When temperatures drop, mice go house hunting. A mouse can squeeze through a gap the size of a dime, and once one gets in, you can bet more will follow. A single pair of mice can produce over 60 offspring in a year, so a small problem becomes a big one fast.
Here's how to keep them outside where they belong.
Why Do Mice Come Inside in Winter?
Mice aren't built for cold weather. They don't hibernate, and they don't have enough body fat to survive extended freezing temperatures. When fall arrives, they start looking for warm shelter with easy access to food and water.
Mice can detect warm air escaping through small gaps in your home's exterior. That warm draft is essentially a welcome sign. Once a mouse finds an entry point, it leaves scent trails that guide other mice to the same spot.
In Nashville and Middle Tennessee, mouse activity peaks between October and February. But the best time to prevent a mouse problem is before those first cold nights arrive.
Signs You Already Have Mice
Mice are nocturnal and cautious, so you'll usually notice the evidence before you see the mice themselves.
Droppings are the most obvious sign. Mouse droppings are small, dark, and pointed at the ends — about the size of a grain of rice. You'll find them near food sources, along baseboards, and in cabinets. They look different from rat droppings, which are larger and more rounded.
Scratching sounds in walls at night are another telltale sign. Mice are most active between dusk and dawn, and you'll often hear them running through wall voids, above ceilings, or under floors.
Gnaw marks on food packaging, wires, or wood indicate active chewing. Mice gnaw constantly to keep their teeth worn down, and they'll chew through almost anything that isn't metal or glass.
Nesting material like shredded paper, insulation, fabric, or plant material means mice have set up a permanent home. Check behind appliances, in attic insulation, and in rarely disturbed storage areas.
Grease marks along baseboards and walls appear as dark smudges. Mice tend to follow the same paths repeatedly, and the oils in their fur leave visible marks over time.
You can learn more about common hiding spots in our article on where mice hide in a house.
How Mice Get Into Your Home
Mice are incredible at finding entry points. A mouse can fit through any gap that's large enough to fit a pencil — about a quarter inch.
Gaps around pipes and utility lines are the most common entry points. Every pipe, wire, or cable that enters your home creates a potential opening.
Cracks in the foundation develop naturally as homes settle. Even hairline cracks in concrete can widen over time, and mice are patient enough to work at them.
Garage doors with worn weather stripping are one of the most overlooked entry points. The rubber seal along the bottom of your garage door deteriorates with use, and even small gaps along the edges are enough.
Open crawlspace vents give mice direct access to the underside of your home. From there, they can find their way into wall voids and living spaces.
The roofline is another common entry point, especially for roof rats. Overhanging tree branches give rodents a direct highway to your roof.
Homes in Mt. Juliet, Lebanon, and Thompson's Station with crawlspaces are particularly vulnerable. Crawlspace construction is common in Middle Tennessee, and it gives mice a sheltered staging area right beneath your floors.
10 Ways to Mouse-Proof Your Home Before Winter
Prevention is always more effective than reaction. Here's how to make your home as unappealing to mice as possible.
1. Seal all gaps larger than 1/4 inch with steel wool and caulk. Steel wool is key — mice can chew through caulk alone, but they won't chew through steel wool. Pack it into the gap first, then seal over it with caulk.
2. Install door sweeps on exterior doors. The gap under your front door, back door, and garage entry door are all potential entry points.
3. Replace damaged weather stripping on garage doors. Check the bottom seal and the seals along the sides of the door. Replace any sections that are cracked, compressed, or missing.
4. Screen crawlspace and attic vents. Use 1/4-inch hardware cloth to cover vents. Standard window screen isn't strong enough — mice will chew right through it.
5. Store food in airtight glass or metal containers. Mice can chew through cardboard, paper, and most plastics. Glass and metal are the only truly mouse-proof storage options.
6. Keep bird feeders away from the house. Bird feeders are a major food source for mice. If you have feeders, place them at least 20 feet from your home.
7. Trim tree branches within 6 feet of your roofline. Mice and rats are excellent climbers. Branches that touch or hang near your roof give them easy access.
8. Stack firewood 20 or more feet from the house. Woodpiles are ideal mouse habitat. Keep them far from your home and elevate them off the ground.
9. Remove clutter from your garage and storage areas. Clutter provides nesting material and hiding spots. The less cover mice have, the less comfortable they'll be.
10. Schedule a fall perimeter treatment. A professional perimeter treatment creates a chemical barrier around your home's foundation that deters mice and other pests from entering.
What to Do If You Already Have Mice
If mice are already inside, prevention alone won't solve the problem. You need to address the existing population and then seal them out.
Don't rely on a single snap trap. Mice multiply fast, and one trap isn't going to make a dent in an established population. Multiple traps placed along walls and in high-activity areas will be more effective.
Poison bait stations can be effective, but they require professional placement. Improperly placed bait can be accessed by children, pets, or wildlife. And if a poisoned mouse dies inside your walls, you'll be dealing with the smell for weeks.
The most important step is finding and sealing entry points. If you kill the mice inside but don't close the door behind them, new mice will move in within weeks.
Thrive's mice removal service includes entry point identification, exclusion work, and ongoing monitoring. We also offer rat extermination for homes dealing with larger rodent problems. We serve Nashville, Salt Lake City, and all surrounding areas.
Frequently Asked Questions
Can mice climb walls?
Yes. Mice are excellent climbers and can scale most textured surfaces, including brick, wood siding, and stucco. They can also jump up to 12 inches vertically. This is why sealing entry points at every level of your home — not just ground level — is important.
How many mice is considered an infestation?
There's no official number, but if you're regularly finding fresh droppings, hearing scratching at night, or seeing mice during the day, you're dealing with an infestation. Mice are social animals, so where there's one, there are almost always more.
Do mice come back to the same house?
Yes. Mice leave scent trails that persist even after they're removed. If you don't seal the entry points, new mice will follow those trails right back into your home. Thorough exclusion work is the only way to prevent re-entry.
Is it one mouse or more?
If you've seen one mouse, assume there are more. Mice are social and rarely live alone. By the time you see one, there's usually a small group already established nearby.
