A bat in the house
By accident, an individual bat may enter your home through an open door or window, or drop down a chimney. When this occurs, chase the bat out open doors or windows with a broom. Or wait until the bat settles, then cover it with a can or jar so you can slip a cover under the opening without touching the bat. Wearing gloves during this procedure is recommended. Release the bat outdoors.
Bat roosts in buildings
When a colony of bats occupies a building, the accumulation of droppings and the odor of bat urine are objectionable. Bat droppings are the size of mouse droppings, crumble easily, usually are shiny black, irregular in shape and contain insect fragments. They accumulate below the walls and rafters where bats roost. Bat squeaks and the rustling noise they make as they enter or leave the roosts may also be bothersome to the building's occupants.
Wait till they leave, then bat-proof the building
The only permanent method of preventing these roosts is to bat-proof the building. Do this by locating and blocking all entrances through which bats gain access. Entryways may be located by watching outside the building during the last half-hour of daylight and noting the points from which the bats emerge. Note such places as attic louvers, jointure of chimney and house, and gable ends. After the entryways are located, plan the needed repairs. Nail loose siding, caulk crevices, replace missing moulding or trim, and cover larger openings with 1/4-inch mesh hardware cloth. Keep in mind that sealing the openings must be done after the bats leave the roost at twilight or after they disperse in the fall. If the openings are blocked during daylight roosting hours, the bats will be sealed inside the building.
Bright lights may help
Bright lights may disperse certain bat roosts. Where it is possible to illuminate entire roost areas in structures, the bats may be dispersed before bat-proofing. Illumination for several days may cause the bats to seek alternative dark areas for daytime roosting. Bat roosts in sites such as wall or floor partitions are impossible to illuminate for this method of dispersal.
Naphthalene flakes (moth crystals) are legally registered as a bat repellent. If the bats are in a confined space such as between walls or restricted attic areas, the odor of naphthalene flakes may discourage bat roosts.
In case of a bite ...
The incidence of bats transmitting disease to man is low, but if such a situation occurred, it would suggest a need for control. Bat bites can be dangerous. As a precaution against exposure to disease, do not handle live bats. In case of bat bites, wash the area immediately with hot, soapy water and promptly notify a physician. If possible, capture the bat without damaging the head, place it in a jar or plastic bag and refrigerate. Health authorities may want it for a rabies test.