April 2001. Palau wanted to know the identification of a caterpillar attacking poinsettia (Euphorbia pulcherrima). The same caterpillar has been found defoliating crotons (Codiaeum variegatum). The maximum length appears to be about 3-5 cm. The color of the caterpillars is variable, and appears to depend on the color of the leaves they are eating.
Later, in 2005, Fiji found the caterpillar of this moth feeding on croton, which is ground for sale in the country for its colourful foliage. The larvae grew to about 6 cm in the lab and pupated for 16 days. It is also abundant in Hawaii on croton and castor bean (Ricinus).
The caterpillar was identified online as the castor oil caterpillar or semi-looper, Achaea janata (Noctuidae: Catocalinae). It can cause severe damage to new growth flushes on lychee, cocoa and tamarillo (amongst others) but is generally regarded as a minor and sporadic pest in Australia. In Australia, this caterpillar also feeds on crotons. The adult moth is a ‘fruit sucking’ species, causing primary damage to soft fruits such as carambolas, but is mainly a secondary feeder on lychees damaged by Eudocima spp.). Poinsettia is also a host.
The adult is variable with either fawn or yellow-brown fore wings and black hind wings with a couple of white dashes. It can eat a variety of plants; outbreaks often occur after droughts or hurricane. See E.C. Zimmerman, Insects of Hawaii Macrolepidoptera.