Anopheles, Aedes, Mansonia, and Culex mosquitoes endemic to Panama were killed when they were exposed to synergized pyrethrin, resmethrin, or d-phenothrin formulated as aerosols applied to rooms. The avidity of the mosquitoes was much reduced after treatment. The pyrethroid formulations had no odor and did not irritate skin or eyes; the synergized pyrethrin containing kerosene had an odor and was irritating.