Insecticidal compounds available for controlling pests of medical importance such as mosquitoes and flies are becoming increasingly limited. Thus it is imperative that already existing compounds should be applied wisely but also new, more effective compounds and methods should be developed. Volatile insecticides have been widely used for the protection of stored agricultural products and for the management of structural pests. However, they have not been evaluated for the control of pests of medical importance. This study examined vapor toxicity of volatile, low molecular weight esters on mosquitoes and flies. The USDA-CMAVE strain of Aedes aegypti and the Horse-Teaching-Unit (HTU) strain of Musca domestica reared at the University of Florida were used exclusively in all experiments, and each strain was studied separately. The volatility bioassay used for this study was described by Scharf & Nguyen (Pest Management Science, 2006).