In prelim. tests by the turntable and Peet-Grady methods, DDT formed very effective contact sprays against adult houseflies, Musca domestica, when used in deodorized kerosene, either alone or in conjunction with pyrethrins, [beta]-butoxy-[beta]''-thiocyanodiethyl ether, or fenchyl thiocyano- acetate. Compared by the turntable method, DDT and pyrethrins had the same toxicity to houseflies at a conc. of 0.7 mg. per ml.; below this conc. the pyrethrins were more toxic and above it DDT was more toxic.