House Mouse
Mus musculus
NuisanceWhat it is
A small gray-brown commensal rodent that lives closely with people. It nests in wall voids, stored materials, insulation, equipment, and other sheltered spaces and can contaminate food with droppings and urine.
How to recognize it
- About 3 inches long, with a tail of similar length
- Gray-brown with a lighter belly
- Large ears, small eyes, and a pointed nose
- Droppings about 1/4 inch long, dark, with pointed ends
- Signs include gnaw marks, greasy rub marks, shredded nesting material, and scratching at night
Where you will find it
Inside walls, attics, cabinets, behind appliances, and in garages and storage areas. They can enter through gaps about the size of a dime.
Why it matters
They contaminate food with droppings and urine, chew wiring and materials, and breed quickly.
Look-alikes
- Deer mouse: White belly and a two-toned tail. It can carry hantavirus and is more common in rural areas and outbuildings.
- Young rat: Larger feet and head compared to its body.
- Shrew: Long, pointed snout and tiny eyes. Not a rodent.
What to do
- Store food, pet food, and birdseed in sealed containers.
- Keep clutter down, especially in garages, basements, and closets.
- Clean up safely: wear gloves and a mask, wet droppings with disinfectant, and don't sweep or vacuum them dry.
- Avoid store-bought poison. It's risky around children and pets, and mice can die inside walls.
When to call a professional
- You hear noises in the walls or ceiling, see droppings, or notice gnawing.
- You find droppings in more than one room or in the attic.
- You think you may have rats.
Questions
If I see one mouse, are there more?
Usually. Mice breed quickly, so it's best to act early.
Do mice carry disease?
They can spread germs through droppings, urine, and contaminated food. Wear gloves and a mask when cleaning up.
Do peppermint oil or ultrasonic devices work?
Not reliably. Mice get in through gaps that are hard to find, so a professional inspection is the dependable fix.
Related reading
Related pests
Chipmunks
Small striped ground squirrels that burrow near foundations, landscaping, retaining walls, and gardens. They can disturb soil, raid birdseed, and occasionally enter garages or structures.
Read more →Deer Mice
Small mice with a brownish back, white underside, large eyes, and a distinctly bicolored tail. They are common in rural or wooded settings and may enter sheds, garages, attics, and homes.
Read more →Flying Squirrels
Nocturnal squirrels with a skin membrane that allows gliding between trees. They may enter attics and wall spaces through small openings and can create noise, nesting, contamination, or chewing damage.
Read more →Ground Squirrels
A group of burrowing squirrels that live primarily on or below the ground. Their tunnels can damage landscapes, undermine structures, and create trip hazards, while the animals may feed on gardens and crops.
Read more →This page is general information, not a diagnosis. Pests vary by region and situation, and an on-site inspection is the reliable way to know what you have.