This caterpillar was very well camouflaged in acacia leaves. I found it after noticing frass and working out where it was coming from... right in front of me!
About 40mm long, a real Aussie in vivid green with yellow/gold flecks throughout. Only one set of prolegs and claspers says geometridae. http://lepidoptera.butterflyhouse.com.au/enno/senilis.html