Vegetable bug on a lemon (it's confused!)

This vegetable bug was found sunning itself on a lemon on our tree - I think it's confused, but then I guess there aren't many vegetables around so any port in a storm!

introduced to NZ they are a pest in the garden and are widespread. They are a beetle,, only about 15mm long so pretty small. They have wings under a split carapace.

(turns out I'm the confused one because it looks like the bug is not a vegetable bug at all but a shield bug!)