There is also the odor and expense of placing several pounds of naphthalene in a building where people live. If people are sensitive to the odor of moth balls, avoid using naphthalene. If naphthalene is used to repel bats from a structure, a nuisance animal permit is recommended to protect the user legally in the event that bats are accidently killed. Since bats are beneficial, many people want to keep them in the neighborhood while excluding them from a building. This may be accomplished by putting up one or more commercially available bat houses.
Bat houses are similar to bird houses in size and shape.
However, they lack a circular entry hole. Bats enter and exit the house from the bottom of the house, which has been left open. Bats will not leave a building to move into a bat house. But if a colony is excluded, bats may move into the closest new accommodations. There should be no branches directly below the bat house to obstruct the entry or exit of bats.