It is an endemic Australian stink bug which attacks citrus. It was identified for me in the Pest and Diseases section by rhizo_1 from Alabama of all places. I thought I would add it complete with the photo that identified it but all I get is a message "this bug is not familiar to us so go to the Bugs How to Do Forum." or words to that effect. I've done that and I'm none the wiser so what do I do now?
Someone please help.