Green Nettle Weevil (Phyllobius pomacues)
Nettles are one of the best places to look for insects, all sorts of things can turn up on them. They sting us but insects seem immune from the effects.
If you look closely you will some times see small, shiny green weevils like this one, no more than 1/4" long. Until they move you might think they are not even insects at all. This particular species is often abundant on nettles and hence its common name.
The green colour comes from tiny scales that easily rub off leaving a black 'shell' underneath. As a result they can be very variable in appearance depending on their age.
Around from April to September but best viewed with a magnifying glass or hand lens.