The first sign of mice I ever saw wasn’t a mouse. It was in my family’s storage room: tiny dark droppings along the wall and the corner of a cardboard box chewed open. My first instinct was to grab a broom and sweep it all up. It turns out that is exactly what you shouldn’t do, and it’s only one of several things most people get wrong about mice.
Fall is when this happens to a lot of homes. As temperatures drop, mice look for a warm place with food, and a garage, a basement or a kitchen cabinet is perfect. In a survey for the National Pest Management Association, about 27% of Americans said they had found a rodent in their home in the past year. This guide shows how to get rid of mice in your house for good, following the method the CDC recommends, and how to clean up afterward without putting your health at risk.
Three things most people get wrong about mice
| What most people do | What the experts say |
|---|---|
| Sweep or vacuum the droppings right away | The CDC says never sweep or vacuum rodent droppings, urine or nests: it can put virus particles into the air you breathe. There’s a safe method below. |
| Use a “humane” live trap or a glue trap | The CDC advises against both: they scare the mouse, which then urinates, increasing your chance of getting sick. Snap traps are the recommended option. |
| Plug in an ultrasonic repeller or use peppermint oil | The Federal Trade Commission warned more than 60 sellers of ultrasonic pest devices that their claims must be backed by scientific evidence. Neither gadget seals the holes mice use to get in. |
How to tell if you have mice
Mice are active at night and good at hiding, so you usually see what they leave behind before you see them. The National Pest Management Association lists these signs of a house mouse infestation:
- Droppings: small and pointed, about 1/8 to 1/4 inch long, often along walls, in drawers and under the sink.
- Gnaw marks on food packages, boxes, wood or wiring.
- Nests made of shredded paper, fabric or insulation in quiet corners.
- Greasy smudges on walls and baseboards along the routes they use every night.
- A musky smell, strong when there are many mice.
- Scratching sounds in walls or ceilings at night.
- A mouse in daylight, which often means there are more hidden nearby.
Don’t wait to see how bad it gets. According to the same guide, a female mouse can have about six babies every three weeks and up to 35 young a year. A couple of mice in October can be a real infestation by Christmas.
Where mice hide: a room-by-room check
Before you set a single trap, spend ten minutes finding where the mice are actually living. Traps work best within a few feet of their routes, and the same check tells you which holes to seal first. Take a flashlight and look in these spots:
| Room | Where to look | What gives them away |
|---|---|---|
| Kitchen | Under the sink, the back of lower cabinets, the drawer under the oven, behind the fridge | Droppings in corners, chewed packages in the pantry |
| Laundry room | Behind the washer and dryer, around the dryer vent | Lint pulled into a nest, droppings along the wall |
| Basement or utility room | Near the furnace and water heater, where pipes enter the wall | Greasy marks along beams and walls, chewed insulation |
| Garage | Under shelves, in boxes on the floor, around pet food and birdseed | Chewed bags, droppings on the floor near the walls |
| Living areas | Behind the sofa, inside closets, under heating units | Scratching at night, droppings behind furniture |
A useful trick: after you clean an area, check it again two days later. Fresh droppings tell you the mice are still using that route, and that’s exactly where your traps should go. If an area stays clean after a week of trapping and sealing, you’ve likely closed that path.
Step 1: Seal up every way in
This is the step that actually solves the problem, and the one most people skip. Traps remove the mice you have; sealing stops new ones from coming in. And the openings are much smaller than you’d think: the CDC explains that a mouse can get through a hole the width of a pencil, about a quarter inch. If you can fit a pencil into a gap, a mouse can fit through it.
Walk around with a flashlight and a pencil and check these places, which the CDC lists as the most common entry points:
| Inside the house | Outside the house |
|---|---|
| Inside, under and behind kitchen cabinets | Where the foundation meets the ground |
| Behind the fridge, stove and dishwasher | Around pipes, cables and utility lines entering the house |
| Around pipes under the sinks | Vents, including the dryer vent |
| Near the water heater and the furnace | Gaps under exterior doors and the garage door |
| Corners of closets and the pantry | Eaves, soffits, gables and roof rafters |
Then use the right material. Mice chew through foam, plastic and wood, so these won’t hold on their own:
- Small holes: pack them with steel wool, then hold it in place with caulk or spray foam over it.
- Larger holes: cover them with hardware cloth, metal sheeting, lath screen or cement.
