Bat removal devices are one-way exclusion tools that let bats leave a building on their own but prevent them from getting back in. They’re the standard method for clearing bats from attics, walls, and soffits, and in most states they’re the only legal approach. The two main types are exclusion tubes and exclusion netting, both of which work on the same principle: bats crawl or fly out through the device at dusk and find themselves unable to return.
How One-Way Exclusion Tubes Work
Exclusion tubes are smooth plastic or PVC pipes, typically about 2 inches in diameter and 10 inches long, placed over the holes bats use to enter and exit your building. The tube is secured over the opening so it barely protrudes inside, no more than a quarter inch. This lets bats easily find and enter the tube from inside. On the outside end, a piece of lightweight clear plastic is taped around the tube to form a collapsible sleeve. When a bat crawls through and exits, the plastic sleeve collapses behind it, blocking re-entry.
The key design feature is the smooth surface. Bats grip rough materials like wood, brick, and stone with ease, but they can’t cling to slick plastic or PVC. Once they’ve passed through and dropped out the far end, they have no way to climb back in. You can buy commercial exclusion tubes or make your own from PVC pipe, flexible plastic tubing, or even cleaned-out caulk tubes.
How Exclusion Netting Works
For larger openings, like attic louvers or long gaps along a roofline, netting is more practical than tubes. You use lightweight, flexible plastic netting with a mesh size of one-sixth of an inch or smaller. The netting gets secured along the top and both sides of the opening, but the bottom edge hangs free, extending 18 to 24 inches below the lower edge of the gap.
Bats push past the loose bottom edge to leave, but when they return and try to land at the opening, the hanging netting blocks their path. They can’t lift the netting from the outside or navigate behind it to reach the hole. This approach covers wide areas efficiently and works especially well on flat, smooth exterior walls where bats exit from long horizontal cracks.
Installation Steps That Matter
The devices themselves are simple, but the process around them determines whether they actually work. Before installing any exclusion device, you need to identify every entry point the bats are using. Watch the building at dusk over several evenings and note where bats emerge. Look for dark staining or greasy marks around gaps, which indicate regular use. Common entry points include ridge vents, soffit gaps, spaces behind fascia boards, and cracks where different building materials meet.
Once you’ve mapped the entry points, seal all of them except the primary exits with caulk, mesh, or foam. Then install your one-way devices over the remaining active openings. Leave the devices in place for at least several nights to give every bat in the colony time to leave. After you’re confident the bats are gone (no more activity at dusk), remove the exclusion devices and permanently seal those final openings.
Missing even one secondary entry point can undermine the whole effort. Bats can squeeze through surprisingly small gaps, so any crack or hole large enough to fit a pencil deserves attention.
Seasonal Restrictions on Exclusion
You cannot legally exclude bats during maternity season in most states. The exact dates vary by region, but as a representative example, Florida prohibits bat exclusion from April 16 through August 14. During these months, female bats are raising pups that can’t fly. If you install exclusion devices during maternity season, the mothers leave to feed but can’t return, and the flightless young starve inside your walls or attic. This creates a worse problem than the original colony: dead bats in inaccessible spaces, potential odor, and insect infestations.
The legal exclusion window in Florida runs from August 15 through April 15. Your state’s dates may differ by a few weeks depending on local bat species and climate, so check with your state wildlife agency before starting. The best time for exclusion in most of the U.S. is late summer through early fall, after pups can fly but before bats enter winter hibernation.
Why Ultrasonic Repellents Don’t Work
Ultrasonic bat repellent devices are widely sold online, but the evidence for their effectiveness is poor. These devices emit high-frequency sound meant to interfere with bats’ echolocation, theoretically making an area uncomfortable enough that bats leave. In practice, the results range from negligible to counterproductive.
A study published in PLOS One tested ultrasonic deterrents and found they provided no meaningful reduction in bat activity. For species that echolocate at lower frequencies, the effect was ambiguous, somewhere between a 55% reduction and a 23% increase in bat presence. For eastern red bats, which echolocate at higher frequencies, the results were worse: mortality near the deterrents was estimated to be 105% higher when the devices were active. The researchers concluded that ultrasonic deterrents “may not be effective for both high and low frequency echolocating bats” and warned against assuming all bat species respond the same way.
In short, ultrasonic devices are not a substitute for physical exclusion. One-way valves and netting remain the only reliably effective approach.
Cleanup After Exclusion
Once the bats are gone, you’ll likely need to deal with accumulated droppings (guano) in your attic or wall cavities. Bat guano can harbor a fungus that causes histoplasmosis, a lung infection you can contract by breathing in spores stirred up during cleanup. The risk is highest when dry droppings become airborne dust.
Protective equipment for guano cleanup includes:
- Respirator: An N95 or N99 mask is recommended for the most protection.
- Eye protection: Goggles or safety glasses to keep spores out of your eyes.
- Gloves: To prevent skin contact with the fungus.
- Disposable coveralls, boots, and a hat: Clothing that can be removed at the work site so you don’t track contaminated material through your home.
Before disturbing any guano, wet it thoroughly with a spray bottle or garden sprayer to keep dust levels down. Avoid cleanup on windy days if the area is ventilated to the outside. Place contaminated material in sealed bags or containers while it’s still damp, and wash your hands thoroughly after removing your protective gear. For large accumulations, especially in enclosed spaces with poor ventilation, hiring a professional remediation service is the safer choice.