House flies,Musca domesticaL., were given a choice of either an electrostatic field gradient ranging from 200–1500 v/cm or no field. They preferred no electrical field to one of 1000 v/cm or higher. At 750 v/cm slightly, but significantly, more flies preferred the electrostatic field. At less than 500 v/cm no preference was observed.A significant effect on wingbeat frequency among male cabbage loopers,Trichoplusia ni(Hübner), was observed for electrostatic field gradients ranging from 200–1500 v/cm. There was so significant effect among females. The change in wingbeat of males in response to the fields was inconsistent. Among females the wingbeat tended to decrease.