Less than 7% of the 10,000+ Australian moth species have known caterpillars. It is a ecological black hole. We need to discover what caterpillars turn into what moths. Could you not take 10 minutes to capture it and put in a bottle to photograph it properly and rear it?
Don, I'd be happy to. It was on mulch or leaf litter, two different eucalypts, what food source would I use - perhaps leaves of both?
We are rearing some Dainty Butterflies and feed the larvae with citrus leaves but I have no idea what leaves to give a nondescript green larva, presumably a moth. I searched the internet to find out what it was to no avail.
Some Paralea and some Fisera have a flat head with a pale collar, but one really needs to see the prolegs to resolve this. But given the size, I think you are right Ian : that it is in Geometridae.