How to Get Rid of Mice in Your House: A Step-by-Step Plan for Canadian Homes

How Do You Know You Have Mice in the House?

Mice in the house leave clear signs: droppings, gnaw marks, scratching at night and shredded nesting material. Health Canada lists scampering and scratching in walls at night, gnawing marks, damaged food packages, droppings and urine, holes around foundation walls and tracks on dusty surfaces. Our guide to the signs of a mouse infestation covers each one in detail.

Mouse Droppings

Mouse droppings are usually the first sign you find. They are usually about 1/8 to 1/4 inch long (about 3 to 6 mm), dark, smooth and pointed at one or both ends, a bit like small dark grains of rice. According to the US National Park Service, a single house mouse can leave 50 to 75 droppings a day, so they build up fast along walls, in cupboards and behind appliances. Rat droppings are much larger. See what mouse poop looks like for photos and comparisons.

Gnaw Marks

Gnaw marks show where mice have been chewing to reach food or nesting material. Look for small holes in cereal boxes, bags of flour or pet food, chewed corners on cardboard and nibbled wires. Damaged food packages in the pantry are one of the signs Health Canada lists.

Scratching Noises

Scratching noises in the walls or ceiling at night are a classic sign of mice. Mice are mostly active at night (UC IPM), so you tend to hear them once the house is quiet, scampering inside walls, above ceilings or under floors.

Nests

Nests are typically balls of finely shredded paper, fabric or insulation, often hidden behind boxes, in drawers or in quiet corners of the basement or attic (UC IPM). A musky odour is common when an infestation is large or has been there a long time.

House Mouse or Deer Mouse?

House mice and deer mice are the two kinds of mice you are most likely to find indoors in Canada. According to Health Canada, the house mouse has large ears and is light brown to dark grey with a lighter belly. The deer mouse is brown or grey with a white belly, white feet and a white underside on its tail, and it often moves into buildings near fields and woodlands in the fall. The difference matters: Health Canada names the deer mouse as the most common carrier of hantavirus, so cleanup needs extra care (see the last section). Also make sure it is not a rat: Health Canada notes that a rat trap is too large for a mouse, and rats need their own approach.

How to Get Rid of Mice in the House With Traps

Getting rid of mice in the house is fastest with traps. Health Canada says snap and electronic traps are very effective when they are well placed and set properly, and they generally kill instantly. Traps also let you remove the bodies, so you do not end up with a dead mouse rotting inside a wall.

Snap Traps

Snap traps are the cheapest and most proven way to get rid of mice. Wooden models such as the Victor classic and plastic models such as the Tomcat Press 'N Set are often sold at Canadian hardware stores and can be reused. Health Canada even suggests reusing traps, since they become more attractive to rodents over time. Our step-by-step guide explains how to set a mouse trap, and our tested picks are in the best mouse traps roundup.

Electronic Traps

Electronic traps kill mice with a high-voltage shock inside a closed box, so you never see or touch the mouse. They run on batteries (the Victor model typically uses 4 AA batteries), have a built-in bait cup and are made for indoor use only. Health Canada advises placing them with the entrance parallel to and flush against the wall.

Live Traps

Live traps catch mice without killing them, but they come with drawbacks. The US Centers for Disease Control and Prevention (CDC) advises against live traps because frightened mice urinate in them, which raises the risk of disease. Releasing mice elsewhere is also often ineffective, according to UC IPM. If you use one, check it often and wear gloves.

Glue Traps

Glue traps hold a mouse on a sticky board until it dies or is killed. The CDC advises against them for the same reason as live traps, and many people find them inhumane.

Best Bait for Mice

The best bait for mice is a strong-smelling, sticky food. Health Canada suggests peanut butter, bacon grease mixed with oats, raisins or gumdrops. Use only a small amount: a pea-sized dab of peanut butter is usually enough (Victor), and too much bait can let a mouse eat without setting off the trap (UC IPM).

