During 1984, larval susceptibility tests of temephos were performed on Aedes taeniorhynchus and Culex nigripalpus collected from the same general areas as in 1980-82, and the results compared to the susceptible laboratory strains. No resistance was detected against these two species. When strains of Culex quinquefasciatus from some new areas were tested against temephos, malathion, naled, fenthion and chlorpyrifos, their tolerance varied according to the insecticide tested and the origin of the strain. Some strains ranged from 1.6 to 43.0X more tolerant to temephos when compared to the West Florida Arthropod Research Laboratory strain (WFARL strain).