Jaap showed me an insect cluster on a tree in a rainforest patch being given some love and attention by Land Care. I returned with my camera and filmed what looked more like worms than caterpillars, writhing on the tree. I thought of caterpillars because I had seen them clustering on bushes in Bellingen, New South Wales, years ago.
PS I was subsequently told that they were Sawfly larvae. Perhaps that is what I saw in Bellingen.