How Mice Get Into Your House in Fall (and How to Keep Them Out)

Mice get into houses through small gaps around garage doors, pipes, vents and foundations, and most of them move in between September and November. A young mouse can fit through a hole about 6 mm wide, smaller than a dime. Find and close those openings before the weather turns, and you stop most of the problem before it starts.

Why Mice Move Indoors in the Fall

Through the summer, mice live outside in fields, gardens, hedges and wood piles. When nights get cold and the rain sets in, food outdoors gets scarce and they look for somewhere warm and dry. Your garage, crawlspace or the insulated space behind the stove fits that description. If you live near farmland or open fields, as many Ladner homes do, more mice are nearby to begin with.

If you're already seeing signs of mice inside, our mouse control service covers removal and sealing.

The Most Common Ways Mice Get In

• Garage doors. A worn or torn rubber seal along the bottom leaves a gap mice slip under easily.

• Pipes and wires. Where water lines, gas lines and cables enter the house, there is often a loose gap around the hole.

• Dryer and bathroom vents. Missing or broken flaps give mice a direct path inside.

• Foundation cracks and weep holes. Settling over the years opens small gaps near ground level.

• Crawlspace vents. Screens rust or get pushed in, especially on older homes.

• Doors and windows. Worn weatherstripping and gaps under exterior doors.

• Items you bring in. Boxes, firewood and garden furniture moved inside for winter can carry mice with them.

Early Signs Mice Have Moved In

Droppings in the back of drawers, under the sink or along the garage wall

• Nibbled pet food, bird seed or grass seed bags in the garage

• Bits of chewed paper, fabric or insulation tucked into corners

• Pets staring at or pawing at one spot on a wall or appliance

• Light scratching sounds in the evening when the house is quiet

What You Can Do Yourself

Walk around the outside of your home in September and check every place a pipe, wire or vent goes through the wall. Pack small gaps with steel wool or copper mesh, then seal over them with caulking. Mice chew through plain foam and caulking alone.

Replace the bottom seal on the garage door if you can see daylight under it. Put covers on vents that are missing them. Inside, store pet food, bird seed and dry goods in hard plastic or metal containers, and keep firewood stacked away from the house.

If you find droppings, don't sweep or vacuum them. Put on gloves, wet the area with disinfectant and wipe it up with paper towels, then throw them out in a sealed bag.

When to Call a Professional

Call for help if you're seeing fresh droppings every few days, hearing activity in walls or ceilings, or you've sealed what you can find and the mice keep coming back. That usually means there's an entry point you can't see, often at the roofline or inside the crawlspace. A professional inspection finds those gaps and deals with the mice already inside.

Mice in Ladner, Tsawwassen and South Delta

South Delta has a lot of open land next to homes, from farm fields in Ladner to the green spaces around Tsawwassen. That gives mice plenty of places to live in summer and plenty of reasons to move into houses in the fall. Garages that stay open during yard work are one of the most common ways they get in here. We serve all of Ladner, Tsawwassen and South Delta.

FAQ

What month do mice come inside?

Most move indoors from September to November, once nights get cold and wet.

Can mice climb walls?

Yes. They can climb rough surfaces like stucco and brick, so gaps higher up the wall count too.

Do mice leave on their own in spring?

Not usually. Once they're nesting inside with food nearby, they stay and keep breeding.

Is it mice or rats in my ceiling?

The sounds and droppings are different. Read Scratching in the Ceiling: Rats or Mice? to tell them apart.