It certainly has the femurs for a flea beetle but it's huge... and you're right about the third shot - frightening. Maybe Alticini... (5000 species known)
I've finally found another photo of this beetle online! Unfortunately they don't know the species either: http://www.ozanimals.com/Insect/Leaf-Beetle/Chrysomelidae%20family/sp2.html
They state that males are black and females are metallic blue so looks like I found a female.
It looks very similar to the picture you posted of the Green dock beetle, but as far as I can see it is only found in Europe - so I need to find an Australian equivalent!
Comments (6)