The Swarm of the Caterpillars

Recently the kids witnessed an interesting natural behavior of some hairy caterpillars.
These Caterpillars march along in single file obviously following some sort of chemical signal. When they get to their destination they congregate together.

This time they decided to take over a tree trunk.



These caterpillars are usually left to themselves as the hairs that cover them cause a skin rash on people. This rash can persist for months and in some people the rash can easily become infected.
I think these caterpillars are Ochrogaster lunifer.
I found some great info at the following site
http://lepidoptera.butterflyhouse.com.au/noto/lunifer.html