How to Identify Field Mice & Stop Them Damaging Your Home and Car
The field mouse (Apodemus sylvaticus), also known as the wood mouse, is the most common wild mouse in the UK. It is found in fields, woodlands, gardens and hedgerows throughout the country. Although field mice usually live outdoors, they may enter homes, garages and vehicles in search of food, water and shelter, particularly during colder weather. In the UK, field mice are usually the wood mouse (Apodemus sylvaticus). This article focuses on UK field mice.
Many people search for "field mice in the house", "field mice in the loft" or "field mice in cars". Although these rodents normally live outdoors, they will readily enter buildings and vehicles when food and shelter are available.
How To Identify Field Mice
They can be identified by their yellow-brown or brown fur, white bellies, long tails and large black eyes in comparison to other small rodents. Voles may be confused with field mice; check out our image for tips on how to identify field mice. They are also similar to house mice except that they have larger ears and eyes.
Tail length: 7-9cm
Body length; 8-10cm
Weight: 25g
Lifespan: 1 year
Signs Of A Field Mouse Infestation
Signs of field mouse infestation include;
1) Droppings. These are small, brown and pointed and often appear in small groups. These can help you identify field mice as the cause of an infestation.
2) Smell. Field mouse urine has a strong smell, like ammonia.
3) Nesting material. There may be small piles of grass, hair or other similar materials which have been used to make a nest.
4) Damage. You might find chew marks on fabric, upholstery, wires or access areas to food.
4 Tips On How To Stop Field Mice Damaging Your Home
1) Block holes. They are tiny and can fit through a gap of a quarter of an inch (6-7mm), about the size of the end of a pencil. This can make keeping them out very difficult in some situations. If you want to prevent them damaging your property the first thing you need to do is to block up all the holes and entry points. Fit door sweeps and edging around poorly fitting doors. Fill gaps under the edges of roof tiles and corrugated roofing. Make sure they can’t climb up cabling conduits or drainage pipes. Always use chew-proof materials such as wire wool, cement or metal sheeting when filling gaps. For a detailed guide, read our article on DIY rodent proofing for buildings and garages; https://www.hammertechltd.com/blog/diy-rodent-proofing-for-buildings-and-garages-a-practical-guide.
2) Clean and tidy up. Food will entice them into your home. Remove all traces, along with waste and packaging wherever possible. Keep animal feed and other edible material in metal bins. Avoid feeding your pets on the floor outside and keep birdseed off the floor.
3) Remove all sources of water. This includes puddles, dripping taps and any other standing water wherever possible. Mice need water and will hunt for it in dry conditions. Don't give them another reason to enter your property.
4) Get rid of smells. When rodents have previously been on your property they will leave a scent trail. This will remain for some time, even if you remove the rodents; others will soon follow the trail if you don't get rid of it, causing the problem to return. Pressure wash the area if possible, use soap, disinfectant and scrubbing brushes to remove oils and scents. Use strong essential oils such as peppermint and other strong odors such as camphor and cayenne pepper to mask odors and repel field mice. For more information on this check out or post on the best rodent repellents.
How Do Field Mice Behave?
Field mice are nocturnal which means that they are more active at night than during the day. This helps to protect them from predators, although breeding females often forage more in the daytime as this can make it easier to find food. Interestingly, they may make markers when foraging, using natural objects they find lying around. They use these prominently as landmarks to navigate and find their way around. They are timid and are good climbers. They run fast for their size, making them difficult for predators to catch.
They enter garages and outbuildings looking for a safe place to make a nest and raise their young. They are also looking for food and water. They will travel a short distance of 3 to 10 meters from their nest looking for food. If they are relocated they can navigate over a mile to find their way home.
What Damage Can Field Mice Cause?
Chewing electrical wiring. This can cause failure of household appliances and car engines. Repairs can be expensive and may result in significant vehicle downtime.
Damaging insulation. Insulation makes a great nesting material for field mice. They may damage it leading to pipes freezing and condensation forming. This can result in further damage from water.
