A method for the control of insects breeding on water surfaces and particularly mosquitoes, comprising blending in a high shear mixer water, the ester of a fatty acid of 10 to 25 carbon atoms and a low molecular weight alcohol, such as methanol or ethanol, an emulsifying agent and a thickener until an emulsion containing the ester with droplet sizes ranging from 1 to 20 microns in diameter is obtained and applying such to the surface of insect infested water in sufficiently diluted form, to break the emulsion and form a thin continuous film.