Of the 925 bats species worldwide, 44 bat species are in the United States. Most of the 18 species are in small colonies, roosting in trees, caves, crevices, bridges and cliffs. Five species are known to colonize in buildings. The two most common of these are the Brazilian free-tailed bat and the big brown bat.
Bats are ecologically beneficial, keeping the insect population down by feeding on night-flying beetles, moths, flies ants and other bugs. However, bats can often be a nuisance. Some bats can be found harboring in buildings. Besides the physical appearance of the bats themselves, these mammals bring with them parasites and bed bugs. They can also transmit disease, histoplasmosis or rabies, to humans. They also leave feces, known as guano, which has a pungent smell that attracts flies and other insects in large quantities.
To deodorize and eliminate odor from the guano, a pyrethrum fogging agent can be used. This agent will also help to rid the area of parasites and insects.
Removing bat colonies from buildings can be difficult. All species of bats are protected under most state's laws, making it illegal to kill them. The ideal way of ridding a building of bats is to wait until the colony migrates. Once the bats have left, their entry holes should be sealed off, preventing them from returning. If the colony is not a maternity colony, the eves of a building can be sealed and bat doors can be placed over the entry holes. The bat doors allow the bats to leave but stops them from re-entering. Since bats can fit through small cracks and holes, the eves should be completely sealed.
If you would like to keep the bats in the area, bat houses can be placed on the outer wall of the harborage area near the entry holes. If available, place some of the “guano” inside the bat house prior to mounting it on the outer wall.