The larvae of the china mark moth is the one that attacks the waterlilies. They often cut pieces of the waterlily pad and attach themselves between two layers.
CADDIS FLY is a small white moth like insect that will pupate under water and usually it will pupate in the stem or under the leaf of the waterlily. They will cut a piece of the stem and house inside it and attach themselves to another stem.
Naturally occurs in pond water and is not harmful. Algae is a plant which provides shelter and food for your fish. The only down side of Algae is that it’s not attractive and presents an untidy pond.