N-methyl-l-naphthyl carbamate (Sevin) was demonstrated to have systemic activity when fed to poultry as a food additive. Complete control of the northern fowl mite, Ornithonyssus sylviarum was obtained within 48 hours after offering infested birds a medicated ration for one day, during which the fowl ingested approximately 140 mg of N-methyl-1-naphthyl carbamate per kg of body weight. That the compound may be selective in action was indicated by an apparent lack of effect on Cimex columbarius when fed on medicated hens.