Do It Yourself Bat Exclusion
Bats natural habitats are caves and hollow trees where they live in large colonies. Urban sprawl has forced people and animals to live together. Sometimes this causes bats to find refuge in houses, barns, other buildings, and structures used by people. Despite the general publics fear of bats, they are extremely beneficial insect predators. It is good to keep them around....just not in your house. Here are some steps you can take to exclude bats from your residence.
1. Purchase and install one or two Nature's Friend nursery bat houses, depending on the size of the colony. All too often exclusions are done with no place for the bats to go once they are excluded. This often forces the bats to find another undesireable location(e.g. another structure). Ideally the bat houses should be installed as far in advance of the exclusion as possible. This gives the bats time to familiarize themselves with the location of the bat house.
2. Locate the bats entrance and exit holes by observing the building at dusk. You can also look for staining around the opening of entrance-exit point.
3. Seal all other cracks or crevices 1/4 inch or larger with caulk, wood, sheet metal flashing, exterior spackling compound, cement, 1/4 inch hardware cloth, or window screening, leaving the entrance-exit points.
a one way device at the colonies exit points. A plastic "sleeve",
once the bat exits, collapses behind them, and they can not re-enter on
sleeve made of heavy plastic sheeting.
Netting, (shown below) also works well. Fiberglass window screening can
also be used. Something that allows the bats to fly
Leave this in place for a several days to make sure all of the bats are
Returning bats may fly around roost openings, but will fly away in a day
Plastic sleeve device and netting examples.
5. Wearing protective clothing and a cartridge respirator capable of filtering 2 microns to avoid breathing any guano dust. Spray bat feces with a one to ten ratio of bleach and water. This holds down the dust and kills a fungus created by the bat guano. Clean the entire roost area. An application of insecticide might be beneficial after cleansing to kill any remaining insects or mites.
6. Permanantly seal any exit-entry points.
Plan exclusions in the spring, or fall, after the bats maternity season. As bats give birth in the summer and the pups do not fly until almost full grown, they would be trapped, and perish. Bats only have one pup a year and there could be many depending on the size and maturation of the colony. Intentional killing of bats is against the law.
Bats do not usually fly when temperatures fall below the 45-50 degree range. At these temperatures bats enter torpor (a form of deep sleep).
Never pick up a bat you find lying on the ground with your bare hands. If it is alive it will bite to try to defend itself. It sees you as a threat. Keep children and pets away and if necessary move it to an inaccessible location with a shovel or similar implement. Call animal control to have the bat removed.
For large buildings such as warehouses, bright lights or fiberglass insulation may deter roosting due to the irritation of light or fiberglass. Ultrasonic devices for control of bats are expensive and there is no scientific evidence to indicate that they actually work.
This information is obtained in part from publications from the University of Florida. Even though the research was done in Florida, the principal theory of exclusion remains the same at any location. Contact your local coopreative extension agency for more information.
If you are not up to the task of exclusion, hire a professional experienced in bat exclusion. Ask for references, and make sure they are licensed and insured. This varies state to state but it is always good to ask. A professional will never be insulted if you ask for their credentials. Even if you hire a professional, before the exclusion begins, purchase and install one or two Nature's Friend nursery bat houses, as the bats still need somewhere to roost after exclusion.