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Rodents · October 2025 October 2025 · 5 min read

Why Mice Enter Ontario Homes in Fall and How to Stop Them

Ontario mice start looking for warm shelter as temperatures drop in September and October. Learn why they come in, where they hide, and how to keep them out.

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Every fall across Toronto, Peterborough, and the GTA, pest control calls for mice spike dramatically. It is not a coincidence. As outdoor temperatures drop below 10°C, house mice begin aggressively searching for warm shelter and your home is exactly what they are looking for.

Why Fall is Mouse Season in Ontario

House mice do not hibernate. They need a consistent food source and warm environment to survive the Canadian winter. When the temperature starts dropping in September and October, mice that have been living outdoors in gardens, fields, and under decks start moving toward structures. A single mouse can squeeze through a gap as small as 6mm about the diameter of a pencil.

Where They Get In

The most common entry points include gaps around pipes and utility lines where they enter your foundation, cracks in the foundation itself, gaps under exterior doors, gaps around garage doors, weep holes in brick construction, and openings in roof soffits. Many homeowners are shocked to discover that mice are not coming in through obvious holes they are exploiting tiny gaps that have been there for years.

Hearing scratching sounds at night? XtermaPro Pest Control offers free quotes and same day service across Toronto, Peterborough and surrounding areas.

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Signs You Have Mice

The most obvious sign is droppings small dark pellets about 5mm long found along walls, in cupboards, and behind appliances. Other signs include gnaw marks on food packaging or wood, a musky odour in enclosed spaces, scratching or rustling sounds in walls and ceilings at night, and nests made from shredded paper or insulation.

Why DIY Mouse Control Rarely Works Long-Term

Snap traps and glue boards can catch individual mice but do nothing to address the colony or seal entry points. A female mouse produces 5 to 10 litters per year with 5 to 6 pups each populations grow fast. Without locating and sealing entry points, new mice will continue to enter after every removal.

What Professional Mouse Control Includes

A professional treatment from XtermaPro Pest Control starts with a full inspection to identify active runways, nesting areas, and entry points. We deploy commercial-grade bait stations in strategic locations and, critically, we identify and seal the specific entry points being used. A follow-up visit confirms complete elimination.

Don't wait until the problem gets worse. XtermaPro Pest Control offers free quotes and same day service across Toronto, Peterborough and surrounding areas.

Free Quote. Call Now(647) 286-9120

Prevention Tips for Ontario Homeowners

  • Seal gaps around all exterior pipes and utilities with steel wool and caulk
  • Install door sweeps on all exterior doors including the garage
  • Keep firewood stored away from the house
  • Store food in hard-sided airtight containers
  • Keep garage doors closed when not in use
  • Trim vegetation and remove leaf piles from around the foundation

If you are hearing scratching in your walls or finding droppings, do not wait. Mouse populations double every 3 weeks. XtermaPro Pest Control serves all of Toronto, Peterborough, Oshawa, and surrounding areas with same-day emergency response.

A
About the Author

Aamir, Founder of XtermaPro Pest Control

Aamir founded XtermaPro Pest Control in 2015 and has personally led thousands of pest control jobs across Toronto, Peterborough, and the surrounding Ontario cities. He holds a Ministry of Environment exterminator licence and specializes in bed bug heat treatment, rodent exclusion, and discreet unmarked service for condo and apartment clients. Aamir responds to phone calls directly and inspects most high severity jobs himself before a treatment plan is written.

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