Bats are an all-natural insecticide. A bat can eat its full body weight in insects in only one night. Having bats in your yard may be a useful thing, but sometimes bats can roost in your attic or chimney, creating a nuisance. If bats have moved into your house, there are humane ways to get rid of them that will not cause harm to your family or household pets. Keep in mind that bats are a protected species by the EPA, so no exterminator will put them down.
Most animals do not like the scent of strong eucalyptus or menthol. If you have noticed that bats have begun to roost in your attic, try placing an open jar of a vapor rub product in your attic near the entry point. Crushing several menthol cough drops to release the menthol oils may also work. Of course, it is best to wait until evening when you are sure the bats have left your home to hunt for the night. While bats rarely bite humans, they are rabies carriers and it is best not to disturb them during the day. The scent of the vapor is not harmful or unpleasant to people, yet will keep animals from invading your attic or chimney.
Mothballs are toxic and strong-smelling. They will effectively repel bats and other pests, but are not always safe for household pets and children. Mothballs can be extremely dangerous to those with breathing problems. Use care and caution when using these toxins in your attic to repel bats.
Most animals cannot stand the smell of strong mint. As with the menthol vapor rub, be sure the bats have left for the evening before attempting to go near their roost. Use a few drops of peppermint or spearmint extract near the bats' point of entry into your home. If you notice that the bats have come back after using the extract, try again. Soak a cotton ball in mint extract and place in the bats' roost.