Bats in Buildings
Bats are extremely beneficial animals in Florida’s environment. Most people know that they eat pesky insects, but they are also important pollinators.
These mammals are active at night and roost in caves, hollow trees, crevices—and buildings. Bats in your house can be a nuisance, so here are ways to get bats out safely and humanely.
Bat Colony Exclusion
If you suspect you may have bats roosting in your home, look and listen for these signs to confirm a bat presence:
- Squeaking and rustling noises in ceilings and walls. (These sounds also come from mice and squirrels.)
- An entrance hole with a dirty stain below it. The hole can be as narrow as ¼ inch.
- Droppings around sidewalks, ledges, patios, or under rafters. The black or brown droppings are similar to the size and shape of rice grains and are made of insect parts.
- Bats emerging from the building in the evening.
Exclusion is the best and most permanent method of removing bats from unwanted areas. Plan on starting exclusion in the fall through the spring; exclusion should only be done from August 15 to April 14.
Since bats give birth in May and June, exclusion during that time and several months after will trap baby bats inside where they will die of starvation (considered animal cruelty) and cause odor and pest problems. Exclude bats once the young are flying.
Also avoid excluding during cold weather since bats normally do not leave the roost when temperatures are lower than 45ºF.
- Observe the building at dusk for several evenings to find the entrances the bats use.
- Seal and bat-proof openings that the bats do not use (but could in the future) with caulking, wood, plaster, hardware cloth, or window screen.
- Place one-way exit devices on the building openings the bats use. These include plastic "sleeves," 1¾-inch PVC pipe, used caulking tubes, or bat netting secured over the roost opening with the bottom of the netting unattached. These methods create exits that allow the bats to leave but not reenter because the entrances will be collapsed, too smooth to climb through, or blocked.
- Leave the one-way exit devices in place for at least a week (two weeks in cool weather).
- Permanently seal entrances once you are sure the colony has left.
Once the bat colony has been excluded, you’ll need to clean the rooting site. Clean away guano to prevent disease and use an insecticide to kill parasites left behind by the bats. Wear protective clothing and masks to prevent breathing guano dust.
Traps are sometimes advertised for getting rid of bat colonies in buildings, but these devices are not recommended. There is no reason to use traps for bat control since it puts stress on the animals and increases human exposure to bats.
There is no scientific evidence that ultrasonic sound devices are effective in discouraging bats.
If a large structure is difficult to seal, direct bright lights or fans toward the ceiling to discourage bats from roosting.
Removing Single Bats
Sometimes single bats will enter buildings accidentally. Most of the time all you need to do is open a door or window to let it escape.
If that’s not possible, trap it against the wall or floor with an empty coffee can (or similar container). Slide cardboard or heavy paper between the container and wall or floor surface. Take the container with the lid outside, remove the cover, and place it high on a tree branch or wall to let the bat fly away.
Never pick up a bat with your bare hands—they will bite to defend themselves, like any wild animal.
Do not try to catch a flying bat. It is almost impossible and will usually injure the bat.
A Note on Rabies
There is large public fear of bats as rabies carriers. When bats become infected, they usually become paralyzed and die.
For this reason, do not pick up bats you find on the ground. This can significantly reduce your chance of getting rabies from bats. Call your county animal control to have the bat removed.
If anyone is bitten, clean the wound with soap and water and call your county health department for information and instructions. Call your animal control office to collect the bat for rabies testing.
Bats are misunderstood and sometimes unfairly feared animals. They are an important part of the environment, including your backyard. As long as they’re not in your home, you should want these helpful bug-eaters and pollinators around.
Consider putting up bat houses in your yard, especially if you are excluding a bat colony. Bats won’t leave a building to move into a bat house, but if they’re removed from the building they may look for places to roost nearby.
For information on bat house plans, read Effective Bat Houses for Florida.
To learn more about the ecological benefits of bats, ways to exclude bat colonies from a building, and more, contact your local Extension office.
Adapted and excerpted from:
W. Kern, Bats in Buildings (ENY-268), Entomology and Nematology Department (rev. 8/2009).
Related Sites & Articles
- UF/IFAS Publications
- Bats of Florida
- Dealing with Unwanted Wildlife in an Urban Environment
- Effective Bat Houses for Florida
- Insect Pest Management Services Provided by Bats
- UF/IFAS Sites
- Bat FAQs
- The Bats of the University of Florida Bat House
- Other Sites & Publications
- Bats & Rabies--CDC