The Caper White lives mainly west of the Great Dividing Range, where it feeds on caper shrubs, but is sometimes blown towards Sydney while on its northward migration in about November.
Adult Caper White Butterflies are mostly white with black margins to their upper wings and yellow-orange, black and white underwings. The caterpillars are dark brown to olive green with white and yellow dots.
Caper White Butterflies live in urban areas, forests and woodlands.
Caper White caterpillars are associated with caper plants that grow in the northern parts of inland New South Wales and in Queensland.
In spring many Caper White Butterflies migrate to where caper shrubs and creepers are more common. They usually fly inland, west of the Great Dividing Range, but a westerly wind may blow them off course and they may then be seen by people living along the coast. They maintain a rapid flight about 2 m - 3 m above the ground during the day, resting on shrubs and trees at night.
Migrations in New South Wales have been observed moving in a southerly direction during November and December. However, in the Australia Capital Territory, north-easterly flights have been observed, and both northerly and southerly flights have be reported near Sydney.
Numbers in migrations can be very large. In some cases, the adult butterflies can clog car radiators, causing overheating.
An interesting feature of this species is that it regularly migrates to areas where there are no food plants for its caterpillars. It is not understood why this behaviour has evolved.
Feeding and diet
The caterpillars of the Caper White Butterfly eat only plants belonging to the caper family (Capparis spp). These include native capers and warrior bushes. In fact, the caterpillars often occur in such large numbers on their food plants that they completely strip them of edible leaves. However the plants normally recover from this seemingly destructive behaviour.
Predators feed on Caper Whites at various stages of their life cycle. Many invertebrates feed on the eggs and emerging larvae, wasps and flies eat the caterpillars, and birds eat the emerging butterflies.