July 2006. This caterpillar was found on Crinum ?asiaticum in Palau. It is on the native Crinum. The caterpillars are eating the leaves, and getting into the leaf axils. The largest specimens are about 6 cm long. As a control measure, the plants will be cut down and the caterpillars destroyed.

It was identified as Spodoptera picta. It is widespread in Indo-Australian tropics and the caterpillars are often found feeding on Amaryllidaceae. The following information was provided:

The same problem occurs in north Queensland. It is quite spectacular how quickly the larvae can turn the centres of the Crinum plants into a frass ‘soup’. The larvae will feed initially on the leaves and then as they grow larger start feeding down in the crown of the plant ultimately destroying the central growing point. Secondary rots then invade the base and may lead to the death of the plant.

If the plants are in a garden situation then the options for control range from hand picking through to use of insecticides (bacterial insecticides such as Bt are effective when the larvae are small).

This problem like most Spodoptera problems seems to be worse in some years than others. They are often a problem after volcanic eruptions and cyclones. In Queensland, the problem flared up after Cyclone Larry (Category 5) in March this year and the insects caused minor defoliation of some crops, including bananas (definitely S litura). Normally there is a complex of biocontrol agents that keep Spodoptera in check, including birds, spiders and tachinid flies, and these take a while to recover after such events.