@WendyEM @Hejor1 @DiBickers Peltoschema hamadryas would make sense as I had many of these still on my Queensland Silver Wattle even throughout winter. I now have so many larvae falling into the bird bath under the tree that I had to empty it rather than saving caterpillars every morning.
I wrote to Martin Lagerwey from Vic. Ento. Soc. this is his reply " I'm pretty certain these are Peltoschema hamadryas. Adults lay eggs on flower stems during winter and the larvae eat into the stem, feeding on flowers even before they open. "