I still have some living in my walls even though the bat guy installed excluders at various places on my roof (shutter things that let them out but won't let them back in.) Feel free to visit and take some home with you!
I've been sticking steel wool around pipes and other small holes I see inside to keep them from coming into the interior of my house.
The bat guy said bats become active over 32 degrees and will fly out of the house at dusk, but can slow their metabolism and hibernate under 32 degrees, so they won't be leaving my walls until spring. Ick. I'm praying for a January Thaw.
My neighbors have two bat houses up beside my garage, and I'll put a few more up in the spring. Outside, I love 'em. Inside, not so much.
Here's a picture of the breed the bat guy says live with me - the Minnesota Small Brown Bat: