|http://anpsa.org.au/m-aze.html. Tony Cavanagh.|
Tie a piece of hessian or other thick soft material around the trunk of the tree. As the caterpillras crawl down the tree they will gather among the cloth to hide from the heat and light of the day. Simply gather up the cloth after sunrise and shake it over a tub of soapy water, maybe stirring it to ensure the caterpillars sink. Repeat the process for a few mornings and numbers will be rapidly reduced. Keep an eye on the tree's pest numbers from time to time by shining a torch into the canopy to see if there are problematic amounts present.
Hairy caterpillars are hard to control with sprays as the hairs protect them. Natural predators can be encouraged to help reduce numbers of cape lilac caterpillars. Paper wasps can control larvae, as can micro bats.
Microbats live throughout the Perth region, living in holes in trees, under bark and in some wooden houses where there are good gaps. You can also build and instal a bat box. http://gobatty.com.au has some designs and info on bats.This page from Perth Zoo also has some good information about Perth's micro bats.
Cape lilac trees are a fantastic shade tree and it is quite easy to keep the numbers of cape lilac moth under control by using some simple measures that need no poisonous pesticides. Any tree that can help support the red-tailed blackcockatoos are pretty important too.