Cypermethrin was evaluated against caged mosquitoes using a truck-mounted Leco HD model ULV cold aerosol generator and the results were compared to malathion. Calculated effective dosages (ED) for 90% and 95% control with cypermethrin against Aedes taeniorhynchus were 1.8 and 4.5 h/ha, and against Anopheles quadrimaculatus were 0.3 and 0.5 g/ha, respectively. Cypermethrin was 30 X more effective than malathion against An. quadrimaculatus and 5 x more effective than malathion against Ae. taeniorhynchus.