Phoebis sennae

The cloudless sulphur starts off as a pitcher-shaped white egg. Eventually it will turn to a pale orange. The egg stage lasts six days.

Cloudless sulfur caterpillar (Phoebis sennae) eating yellow jessamine flower (Gelsemium sempervirens)

Once the egg hatches, a caterpillar emerges that is yellow to greenish, striped on sides, with black dots in rows across the back. The host plant may be sensitive peas (Chamaecrista),[6] sennas (Senna),[7] clovers (Trifolium), or other legumes (Fabaceae). The caterpillar will usually grow to a length between 41 and 45 mm (1.6 and 1.8 in).

The caterpillar will form a chrysalis that is pointed at both ends and humped in the middle. The chrysalis will be either yellow or green with pink or green stripes. From the chrysalis comes a medium-sized butterfly (55–70 mm (2.2–2.8 in)) with fairly elongated but not angled wings.

The male butterfly is clear yellow above and yellow or mottled with reddish brown below and the female is lemon yellow to golden or white on both surfaces, with varying amounts of black spotting along the margin and a black open square or star on the bottom forewing. Wing spans range from 4.8 to 6.5 cm (approximately 1.9

to 2.6 in)[6].

• 
  Female
• 
  Male
• 
  Monsanto Insectarium, St. Louis Zoo
• 
  Caterpillar
• 
  Yellow version of caterpillar feeding on senna tree, Vista, California
• 
  Chrysalis on senna tree, Vista, California
• 
  Male P. s. marcellina
  in the Pantanal, Brazil
• 
  Male P. s. marcellina
  in Panama, some males are unmarked