Concerned that this species is considered a pest in North America and that the Atlas of Living Australia contains no ACT or NSW records of this species I sought information from my ACT forest colleges. They sought information from their stare colleges and the following information came back from NSW DPI - " I would guarantee that it has been in ACT for decades. It has been in Australia since the 1930s or 40s. I suspect it just hasn’t been reported anywhere."
Interesting, Michael. Thanks for looking into that and posting the comment. Perhaps the reason they're not a significant threat here is that they don't know what their proper substrate is meant to be - metal fencing won't do them much good! ; )