If you spotted a mouse in your kitchen or heard scratching inside your walls at night, do not wait. Mouse activity across Toronto and the GTA spikes every fall as temperatures drop and mice start moving toward heated structures. A single mouse sighting almost always means more are already inside. Here is what you need to know and what actually works.
Why Toronto Homes Get Mice Every Fall
Toronto’s cold winters make every home a target. As outdoor temperatures drop in September and October, mice start actively searching for warm shelter with a reliable food source. Your home provides exactly that.
Construction across North York, Scarborough, and the downtown core is making things worse. Major excavation displaces established mouse colonies into surrounding residential streets. Rodent service requests in Toronto more than doubled between 2015 and 2024 according to city data, and that pressure has continued into 2026.
Older homes in established GTA neighbourhoods face the highest risk. Aging foundations, deteriorating weatherstripping, and gaps around decades-old utility penetrations give mice multiple ways in. Newer builds in areas like Vaughan, Brampton, and Markham that sit on former farmland face pressure from field mice displaced by development. Either way, September through November is the window when it happens every year.
How Mice Actually Get Into Your Home
Mice fit through a gap as small as 6mm. That is roughly the diameter of a pencil.
The most common entry points in GTA homes are the gap between the bottom of your garage door and the concrete floor, spaces around utility pipes under kitchen sinks, dryer vent openings without proper screens, gaps where cables and conduits enter through exterior walls, and cracks along the sill plate where your home sits on the foundation.
House mice are curious and investigate immediately. Unlike rats which avoid new objects for days, mice explore right away. A gap that opened up last summer from shifting concrete or weathered caulking becomes an entry point by October.
Condos and apartment buildings in Toronto face a different version of the same problem. Mice enter through shared walls, utility chases, and elevator shafts and travel between units quickly. What starts in one unit can become a building-wide problem within weeks.
Signs You Have Mice in Your Toronto Home
Most people hear scratching before they see anything. House mice are nocturnal and most active between 11pm and 2am, moving through wall voids while the house is quiet.
Small dark droppings measuring 3 to 6mm with pointed ends along baseboards, inside kitchen cabinets, and behind appliances confirm active mouse presence. Fresh droppings are dark and moist. Older ones turn grey and crumbly, which tells you how long the infestation has been going on.
Gnaw marks on food packaging, cardboard boxes, and wooden baseboards indicate active feeding. Mice gnaw continuously to wear down their teeth and will chew through almost anything including electrical wiring.
A musky ammonia smell in enclosed spaces like pantries and utility rooms comes from mouse urine accumulating along their regular travel routes. If you notice this smell in a cabinet or closet you do not open often, check for droppings immediately.
Nesting material including shredded paper, insulation, and fabric packed into dark corners, behind appliances, and inside stored items confirms an established population is living inside your home, not just passing through.
If you find any of these signs, the population inside your walls is almost certainly larger than what is visible. A single breeding pair produces up to 60 offspring per year inside a heated home.
Why DIY Mouse Control Rarely Works
Store bought snap traps and bait boxes work in some situations but they address the mice you can see, not the ones you cannot.
The core problem with DIY mouse control is that it treats the population without addressing the entry points. You can trap every mouse currently inside your home and have a new group move in within weeks through the same gaps they used the first time.
Glue traps are considered inhumane by most pest management standards and are largely ineffective against established populations. Ultrasonic repellers have no documented effectiveness against house mice.
Rodenticide sold over the counter in Canada is significantly weaker than what licensed technicians use. Over-the-counter bait also carries risk to pets and children when placed without proper tamper-resistant stations.
The one DIY step that does help is exclusion, which means sealing the gaps mice use to get in. Steel wool packed into gaps and sealed with caulk, metal flashing around utility penetrations, and new weatherstripping on garage doors all reduce pressure. But identifying every entry point on a full GTA home requires a trained eye and a flashlight in places most homeowners never check.
What a Professional Mice Control Program Looks Like
A proper mice control program follows three phases.
First is a full inspection. Every room, every utility space, and every exterior wall is checked for entry points, droppings, gnaw damage, and grease marks. The goal is to map exactly where the population is concentrated and how they are getting in.
Second is treatment. Licensed technicians use a combination of snap traps at high-activity points and tamper-resistant bait stations placed along travel routes. Product placement follows MECP regulations and is positioned safely away from children and pets.
Third is exclusion. Every identified entry point is sealed with appropriate materials including steel mesh, metal flashing, and commercial grade sealant depending on the location. This step is what separates a professional program from a temporary fix. Without it, the problem returns.
Our rodent control program includes all three phases and comes with a written warranty. If mice return within the warranty period, we come back at no charge.
When to Call a Professional
Call immediately if you are hearing scratching in multiple rooms, finding droppings in your kitchen, seeing actual mice during daylight hours, or noticing gnaw marks on electrical wiring.
Daytime sightings are particularly important. When mice are active during the day it usually means the population is large enough that individuals are being pushed out of their nesting areas by competition. That is not a one mouse problem.
Do not wait until November. By the time GTA temperatures drop below zero, mice that entered in September have already established nesting sites, found food sources, and begun breeding inside your walls. Treating an established winter infestation takes significantly more time and effort than catching them at the entry point in early fall.
If you are in North York, Toronto, Scarborough, Vaughan, Markham, Mississauga, or anywhere across the GTA, Saba Pest Control responds 24 hours a day with a guaranteed 30 minute arrival time. Call (647) 867-7378 or visit sabapc.ca to book a free inspection.
Frequently Asked Questions
How do I know if I have one mouse or an infestation?
A single mouse sighting inside your home almost always means more are present. Mice are social and rarely travel alone inside a structure. If you are finding droppings in multiple locations or hearing scratching in more than one area, you have an established population rather than a single animal.
Can mice make my family sick?
Yes. House mice contaminate food and surfaces with Salmonella and Lymphocytic choriomeningitis virus through their droppings and urine. Deer mice, which are common in GTA communities near ravines and green space, carry Hantavirus Pulmonary Syndrome. Never sweep or vacuum mouse droppings dry. Wet them with a disinfectant first before wiping them up.
How long does professional mice control take to work?
Snap traps produce immediate results. Bait stations take 7 to 14 days to significantly reduce the population as product moves through the colony. Full resolution including follow-up visits typically takes 2 to 4 weeks depending on the size of the infestation.
Is it true mice can get into condos and apartments too?
Yes. Multi-unit buildings in Toronto are particularly vulnerable because mice travel freely through shared plumbing chases, wall voids, and utility penetrations between units. A professional inspection of all affected units and common areas is required to resolve a mouse problem in a condo or apartment building.
