The House mouse is approximately 7 to 9cm in length (excluding the tail that is slightly shorter than the body), with large ears and small eyes. House mice are light to dark grey in colour and weigh between 10 and 25 grams. The underside is often darker than the rest of the body.

The Wood mouse is a likely visitor to your home especially at the onset of Autumn. They are similar in appearance to the  House mouse but  have dark brown fur above, and silvery grey fur below. They have large ears and large protruding eyes.

Disease risk and damage

Mice urinate and defecate indiscriminately, producing up to 80 tiny droppings per day, thus contaminating the areas in which they live. Mice are particularly implicated in the spread of diseases such as salmonellosis. Mice can cause extensive damage to property by gnawing through a wide range of materials. There is a significant risk of fire and electrocution as a result of mice chewing through electric cables and wiring.

Proofing against mice

Buildings can be proofed against mice by blocking any openings through which they can enter. It is important to check that airbricks are in place and intact, that doors fit properly and that there are no unnecessary gaps around water, electricity and gas pipes through which mice can gain access.

Mice enter buildings in search of food and shelter. Improved hygiene will restrict the availability of food, thus decreasing the chances of mice remaining within a property and breeding successfully. Examples of how hygiene can be improved are:

  • Keeping food in sealed containers
  • Sweeping up any spillages immediately
  • Not leaving pet food lying around
  • Removing rubbish and other materials
  • Cleaning up under units and work surfaces
  • Removing food residues from under cookers


Problems with house mice may occur despite the best efforts of householders. Control can be achieved through the use of poison baits or traps.

It is very important that the pesticides are used in accordance with the instructions so that treatment is undertaken both safely and effectively. Rodent bodies and unused poison should either be burnt or buried to minimise the risk of accidental poisoning.

Signs of a mouse problem

The typical signs of a mouse problem are:

  • Scratching – noises in the walls or ceilings as mice scurry around
  • Droppings – mice leave small, dark droppings particularly along walls or in areas of significant mouse activity such as in cupboards or under sinks
  • Distinctive smell – mice leave a trail that leaves an ammonia-like smell that will be particularly strong in more enclosed areas such as under cupboards
  • Damage – mice have teeth that grow continuously and will gnaw on wood, plastic, cables and other hard materials
  • Nests – mice build nests with shredded material such as newspaper and fabrics. These will tend to be in hidden places.