Deer Mice in Wisconsin: What You Need to Know About These Common Rodents
When people think of mice in Wisconsin, the first image that usually comes to mind is the typical house mouse. But there's another, more outdoorsy cousin that you should be aware of—the deer mouse. Known for their big eyes, bi-colored tails, and white bellies, deer mice (Peromyscus maniculatus) are widespread across the state and, unfortunately, more than just a nuisance.
Let’s take a closer look at what makes deer mice unique, why they’re a concern for homeowners, and how to keep your family safe from the diseases they can carry.
🐭 What Are Deer Mice?
Deer mice are small, nocturnal rodents often found in fields, forests, barns, and sheds. They get their name from their deer-like coloring—brown on top and white underneath. Unlike house mice, deer mice are more commonly found in rural or semi-rural areas, but that doesn’t mean they won’t find their way into your attic, garage, or cabin—especially when temperatures drop.
They’re excellent climbers and nest builders, often using soft materials like insulation or shredded paper to make themselves at home in secluded spaces.
⚠️ Why You Should Be Concerned: Disease Risks
While deer mice might seem less threatening than rats or larger pests, they pose a serious health concern—especially because they’re known carriers of Hantavirus.
🔬 Hantavirus Pulmonary Syndrome (HPS)
This is a rare but potentially deadly respiratory disease. People typically become infected by breathing in airborne particles from deer mouse urine, droppings, or saliva, especially in poorly ventilated areas like sheds or attics that haven’t been cleaned in a while.
Symptoms may start like the flu—fever, fatigue, muscle aches—but can quickly progress into serious breathing difficulties. Although rare, the mortality rate for HPS can be as high as 30–40%.
🧬 Other Potential Risks
Deer mice may also carry:
Salmonella (from contaminated droppings)
Lyme disease (indirectly, by hosting ticks that transmit it)
Leptospirosis (a bacterial infection spread through urine-contaminated water)
🏠 Where You Might Find Deer Mice in Wisconsin
Deer mice are found throughout all regions of Wisconsin, from wooded northern counties to rural farms in the south. They're most active in the fall and early winter, when they start looking for warm places to nest.
You’ll often find them in:
Cabins and cottages (especially seasonal ones)
Barns and sheds
Basements and crawl spaces
Garages and attics
Woodpiles and old furniture
🧹 Prevention and Safe Cleanup Tips
If you suspect deer mice are nearby, take precautions to prevent them from becoming a problem—or from putting your health at risk.
✅ Prevention
Seal up gaps and cracks around the home (they can squeeze through holes as small as a dime).
Store food in airtight containers.
Keep woodpiles and debris away from the house.
Use tamper-proof bait stations if you suspect activity (professional pest control is safest).
🧼 Cleanup (Especially After Droppings)
Never sweep or vacuum mouse droppings dry—this can release particles into the air.
Wear gloves and a mask.
Spray droppings with a bleach solution (1 part bleach to 10 parts water), let sit for 5+ minutes, and wipe with disposable towels.
Dispose of materials in sealed plastic bags.
