As cold winds sweep across the Twin Cities and the first frost coats our lawns, most of us are preparing our homes for the long Minnesota winter. But while you’re sealing windows, tuning up the furnace, and swapping iced coffee for hot cider, some unwelcome pest are scurrying their way into your property.
Each fall, as temperatures drop, insects, rodents, and wildlife in the Minneapolis–Saint Paul metro area start seeking warm, protected shelters to ride out the season. Unfortunately, your walls, attic, and basement often provide the perfect refuge.
This article dives into Minnesota’s most common overwintering pests, how to spot them, and what you can do to prevent infestations before they become full-blown winter problems.
For professional prevention or exclusion services, explore Abra Kadabra Environmental’s Residential Pest Control and Rodent Control pages.
The Usual Suspects: Who’s Hiding in Minnesota Homes
1. Deer Mice and White-Footed Mice
When it comes to overwintering rodents in Minnesota, the deer mouse (Peromyscus maniculatus) and the white-footed mouse (Peromyscus leucopus) top the list. These small, soft-furred mice are recognizable by their distinctive white bellies and feet, and they thrive in wooded or semi-rural areas — making them common in suburban and exurban neighborhoods throughout the metro area.
While house mice (Mus musculus) tend to infest multi-family buildings and apartment complexes, deer and white-footed mice are the main culprits for single-family homes, cabins, and rural properties. Norway rats, by contrast, are far less common here; Abra Kadabra only handles a handful of rat infestations each year.
Signs of activity:
- Droppings or nesting material in attics, basements, or garages
- Small gnaw marks on wood or wiring
- Noises behind walls, especially at night
- Tiny, dime-sized entry holes near siding, foundations, or utility lines
Risks:
These mice aren’t just a nuisance — they’re also known carriers of Hantavirus, which can spread through contact with rodent droppings and urine. According to the CDC, proper cleanup and control measures are critical to preventing illness.
If you suspect activity, don’t wait. Professional exclusion and sanitization — like Abra Kadabra’s inspection services — ensure both removal and long-term prevention.
2. Grass Spiders (Agelenopsis potteri)
Despite popular myths, hobo spiders are not found in Minnesota — not even invasive populations. The more familiar and impactful spiders here are grass spiders (Agelenopsis potteri). These funnel-web weavers are fast runners and are often seen darting across driveways or lawns.
In late summer and fall, their dense webs become visible on home exteriors, shrubs, and porch corners. While they’re harmless and even beneficial as insect predators, their webbing can cover siding, eaves, and windows — creating an unsightly mess.
Signs of activity:
- Thick, sheet-like webs along siding, soffits, and outdoor furniture
- Increased sightings in garages, basements, and lower-level windows
Management tips:
Vacuum or sweep webs regularly, seal gaps around doors and windows, and reduce outdoor lighting that attracts insects (spider food).
Remember: spiders are often symptoms of other pest issues. Fewer insects mean fewer spiders. A seasonal exterior pest treatment from professionals can help break that cycle.
3. Boxelder Bugs and Stink Bugs
Every fall, boxelder bugs swarm sunny walls and window frames throughout the Minneapolis–Saint Paul metro. These black-and-red insects gather in huge numbers, drawn to warm exterior surfaces as they prepare to overwinter.
Alongside them, brown marmorated stink bugs — an invasive species now well established in the Upper Midwest — exhibit the same behavior. Once temperatures dip below freezing, they slip into cracks around siding, vents, and windows to overwinter inside wall voids.
Signs of activity:
- Clusters of bugs on sunlit south or west-facing walls
- A few insects crawling around windows in winter (especially on warm days)
They won’t reproduce indoors, but their presence is a major nuisance — and crushing them releases their namesake odor. Preventative exclusion treatments in late summer and early fall dramatically reduce winter sightings. Learn more on our Exterior Pest Control page.
4. Cluster Flies and Other Overwintering Flies
Cluster flies, relatives of common houseflies, invade homes in late fall to overwinter in attics, wall voids, and ceilings. During warm spells, they emerge sluggishly, buzzing around windows and light fixtures.
While they’re harmless, their activity can become frustrating — especially in older homes. Vacuuming stragglers and sealing cracks in upper walls and attic vents helps reduce future infestations.
5. Bats, Raccoons, and Squirrels (Wildlife in Attics)
When we think of overwintering pests, insects and rodents often come to mind first — but larger wildlife can also find their way indoors. In Minnesota, little brown bats, big brown bats, gray squirrels, and raccoons are the most frequent attic invaders.
