Because of "P. crassipes" invasiveness, several biological control agents have been released to control it, including two weevils (Coleoptera: Curculionidae), "Neochetina bruchi" Hustache and "Neochetina eichhorniae" Warner, and the moth "Niphograpta albiguttalis" (Warren) (Lepidoptera: Pyralidae). "Neochetina eichhorniae" causes "a substantial reduction in water hyacinth production" (in Louisiana); it reduces plant height, weight, root length, and makes the plant produce fewer daughter plants. "N. eichhorniae" was introduced from Argentina to Florida in 1972. A semi-aquatic grasshopper, "Cornops aquaticum", is being investigated in South Africa as an additional control agent.