Caulk or plug any openings around water or gas pipes or electrical conduits that go into the home. Flies also can enter a home through ventilation holes, so use screening to exclude them. Non-chemical control such as sticky fly traps, fly swatters, baited fly traps and other devices can eliminate many flies inside a home. But a fly swatter remains an economical way to control the occasional fly. Chemical control for flies should be a last resort.
All pesticides are poisonous, and sprays give only temporary relief.