Why Mice Move Indoors Every Fall (And How to Stop Them)

Every October, pest control companies across Georgia see the same spike in calls: homeowners hearing scratching in the walls at night, finding mouse droppings in the back of kitchen cabinets, or discovering chewed food packaging in the pantry. It’s not a coincidence, it’s a predictable biological response to the changing season.

The Fall Migration Pattern

House mice and deer mice, the two most common species in northeast Georgia, are what biologists call “commensal” pests. That means they’ve evolved to live alongside humans and depend on our structures for food and shelter.

In warm months, mice can find enough food and shelter outdoors. But as temperatures fall and their outdoor food sources dry up, they shift their focus inward. They’re not randomly wandering into your house, they’re actively searching for entry points, and they’re very good at finding them.

A house mouse can compress its body to fit through an opening the size of a dime (roughly ¼ inch). A rat can fit through a hole the size of a quarter. They probe every inch of your foundation and exterior walls looking for gaps, and once one finds a way in, others follow the pheromone trail it leaves behind.

The Risks Are Bigger Than You Think

Most people think of mice as a nuisance. They’re actually a health and property risk:

Disease: Mice are known carriers of hantavirus (through droppings and urine), salmonella, and leptospirosis. Their droppings and urine contaminate food preparation surfaces and stored food.

Structural damage: A mouse’s incisors never stop growing, so they gnaw constantly to wear them down. They chew wood, insulation, and plastic, including electrical wire insulation. Rodent-chewed wiring is a documented cause of house fires.

Population explosion: A single female mouse can produce 5-10 litters per year with 5-6 pups each. A “mouse or two” becomes a serious infestation within weeks if not addressed.

How to Find the Entry Points

Walk the exterior of your home at ground level and look for:

• Gaps where pipes and conduit enter, the most common entry point, especially in older homes where original pipe penetrations were never properly sealed
• Gaps at the base of doors, pay special attention to garage doors, which often have worn seals
• Foundation cracks, especially where the slab meets the wall or around window wells
• Gaps behind exterior faucets (hose bibs)
• Roof vents and attic vents with deteriorated or missing screens, roof rats and squirrels enter here

Sealing Entry Points

Once you find gaps:

1. Pack steel wool or copper mesh into the opening first, mice can chew through foam and caulk alone, but not through metal mesh
2. Seal over the mesh with exterior-grade caulk or expanding foam
3. For larger gaps, use sheet metal flashing or hardware cloth (¼-inch galvanized mesh)

Replace worn door sweeps on every exterior door. If you can slide a piece of paper under a door, a mouse can get under it.

If They’re Already Inside

Entry-point sealing is the long-term solution, but if mice are already inside, you need to address both the infestation and the entry points simultaneously, otherwise you’re just trapping the mice that are already inside while new ones come in.

Snap traps are the most effective and humane option for catching mice that are already inside. Place them perpendicular to the wall (mice run along walls), baited with peanut butter. Check and reset daily.

Bait stations (rodenticide): Effective but slower, and require careful placement away from children and pets.

Glue traps: Not recommended, inhumane and ineffective for controlling an active infestation.

When to Call a Professional

If you’re finding droppings in multiple rooms, hearing scratching regularly, or catching more than 2-3 mice per week, you likely have an established infestation that needs professional attention. A professional can identify all the entry points (not just the obvious ones), place traps strategically, and provide exterior bait stations that intercept mice before they reach your foundation.

Don’t wait until you have a full infestation. Contact Kilz Pest Control for a free rodent inspection, or call/text us directly at (706) 754-6248. We serve Gainesville, Cornelia, Clarkesville, Dahlonega, Toccoa, and all of northeast Georgia.