What's eating my stuff?

Most of the leaves on my broad beans/peas/mangetout and sweet peas have been nibbled round the edges. Just like a little bite has been taken out all the way round. What could it be that's eating them?

Here's one - this has been raised several times recently so guess the weather conditions must favour them.

http://chat.allotment-garden.org/index.php?topic=35107.msg420576#msg420576

They should still grow. It just sets them back a bit. This wet weather may help.

Thanks for posting, my mangetoute have been well & truly nibbled, just sown some more last week, so hope they'll catch up! I have about one dose of derris left, but it's probably about 15 years old! - will it be any good?