Why do mice come into Toronto homes in winter, and how can I keep them out?

You can keep mice out of your home by sealing every possible entry point, eliminating what attracts them (food and clutter), and staying vigilant with preventative measures and inspections. In other words, “mouse-proof” your house so these rodents can’t get in or want to stay. A few simple home maintenance steps done in the fall and early winter can spare you the headache of dealing with unwelcome furry tenants later on. Let’s break down the most effective strategies to mouse-proof your Toronto home during the cold season:

• Seal All Entry Points: The first line of defence is blocking the ways mice get inside. Do a thorough inspection of your home’s exterior and foundation; remember, mice can squeeze through holes as small as a dime, so no gap is too minor to fix. Common entry points include cracks in the foundation, gaps around utility pipes and wires, openings in siding or brickwork, broken or missing vent covers, and spaces under doors or around window frames. Use weather-resistant caulk or expanding foam to seal small cracks. For larger gaps or holes, especially ones that might be gnawed, fill them with steel wool or metal mesh and then caulk over – mice hate chewing through metal fibres. Check that door sweeps and weatherstripping on exterior doors are intact (if you can see light under a door, a mouse can likely get under it). Don’t forget to cover vents and chimney openings with fine mesh screens as well. By blocking every tiny doorway a mouse might use, you essentially lock them out before they can become a problem.
• Eliminate Food Sources: Like any creature, mice are on the hunt for food. Make your home less appetizing by practicing good kitchen hygiene and food storage. Keep all pantry and dry foods in airtight containers (preferably sturdy plastic or glass jars that mice can’t chew through). Don’t leave pet food sitting out overnight, and clean up any spills or crumbs right away. Take garbage out regularly and use trash bins with tight-fitting lids – in winter, a garbage can in a warm garage can smell like a buffet to a hungry mouse. Outside, ensure your compost bin is rodent-resistant (use a closed bin, and avoid composting meats or greasy foods that particularly attract pests). If you remove the easy meals, mice are far less likely to stick around. A hungry rodent is a determined rodent, so don’t let your home be an all-you-can-eat buffet for them.
• Keep a Tidy Yard and Exterior: Surprisingly, your yard maintenance affects your mouse problem. Clear away any debris or clutter around the outside of your house that might shelter rodents. Piles of fallen leaves, overgrown bushes, or stacked firewood right up against the house can all act as inviting hiding spots where mice will hang out until they find a way in. Rake up leaves and dispose of them; don’t let them accumulate near the foundation. If you store firewood, keep it elevated at least a foot off the ground and ideally keep the pile several meters away from your house – this prevents it from becoming a mouse motel right next to your walls. Trim back any tree branches or shrubs that touch your siding or roof; mice are adept climbers and can use overhanging branches like a highway to your attic. By keeping the perimeter of your home clean and trimmed, you remove convenient nesting sites and make it harder for rodents to approach unseen.
• Reduce Indoor Clutter (Especially in Storage Areas): Inside the home, eliminate clutter that could serve as nesting material or hiding places for mice. Basements, attics, and garages are prime real estate for rodents because they’re often quiet and filled with junk. Go through those areas and tidy up: cardboard boxes, old newspapers, fabric piles, and general clutter in dark corners are basically luxury condo units for mice. Dispose of what you don’t need, and store important items in plastic bins with secure lids instead of chewable cardboard boxes. Keeping things off the floor and organized will not only deter mice from nesting, but also make it easier for you to spot early signs of activity (like droppings or gnawed items) before an infestation gets out of hand.
• Manage Garbage and Waste Properly: Garbage can be a huge attractant for rodents, so handle it wisely. Always use garbage cans with tight lids, and don’t let trash overflow. If possible, put your trash out on the morning of pickup rather than the night before, especially in winter – you don’t want a warm bag of garbage sitting out all night to tempt mice or rats. For businesses or if you have to store garbage outside, keep dumpsters or bins well away from doors and windows, and ensure they are regularly cleaned; overflowing dumpsters are like a neon welcome sign for mice. Good sanitation goes a long way in making your home less appealing to pests.
• Be Vigilant and Inspect Regularly: Don’t wait until you physically see a mouse to take action. Regularly checking your home for signs of rodents can catch a problem early. Every few weeks, especially in fall and winter, do a quick sweep: look in the backs of kitchen cabinets, around the furnace or water heater, along baseboards in the garage or basement, for any mouse droppings or gnaw marks. Listen for scratching or scurrying noises in walls or ceilings at night. If you find suspicious evidence but aren’t sure, consider scheduling a professional pest inspection in Toronto. Many pest control services (including our team at Insectica) offer free inspections, which can give you peace of mind or alert you to an issue before it grows. Early detection is key – it’s much easier to mouse-proof a home or set a few traps preemptively than it is to evict a large, established mouse colony.
• Use Traps Proactively: If you’ve had mice before or know they’re common in your neighbourhood, it can be wise to set a couple of mouse traps as a preventive measure in late fall. High-risk areas like the attic, cold cellar, or garage corners could have a few snap traps or enclosed bait stations set up, just in case a curious mouse wanders in. The goal is to catch intruders before they multiply. If you’re using traps, check them regularly (daily if possible) so you can dispose of any caught mice promptly and reset the trap. Always place traps out of reach of children and pets for safety. While traps can help reduce small incursions, remember that if you start catching mice frequently or suspect a bigger infestation, it’s time to escalate the strategy – which brings us to the next point.
• Call a Professional Exterminator when Needed: Sometimes, despite all your best prevention efforts, those crafty rodents still find a way in. If you’re dealing with an ongoing or larger infestation – say you’re hearing constant activity in the walls, or the traps keep filling up – don’t hesitate to call a professional exterminator in Toronto for help. Professional pest control technicians can assess the situation and use specialized tools and treatments to eliminate the mice safely and effectively. They’ll also help identify how the mice are entering and advise on long-term fixes. There’s no shame in bringing in reinforcements; even the most diligent homeowners can get a mouse or two sneaking by. The sooner you get expert help, the sooner you’ll resolve the issue and prevent a minor mouse problem from turning into a major nightmare. Remember, in Toronto, there are many capable pest control companies (Pestend, GreenLeaf, Advantage, Maple Pest Control, etc.) ready to assist – and our own team at Insectica is always available with same-day pest control in Toronto when you need prompt, reliable service.