Bats may not be your idea of fun house guests. They are nocturnal, and seek cool, dark places to hang upside down and catch some sleep during the day. The walls of your house make a perfect spot for them to roost. "National Geographic" states that bats eat their body weight in insects each night, which makes them important to keep around--just not in your walls. Fortunately, it's possible to get bats out of your home safely and humanely.
Turn on strong fans to bother the bats and encourage them to find a new roost. Open the windows during the day. Bats who are trapped inside a house feel the air movement and gravitate toward it to escape.
Seal off the insides of the walls so bats don't sneak out of the walls and into your house. Bats can squeeze through spaces as tiny as 1/2-inch wide, according to Bat Management. Use fiberglass insulation, which acts as a repellent to bats.
Sprinkle naphthalene flakes, or moth crystals, along the walls where the bats are roosting. Bats dislike the odor and should seek another roosting place.
Turn the lights off at night if you want to catch the bats in your house and lure them back outside. In the light, they may become disoriented and hide behind curtains, according to Critter Control. Keeping it dark helps them navigate to the outdoors. Beware of keeping windows open at night, however, as you don't want more outdoor bats flying inside.