The fix the Michigan DNR recommends for bats in an attic is exclusion: one-way doors let the bats leave, and the openings are sealed once they are out. Bats are protected in Michigan, and the DNR says killing them is not permitted except for human safety issues. This page covers what you can safely check yourself, which common remedies are not worth trying, and when to bring in a professional. For the full professional process, see our bat removal page.
First, rule out a health risk
Could anyone have had contact with a bat, including someone asleep in a room with one? Bat bites can be minor and hard to notice. If contact is possible, do not shoo the bat out. Contain it if you can do so safely, and call the Kent County Health Department at 616-632-7228 for a risk assessment. The full containment and testing steps are on our bat removal page. If a pet had contact, call your veterinarian and the health department too. This page is not medical advice; the health department and your doctor come first.
What does not work
- Sprays and poisons. Bats are protected in Michigan, and three species (little brown, northern long-eared and tricolored) have been listed as state threatened since 2023 after population declines from white-nose syndrome. The DNR calls one-way exclusion plus sealing the most effective and humane way to resolve bat conflicts.
- Ultrasonic devices. The Minnesota DNR, which publishes bat-specific repellent guidance, says they are not effective at repelling bats.
- Bright lights and fans. Lights may disturb bats enough to leave, but they can also push them into more concealed spots behind boards or between walls. Fans have had very limited success (Minnesota DNR).
- Mothballs. They are a pesticide, and the label decides where they can legally be used. The National Pesticide Information Center says they are not meant as animal repellents and have little or no effect, and the vapor can cause headaches, nausea and eye and nose irritation.
- Sealing the hole yourself. If bats are still inside, closing their exit traps them, and some will look for a way into the living space instead.
Find where they are getting in
In the warm months, watch one side of the roofline from the yard, from just before sunset until it is too dark to see. Note each spot bats leave from and roughly how many, then do another side another evening. In daylight, look for dark, greasy rub marks around gaps and small dark droppings below them. Bats fit through gaps as small as half an inch, so check eaves, soffits, rooflines, vents, chimneys and trim. Write it down; it makes the professional inspection faster.
From late fall through winter, bats in an attic may be hibernating, so a dusk watch can show nothing. Droppings and rub marks are the signs to look for then.
What the job involves
The professional work runs in a set order: inspection, sealing the gaps bats are not using, one-way doors on the active entry points, a final seal once they are out, and cleanup if needed. Our bat removal page walks through each step, what to expect on inspection day, and the questions to ask any company.
If there are droppings
Bat droppings are not a sweep-it-up job. The CDC notes that the fungus behind histoplasmosis spreads in bird and bat droppings, so cleanup is protective-gear work, quoted separately. Our attic cleanup page covers what it involves.
Timing by season
- May through mid-August: maternity season. The Michigan DNR advises avoiding exclusion then, because young that cannot fly yet would be trapped inside. A professional can still inspect and plan.
- Late summer, once the young can fly: the window the DNR points to for exclusion.
- Winter: bats can hibernate in attics. An inspection now gets you a written plan, and the professional can say when exclusion can safely happen for your home.
If the bats are in the walls
Bats in walls get in through the same kinds of gaps: soffits, trim and siding transitions. Sealing the opening with bats in the cavity traps them and can push them toward the living space. The fix is the same as for the attic: a one-way device on the outside opening, and a final seal once they are out.
When to call a professional
- A bat inside the house, bats leaving the roofline at dusk, or droppings and stains along it.
- Any work at roof height.
- Anything during maternity season, typically May through mid-August.
- Any cleanup of droppings or soiled insulation.
Call (616) 747-8153 or send the short form, and a local wildlife control professional will call you back to set up an inspection. You decide whether to hire anyone.
Sources: Michigan DNR: Bats · Michigan DNR: 2023 threatened and endangered species update · Kent County Health Department: Bat in the Home · CDC: About Histoplasmosis · National Pesticide Information Center: mothballs · Minnesota DNR: repellents for unwanted bats (out-of-state, bat-specific)