Anestia females usually lay their eggs on their own cocoon. I think you will have to rear a couple of hatchlings to adult moths to discover the species.
Obviously the leaf you found them on, and if that fails, then try each of the five basic common Australian caterpillar foods : Gum leaves, Wattle leaves, Herbaceous plant leaves, Grass, and Lichen. If it rejects all five, then rose petals and thinly sliced apple are good standbys. Apparently plants in Rosaceae have developed very few poisons.