House Mice: Identification, Behavior, and How to Get Rid of Them in Ontario

House mice (Mus musculus) are one of the most common and persistent pests found in homes across Ontario. Small, adaptable, and fast-breeding, they can quickly turn a minor issue into a full-blown infestation.

Identification

House mice are small — typically 7–10 cm in body length with a tail nearly as long. They have:

• Light brown to grey fur on the back, lighter underneath
• Large ears relative to body size
• Pointed snout and small, dark eyes
• Droppings roughly 3–7 mm long, rod-shaped with pointed ends

Behavior and Why They Enter Ontario Homes

Mice are opportunistic. As temperatures drop in fall and early winter, they seek warmth, food, and nesting material inside structures. A mouse only needs a gap the size of a dime — about 6 mm — to squeeze through.

Once inside, they establish nesting sites near food sources: inside wall voids, behind appliances, in attic insulation, and inside cabinets.

Health Risks

House mice are more than a nuisance. They can transmit:

• Salmonella via contaminated droppings
• Hantavirus (rare in Ontario, but present)
• Lymphocytic choriomeningitis (LCMV)

They also chew through electrical wiring — a leading cause of unexplained house fires.

DIY Prevention Tips

1. Seal entry points — caulk gaps around pipes, install door sweeps, check foundation cracks
2. Eliminate food sources — store food in sealed containers, clean up crumbs immediately
3. Reduce clutter — mice nest in undisturbed piles; declutter storage areas
4. Yard maintenance — keep firewood away from the house, trim back vegetation

When to Call a Professional

If you’re hearing scratching at night, finding droppings in cupboards, or noticing chewed packaging — you likely have more than one mouse. Mice breed rapidly: a single female can produce 5–10 litters per year with 5–6 pups each.

A Sani IQ technician will inspect your property, identify all entry points, and deploy professional-grade bait stations and traps — deliberately leaving exit routes open so mice exit and die outside, not in your walls. We then return in about three weeks to verify the knockdown and seal minor entry points. Sani IQ bills every visit after it’s done — no monthly fees. Mice inside? The Sani IQ Rodent Program is $445 at the first visit, then $150 after each quarterly visit, with a 12-month warranty. Want the whole house covered? Sani IQ Protect is $249 a visit, four visits a year, rodent prevention included. Compare plans →

Same-day service available. Call (705) 302-1887 or get a free quote.