Mice or Rodents in Walls
moderate 1–3 h
Tools: flashlight, gloves, caulking gun, putty knife · Materials: snap traps, steel wool or copper mesh, expanding foam or sealant, airtight bins
Steps
- Walk the outside of the house at dusk with a flashlight looking for openings the width of a pencil — around pipes, cables, vents, and where siding meets the foundation. Mice need only 6 mm.
- Stuff steel wool or copper mesh into each opening and seal over it with caulk or foam.
- Set snap traps along walls where droppings are, trigger end toward the wall, baited with peanut butter; check daily and wear gloves to dispose.
- Remove food sources: bird seed, pet food and grain in sealed bins; clear clutter that gives cover.
- Keep trapping until you have three quiet nights in a row, then re-check the exterior seals.
Stop and call a pro if
- you hear activity in more than one part of the house, or catch more than a few mice a week — an established population
- you find rats (larger droppings, gnawed wood) rather than mice
- droppings are in air ducts or insulation, which needs cleaning or replacing
- you are considering poison — bait must be placed by someone who knows how to keep it from pets and wildlife
What a pro does that you can't
A pest technician finds entry points on the roofline and in the foundation, exclusion-proofs the house, places tamper-resistant bait safely, and removes contaminated insulation.
DIY cost: $15–40 for traps and sealant