The first thing to be aware of when confronting an infestation of bats in the attic is that their fecal matter, which is usually deposited around the perimeter of a home and looks a lot like mouse droppings, can be a health hazard. In confirming the presence of bats through the repeated deposit of such droppings, it is important not to inhale any dusty debris as it may contain a fungus that can cause the disease Histoplasmosis. The best way to guard against this is to moisten the bat droppings before removing them.
Sealing Off Entry Points
Once the presence of bats in the attic has been confirmed, the task of removing them comes down to a very simple goal: sealing off their nightly points of entry and exit. The way in which bats have gained access to an attic may be obvious or hard to detect. In the former case, it usually amounts to one or more openings that are clearly visible to the naked eye. As these are all gradually sealed, it is advisable to install a one-way valve tube over one of them, so that any bats still hiding in the attic will be able to subsequently exit, but not re-enter.
Valve tubes can be constructed out of a six to eight-inch piece of two-inch diameter tube. A piece of plastic or drop cloth is inserted into one end of the tube and taped to one side of what will be the exterior opening of the tube. The tube is then threaded through the attic opening. Bats will exit through the tube but because of the presence of the fabric or plastic at the other end, will not be able to re-enter through it.
Another more cumbersome and ultimately less effective method of getting rid of bats in the attic is to install floodlights in the area and leave them on at night. Even if this fails to completely eradicate the problem, it can help homeowners identify the smaller openings being used by bats that are invisible to the naked eye.
Internet Center for Wildlife Damage Management – Bats, Retrieved August 31, 2010 from http://icwdm.org/handbook/mammals/bats.asp
Bat Conservation International – Bat Exclusion Instructions, Retrieved August 31, 2010 from http://www.batcon.org/index.php/bats-a-people/bat-exclusion-instructions.html