It's an interesting dilemma - the bats are good little insect eaters, but I agree - wouldn't want them in my house! We had one in our unfinished bonus room this summer, and I guess it only takes a quarter inch opening to let them in. We put a sonic device in there, and haven't seen a sign of him back. We are getting ready to finish that room, and don't want to share! I think he was a lonely bachelor bat, not a colony. I'm so glad we found him before he got married!