Pre-Baiting Traps

Pre-baiting means leaving baited traps unset for 3 to 4 days so mice get used to feeding at them, as Health Canada recommends. Once the bait is being taken, set all the traps on the same night.

Where to Put Mouse Traps

Mouse traps work best along walls, where mice travel. Health Canada recommends placing uncovered snap traps at right angles to the wall with the bait end nearest the wall. Good spots include behind the stove and fridge, under sinks, along basement walls and near any droppings or holes you found. Keep every trap out of reach of children and pets (CDC), or put it inside a covered trap box.

How Many Traps You Need

You need more traps than most people think. Health Canada recommends 1 trap per metre along walls where you see activity, or 5 to 10 traps per visible mouse hole. UC IPM advises spacing traps no more than about 10 feet (about 3 metres) apart and using enough traps to make the trapping period short and decisive. UC IPM also notes that pairs of traps set close together can improve catches.

Checking Traps

Checking traps every day is part of the job, according to Health Canada. If the bait is not disappearing, move the trap to a new spot. Keep trapping, and reset your traps after 2 to 3 weeks to catch young mice as they mature. Wear gloves to empty and reset traps.

How Do You Seal Mice Out of Your House?

Sealing entry points keeps new mice from replacing the ones you trap, so do it the same week you start trapping. Health Canada calls this rodent-proofing, and it is the step that makes the result last. Our guide on how to find mice entry points helps you track down every gap.

Gap Size

The gap size to worry about is tiny. Health Canada says mice can squeeze through cracks as small as a dime, and UC IPM gives about 1/4 inch (about 6 mm). Check every gap, even ones that look too small.

Sealing Materials

Sealing materials must be ones mice cannot chew through. UC IPM recommends metal, concrete, wire screen or coarse steel wool, and warns that plastic screening, rubber, vinyl, insulating foam and wood are often ineffective because mice can gnaw through them. Steel wool on its own may be only a temporary plug and can rust, so Health Canada advises stuffing steel wool into gaps first, then caulking or plastering over it. Patch foundation cracks with concrete or mortar.

Doors

Doors are a common way in, especially when a worn threshold leaves a gap at the bottom (Health Canada). Installing metal weather stripping or a door sweep under exterior doors, and weather stripping your windows, can help.

Gaps Around Pipes

Gaps around pipes, cables and gas lines are where mice most often slip through walls. Stuff the space around each pipe with steel wool, then seal it with caulk or plaster, as Health Canada recommends. Check under sinks, behind the washer and where utilities enter the basement.

Vents

Vents need screening because mice climb to reach them. Health Canada recommends covering dryer vents, attic vents and soffits with fine mesh metal screening. For a full home checklist, see our guide on how to keep mice out of your house.

How Do You Remove the Food and Shelter Mice Need?

Removing food, water and shelter makes your home a poor place for mice to live. UC IPM notes that good sanitation seldom gets rid of mice on its own, but poor sanitation can let them thrive, so do this alongside trapping and sealing.

Food Storage

Food storage is the first thing to fix. Health Canada recommends keeping dry food and dry pet food in metal or glass containers, not in thin bags or cardboard boxes. Wipe up crumbs, do not leave pet food out overnight and keep the kitchen clean.

Water Sources

Water sources keep mice going even when food is scarce. Health Canada suggests fixing leaky taps and sweating pipes and covering open drains.

Clutter

Clutter gives mice safe places to nest. Health Canada recommends removing clutter in and around the house and garage. Store boxes off the floor, in plastic bins with tight lids, and keep storage areas tidy so you can spot droppings early.

Outdoor Shelter

Outdoor shelter close to the house gives mice a base to move inside from. Health Canada recommends cutting back tall grass and weeds near the house, raising woodpiles about 30 cm (1 foot) off the ground and keeping them away from the house, keeping garbage in containers with tight-fitting lids, and not putting fatty or oily food waste, eggs or milk products in the composter.

What About Poison and Repellents for Mice?

