What's eating my nymphaea 'firecrest'?

Nymphaea 'Firecrest' shares the same aquatic pest complex as all hardy water lilies. Water lily aphids are the most frequent nuisance, clustering on pads and buds in summer. Stocking fish, hosing aphids into the water, and physically removing beetle larvae are the reliable controls.

Large black-brown colonies on pads and buds cause puckered, yellowing leaves, reduced flowering, and sticky honeydew that promotes sooty mold. Hose colonies into the pond where fish will feed on them. Avoid all insecticide sprays near pond water. Remove and compost worst-affected pads.

Larvae scrape channels across the pad surface; feeding tracks turn brown and rot, eventually sinking pads and reducing the plant's photosynthetic area. Knock larvae off with a hose and let fish eat them. Manually clear adult beetles in early summer before egg-laying peaks. Cutting off infested pads is effective.

Larvae construct protective oval cases cut from leaf surface, causing distinctive oval holes and progressively ragged, sinking pads. Physically remove cases. Submerge the pot for 24 hours to drown larvae. Goldfish or koi will graze larvae from the water surface.