Bats are nasty creepy and gross- who in the world wants them anywhere in their home? Here is a great tip on how to proof your home and keep icky bats out (hmm...wonder if this works n other pests... need to husband proof the house as well!)
This time of year, bats are looking for a cave to settle down in for the winter. So that your attic won't be mistaken for a cave, cover any holes and repair any ripped screens. They only need a hole the size of a quarter to enter your house.
After the house is sealed up, consider placing a bathouse nearby. Bats are wonderful natural insect predators, and will consume mass quantities of mosquitoes and garden pests.