Fun facts - Cloudless sulphurs are strong fliers and can migrate long distances; some populations move seasonally. - Males patrol territories and can be seen flying persistently in search of females. - Females show more color variation than males, sometimes appearing nearly white (a form called 'albino' or pale form in common usage). ## Frequently asked questions ### Do cloudless sulphurs bite or sting? No. They are harmless to humans and do not bite or sting. ### Why do I have cloudless sulphurs in my garden? They are attracted to nectar flowers and to host plants in the pea family (Senna), which you may have in or near your garden. ### Are cloudless sulphurs harmful to plants? Larvae eat leaves of senna and related plants. While they can defoliate small plants if numerous, they rarely cause lasting damage to established shrubs or crops. ### How can I get rid of cloudless sulphurs? They are beneficial pollinators and not typically pests. To reduce local breeding, remove or relocate host Senna plants. Handpick caterpillars if necessary. Avoid broad insecticides to protect pollinators. ### When and where will I see them? In temperate areas from spring to fall; year-round in the tropics. Look in sunny, open habitats, garden flowers and where host plants grow. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/48550), [Wikipedia](https://en.wikipedia.org/wiki/Phoebis_sennae). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.