To rid an attic or other part of your house of a bat colony, seal, caulk, weatherstrip, or screen all exterior openings more than 1/2-inch wide except one, through which the bats can escape. Wait 3 days; then, about half an hour after dark (when bats are feeding), seal the last opening.
If an area can’t be sealed, install a light that shines directly at the roosting area. In confined areas, suspend mothballs in porous bags as a repellent. Avoid exterminating bats; they are desirable as insect eaters.
If a single bat strays into a room, after dark open the windows and any doors to the outside and turn off all lights. The bat will fly outside.
Caution: Never touch a bat; they can be carriers of rabies. If you are bitten by one, get to a hospital immediately.