These animals often enter through gaps in soffits, vents, or loose roof shingles while seeking warmth and safety from predators. Once inside, they can cause significant contamination and health hazards.
Risks:
- Raccoon feces can contain Baylisascaris procyonis, a roundworm that poses serious risks to humans and pets.
- Bat guano can harbor Histoplasma fungus, which can lead to respiratory illness.
- Both raccoons and bats may carry rabies, so handling or cleanup should only be done by trained professionals.
If you suspect wildlife activity, such as thumping in the attic, foul odors, or visible droppings, schedule a humane removal service. Abra Kadabra specializes in safe, certified Wildlife Control and cleanup.
Why Walls and Attics Are Perfect for Pests
Your home’s structure provides exactly what overwintering pests are looking for:
- Warmth: Insulation holds heat and provides nesting material.
- Protection: Wall voids and crawlspaces keep pests safe from weather and predators.
- Food access: Pet food, seeds, and pantry goods attract rodents and insects.
- Entry points: Cracks around vents, soffits, and utility lines act as doorways.
Even the smallest unsealed gap can invite an infestation — and once pests are inside, they often remain undetected until spring.
The Hidden Costs: Damage, Contamination, and Health Risks
Pests inside your walls aren’t just an annoyance. Over time, they can:
- Chew wires and insulation, creating fire hazards.
- Contaminate food and storage areas with urine, feces, and nesting debris.
- Damage to drywall and insulation, leading to costly repairs.
- Spread disease, from Hantavirus and Salmonella to parasites like roundworm.
The CDC’s Rodent Prevention Guide offers a comprehensive overview of these health concerns — but the safest solution is professional prevention before problems start.
Homeowner’s Late-Fall Inspection Checklist
Minnesota’s late fall is the perfect time for a pre-winter pest check. Walk your property with this quick guide:
- Exterior walkaround: Look for gaps, gnaw marks, and droppings near the foundation or siding.
- Attic and basement: Check insulation for signs of tunneling or nesting; listen for noises, especially at dusk or dawn.
- Vents and chimneys: Confirm all vents are screened and chimney caps secured.
- Doors and windows: Install or replace weather stripping and door sweeps.
- Utility lines: Seal around electrical and plumbing penetrations.
- Yard: Keep firewood 20+ feet from the house, trim overhanging branches, and clean up leaf litter.
- Storage: Place food, pet feed, and birdseed in sealed containers.
For professional-grade inspection, schedule an appointment with our certified technicians. We’ll identify entry points and recommend customized exclusion strategies for your property.
Do’s & Don’ts in Pest Control DIY
Do:
- Use steel wool and caulk to seal small gaps.
- Install door sweeps on all exterior doors.
- Store food in rodent-proof containers.
- Keep gutters clean and trim vegetation away from walls.
Don’t:
- Rely solely on over-the-counter “foggers” or “pest bombs.”
- Use loose bait or poison blocks where pets or children can access them.
- Ignore small infestations — one mouse often means more nearby.
Abra Kadabra’s About Us page details our science-based, humane approach to long-term pest prevention.
When to Call a Professional
Call in professionals if you:
- Hear scratching, thumping, or rustling in ceilings or walls
- See droppings, grease marks, or gnawed openings
- Notice strong odors or visible damage in attics
- Spot wildlife or nesting material inside your home
A professional visit includes:
- Inspection: Interior and exterior analysis to identify all entry points.
- Exclusion: Sealing openings with durable, chew-resistant materials.
- Sanitation: Removing droppings, soiled insulation, and contaminated materials.
- Monitoring: Setting up secure traps or stations for continued protection.
- Follow-up: Ensuring activity has stopped and entry points remain sealed.
See where we work on our Minneapolis Service Area page.
Late Fall to Winter Pest Control Preparation Tips
- Late Fall: Seal gaps, inspect attics, and install door sweeps. Move outdoor storage and woodpiles away from the home.
- Winter: Stay alert for pest activity. Address noises, droppings, or sightings immediately — overwintering pests are still active, just hidden.
- Spring: Reinspect exteriors after snowmelt. Patch winter damage and reseal entry points before pest season begins.
In Conclusion
Overwintering pests are a fact of life in Minnesota. Infestations aren’t inevitable. With the right combination of exclusion, sanitation, and professional oversight, you can enjoy a quiet, pest-free winter.
Abra Kadabra Environmental Services provides comprehensive pest and wildlife management services for homes throughout the Twin Cities. Start with a free inspection request or learn more about our Residential Pest Control solutions today.
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