Fly swatter
A fly swatter was a device used to kill flies and other insects.
In 1957, a fly swatter hung on the wall of T'Mir, Stron, and Mestral's temporary home. (ENT: "Carbon Creek")
In 2373, The Doctor suggested a fly swatter be used against a macrovirus that was invading USS Voyager, as the antigen he was creating for the smaller version of the virus would be ineffective on one that size. (VOY: "Macrocosm")