Admiring the Beautiful Yellow Cloudless Sulphur Butterfly

The Cloudless sulphur is a small butterfly that lives in the US, Mexico, Argentina, and Canada; known for its lemon-yellow color and similarity to the Clouded sulphur butterfly.

Cloudless sulphur species summary

Scientific Name Phoebis sennae
Family NamePieridae
Kingdom Animalia
Genus Phoebis
HabitatWatercourses, gardens, open areas, seashores
RangeCanada, the US, Mexico, Argentina
Host PlantsPlants from the pea family
Butterfly DescriptionYellow, with faint dark spots on its forewings and occasional reddish-brown patches
Caterpillar DescriptionHave yellow bands and blue dots that cover the entire thorax

What colors do Sulphur butterflies have on their wings?

Cloudless Sulphur Butterfly
Cloudless Sulphur Butterfly

Male Sulphur butterflies have a bright yellow shade with occasional reddish-brown mottling on the ventral surface. During the winter, their bodies tend to be larger and have darker ventral markings.

On the other hand, female Sulphur butterflies are golden yellow, lemon yellow, or white on both dorsal and ventral parts of their wings. They tend to emerge with brighter wings if their eggs hatch in the summer. 

These yellow butterflies have elongated wings and a distinct black star or square-shaped dark spot on the bottom or middle part of their forewings. The females’ bodies also have a narrow brown or black border that irregularly outlines their forewings and hindwings.

An adult Cloudless sulphur yellow butterfly is considered medium-sized because its wingspan can range from 2 to 3 inches.

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Clouded Sulphur vs. Cloudless Sulphur

The Cloudless sulphur is quite similar to the Clouded sulphur (family Pieridae), with one small difference — the Clouded sulphur has black edges on its forewings, while the Cloudless doesn’t. The Clouded sulphur also has two darker spots on the upper side of its forewings.

Caterpillar Physical Description

The greenish to yellowish Cloudless sulphur caterpillars emerge from white, cream-colored, or pale tiny orange eggs. Yellow lateral lines and brown bands with black dots encompass their bodies.

Some larvae also have yellow bands and blue dots that cover the entire thorax. Another variety has black traverse bands and a yellow body.

The Cloudless sulphur butterflies can grow somewhere between 1 to 2 inches during this part of their life cycle. Once they reach their full length, they will work on forming their chrysalis, which appears to have a hump in the middle with pointed ends.

Why is it called sulphur butterfly?

This butterfly got its name from the Senna family of plants. This member of the pea family happens to be one of the Cloudless sulphur butterfly’s favorite food.

Where do cloudless Sulphur butterflies live?

Cloudless Sulphur butterflies love to inhabit areas like:

  • Watercourses
  • Gardens
  • Open areas
  • Seashores
  • Glades

Some of the locations where they have been found include Colorado, Nebraska, Iowa, Illinois, Indiana, and New Jersey (in the US), Mexico, Argentina, and Southern Canada (especially in southwest Ontario).

Host Plants

Female Cloudless sulphur butterflies like to lay their eggs while the caterpillars feed on the stems and leaves of the Legumes/Pea family and:

  • American senna (Senna hebecarpa)
  • Florida Keys sensitive pea (Chamaecrista deeringii)
  • Partridge peas (Chamaecrista fasciculata)
  • Sensitive pea (Chamaecrista nictitans)

What do Cloudless Sulphur butterflies eat?

Adult Sulphur butterflies usually feed on the nectars of flowering plants with long tubes (especially red ones), thanks to their long tongues. Some of their preferred plants are the following:

  • Partridge peas
  • Scarlet creeper
  • American senna
  • Red morning glory
  • Clovers
  • Sennas
  • Scarlet sage/Salvia coccinea
  • Wild morning glory

In some instances, male Sulphur butterflies feed on mud in preparation for the reproductive season.

Behavior and courtship display

The adult Cloudless sulphur butterflies will breed depending on the predominant climate in the area where they are currently at. They reproduce in the middle or late summer until autumn if they are in a cool area, while they do this throughout the year if the weather is warmer.

A male Sulphur butterfly flies around the host plants to look for a female mate. Once it chooses its partner, it begins courtship by contacting its wings.

If the potential partner likes the courting male back, she will flick and close her wings. Otherwise, she will refuse him by raising her abdomen and opening her wings.

A few days after coupling, the adult female butterflies will lay their eggs on their chosen host plant.

Like some butterfly species, adult Cloudless sulphur roost on leaves during storms, cloudy days, and even in the dark. They change their flight pattern to erratic wing flapping at a shrub or tree and briefly settle on the chosen area before continuing with the same pattern.


Most of the predators of the Sulphur butterflies come from the Chalcididae species and are considered parasitoids:

  • Conura transitiva walker
  • Brachymeria incerta cresson
  • Schizomicra tucumana blanchard
  • Conura eubule cresson

Is the cloudless Sulphur butterfly poisonous?

Since Cloudless sulphur feed on toxic host plants, their caterpillars are toxic to predators.

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