Hi,

I've noticed holes appearing in my plant leaves, most of which are in
planters on the patio, I took a photo of one:

http://img254.imageshack.us/img254/3966/p1030079t.jpg

I haven't seen any snails or slugs around, and there never seems to be any
insect life on or around the plants but these holes keep appearing!

Can anyone give me a rough idea of what's causing this and how to stop it?
This year is the first year I haven't actually killed everything by May but
something else seems to be doing it for me!! Thanks in advance for any help.