Attempts to culture Wolbachia from mosquitoes will be continued in cell cultures. A fluorescent antibody test for identification of Wolbachia will be attempted. Gene flow between populations of Culex pipiens in Southern Californa will be studied by morphological criteria and perhaps by electrophoresis of enzymes as well. Population studies will emphasize cause-specific mortality rates. A microscopic study on the effect of Wolbachia on spermatogenesis in Culex pipiens will be resumed.