Bats seeking shelter on your property can create a dilemma for homeowners who wish to protect their structures while respecting wildlife. The presence of a bat colony, particularly in an attic or wall void, necessitates a careful and humane strategy for removal. Successfully getting bats out of your immediate vicinity requires a methodical approach that prioritizes legality, safety, and non-lethal exclusion methods.
Safety and Legal Requirements for Bat Removal
Attempting to remove bats from a structure must begin with a clear understanding of the health risks and the legal obligations involved. One of the most serious health concerns is Histoplasmosis, a respiratory disease caused by inhaling fungal spores found in dried bat guano. Disturbing large accumulations of guano can aerosolize these spores, so cleanup requires an N-95 respirator and proper protective gear.
While less than one percent of bats carry rabies, any direct contact or suspected bite must be taken seriously. Bats are protected under various federal and state regulations, meaning it is illegal to kill, poison, or trap them. Violating these laws can result in significant fines and penalties.
The most restrictive legal consideration is the bat maternity season, which typically runs from mid-April or late May through mid-August, depending on the region and species. During this time, female bats give birth to flightless pups that are unable to exit a structure on their own. Performing an exclusion during this window would trap the young inside, causing them to perish and creating a biohazard within the structure, which is both inhumane and illegal.
Humane Exclusion and Physical Deterrence
The only effective, long-term solution for removing bats is exclusion, which must be performed outside the protected maternity season. The first step is a meticulous inspection to locate all entry points, which can be small gaps as tiny as a half-inch wide.
Common access areas include:
- Loose flashing.
- Unsealed utility openings.
- Gaps where dormers meet the roof.
- Poorly fitted vents.
Once entry points are identified, all but the primary exit points must be sealed using materials like caulk, hardware cloth with a quarter-inch mesh, or weather stripping. Expanding foam should be avoided, as bats can become entangled in the hardening material. The remaining active openings are then fitted with one-way exclusion devices that allow bats to fly out at dusk but prevent them from re-entering at dawn.
These devices are typically constructed from lightweight plastic netting, extending 18 to 24 inches below the opening and attached only at the top, or they can be rigid plastic tubes. The exclusion devices must remain in place for a minimum of five to seven nights to ensure all bats have left, especially when temperatures are above 50 degrees Fahrenheit. Only after confirming the structure is empty should the one-way devices be removed and the final openings permanently sealed.
Non-lethal physical deterrents, such as bright floodlights or fans creating strong drafts, can sometimes be used to discourage bats from roosting. However, these methods are not a substitute for complete physical exclusion from a structure, as they may simply cause the colony to move deeper into a wall void. Deterrents based on odor, such as mothballs or strong-smelling oils, are generally ineffective because bats can easily navigate around them or become accustomed to the scent.
Modifying Your Yard to Discourage Bats
Long-term prevention focuses on making the area less attractive to bats by reducing their food sources and removing available outdoor roosting spots. Bats are primarily attracted to a yard due to the presence of insects, which are often drawn to exterior lighting. Switching standard white outdoor lights to yellow or sodium vapor bulbs can reduce the number of insects congregating near the home, thus minimizing the bats’ local food supply.
Minimizing standing water is another effective strategy, as it reduces breeding grounds for mosquitoes and other flying insects that bats consume. Bats prefer sheltered areas for temporary roosting, so removing heavy vine coverage, trimming back dense tree branches close to the house, and securing loose shutters eliminates these potential daytime resting spots.
For areas like porch overhangs where bats may roost temporarily, physical modifications can be made to eliminate the sheltered corner or surface by changing the microclimate or making the surface slippery or exposed. As a final measure, installing a dedicated bat house on a pole or tree away from the main structure provides a humane alternative roosting site.