Notes on the Weevils Tyloderma, Auleutes, and Onychylis That Feed on Ludwigia and Other Aquatic Plants in Southern South America

Adults of the weevils Tyloderma spp. A and B and Auleutes bosqi (Hustache) fed on the leaves of Ludwigia peploides (H.B.K.) Raven (water primrose) and appear to have it as their only host plant. They fed only on L. peploides in laboratory tests and were collected only from this plant in the field. Onychylis sp. nr. nitrirostris (Boheman) was collected from L. peploides, Eichhornia crassipes (Mart.) Solms (waterhyacinth), and Pistia stratiotes L. (waterlettuce) in the field; in the laboratory it fed on L. peploides, P. stratiotes, and Limnobium stoloniferum (G. F. W. Meyer) Griseb. (frogbit), but not on E. crassipes. The larvae of Tyloderma sp. A and of O. sp. nr. nigrirostris were probably stem borers, but the larvae of A. bosqi fed on the leaves. All 4 species of weevils could be candidates for biological control of these aquatic weeds in the United States and other countries.