Bats are one of the most misunderstood creatures in Wisconsin. Often associated with myths, horror movies, and Halloween, they actually play a crucial role in controlling insect populations and maintaining healthy ecosystems. But when bats move into your home—particularly your attic—they can cause serious problems for homeowners.
At Critter Control of Southern Wisconsin, we’ve helped countless homeowners safely and humanely deal with bat intrusions. Understanding the hidden habits of these flying mammals can help you spot the signs early, protect your home, and avoid potential health risks.
Why Bats Choose Homes
Bats in Wisconsin are typically looking for a safe, dark, and quiet place to roost—especially during the maternity season, which runs from late spring through early summer. Your attic, chimney, or wall voids may provide the perfect substitute for their natural habitat of caves and hollow trees.
Here’s why your home might look like prime real estate to a bat:
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Warm, stable temperatures in attics
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Minimal human disturbance
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Easy access through vents, eaves, or damaged rooflines
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Close proximity to water and insect food sources
The Hidden Behavior of Bats Indoors
Bats are nocturnal, so you’re unlikely to see much activity during the day. However, once the sun goes down, a hidden colony can become active, leaving and returning multiple times a night.
Here are some of the lesser-known behaviors bats exhibit when they live in homes:
Roosting in Tight Spaces
Bats can squeeze through openings as small as ⅜ of an inch. Once inside, they cluster in tight groups in rafters, wall voids, or behind insulation. You may not see them directly, but staining near entry points and bat guano are key indicators.
Maternity Colonies in Summer
Female bats gather to raise their young in what’s known as a maternity colony. These colonies grow rapidly in early summer, with pups typically being born in June or July. During this time, bats are particularly vulnerable and protected by law in many cases, making removal a delicate process.
Seasonal Movement
While some bats leave in fall to hibernate elsewhere, others may attempt to overwinter in your home. These bats will enter torpor (a hibernation-like state), but unusually warm winter days can cause them to wake and become active inside the structure.
Risks of Bats in Your Home
Although bats are beneficial outdoors, they pose several risks when living inside your home:
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Health Hazards: Bat droppings (guano) can harbor histoplasmosis spores, which are dangerous when inhaled. Accumulated guano can also attract insects and create foul odors.
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Rabies Risk: While rare, bats are one of the primary carriers of rabies in Wisconsin. Any physical contact should be treated as a potential exposure.
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Structural Damage: Over time, bat guano and urine can corrode wood and insulation, leading to costly repairs.
Signs You Have a Bat Problem
If you suspect bats may be living in your home, look for these common signs:
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High-pitched squeaking or fluttering noises at dusk or dawn
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Stains or dark smudges near vents, chimneys, or attic louvers
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Droppings in the attic, on windowsills, or around entry points
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A strong ammonia-like odor from accumulated guano
What You Should—and Shouldn't—Do
If you think bats are living in your home, avoid DIY removal. Bats are protected in Wisconsin, especially during maternity season. Improper removal can harm the colony and may even result in legal consequences.
Instead:
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Avoid sealing entry points until bats are professionally excluded
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Do not attempt to catch or handle bats
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Keep pets and children away from suspected bat areas
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Contact a licensed wildlife control professional
How Critter Control of Southern Wisconsin Can Help
Our team is experienced in humane, legal bat removal and exclusion services. We follow state guidelines to ensure bats are safely removed and that your home is protected long-term.
Our bat control process includes:
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Thorough inspection to identify entry points and colony size
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Professional exclusion using one-way doors that let bats out, but not back in
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Sealing of all potential re-entry areas
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Cleanup and sanitization of affected areas, including guano removal
We understand the laws that protect bats in Wisconsin and take care to provide services that are both effective and responsible.