Mist timers usually contain pyrethrins. Aerosol sprays can be used to control flies, but in areas of commercial buildings where food is prepared all dishes and utensils must be covered and work surfaces washed after they are used. Aerosols usually contain pyrethrins. Outdoors, and in some buildings, residual sprays of insecticide can be used. Residual sprays cannot be used in food preparation areas of commercial buildings.
Products containing permethrin are good residual sprays for flies.
It is important to read and carefully follow all label directions when using insecticides.