Waspish

I think this is one of those hoverfly type things which pretends be a  big scary wasp to deter predators. It's not a very good camouflage though because my eye was drawn to it immediately when I went prowling the garden for bugs for TT,  whereas it took me a couple of minutes to spot the copulating pair of shield bugs on a neighbouring leaf, which was exactly the same colour as they were. 
An evolutionary  dilemma , whether to go down the big and scary looking path,  or hide away in plain sight hoping no hungry bird  will notice your buddleia-leaf based shenanigans.