What's eating my myriophyllum aquaticum?

Parrot's feather, grown as an aquarium or pond plant, is most troubled by aphids congregating on its feathery emergent stems above the waterline. In outdoor ponds, grasshoppers and other foliage insects may also chew the fine leaves. Herbivorous fish and snails damage submerged stems. Its vigorous growth usually outpaces light pest pressure.

Colonies on emergent stem tips above water; sticky honeydew and distorted, yellowing foliage Blast off with water spray; introduce ladybirds or lacewings; trim and remove heavily infested tips

Fine submerged leaves stripped or grazed, leaving bare stems Hand-remove snails; reduce snail populations with assassin snails; quarantine new plant additions

Stems nibbled back or uprooted; feathery leaves grazed to stubs Keep with non-herbivorous fish; provide ample floating cover so plant can recover; use pond baskets to protect root zone