Seven species of bats live in Minnesota. All are small and feed exclusively on insects.

Although bats have notoriously poor eyesight, they are excellent hunters and navigators. Bats use a sophisticated sound system, giving them a ready ability to distinguish their insect prey from larger objects, like people.

Bats mate in fall and winter; the young are born from April through July. While most adult females produce only a single newborn each year, the litters of some species can range up to four. Young bats grow rapidly and are able to fly within three weeks.

Bats may use the interiors of buildings as roost sites. Their natural squeaking, scratching and crawling sounds can cause a nuisance. Bats may also cause other problems. Droppings stain floor and walls and, in sufficient quantity, cause odor problems. Because they are mammals, bats can carry rabies but this danger is minor. In addition, some people have a strong aversion to bats. If you do and you have a bat in your home, isolate the bat in a room with a door or window that opens to the outside. The bat will sense the air current and will usually leave your home voluntarily. To be sure this has happened, it's important to observe the bat leaving. An alternative is to capture the bat using a wide-mouthed container and a sheet of cardboard, and then to release the bat outside. With both these methods you may wish to enlist the services of another person who's not afraid of bats. Use of tennis rackets, fish nets, and blankets tend to be ineffective.

Repellents like high-frequency sound, bright lights, and naphthalene can force bats out of your home but relief is temporary, lasting only as long as the repellent is applied. Other approaches include installing exclusion devices and providing alternate roost sites on your property.

Bat proofing is the only way to permanently rid a building of bats. Bat proof your home in the fall after the bats have left for the winter. Earlier exclusion may result in young bats being trapped inside where they die and decay.

After the bats have left, plug all holes. Bats can squeeze through openings as small as 3/8" in diameter. Permanent bat proofing requires the use of substantial materials such as sheet metal, nylon netting, or wood.

For more information see Minnesota Extension Service fact sheet 1141

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