Contaminating food. Field mice can get into food stores. This can lead to droppings and urine in food. This will need to be disposed of as field mice carry diseases such as hantavirus. Damage to food leads to extra costs, as well as the time required to clean up the mess.
Nesting in lofts and garages. Nesting can lead to noise, droppings and mess in cupboards and storage areas. As mice are nocturnal, they can keep you awake at night scaring about looking for food. If they are in your house they can damage your clothes and carpets.
Damaging upholstery in vehicles. Upholstery makes a great nesting material. Field mice may chew through the seats and seatbelts in your car whilst they are making themselves at home.
Gnawing stored items. Anything which is stored for some time is at risk of being damaged. Winter clothes, food stores and other materials may be eaten, contaminated and ruined by field mice.
RatMat Stopping Field Mice Damaging A Tesla
3 Tips On How To Stop Field Mice Damaging Your Car
1) Block holes in your garage. Garages are great for protecting your car from the elements. Unfortunately sometimes they aren’t ideal for keeping mice out. Old garages and those built from corrugated iron or plastic can have many holes which field mice can use to access your car. Block the holes with hard materials like cement and metal sheeting which field mice won’t be able to chew through. Learn more in our guide to protecting cars and RVs from rats and mice. https://www.hammertechltd.com/blog/keep-rats-away-the-ultimate-guide-to-rat-protection-for-cars-and-rvs
2) Cut back foliage and tidy up. Bushes and piles of leaves or overgrown flowerbeds near your garage will give cover to field mice, as well as a route in and out of your garage. Clear these away and get rid of debris to help keep field mice away.
3) RatMat. When everything else has failed, RatMat is the ideal choice. Acting as an electric fence on the floor you can create a perimeter around your car or a strip across a doorway. This will prevent field mice damaging your property. The system effectively keeps mice out, despite it frequently being used in situations where there are a large number of rats or mice around. People often use RatMat when conventional pest control has failed. This means these are particularly difficult situations to manage. RatMat is the ideal solution here. Visit our homepage to find out more.
Field Mice FAQ
Are field mice dangerous? Field mice aren’t usually aggressive towards humans but they can spread bacterial and viral diseases which can cause harm. They can damage property by gnawing and chewing. As a result, infestations should be handled immediately.
Do field mice enter houses? Yes, field mice do enter houses, garages and outbuildings. This is more common as the temperature drops. As they can squeeze through a gap the size of the end of a pencil it can be very difficult to keep them out.
Can field mice damage car wiring? Yes. Modern car wiring can contain organic materials such as soya which can entice field mice and encourage chewing. Damage can lead to electrical faults and expensive repairs. In severe cases, damaged wiring may increase the risk of electrical problems.
What is the difference between a field mouse and a house mouse? Field mice have larger eyes and ears than a house mouse. They also tend to have longer tails. Their fur is brown or yellow and they have a pale or white underside. House mice are usually grey or brown all over.
Where do field mice nest? Field mice usually nest in farmed fields or hedgerows. During colder months they enter buildings where it is warmer and sheltered from rain.
Why are field mice attracted to vehicles? Warm engines, protection from cold air and rain are common reasons for field mice to enter vehicles. Electric vehicles can provide sheltered areas that rodents may use for nesting, just as conventional vehicles do. If you leave empty sandwich or crisp packets in the footwell the smell will also draw them in.
How big a gap can a field mouse fit through? Field mice are tiny and can fit through a gap as small as 6-7mm, the size of the end of a pencil. This means they can get in through a crack around a pipe or under a door. Make sure these tiny holes are filled.
Conclusion
Field mice are common throughout the UK and can cause significant damage to homes, garages and vehicles if left unchecked. The best approach is to prevent access by sealing entry points, removing food and water sources, and keeping storage areas clean and tidy. Where mice continue to be a problem, specialist solutions such as RatMat can provide an effective additional layer of protection.
Dr Toby Bateson for Hammer Technologies Ltd
Photo by Nick Fewings on Unsplash
Vole photo by Heather Wilde on Unsplash
https://www.wildlifetrusts.org/wildlife-explorer/mammals/wood-mouse