The effects of the insecticide used for the control of GIossina morsitans (tsetse fly) on the weevil Cyrtobagous salviniae Calder & Sands were investigated. The latter is currently used as a biological control agent against the aquatic weed Salvinia molesta Mitchell. The survival of C. salviniae was measured after the application of an insecticide mixture of endosulfan and alphamethrin at different dosages. Keywords: Insect densities, Insecticide residue Ievels, Okavango Delta, Petioles, Pupae, Rhizome, Water analysis, Weevil's food source.