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My rhubarb leaves are covered in holes. Every single leaf has been got at. Any idea what could be doing this? I have checked the leaves and surrounding earth but can't see any pests. Any help and advice would be appreciated.

I am fairly sure that it is snails which cause the damage to my rhubarb leaves although I rarely see them. I don't worry about it too much as they don't seem to eat any of the nearby plants or damage the stalks or even stop the rhubarb growing well.