What are the most common pests in winter and how do you prevent them?

The mouse is drinking coffee

As the last warmth of autumn begins to fade and the chill of winter starts to take its grip, many of us start spending more time indoors. And we’re not the only ones to head inside to take shelter in the warmth of our homes – many pests follow, seeking to see out the winter in the nooks and crannies of our houses. Here’s a list of the five most common winter pests, and how to prevent them.


One of the most common pests to find in and around your home in the winter months is the rat. In the UK, brown (Norwegian) and black rats are by far the most widespread species, able to breed rapidly if left unchecked – they produce 3-6 litters a year, each with up to 10 pups. Found in large numbers in urban areas, rats are known to carry various infectious diseases, including salmonella, tuberculosis, cryptosporidiosis, and E.coli. If you find droppings and items that have been chewed around your house, or you hear scuttling under the floorboards or in the walls (rats can climb), then it’s likely you have an infestation.

How to prevent them?

To prevent rats from coming inside during winter, the most effective safeguard is to block all possible entry points into your home. Pipes, gutters, ground vents, and even gaps in the attic should be sealed to prevent them from entering. If they do make their way in, you can lay down rat traps – be sure to check them regularly however, as dead rats caught in traps can fester. It’s a much better idea to call a professional pest controller.


Mice also tend to seek out the heat of your home during winter. While they might seem cute, they can cause significant damage to your property and carry some nasty infections. The most common mouse to enter homes is the aptly-named house mouse, and it has a voracious appetite. It will gnaw through almost anything, from plants to electrical wires and even wall insulation. If small chew marks on items doesn’t convince you of their existence, then you may also notice small droppings and even nests in small spaces around your house – check behind the radiator or under the cupboard. Mice are known to carry hantavirus (a respiratory infection), salmonella, and Lyme disease (carried by ticks in their fur).

How to prevent them?

As with preventing a rat infestation, the first step is to block access into your property. Once you’ve sealed up all entry points, good organisation and hygiene around your home are key. Make sure that you don’t have unnecessary cardboard boxes full of unused stuff around – they provide mice with the ideal material with which to make their nests. Also ensure that food waste is properly disposed of and that food is generally stored correctly, using airtight containers – any food left out will entice mice in from the wintery cold outside.

Cluster flies

Although fly numbers significantly decrease during winter, you may still catch sight of one or two of them in your home. If you do, they’re likely to be cluster flies – larger than the house fly, with overlapping wings and a slow flight. They generally only pose a risk if they reach large numbers, as they can transmit harmful pathogens like salmonella and E. Coli in their excrement.

How to prevent them?

Again, sealing openings into your property and maintaining good general hygiene around your home will go some way to preventing an infestation of cluster flies. If their numbers do build up for any reason, then the best treatment is to spray the affected areas – this not only kills flies that come into contact with the spray immediately but will prevent a relapse in the following few weeks.


The image of a wasp buzzing around a cold soft drink on a hot day is a common one. Although they are more readily associated with Summer, wasps can also appear unexpectedly in the colder months of the year. Most wasps die off towards the end of September due to a lack of food. Some venture indoors, however, seeking sweet substances and an escape from the cold. Although they might not be a great nuisance at this stage, it’s better to deal with them before the seasons change again and their numbers bounce back. Failure to nip the problem in the bud at this stage could result in an infestation come Springtime.

How to prevent them?

To discourage wasps from coming inside, make sure all bins are closed shut and food waste is properly disposed of. If you do come across a stray wasp or two, you can quickly dispatch them using an instant spray. At the same time it’s a good idea to check to see if there is a wasp nest that’s been made for use when the warm weather returns. Lofts and under-roof ledges are the preferred places for wasps to nest. If there is activity in the nest, then call a professional pest controller to avoid any injury and ensure permanent disposal.

Grey squirrels

Originally from North America, the grey squirrel can sometimes cross the line that separates wildlife from pest. They can make their way into homes by way of the roof, not distinguishing their natural tree-top habitat from buildings. Once inside, they can cause extensive damage to electrical wires and loft insulation, which they might use to make nests.

How to prevent them?

The best way to prevent squirrels from entering your property is to block their access – check the roof for any openings large enough and consider how they gain access to the upper levels of the property. This might mean cutting down a branch or two from a neighbouring tree that provides them with a path to the roof (as long as you own the tree!). It might also mean fitting an inverted collar on the rain pipes that run up to the gutter. If they’re still managing to get into your home after these measures, then it’s time to call a pest controller – they’ll probably use a warfarin-based pesticide.

In from the cold…

With our tips on the five most common winter pests and how to prevent them, the only thing coming in from the outside this winter will be festive cheer.

If you’re concerned about pests in your home this winter and would like some advice from our expert pest controllers, please give us a call on 020 3405 5000 or send us an email at info@inoculandpestcontrol.co.uk.