Behaviour and Biology

House mice are small, usually between seven to nine centimetres long and are grey in colour. House mice are mainly active at night, although you might see them during the day. Nests are made of shredded fibrous materials such as paper and look like a ball of material loosely woven together, usually about 12 to 15 inches across. You may find partially nibbled food and small droppings.

Mice can cause extensive damage to property as a result of their gnawing activities, and also by eating and contaminating human food. There is a significant risk of fire and electrocution as a result of mice chewing through electric cables and wiring.

Mice carry a wide range of diseases, including Weils disease, which can be passed to humans, either by directly contaminating food with droppings and urine or by contaminating surfaces. Among the diseases mice or their parasites may transmit to humans are salmonellosis (food poisoning), rickettsial pox, and lymphocytic choriomeningitis. Mice may also carry leptospirosis, rat bite fever, tapeworms, and organisms that can cause ringworm (a fungal skin disease) in humans. They have also been found to act as reservoirs or transmitters of diseases of veterinary importance, such as swine dysentery, a serious bacterial disease of swine often called "bloody scours."

In food business premises, contamination of food for human consumption would result in failure to comply with hygiene requirements such as those contained in the Food Safety (General Food Hygiene) Regulations 1995.

Look Out For:

• droppings - these are normally about ½cm long and rod shaped;
• gnawing, particularly on sacks and boxes which may cause spillage of food.

Remember, if you can fit a pen into a gap then a mouse can get through.