I was really surprised to spot this on a Eucalypt..I'm fairly sure amygdalina. It was big...about 12mm...slightly tucked under bark (I did take a little strip of the bark off one for the photo. The second I left alone. I feel like this doesn't fit Monophlebid but it's the closest of the scales that I can think of.
There are two individuals here. The first has multiple photos, and the second has only one image and is obscured on both sides by bark.
These are fascinating critters. tasmanianinsectfieldguide.com/hexapoda/insectsoftasmaniah...
A couple of older Apiomorpha galls, one with its exit open and the other closed. I think the females can live up to 3 years.
These Apiomorpha galls are interesting big things. The creatures themselves are amazing (have a look here). tasmanianinsectfieldguide.com/hexapoda/insectsoftasmaniah....
Bird-of-paradise bug Callipappis species, female, Peter Murrell Reserve, Blackmans Bay, Tasmania, February 2018
I've found so many females of this: It's about time I stumble upon a male too.
Grape Galls on leaf of Eucalyptus obliqua