What's eating my common water hyacinth?

Common Water Hyacinth (Pontederia crassipes) is aggressively vigorous and in natural water bodies its key pests are two weevil species — Neochetina eichhorniae and N. bruchi — plus the water hyacinth moth. These insects are actually used as biological controls in regions where the plant is invasive.

Adults chew distinctive circular scars on leaves; larvae mine petioles internally, causing petiole collapse and loss of buoyancy so the plant sinks. In ornamental ponds, remove and dispose of heavily damaged material; in invasive situations, these weevils are intentionally used as biocontrol agents.

Larvae bore into stems and flower buds, interrupting flowering and causing stem collapse in developing colonies. Physical removal of affected plants; the moth is an intentional biocontrol agent in Florida and other southern US states where the plant is invasive.

Tiny black mites tunnel through leaf tissue, creating silvery streaks and reducing photosynthesis. Maintain good water circulation; in ornamental settings, manual thinning of dense mats reduces mite pressure.