Moisture, mold & pests

Signs of mice in the house

Small droppings, scratching sounds, and gnaw marks are the classic early signs of a mouse presence, and acting quickly limits both damage and the chance of a bigger infestation.

Difficulty
Easy
Time
1–2 hours
DIY cost
$15–$40
Pro cost
$150–$500

Symptoms

  • Small, dark, rice-shaped droppings near food, cabinets, or along walls
  • Scratching or scurrying sounds in walls, ceilings, or under cabinets, especially at night
  • Gnaw marks on food packaging, wires, or wood
  • A stale, musky odor in an enclosed space

Likely causes

  • CommonSmall gaps or holes providing an entry pointMice can squeeze through openings as small as a dime, often around pipes, vents, or foundation gaps.
  • CommonAccessible food sourcesUnsealed pantry food, pet food, or crumbs give mice a reason to stay once inside.
  • CommonSeasonal movement indoors seeking warmthMice often move into homes in fall and winter looking for shelter from the cold.

What to do

  1. Inspect the areas where signs were found and look for entry points, gaps, or holes nearby.
  2. Seal obvious gaps with steel wool, caulk, or hardware cloth, since mice can chew through plain caulk or plastic.
  3. Store food, including pet food, in sealed containers rather than bags or boxes.
  4. Set snap traps or bait stations along walls where droppings or activity are seen, since mice travel along edges rather than open floor space.
  5. Clean droppings carefully with gloves and a disinfectant spray rather than sweeping or vacuuming dry, which can spread particles into the air.
  6. Check traps regularly and reset or add more if activity continues after a few days.
  7. Call a pest control professional if signs continue despite trapping and sealing, since there may be a larger population or hard-to-find entry points.

Tools and parts

  • Gloves
  • Flashlight
  • Steel wool
Snap trapsSearch: “mouse snap traps”
Steel wool for gap sealingSearch: “steel wool pest exclusion”

When to call a pro

Call a pest control professional for a larger infestation or if you can't find and seal all entry points yourself.

Safety

Use caution

Wear gloves and avoid sweeping or vacuuming dry mouse droppings, which can release particles that carry disease; disinfect the area instead.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.