Starting just before dusk station yourself at one corner of the house and your spouse at the opposing corner. This way you can each see two sides of the house. Watch the house up at the eves and around the roof line, so that you will see where the bats leave from. Normally, there are only two or three places that they use as entrances/exits. As you see a bat leaving from an opening, mark down exactly where it is located along the house, so that you can find the opening in the daylight. Stay at your position until you can no longer see the bats. 

In the morning or as soon as you can, get a roll of 24 inch wide hardware cloth wire, some duct tape, a staple gun or some small wire staples. You will cut the so that you have one piece 24 inches square for each opening. Bend the wire to create a tunnel with side flaps that you can staple or tape the roof etc. Next cut one end of the tunnel so that you can bend the wire down to close off that end, this will be the top. You can place the wire tunnel over the opening and staple and or tape it in place securely. You shouldn't have any problem telling where the opening is the area around the entrance is always darker from the bats fur polishing the surface. Make sure that the tunnel is pointing straight down. The bats will come out and travel down the wire or roof to the opening and fly away, upon returning, they will not know how to get in and will sit on the wire in front of the entrance for awhile and then leave. Do not remove the tunnel for several years, since the bats will return every spring. This will work, provided you don't have a slate or tile roof.

Bats staying behind shutters and such can be deterred by putting some mothballs behind the shutter at the bottom. If the shutters are of the plastic design, there is usually a shelf at the bottom edge. Just set 3 or 4 mothballs on this shelf and the bats will leave and not return. This will not happen immediately they will keep trying to return for a week or two, so make sure you replace the mothballs as they dissipate. On wooden shutters, put the mothballs in a piece of nylon stocking and staple it behind the shutter at the bottom.

Sometimes we find bats flying around inside the house and this is very upsetting to our ladies. Usually these are young bats born this year, not real smart yet. A bat can feel air movement, like your breath, from 50' away and this is why the get into the living quarters of the house. Picture this; the bat is hanging in the attic on a rafter and wants to go outside. It feels this warm air flow over in the opposite direction the other bats went and decides to investigate this new entrance. Unfortunately, you’re house was build back when they run the studs from the basement wall all the way up to the top of the second or third floor walls. Now in most of these they nailed cross blocks for strength, but some were left open all the way up so wiring, plumbing and furnace ducks could be installed. This is where the bat gets into trouble, he assumes this is another way outside, but finds himself trapped. Then he senses an opening from his radar/sonar and now ends up in the kitchen. That’s when you get into the act, because he is upset and swooping all over the place...InPanic! Leave the lights on or off, makes no difference. Open some doors and windows and it will leave as soon as it senses the opening. Sometimes the bat is too tired and lands on a horizontal or vertical surface, when this happens do the following: Wearing leather work gloves, if it’s on a horizontal, throw a towel over it. Scoop it up in the towel and throw it towel and all, outside. On a vertical surface, put a large plastic bowl, like Cool Whip comes in, over it. While holding the bowl against the wall, slide a tablet cardboard between the bowl and the wall trapping the bat inside the bowl. Just throw everything outside. Later retrieve your stuff.

Recently I was asked about hanging "Bat" houses.   You can get plans for building a bat box by calling the Pa. Game Commission's regional office or going to their website at www.pgc.state.pa.us/  and purchasing their book, Woodcrafting for Wildlife.   The book also includes information on placing the bat house properly.