Four compounds, American Cyanamid AC-222,705, (+)-cyano (3-phenoxyphenyl) methyl (+) - 4- (difluoromethoxy) - a(1 - methylethyl) benzeneacetate; Montedison M-9270, 0 - [3- chloro -1-(1-methylethyl)-1H -pyrazol -5 - y1] 0,0-dimethyl phosphorothioate; Montedison M-9580, 0- (3-chloro-1-methyl-1H - pyrazol -5- yl) 0-ethyl 0 - methyl phosphorothioate; and Montedison M-9751, 0-(3-chloro-1-phenyl - 1H - pyrazol - 5- yl) 0- ethyl 0-methyl phosphorothioate, were tested as wind tunnel-generated aerosols against field-collected females of Anopheles quadrimaculatus and Psorophora columbiae. American Cyanamid AC-222,705 was 778X and 3.6X, Montedison M-9270 was 0.7X and 0.4X, Montedison M-9580 was 3.2X and 2.4X, and Montedison M-9751 was 0.8X and 0.7X as effective at the LC-90 level as the malathion standard against An. quadrimaculatus and Ps. columbiae, respectively. Based on these data, American Cyanamid AC-222,705 and Montedison M-9580 are promising candidates for further development as mosquito adulticides.