Cyfluthrin was evaluated against caged mosquitoes using a truck-mounted Leco HD model ULV cold aerosol generator and the results were compared to the effectiveness of malathion. Calculated effective dosages (ED) for 90% and 95% control with cyfluthrin against Aedes taenorhynchus were 0.2 and 0.3 g AI/ha and against Anopheles quadrimaculatus were 0.09 and 0.1 g AI/ha. Cyfluthrin was about 106X more effective against An. quadrimaculatus and about 69X more effective against Ae. taeniorhynchus at the ED-95 level than malathion.