One pyrethroid and four organophosphorous (OP) insecticides were evaluated as contact aerosols in wind tunnel tests against adult Toxorhynchites amboinensis and Aedes aegypti. Aedes aegypti was not substantially more susceptible than Tx. Amboinensis to the compounds tested. Except for resmethrin, Ae. aegypti was on the average 1.60 times more susceptible to the OP insecticides than Tx. amboinensis; Tx. amboinensis was actually 2.74 times more susceptible to resmethrin than Ae. aegypti. The results suggest that the female Toxorhynchites may be less susceptible than the males to all of the compounds tested.