The only reliable way to get rid of bats in your home is a method called exclusion: letting them fly out through one-way devices, then sealing every entry point so they can’t return. Trapping, poisoning, and killing bats is illegal in most states because nearly all bat species are protected under wildlife conservation laws. Exclusion works with the bats’ natural behavior rather than against it, and timing it correctly is the single most important factor in getting it right.
Why Timing Matters More Than Anything
Bats typically return to roosting sites in late April or early May. Pups are born in late May or early June and can’t fly until mid-July at the earliest. If you seal entry points while flightless pups are inside, they’ll die in your walls or attic, creating a far worse problem: decaying animals, intense odor, and potential disease exposure.
The safe windows for exclusion break down by month:
- January through April: Seal entrances before bats return for the season.
- May through July: Do not seal any openings. Use this time to watch bats at dusk and identify exactly where they enter and exit.
- August through October: Install one-way exclusion devices so bats can leave but not re-enter.
- November through December: Once bats have migrated or moved to winter hibernation sites, seal all remaining openings permanently.
The ideal approach is to act in early spring before they arrive or in late summer and fall after pups can fly. If you discover bats in June, you’ll likely need to wait until August to begin exclusion.
Finding Every Entry Point
Bats can squeeze through a gap as small as three-eighths of an inch, roughly the diameter of a dime. They don’t chew or claw their way in like rodents or raccoons. They exploit existing gaps in your home’s exterior, which means even a well-maintained house can have dozens of potential entry points.
Start your inspection at dusk, 15 to 30 minutes before sunset. Stand back from the house and watch for bats emerging. You’ll see them drop from a gap and take flight. Note every location. Repeat this for two or three evenings to confirm all active exits. During daylight, look for brown staining or small dark droppings (about the size of a grain of rice) near gaps, which marks heavily used entry points.
The most common spots to check:
- Ridge vents and roof vents: The seam running along your roof peak is a frequent entry point, especially where the metal cap has loosened.
- Soffits and fascia boards: Gaps where the soffit meets the wall, or where fascia boards sit behind gutters, are prime locations.
- Gable vents: Louvered vents on the triangular wall sections of your attic often have gaps wide enough for bats.
- Loose or lifted shingles: Particularly where the roofline meets the gutters.
- Chimneys: Gaps between the chimney flashing and the roof surface.
- Behind shutters: Decorative shutters mounted with spacers create sheltered gaps bats love.
How One-Way Exclusion Works
A one-way exclusion device is a simple tube or netting arrangement installed over an active entry point. Bats crawl or drop through it to exit at dusk but can’t navigate back in when they return. You can buy commercial exclusion tubes or make one from PVC pipe or flexible plastic netting.
The device gets mounted directly over each confirmed entry hole, with the bottom left open so bats can drop out. The tube should extend at least a few inches past the wall surface. Leave these devices in place for five to seven nights to ensure every bat in the colony has had a chance to leave. During this period, seal all secondary gaps and cracks that bats aren’t actively using. Once you’re confident the colony has exited, remove the devices and permanently seal those final openings with caulk, hardware cloth, or sheet metal.
This is where many DIY attempts fail. Missing even one small gap means bats find a new way back in, sometimes into living spaces rather than just the attic. A thorough inspection and sealing job is more important than the exclusion devices themselves.
Ultrasonic Devices and Repellents Don’t Work
Ultrasonic deterrent devices are widely sold for bat control, but research consistently shows they’re ineffective. A study at an Ohio wind energy facility found that ultrasonic deterrents provided no meaningful reduction in bat activity. For some species, mortality actually doubled when the devices were active compared to when they were off. The devices had, at best, a weak dampening effect on certain species and increased activity in others.
Mothballs (naphthalene), bright lights, and chemical sprays sold as bat repellents are similarly unreliable. Bats may temporarily avoid a treated area but return once they acclimate or the chemical dissipates. None of these products provide a permanent solution, and mothballs in confined spaces like attics pose a real health risk to the people living in the house.
Cleaning Up After Bats
Bat droppings (guano) accumulate quickly in attic spaces and can harbor a fungus that causes histoplasmosis, a respiratory infection. The spores become airborne when dried guano is disturbed. Cleanup requires real protective gear, not just a dust mask.
Before touching anything, put on an N95 respirator at minimum. You’ll also need eye protection, gloves, and clothes you can remove at the site, either disposable coveralls or clothing you’ll wash immediately after. Dampen the guano with water before disturbing it. Never sweep dry droppings or clean on a windy day with open windows. Wet the material, scoop it into sealed bags, and dispose of it. Wash your hands thoroughly after removing all protective equipment.
For small accumulations (a handful of droppings along a windowsill), cleanup is straightforward. If your attic has a large colony’s worth of guano built up over months or years, particularly if it’s saturated insulation, professional remediation is worth considering. The guano and contaminated insulation get removed and replaced, and the space is treated to eliminate lingering spores.
What Professional Removal Costs
Professional bat exclusion for a small to medium-sized home typically runs $200 to $1,500. That covers inspection, installing exclusion devices, and sealing entry points. For larger colonies, bigger homes, or structures with complex rooflines (like historic buildings or multi-story homes with dormers), costs can reach $8,000 or more.
Attic remediation, including guano removal and insulation replacement, is usually a separate cost on top of the exclusion work. The total depends heavily on how long bats have been roosting and how much material needs to come out. Getting multiple quotes is worthwhile since pricing varies significantly between wildlife control companies.
Installing a Bat House Nearby
Giving bats an alternative roosting spot near your home isn’t strictly necessary for exclusion, but it increases the chances they’ll relocate nearby rather than searching for another gap in your siding. Bats are genuinely beneficial neighbors. A single bat eats thousands of insects per night.
A bat house should be at least 24 inches tall and 14 inches wide, with multiple internal chambers spaced three-quarters of an inch to two inches apart. Mount it 12 to 20 feet above the ground, facing south, east, or southeast so it gets six to eight hours of direct sun daily. Internal temperatures need to reach 80 to 100 degrees Fahrenheit in summer for females to successfully raise pups.
The best mounting locations are on the sides of buildings: your house, garage, or barn. Keep the house at least 20 to 30 feet from tree branches, vegetation, and wires so bats have a clear flight path. Mounting under eaves works well because the overhang protects the house from rain while the building’s thermal mass helps maintain temperature.
If a Bat Gets Into Your Living Space
A single bat flying around a bedroom or living room is usually a juvenile that got lost or an adult that entered through an internal gap from the attic. Close interior doors to contain it to one room, open a window or exterior door, dim the lights, and give it time to find the exit on its own. If it lands on a wall, you can place a container over it, slide a piece of cardboard underneath, and release it outside.
The critical concern with any bat found inside living areas is rabies. If anyone in the household was sleeping in the room with the bat, or if a child, pet, or anyone who can’t reliably report whether they were bitten had contact, the bat should be captured (using thick gloves) and submitted for rabies testing. Bat bites can be tiny enough to go unnoticed. If the bat can’t be captured for testing, a doctor will likely recommend post-exposure treatment: a series of four vaccine doses given over two weeks. Wash any potential bite or scratch immediately and thoroughly with soap and water.