The effectiveness of 4 monomolecular surface films was evaluated against 4th instar Anopheles quadrimaculatus and Aedes taeniorhynchus larvae. At an application rate of 0.04 milliliters per square meter (0.043 gallons/acre). 2 of the 4 compounds tested provided virtually 100 percent control of Anopheles larvae in both laboratory and field tests. Laboratory tests indicate that, at the above application rate, none of the films tested effectively controlled Aedes larvae.