Most bats inhabit crevices in caves and other dark places during the day. At night, they fly for miles in search of food. Many species of bats are beneficial, eating bothersome insects, such as flies, moths and mosquitoes. Occasionally, bats roost where they are not wanted, such as in attics. Removing the bats requires a special trap to allow the bats to leave at night but prevent them from returning, safely forcing them to seek other accommodations.
Locate where the bats are entering and exiting the space. Do this during the day when the bats are sleeping.
Cut a section of wire mesh large enough to completely cover the entrance hole and 2 feet around the entrance. Place the wire mesh over the entrance. Tape the top edge in place well above the entrance. Cut and form the wire, if necessary, to create a good seal at the top of the mesh.
Form the bottom corners of the wire mesh to create a loose funnel form and tape along the sides of the mesh to seal them.
Tape along the bottom of the mesh, working inward from the corners to form an opening in the funnel shape about 3 inches across. This will be big enough for the bats to exit. The funnel shape will make it impossible for them to get back in through the opening.
Observe the trap during the evenings over the next few days. If bats continue to exit, look for other potential entrances and cover those as well. When you no longer notice bats exiting, the area is clear. Remove any traps and seal the entrances permanently.