Question
My water lily leaves are infested with small black caterpillars.
They are about half a centimetre long and live on the upper surface of the leaf. They eat a channel in a semi circle and eventually ruin the leaf.
Hope you can help please
Ken Reynolds

Answer
Hi Ken,
Thanx for your question.  I believe these are leaf miners.  I saw a reference about borers, leaf miners and leaf rollers.  Insects from genii Notuidae and Pyralidae.  Could also be leaf beetle Donacia, but I think it's the leaf miner.  Not much you can do but remove infested leaves, knock of visible pests into the water and let the fish eat them.  I hope this helps.
Tom