Dealing with Bats in the House

While the case can be made that any pest is important to a local ecosystem, bats have a definitive benefit. They can eat up to a 1,000 insects every hour and one of their favorite meals is mosquitoes. It's a lot like free pest control. Nonetheless, when they enter your home, they will present their own problem. The biggest bat problem is bat urine and guano. The nasty odor can easily infiltrate your home. Bat guano can contain potentially dangerous microorganisms. Bat guano must be collected, disinfected, and disposed of, including any fecal matter that may have fallen into hidden attic space. This cleanup requires wearing protective gear.

Like any pest, bat control is easiest when done early. Bats have an acute sense of place and once they become attached to your attic as their roost, they won't be easily displaced. August and September are the most common months for bats to enter your home. Bats give birth near the beginning of June and by the beginning of August they start going out at night on their own. These young bats frequently get lost and can end up in your house. If they find your attic hospitable, they may stay and tell other bats about the new dwelling. This spells trouble for you and your home.

The first thing you should know about bat control is what—and more importantly when—not to do. The exact months can vary depending where you live, but you should never do a bat exclusion from the beginning of May until the end of August. Flightless babies may still be in your attic and you can trap them in, leading to a slow, painful death followed by a rotting bat carcass. This will make the guano seem like no big deal. The best idea is to wait your bat problem out, but if you have an emergency situation or simply can't put up with it any longer, pest control professionals may be able to help. Still, make sure you address this exclusion issue—a reputable professional should be up front about this problem, anyway.

The ideal time for bat exclusion is some time in the winter when your bats have migrated south. Your first step should be creating a one-way guard or screen over any vents. This will allow any remaining or new bats to leave your attic but not re-enter through the vent. Attic vents or gables are the most common entry points for bats, but they can enter through any opening. These openings can be difficult or impossible to detect unless you know what you're looking for. Sealing these smaller attic holes can be the best reason to call a professional. Ultrasound devices that emit high-frequency sounds can be effective to prevent future bat problems but are rarely enough to drive away an established bat colony.

You may have noticed no mention has been made of killing the bats during your bat control program. That's because you shouldn't. Bat poison is more likely to cause more problems than it solves. Again, you can have bat carcasses and the chemicals in the poison can be harmful to pets and household members. Because bats are beneficial and help control other pests, local ordinances may be protecting bats. In some areas, you can be fined for killing your bats.