We own this old brick building and cannot seem to control the bats. How they get in we just can't find. Do you have any method of control you can recommend ? How about the electronic ultrasonic devices ? Most ultrasonic control devices, such as for mouse control, do not appear to work. The bats often get in and fly around, especially at night. They have even set off our alarm system. Joining the police at 2:00 in the morning just to see a couple of bats around isn't my favorite late night activity.

If you can't block off their access in, I believe the only thing to do is provide them with better places to live. Bat boxes are cheap and easy to make. Have you tried an owl decoy - cheap, and simple.

Can you keep cats there? They'll set off your motion detector, too, though. I think I'd rather have the bats and spend the money on a different security camera.

Can you post a picture of the building? Does it have clapboard siding under the eves of the gable ends?

Bing, given your location and the current season I would guess you have a bat colony living somewhere within the structure. I dealt with this last year, wasn't cheap. I was going to handle it myself but bats can gain entry in gaps as small as ~1/2" and I wanted to ensure they were gone for good so I used a wildlife control service. Because they (bats) had already setup shop in my attic they were more likely to search hard for another gap if I wasn't careful to fill them all.

Their process:
Seal all gaps exceeding 3/8" in size (lots of caulk)
Find the most likely spot of entry. Should find guano and a brown greasy film around the spot.
Put a tube or netting on the outside of the hole.
This should be completed prior to the temp reaching 50F
When temps consistently reach 55F (likely April/May) the tube/netting can be removed and the final hole sealed.

The process for bat control is called bat exclusion, tons of info on the Web. I believe many states have laws against killing bats so I would proceed carefully (or quietly) to avoid trouble. I did a lot of research on this and talked extensively with the dude that took care of it for me, can try to answer any questions you have based on what I learned. Good luck.

I used bird netting inside my first home's attic (200 years old house), then I shoveled out the guano. Worked perfectly. Be careful on ladders near shutters. They love resting in the slots. Jumping from a ladder up high when surprised is not a good idea (no I did not do it but a friend did). Different decision in the same circumstance led to very different outcomes. I did not break both my ankles... (well not that way - basketball is another story, but one ankle at a time)

Thank you all for this good information. We have found the hole where they got from the attic into the finished portion of the building and patched it. Now to just get the outside patched when the weather warms up and the bats leave the upper level for their nighttime activities.

I appreciate all of the information.

my lake house in IRON RIVE WI has had bat issues. the bird netting all through the attack is a great idea. seems a good deterrent.