RUNNER BEANS

I have never had this problem but my mate, on the plot next to me, is having trouble with his runner beans.  The leaves are fast getting destroyed leaving a lace like effect.  Can anyone suggest what the cause is, and more importantly, the cure?

Looks like slugs/snails to me 

Blue pellets of death would be the answer 

A considerable number of blue pellets have been laid but the leaves keep getting eaten.  I thought perhaps caterpillars but not a sign of them.  Pidgeons would eat all of the leaf not just leave a hole inthe middle, I think.
One leaf had what looked like a cluster of black and white eggs, very, very small but not hatched and now crushed.

I had this on my french beans in the tunnel,it did not effect them once they start growing all the higher leaves are fine,I think it's some type of beetle or flea.