Quick facts
- Size
- Wingspan about 8 to 13 inches
- Looks like
- Small brown furry body, leathery dark wings
- Peak season
- Summer, when maternity colonies form
- Where in Michigan
- Statewide, attics, barns, cottages and wall voids
- Main risk
- Rabies exposure and guano buildup
- Risk level
- High
Signs you have bats
- Bats flying out of the roofline or chimney at dusk
- Dark, crumbly droppings piled below gaps or in the attic
- Brown, greasy stains around gaps in siding or roof edges
- Squeaking or scratching sounds in walls at dusk
- A bat flying inside the house
Bats in Michigan homes
Big brown bats and little brown bats are the species most often found in Michigan buildings. In spring and summer, females gather in maternity colonies in attics, barns, cottages and wall voids to raise their young. A colony may use the same building year after year. Big brown bats sometimes hibernate inside buildings in winter, which is why a bat can show up in January.
Bats eat large numbers of night-flying insects, including moths and beetles, and they matter to Michigan's ecosystems. White-nose syndrome, a fungal disease, has caused major declines in several bat species in Michigan. Bats are protected, and some species found here are listed as threatened or endangered, so killing them or sealing them in is not the answer.
When to do bat exclusion in Michigan
Do not exclude bats while pups are in the roost and cannot fly yet, which in Michigan is generally June into mid-August. Sealing during that window traps young inside to die, causes odor problems, and often sends desperate bats into the living space. Exclusion is best done in spring before pups are born or after mid-August once the young can fly.
Exclusion uses one-way devices, such as netting or tubes, placed over the main exit points. Bats leave at dusk to feed and cannot get back in. After a week or so with no activity, the devices come down and every gap is sealed. Gaps as narrow as a half inch or less can let a bat in, so a careful inspection of the whole roofline matters.
Bats also roost behind shutters, under ridge vents and in gaps at chimneys. Many Michigan homes need several small repairs, not one big one. Check for wasps and hornets in the same gaps before ladder work in late summer. A good exclusion job covers all of these spots at once, so bats do not just shift to the next gap.
Rabies precautions and bat testing
Most bats do not have rabies, but bats are a known source of rabies in Michigan and bites can be very small and easy to miss. Never handle a bat with bare hands. If a bat is found in a room with a sleeping person, a young child, or someone who cannot say whether they were bitten, do not let it go.
Safely confine the bat by covering it with a container and sliding cardboard underneath while wearing thick gloves, then call your local health department. The state health department laboratory tests bats for rabies when there has been a possible exposure. A negative test can mean nobody needs rabies shots. Do not crush the bat's head, since the brain is needed for testing.
What you can do yourself
- 1Never touch a bat with bare hands.
- 2If a bat is loose and nobody was exposed, close interior doors and open a window so it can leave.
- 3Note where bats exit at dusk so a pro can place exclusion devices.
- 4Install chimney caps and screen attic and gable vents.
- 5Seal small gaps only in fall or early spring, after bats are gone.
When to call a licensed pro
- You have a colony in the attic or walls.
- You need exclusion with one-way devices and roofline sealing.
- Guano has built up in the attic and needs cleanup.
- Bats keep getting into living spaces.
What bats treatment costs in Michigan
$400 to $1,500per home
Typical Michigan ranges, not quotes. Price depends on the number of entry points, the height and pitch of the roof, and whether guano cleanup or insulation replacement is needed.
Typical ranges, not quotes. See the full Michigan pest control cost guide.
Bats: common questions
When can bats be removed in Michigan?
Exclusion is best done in spring before pups are born, or after mid-August once the young can fly. Avoid sealing bats out in June and July, when flightless pups are in the roost. Check our pest calendar for timing.
What should I do if a bat is in my bedroom?
If anyone was sleeping in the room, do not release the bat. Confine it safely while wearing gloves and call your local health department, which can arrange rabies testing and advise whether anyone needs treatment.
Are bats protected in Michigan?
Yes. Bats are protected wildlife in Michigan, and some species found here are listed as threatened or endangered. That is why removal is done by exclusion with one-way devices rather than killing or trapping.
Is bat guano dangerous?
Large accumulations of bat droppings can harbor fungi that cause respiratory illness when the dust is breathed in. Avoid stirring it up. Cleanup of heavy guano should be done with proper respiratory protection or by a pro.