Abstract: The water hyacinth weevil, Neochetina eichhorniae was originally introduced from Argentina into China in 1995. The adult preferred to attack younger leaves and fed on the epidermal layer and the underlying cells and left a lot of "feeding scars" on the leaves. The longevity of the adult was between 29 and 161 d with an average of 104 d. The female laid 84-1091 eggs during this pariod. The larvae tunneled inside the petiole and crown of the host plants, and completed their growth in 30-40 d, then pupated underwater attaching to living roots of the floating plants. Pupae required 25-30 d for development. Two overlapping generations occurred in a year in Wenzhou. Host range tests with 46 plant species from 23 families showed the weevil only attacked and completed its life cycle on water hyacinth in choice and no-choice tests, indicating that the weevil could safely be used to control water hyacinth in China.