Why is a mouse infestation dangerous?
Leptospirosis; murine typhus; rickettsialpox; tularaemia; lymphocytic choriomeningitis – mice carry these diseases and we’re quite sure that a description of the symptoms isn't required for you to agree that they’re to be avoided.
In addition to making the most of available food, mice also like to gnaw on plastic and wooden furniture and have even been known to cause fires by chewing on electrical cables.
How can I tell if there are mice in my house?
The telltale signs of a mouse in the home include:
'A house mouse only eats 3-4g each day, but will produce up to 80 droppings,' says Kevin. Fresh mouse droppings are black, shiny and the size of a large grain of rice.
Holes and gnawing marks
'Damage to food stock is common,' says Kevin. 'A mouse may also damage boxes, wallpaper or furniture.'
It's common for there to be little bits of damage in lots of locations, rather than a lot of damage in a single place.
'A distinctive, musty, pet shop-like smell can suggest a serious mouse infestation,' says Kevin.
'As well as spotting a mouse itself, look for footprints and tail marks in dust or breaks in cobwebs,' says Kevin.
If you see mice outside of their preferred dawn-to-dusk feeding hours, this means they are short of food, says Kevin, or that there are an awful lot of unwelcome visitors.
The talcum powder test
If you think you caught a glimpse of a mouse, but can’t be certain, Kevin’s trick will avoid spending money on pest control measures unnecessarily: 'Put down some talcum powder on pieces of paper or cardboard in the corners of your rooms. You’ll soon see footprints or tail marks if there’s a problem. Also, you’ll be able to see how many rooms are affected.'
How to keep mice away
A mouse seeking food, warmth and a place to nest can squeeze through gaps 6mm and larger. Your challenge is to find and fill these spaces.
Brickwork, air vents, grilles and gratings
'Go outside and have a careful look at your property. Look for cracks in brickwork, air vents, grilles or gratings,' says Kevin.
'A good way to check the size of holes is to use a Biro-style pen. If this fits into a hole or gap, a mouse can get in.'
Airbricks and grilles should never be sealed completely. Instead, buy a mesh with a 5mm or smaller lattice and attach the edges using silicone sealant.
Holes and cracks
Small holes and cracks can be tackled with sand and cement. Larger holes, such as those left by plumbing work, can be filled with a combination of chicken wire and expanding foam.
'Though it might not look neat at first, the excess can be trimmed away and the finish improved by painting once dry,' says Kevin.
'Modern PVC doors usually won’t pose a problem,' says Kevin. 'Wooden doors, on the other hand, will often have a gap at the bottom which is bigger than 6mm – ample space for a mouse to squeeze under.' Consider fitting a 'bristle strip' or draught excluder to fill the space.
Ivy or another plant which grows up the side of a house is a convenient ladder for mice to climb to a higher level.
'There is little point sealing up the ground floor if there are other places for the mouse to enter higher up,' says Kevin. If other mouse control measures fail, you should consider removing climbing plants.
'A pet’s food bowl placed outside will attract mice, as will plastic bin bags – put those into a wheelie bin straight away wherever possible,' says Kevin.
'Keep your garden tidy, too. An overgrown garden will attract mice and other pests.'
How to get rid of mice
'Be sure to remove all other sources of food first,' says Kevin.
'Mice need to be desperate for food before they will eat poison. Wax crayons, bars of soap, and cardboard are other things that a hungry mouse will eat to fill its stomach.'
DIY shops sell various kits. They usually take the form of coloured granules which should be placed in small, plastic trays. The important thing is to read the instructions very carefully, particularly because these poisons can de dangerous to children, adults and pets.
Position the trays at the edges of rooms behind furniture. Ideally, they should be out of sight and, especially if you have children or pets, out of reach.
2. Mouse traps
'Humane' mouse traps
It is also possible to buy humane mouse traps – these trap the mouse in a container.
'They must be checked twice a day,' says Kevin. 'Any mice caught can be let go into fields, but this is stressful for a mouse. They may die anyway.'
Mouse traps should also be placed at the edges of a room. The orientation is important. 'The bar which springs down onto the mouse should be as close to touching the wall as possible,' says Kevin. 'If you imagine the mouse running along in parallel with the wall, then the mouse will run across the trap.'
'Most people think of cheese to attract mice to a trap, but a small smear of peanut butter is best,' says Kevin. 'Bacon rind can also be used, but it should be tied on with a piece of cotton thread so that the mouse has to tug at the food, setting off the trap mechanism.'
'Don’t buy small, cheap wooden mouse traps. A decent one, made of plastic, will cost £2 or £3. They’re more effective because they have a larger area for setting off the mechanism.'
3. Sticky board
When to call the professionals
If DIY methods fail, or you believe an infestation is becoming serious, you should call a pest control professional.
'Rogue pest control businesses do exist, so look for affiliations and recommendations,' says Kevin.
How much will hiring a pest controller for a mouse infestation cost?
A three-treatment job, which is standard practice, will usually cost between £100 and £150. The bigger, national pest control firms charge more, though – 'as much as £400', says Kevin.
About our expert trader
Our expert: Kevin Harrison
Kevin Harrison is the owner of Pest Guard North West, a pest control business based in Stockport.
Pest Guard North West is a member of Trading Standards' Buy With Confidence scheme.
Which? members have praised Pest Guard North West for offering advice and a competitively priced service.
Read reviews for Pest Guard North West