Where to place mouse traps

How a mouse moves, and why it decides the placement

House mice are prey animals with poor eyesight. They navigate by touch — specifically, by keeping their whiskers and one flank in contact with a vertical surface. They use the same routes every night, and they cross open floor only when they have to.

Everything about trap placement follows from that:

• Traps go against walls. Not near them, against them.
• Perpendicular, not parallel. The trigger end should touch the baseboard so a mouse running the wall meets the trigger square. A trap laid parallel presents its long side and gets stepped over.
• Where the droppings are, not where you saw the mouse. The sighting was a mouse in transit; the droppings mark the route.
• In pairs at the busiest points. Mice occasionally leap the first trap; a second one 10 cm behind it catches those.

Reading a runway in two minutes

Take a flashlight and hold it low, almost flat against the floor, pointing along the baseboard. The angle reveals things overhead light does not.

You are looking for:

• Droppings in a line. A line is a route. A scatter is a visit.
• Grease marks — a faint dark smear along the wall at mouse-shoulder height, from oils in the fur.
• Tracks in dust, particularly behind appliances and in the back of cupboards.
• Gnaw damage at cupboard corners, on packaging, at the bottom of doors.

If none of that is visible, slide a few monitoring glue boards under the refrigerator, the washing machine and the base of the pantry overnight. Whichever picks up hair or droppings has found the route — then lift the board and put real traps there. That is the only use we recommend for glue boards, and the reasoning is in snap trap vs glue trap.

Room by room

Kitchen. Behind and underneath the refrigerator is the single most productive spot in most houses — it is warm, dark, undisturbed and there are crumbs. Then under the sink, along the back wall of base cabinets, behind the stove, and inside the pantry against the back wall at floor level.

Utility room and laundry. Behind the washer and dryer, along the wall where pipes enter, and behind any stack of stored boxes.

Garage. Against the wall shared with the house, along the back wall behind shelving, and beside any stored pet food or birdseed. See mice in the garage — it is usually where they come in.

Basement. Along the foundation wall, behind the water heater, and beside the point where the sewer or water main comes through.

Attic. Along the joists at the edges rather than in the open middle, and near any stored fabric or insulation that has been shredded.

Bedrooms and living rooms. Usually not where the problem lives, but behind furniture against an exterior wall if you have droppings there.

The three places almost everybody misses

1. Inside the kitchen kickboard. The void under base cabinets is a mouse motorway: warm, enclosed and directly connected to the wall cavity. Most kickboards clip out. Put two traps in there and leave them.
2. The gap behind the oven and the back wall. Not under the oven — behind it, where the cables run.
3. Wherever the dryer vent or a pipe passes through the exterior wall. That is frequently the entry point itself, which means it is the one spot every mouse in the house has walked past.

Traps that need different placement

Electronic traps work best flat against a wall with the tunnel mouth parallel to the run, so a mouse walks straight in rather than having to turn a corner into a dark tube. They also need to be level; a unit tilted on carpet loses the geometry the plates depend on. More on electronic traps.

Enclosed traps are wider than a bare snap trap, so they often sit slightly proud of the wall. That is fine — what matters is that the entrance faces along the run, not into the room. Pet-safe mouse traps covers the models.

Live traps go on the same runways, with the additional constraint that you have to be able to reach them twice a day without moving furniture. A live trap behind a refrigerator is a live trap you will not check. Humane mouse traps.

Placement in a house with pets or children

Do not solve this with placement. Solve it with the trap.

"Behind the refrigerator where the dog cannot reach" fails the day the dog can reach. An enclosed trap or an electronic trap is safe because of its geometry, which does not depend on anyone remembering anything. That distinction is the whole argument of the pet-safe hub.

If you are using an open snap trap anyway, put it inside a cardboard box with a mouse-sized hole cut in two opposite sides. It costs nothing, it keeps noses out, and mice actively prefer running through an enclosed tunnel.

How long to leave a trap before moving it

Four or five nights. If a trap in a place you believed in has caught nothing in five nights, the belief was wrong — move it to where the droppings are rather than waiting longer.

Do not keep checking through the night. Every visit shifts the trap slightly and adds disturbance to a route mice are judging carefully. Set in the evening, look in the morning.