Merely putting up a bat house will not lure a bat colony out of a house. Successfully evicting a bat colony requires a few steps. The first step is to inspect the inside of the house for small openings through which bats could enter. All openings connecting the attic or other roosting areas to inside living areas should be sealed, although entry places on the outside of the house should be left open, allowing bats to exit. At dusk, watch the bats leaving the house to locate exactly where openings are located. Be sure to scout all sides of the house as there is often more than one opening. Entry places should be covered with a plastic mesh or netting that will allow the bats to exit by crawling under the mesh, but not re-enter the house. You should not evict bats during the months of June, July, or August, because there could be many younger bats that have not developed their flight abilities and are dependent on their mothers for food. Also, remember that you will want to put up a bat house nearby several weeks before the planned eviction. It is best to put the bat house in a place nearby where the bats will become accustomed to it. Click here for detailed instructions on bat eviction.