Cytoplasmic incompatiblity for the control or eradication of Culex pipiens and Aedes polynesiensis is being studied. The relationship of symbiont infections to incompatibility and to meiosis in both males and females is being investigated by "curing" symbiont infections with antibiotics. Symbionts will be characterized morphologically. Attempts are being made to culture the symbionts, especially in living animals. Symbionts will be searched for in other species of mosquitoes. A release strain which produces few females is being developed; genetic factors such as sex-linked lethals will be used to eliminate females. Formal genetic studies of these species are being carried out to produce new tools for carrying out genetic control. The dynamics of a field population will be studied in preparation for a field test of genetic control.