- Gaps under doors: add a door sweep, and replace the rubber seal at the bottom of the garage door if it’s torn.
Step 2: Trap the mice already inside
The CDC recommends traditional snap traps, and gives specific tips that make them work much better:
- Bait with a small amount of chunky peanut butter. A pea-sized amount is enough; too much and the mouse can lick it off without setting off the trap.
- Place the trap against the wall in a “T”. Put the baited end touching the wall, because mice run along walls rather than across open floors.
- Set several traps where you’ve seen droppings or gnaw marks: under the sink, behind appliances, along the back of cabinets and in the garage or storage room.
- Check them every day and dispose of any dead mice right away, wearing gloves.
- Keep traps away from children and pets. In a home with kids or a curious dog, put traps inside cabinets or behind appliances, or use enclosed snap traps.
The CDC specifically says not to use glue traps or live traps: a trapped, frightened mouse urinates, and that increases your chance of getting sick.
What about poison? The CDC suggests keeping poison bait stations for infestations that don’t respond to traps. If you use them, the EPA recommends tamper-resistant bait stations, which have been tested to keep young children and dogs out. There’s also a practical downside: a poisoned mouse often dies inside a wall, where you can’t reach it and the smell can last for weeks.
Step 3: Clean up safely
This is the part I would have gotten wrong in my family’s storage room. Mouse droppings, urine and nests can carry viruses and bacteria, and the CDC lists a long range of diseases rodents can spread. Sweeping or vacuuming puts dried particles into the air. The CDC’s method for cleaning up after rodents is:
- Ventilate first. Open doors and windows for 30 minutes before you start, and leave the area while it airs out.
- Put on rubber or plastic gloves.
- Mix a fresh bleach solution: 1½ cups of household bleach in 1 gallon of water, which is 1 part bleach to 9 parts water.
- Spray the droppings, urine and nests until they are soaked and let it sit for 5 minutes, or as long as the product label says.
- Pick everything up with paper towels and throw it away in a sealed bag.
- Disinfect the area, including countertops, cabinets and the floor nearby.
- Wash your gloved hands, take off the gloves and wash your hands again with soap and water.
Throw away any food the mice may have touched, including opened boxes and bags. Wash dishes and utensils from cabinets where you found droppings before you use them again.
Step 4: Make your home less attractive to mice
Mice come in for three things: warmth, shelter and food. You can’t remove the warmth, but you can remove the rest:
- Store food in glass or metal containers with tight lids. Mice chew through cardboard and thin plastic in minutes.
- Don’t leave pet food out overnight, and keep the bag in a sealed bin.
- Wipe up crumbs and take out the kitchen trash every night. Our 15-minute nightly reset already covers it.
- Get boxes off the floor. Clutter gives mice places to hide and nest.
- Keep firewood, birdseed and grass seed outside and away from the walls of the house.
- Trim plants and branches that touch the house, because they work as a bridge to the roof.
Garages, storage rooms and attics
The places we rarely visit are the ones mice like best: quiet, dark and full of cardboard. Our storage room taught me that. If you keep things in a garage, attic or storage unit:
- Replace cardboard boxes with plastic bins with lids.
- Keep bins on shelves, not on the floor, and leave a gap from the wall so you can see behind them.
- Never store food, birdseed or pet food there.
- Check those spaces once a month in fall and winter, looking for droppings along the walls.
Our guide on how to organize a small attic without wasting space explains how to store things so they stay clean and easy to check.
Mice in an apartment
In an apartment building, mice often move between units through shared walls and pipes, so sealing your own apartment only goes so far. Set traps and keep food sealed, but tell your landlord or property manager in writing as soon as you see signs, with photos and the date. Pest problems that come from the building are usually the landlord’s responsibility, and a coordinated treatment of several units works much better than each tenant fighting alone. Our apartment maintenance checklist for renters explains how to write a request that gets results.
When to call a professional
- You keep catching mice after two weeks of sealing and trapping.
- You hear them inside the walls or ceiling and can’t reach them.
- You find large nests or a lot of droppings, especially in an attic, crawl space or a storage area that has been closed for a long time.
- You see signs of rats, which are larger and need a different approach.
The short version
Getting rid of mice comes down to the CDC’s three steps: seal up, trap up and clean up, in that order. Close every gap a pencil fits through, set snap traps along the walls with a little peanut butter, and when you find droppings, open the windows and reach for the bleach spray instead of the broom.