How to Get Rid of Mice in Your House

The nights turn cold and suddenly there are droppings in the silverware drawer. Mice breed fast: a female can have 5 to 10 litters a year. The good news is that most mouse problems are something you can fix yourself with a flashlight, some steel wool and a box of snap traps. This guide covers how to confirm you have mice, how to trap them and how to keep the next ones out.

How to identify house mice and deer mice

The house mouse is the one that lives in buildings. Adults weigh about 1/2 ounce and are light brown to gray all over, with relatively large ears, small black eyes and a thin tail with almost no fur. Including the tail, an adult is 5 to 7 inches long.

The deer mouse looks similar but matters more for your health. In the US, the deer mouse is the main carrier of the hantavirus that causes hantavirus pulmonary syndrome, a serious and sometimes deadly lung illness. House mice are not known to carry it.

If you think you have a young rat, see our rat guide. Since most people cannot identify a mouse with confidence, treat every cleanup as if deer mice were involved.

Signs of mice

• Droppings: about 1/8 to 1/4 inch long, dark, with one or both ends pointed. A mouse can leave 50 or more a day, scattered along its route.
• Gnaw marks: tiny, about 1/32 inch wide, on food boxes, baseboards and stored items.
• Nests: wads of finely shredded paper, fabric or insulation in drawers, behind boxes, in garages and near warm appliances.
• Sounds: scratching or scampering in walls and ceilings at night.
• Smell: a musky odor in closets and cabinets.

Our signs of rodents guide shows how to tell fresh droppings from old ones, and mouse droppings from cockroach droppings.

Why mice come inside

Mice want food, shelter and warmth. Where they live outdoors, they often move into homes in autumn as nights get colder. They usually stay within about 30 feet of their nest, so if you see one in the kitchen, the nest is close by. Gaps around pipes, under doors and where the siding meets the foundation are the usual way in.

How small a gap can a mouse use?

A house mouse can squeeze under a gap about 1/4 inch tall. The CDC puts it at a hole about the width of a pencil. You may have heard “the size of a dime”: a dime is wider than that, so do not use it as your cutoff. If a pencil fits, assume a mouse can get through, and seal every opening 1/4 inch or larger.

How to get rid of mice, step by step

1. Inspect. Use a flashlight to find droppings, nests and gnaw marks. Check under sinks, behind the stove and refrigerator, inside lower cabinets, the garage and any crawl space.
2. Remove food. Put cereal, grains, pet food and birdseed in glass, metal or heavy plastic containers with tight lids. Feed pets only what they eat at one sitting.
3. Seal entry points. Pack small gaps with steel wool or copper mesh and hold it in with caulk. Use metal, hardware cloth or concrete for bigger openings. Foam, plastic, rubber and wood alone do not stop mice. The rodent-proofing guide has a full checklist.
4. Trap. Snap traps are the standard first tool. Details below.
5. Keep going. Check traps every day. Keep trapping until you catch nothing for a week and see no new signs, and leave traps out at least 15 days.
6. Clean up droppings and nests the safe way (see below).

How to set mouse traps that work

Set the trap so it forms a T with the wall, with the bait end touching the wall. Mice run along walls, so they cross the trigger head-on instead of walking past it.

• Placement: behind objects, in dark corners, along walls and wherever you found droppings. Good spots include behind the stove and refrigerator and at the back of cabinets and drawers.
• How many: more than you think. Space traps no more than about 10 feet apart in active areas. Nebraska Extension suggests about two dozen snap traps for a new infestation in a 1,500 square foot home.
• Double sets: place two traps side by side, an inch or two apart, to catch mice that jump over a single trap.
• Bait: a small dab of peanut butter on the trigger plate. Too much lets the mouse lick it off without springing the trap. If anyone in the home has a peanut allergy, use something else. A small tuft of cotton or dental floss attracts females looking for nest material.
• Trigger: set it lightly. Traps with a wide trigger plate catch more mice.
• Safety: put traps where children and pets cannot reach them, or under a box with a mouse-sized opening.

Battery-powered electronic traps that kill with a shock are another option, though they cost a lot more. For a side-by-side look at every option, see traps vs. bait stations.

Humane options and their realities

Live traps. Multiple-catch live traps can hold several mice at once. The catch is what comes next. Extension specialists do not recommend releasing house mice: they are not native, relocation is stressful for the animal and often fails, and moving them off your property can be illegal (it is in California without a permit). If you use a live trap, check it at least daily, and plan to humanely euthanize the mice. The CDC advises against live traps entirely because frightened mice urinate, which raises your exposure.

Glue boards. They catch mice but kill slowly, mostly catch young mice, and can trap pets, birds and lizards. The CDC recommends against them. If a non-target animal gets stuck, vegetable oil loosens the glue.

Ultrasonic devices. Research has found little evidence that they chase mice out. The sound does not pass through furniture or walls, and mice get used to it.

Bait stations for mice

If trapping and sealing have not solved the problem, a bait station is the next step. Consumer rodent baits are sold only inside ready-to-use stations. Put tamper-resistant stations where children, pets and wildlife cannot reach them, never near food prep areas, and read and follow the label. Be aware that you cannot control where a poisoned mouse dies. If it dies inside a wall, it can cause an odor problem. Many homeowners stick with traps for that reason.

Cleaning up after trapping

• Wear rubber or plastic gloves.
• Spray the dead mouse and trap with disinfectant or a 1 to 9 bleach-and-water mix until wet. Let it soak 5 minutes.
• Pick up the mouse with a plastic bag turned inside out over your hand, seal it, and put it in a second bag before it goes in an outdoor trash can.
• Wet droppings and nests with disinfectant before wiping them up. Never sweep or vacuum them dry.
• Wash gloved hands, remove gloves, then wash your hands with soap and water.

If you develop a fever or feel sick after cleaning up mouse droppings, see a doctor and mention the exposure.

How to keep mice out

• Seal gaps before fall.
• Keep food, pet food and birdseed in sealed containers.
• Keep woodpiles and dense plantings away from the house.
• Cut clutter in garages, basements and storage rooms where mice nest unnoticed.
• Check the seasonal pest calendar for a fall reminder.

When to call a professional

A few mice in the kitchen are a DIY job. Call a pro if:

• You keep finding fresh droppings after three or four weeks of trapping.
• Mice are living in wall voids, ceilings or a crawl space you cannot reach.
• You cannot find how they are getting in, or sealing needs work on the roof line or foundation.
• You found deer mice or a heavily soiled cabin, shed or attic, and the cleanup needs a respirator.

Ask for an inspection that shows you the entry points, and for exclusion work, not just bait.