Wildlife and animal intruders
Mice in the house: signs and how to get rid of them
House mice are small rodents that enter homes for food and warmth, leaving tiny dark droppings, gnaw marks, a musty smell and light scratching at night. They breed quickly, so acting early matters. Remove food, seal entry points and use traps; call your council or a professional pest controller for a persistent infestation.
- Also known as
- house mouse (Mus musculus), field mouse (wood mouse) when coming in from gardens
- Easily confused with
- young rats (larger, heavier droppings), shrews and voles outdoors
- How serious
- Moderate: a contamination and gnawing risk, and they breed fast
- Typical cost
- Usually no cost for DIY control
How to identify mice
House mice are small, about 7 to 9cm in body length with a long thin tail, large ears and grey-brown fur. They are often heard rather than seen.
Signs include tiny dark droppings (like dark grains of rice) along skirting and in cupboards, gnaw marks on food packaging and woodwork, a distinctive musty ammonia-like smell, and light scurrying or scratching in walls, lofts and under floors, usually at night.
How serious is it?
Moderate: a contamination and gnawing risk, and they breed fast
Mice are less of a direct health threat than rats, but they contaminate food, gnaw materials including wiring, and breed rapidly, so a small problem can become a large one within weeks.
A single mouse is a minor issue easily dealt with. Ongoing droppings and noises mean an established population that needs proofing and trapping rather than a one-off catch.
How to fix it yourself
- Find and seal entry points: mice can squeeze through gaps the width of a pencil, so fill holes around pipes, under doors and at air bricks with wire wool and sealant.
- Remove food sources: store food in sealed containers, clear crumbs and spills, and keep pet food off the floor overnight.
- Use snap traps placed at right angles to walls where droppings show, baited with chocolate or peanut butter, and check them regularly.
- Declutter loft and storage areas that provide nesting material and cover.
- Contact your local council if the problem persists, as many offer rodent control.
When to call a professional
- Droppings and noises continue despite trapping and proofing, suggesting a larger population or hidden entry points.
- You would rather a professional locate and seal entry points and treat the infestation thoroughly.
Who to call
- Your local council pest control service, which often handles mice.
- A British Pest Control Association (BPCA) or NPTA member pest controller for treatment and proofing.
Frequently asked questions
How do I get rid of mice in my house?
Seal entry points (mice fit through gaps the width of a pencil), remove accessible food, and set snap traps at right angles to walls where you see droppings. Act quickly, because mice breed fast. If the problem persists, your council or a BPCA pest controller can treat and proof the home.
How do I know if I have mice?
The usual signs are tiny dark droppings like grains of rice along skirting and in cupboards, gnaw marks on packaging and woodwork, a musty ammonia smell, and light scratching or scurrying in walls and lofts at night. You may not see the mice themselves until the population grows.
Do I need to seal entry points if I am trapping mice?
Yes. Trapping reduces the current population, but unless you seal the gaps they used to get in, more mice will follow, especially in cold months. Proofing the home by filling holes with wire wool and sealant is what stops the problem returning after the existing mice are caught.
Sources
Editor, HomesAndHedge
Oliver leads HomesAndHedge's editorial coverage of home and garden problems. He researches and writes the plain-English explainers on pests, invasive plants, damp and mould, drainage and wildlife, drawing on guidance from bodies such as the Property Care Association, the RHS and the NHS, and is clear about when a job needs a qualified professional.
Last reviewed: 8 June 2026