Females look similar but are slightly paler and lacking the androconial scales.

The castor plant (Ricinus communis) is the most common host and gives the butterfly its name.

An irregular set of small spines form a cluster at the end.

The colour is variable, sometimes green with longitudinal dark brown lines, or dark brown with an interrupted broad dorsal stripe of pure white, not extending to either end.

[3] "Slender, wing-cases somewhat dilated, a dorsal protuberance and two small cephalic points: colour variable: rigidly attached by the tail, so that if the surface is vertical, the pupa stands out horizontally."