Rodents · Mus musculus
House mice
House mice are small gray-brown rodents that nest inside walls, attics, cabinets and crawl spaces. They contaminate food with droppings and urine, chew wiring and insulation, and can spread disease-causing germs. They're among the most common household pests in Southeast Tennessee, moving indoors in large numbers as nights cool in fall.
Seasonal activity
When they're active in Southeast Tennessee
Cooler nights push mice indoors to nest in walls, attics and cabinets.
- January: Peak
- February: Moderate
- March: Low
- April: Low
- May: Low
- June: Low
- July: Low
- August: Low
- September: Moderate
- October: Peak
- November: Peak
- December: Peak
Signs
How to tell you have them
- Dark droppings about 1/4 inch long with pointed ends, along walls, in drawers and under sinks
- Scratching or scurrying in walls or ceilings at night
- Gnawed food packages, chewed wires and shredded paper or insulation
- Nests of shredded paper, fabric or insulation tucked into voids, drawers or stored boxes
- A stale, musty urine odor in closed-up areas
- Greasy rub marks along baseboards and around holes where mice travel the same route
Why they're a problem here
Mice live outdoors in fields, fencerows and woodlines all summer, then look for warm shelter as temperatures drop. In Southeast Tennessee and North Georgia that usually starts in September and October. Homes near farmland, woods or new construction tend to see more pressure, and older houses with crawl spaces have more gaps to work with.
Once inside, they breed fast. A female can have a litter of five or six every few weeks, and the young are ready to breed themselves in under three months. Mice nibble at many foods and leave droppings and urine wherever they go, which contaminates far more food than they eat. Their constant gnawing on wiring and insulation is also a real fire and damage concern.
How we treat them
Trapping removes the mice you have. Sealing keeps the next ones out. You need both.
- 01
Inspect inside and out
We trace droppings and rub marks to find travel routes and nesting areas, then walk the exterior for gaps around pipes, vents, garage doors, siding and the foundation.
- 02
Trap and bait safely
Snap traps set along walls where mice run are the core of indoor control. Where rodenticides make sense, they go in tamper-resistant bait stations, used according to the label and kept away from kids and pets.
- 03
Seal entry points
Openings about 1/4 inch or larger get sealed with materials mice can't chew through, such as steel wool or copper mesh packed in and caulked, hardware cloth and sheet metal. Expanding foam by itself won't stop them.
- 04
Clean up and follow up
We check traps until activity stops and advise on safe cleanup of droppings and nesting material.
Prevention
What you can do today
- Seal gaps of 1/4 inch or more, about the width of a pencil, around pipes, wires, vents and the foundation
- Install door sweeps on exterior and garage entry doors and fix gaps under garage doors
- Screen attic, foundation and dryer vents
- Store food, pet food, birdseed and grass seed in sealed hard containers
- Keep boxes and stored items off the floor and cut down clutter in garages and basements
- Keep firewood, brush and dense vegetation away from the foundation
- Set snap traps along walls at the first sign of mice, before numbers grow
When to call us
Rodent control
Inspection, trapping, exclusion and cleanup for mice and rats in walls, attics and crawl spaces.
How we treat itQuestions
House mice FAQ
Why do mice come inside in the fall?
Mice are active year-round, but cooling temperatures and fewer food sources outdoors send them looking for warm, sheltered places in October and November. A small gap around a pipe or garage door is all they need. Sealing up in late summer is the best timing.
How small of a hole can a mouse fit through?
About 1/4 inch, roughly the width of a pencil. If a pencil fits through a gap, assume a mouse can too. That's why sealing every small opening matters more than any trap or repellent.
Are house mice dangerous?
Their droppings and urine can carry germs that contaminate food and surfaces, and mouse allergens can aggravate asthma. Hantavirus in the U.S. is associated with deer mice rather than house mice, but wear gloves and wet down droppings with disinfectant before cleaning instead of sweeping or vacuuming them dry.
Does peppermint oil keep mice away?
Not reliably. Extension specialists note that scent repellents like peppermint oil don't hold up and can even make traps and baits less effective. Sealing entry points and trapping are what actually work.
If I see one mouse, are there more?
Usually. Mice stay within a small area of their nest and breed quickly, so one sighting often means a small family group nearby. Seeing one in daylight doesn't automatically mean a big infestation, but it's a good time to act.
References
Last fact-checked October 15, 2026.
Think you have house mice?
Tell us what you're seeing and where. We'll call you back to schedule.