Poison and repellents are poor first choices for getting rid of mice in a house. Health Canada says baits or poisons should never be the only control method, and repellents usually do not remove mice that are already living inside.

Rodenticide Rules in Canada

Rodenticides sold to homeowners in Canada come with strict rules. Health Canada's Pest Management Regulatory Agency requires domestic rodenticides to be used in bait stations and sold as blocks or other solid baits, and home-use products containing second-generation anticoagulants (brodifacoum, bromadiolone and difethialone) are prohibited. The Government of British Columbia says to use poison only in tamper-proof bait stations and never where children or pets could reach it. Always look for a PCP number on the label, which shows the product is registered by Health Canada, and follow the label exactly. Stronger commercial-class products can only be applied by a certified professional.

Poison Risks

Poison risks go beyond the mice. Anticoagulant blocks can be dangerous for pets, so keep them away from children and pets (Health Canada, NPIC). HealthLinkBC also warns that poisoned rodents can die out of sight, UC IPM notes that baits may take several days to work, and the Government of British Columbia warns that a rodent dying in a place you cannot reach can leave a terrible smell, which trapping avoids. Some poisons can also harm wildlife that eats a poisoned mouse.

Ultrasonic Repellers

Ultrasonic repellers send out high-pitched sound that mice dislike, but they do not get rid of an infestation. Health Canada notes that rodents may adapt and return, so these devices should only be used alongside other methods. UC IPM is blunter: it finds high-frequency devices generally ineffective, because the sound does not reach behind furniture and fades with distance.

Peppermint Oil

Peppermint oil is a popular natural remedy, but there appears to be little good evidence that it drives mice out. Extension specialists describe home remedies like mothballs and strong scents as temporary at best, because the smell tends to fade quickly and mice can get used to it. Use traps and sealing instead, and treat any scent as an extra, not a solution.

How Do You Clean Up After Mice Safely?

Cleaning up after mice safely means wetting droppings with disinfectant first and never sweeping or vacuuming them. The Public Health Agency of Canada (PHAC) gives this advice because deer mice can carry hantavirus, and UC IPM notes that people may breathe it in with dust from droppings, urine and nests.

Disposing of Dead Mice

Disposing of dead mice starts with gloves. Wear rubber or plastic gloves, then put the mouse in a plastic bag, seal it, and place it in a second bag (PHAC, Health Canada). Put it in a garbage bin with a secure lid, following your local by-laws. Wash your gloves before taking them off, then wash your hands with soap and water.

Cleaning Droppings

Cleaning droppings takes a few careful steps, based on PHAC and Alberta government advice:

1. Open doors and windows and leave the area for at least 30 minutes before you start.
2. Put on rubber or plastic gloves. In a closed space such as a shed or crawl space, wear an N95 respirator.
3. Spray the droppings and nesting material with a disinfectant or a mix of 1 part bleach to 9 parts water until soaked.
4. Let it soak for 10 minutes.
5. Wipe everything up with paper towels or a wet mop, and double bag the waste.
6. Wash your gloves, then your hands, and wash any exposed clothing separately (Health Canada).

Our full guide on how to clean mouse droppings covers carpets, insulation and food areas.

How to Know the Mice Are Gone

You know the mice are gone when your traps catch nothing and no new signs appear. The CDC suggests that a week with no catches and no fresh droppings or gnaw marks means the infestation is likely over. Keep a few traps set along walls for a while, especially in the fall, since that is often when new mice try to move in.

When to Call a Pest Control Professional

Calling a pest control professional makes sense when you keep finding droppings after a few weeks of trapping, when mice are in several rooms or floors, when you cannot reach the entry points (roofline, soffits, inside walls), or when you find signs of deer mice in a closed space. A licensed professional usually inspects the inside and outside of the home, seals entry points, sets traps or tamper-resistant bait stations and comes back to check results. Read when to call an exterminator for mice, or get a quote from a recommended local exterminator through Pest Agent's referral form. For everything else about these rodents, visit our mice hub.