ATTRACTING BATS
Studies have shown there is no proven method to attract bats to your yard or make them move into a bat house. Smearing guano (bat feces) around the bat house will not attract bats. This is a myth and will not work.
If you have bats in your attic and installing a bat house does not mean they will move in. If the bats are comfortable in your attic, why would they leave the attic? Think about this. If you were happy and comfortable in your house, would you leave it for a smaller place? Wildlife is the samne. They will stay where they are comfortable.
Excluding bats from your house will not guarantee they move into the bat house. They could just go to a new location and ignore the new house you just installed. I am not trying to discourage anyone from installing a bat house, I am only showing that bats will select locations that are appealing to them.
So what do bats want? They are seeking security, food and water. Provide these three needs and you can increase your odds of attracting bats.
Read "Installation" on how to properly install a bat house.
Security
Food
Bats eat different foods such as insects, nectar, small animals, blood and so forth. All bats in Ohio are insectivores which means they eat insects. That is their diet. So now you need to bring in their food.
The best method to supply the insects is to plant the vegetation that night insects pollinate. So to attract bats, you can start with creating gardens that have flowers that bloom at night.
Stop using pesticides or other methods that kill the insects. Let nature take control of them.
Night blooming plants >> insects >> bats
Water
Bats need water and prefer it to be close to them. They have been known to travel a good distance for water but the closer the source, the better for the bat habitat.
Bats do not land like birds to drink water. Bats will swoop down over water and lap it up as they fly over. So the water pool needs to be large enough for them to accomplish this. Therefore, bird baths will not work.
Water sources can include wetlands, ponds, streams, lakes and other natural water sources. What about swimming pools or other man made sources? Bats have been known to drink from these sources but it may not be their preferred source. Remember, pools usually have chemicals such as Chlorine that could deter a bat from using the pool.
If the water has a lot of obstacles such as tree limbs or brush, try to cut it back so the bats can have easy access without obstacles in the way.