What's eating my sagittaria latifolia?

Broadleaf arrowhead (Sagittaria latifolia) is most damaged by the arrowhead worm (Bellura obliqua), whose caterpillars bore into stems and rhizomes. Ducks and muskrats dig and eat the starchy tubers. Aphids attack stems, and aquatic leaf-mining beetles scar foliage in summer.

Caterpillars bore through petioles and rhizomes, causing stems to wilt and collapse at the waterline Remove and destroy affected stems promptly. Cut stems below the waterline and crush larvae inside. Beneficial nematodes applied to surrounding soil may reduce pupae.

Tubers and rhizomes excavated and eaten, particularly in autumn and winter Protect newly planted stock with wire-mesh baskets; allow plants to spread widely so tuber loss is tolerable. No practical exclusion in open ponds.

Clusters on stems and leaf undersides; honeydew, sooty mould, and weakened growth Knock off with a water jet; encourage ladybirds. Avoid broad-spectrum insecticides near water.