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Pest advice for controlling Grey Squirrels

Have you heard something rustling in your attic or loft and suspect squirrels? As cute as squirrels might appear to be, they can be an incredibly destructive and distressing pest to have in your home or work. Learn all about grey squirrels in our ultimate pest control guide.

Pest controllers get thousands of call-outs for squirrels every year, and this is in part due to the damage they cause to your home and the noises squirrels make at night – which can be very distressing.

Grey squirrels Sciurus carolinensis are invasive pests, not native to the UK.

They were first introduced to the UK from North America in the 1870’s, as ornamental additions to high-class estates and country homes.

Introductions continued until the 1930’s, when the damage they can cause was finally acknowledged and it became illegal to release grey squirrels into the wild.

The dangers: why we control grey squirrels

Even though the grey squirrel is widely appreciated for its grace and ‘cuteness’ by much of the UK – the pest management industry knows that there are times when the lethal control of grey squirrels is necessary.

The grey squirrel is recognised as being in the top worst 100 invasive pest species in the world by the International Union for Conservation of Nature (IUCN).

Here in Britain and Europe, is classed as an Invasive Alien Species (IAS) which is any animal that is not native to the UK.

Because grey squirrels are an invasive pest species, it is against the law to re-release a grey squirrel if it’s been caught alive, per the Wildlife and Countryside Act 1981 and Invasive Alien Species (Enforcement and Permitting) Order 2019.

That means that any person who catches a grey squirrel alive is legally obliged to humanely dispatch it.

As their numbers have increased in the UK, so has the damage they cause. This is where professional pest control comes in.

There are three reasons we control grey squirrels:

  • Their potential to damage to your home, business and health
  • The destruction of UK forests
  • The impact on our native wildlife, in particular the red squirrel.

Grey squirrels can cause damage when they enter roof spaces of houses and buildings. For example, they can:

  • Gnaw on woodwork and ceilings
  • Strip insulation from electrical wires
  • Tear up fibreglass insulation 
  • Contaminate cold water tanks and attic space with urine and droppings.

People also report sleep issues due to the loud noises they make at night while they’re scuttling around your attic.

Squirrels are most active before sunrise, especially in winter. Their peak activity is activity is four-five hours before daybreak.

Grey squirrels often associate humans with food, meaning they sometime approach people. Some people fear being attacked, however it’s very rare for a squirrel to actually attack!

In gardens and allotments, they can take fruit, raid nests of small birds and dig holes in lawns to bury food.

Grey squirrels and UK forests

Grey squirrels cause damage to trees such as beech, oak and chestnut. They strip bark at the base of trees which causes them to weaken and eventually to die.

Grey squirrels also:

  • Raid birds’ nests to prey on eggs and fledglings (figures from the Game and Wildlife Conservation Trust suggest fledgling rates reduced by 15% due to predation by grey squirrels)
  • Damage orchards and gardens, destroying bulbs and corms, eating tree nuts and recently sown seeds
  • Wreak havoc on historic and ancient woodlands.
  • The grey squirrel was deliberately introduced to England, Wales, Scotland and Northern Ireland from North America in the Victorian era. Since then, it’s colonised 90% of England and Wales and is becoming a problem in Scotland.
  • Grey squirrels are responsible for the decline in native red squirrel (Sciurus vulgaris) numbers.
  • The Wildlife Trustsestimates there are only around 140,000 native red squirrels left in the UK, compared to 2.5 million grey squirrels.
  • There have been many scientific studies which have shown that the major contributing factor for the decline of the red squirrel is the introduction of its grey cousin.
  • As well as outcompeting the red squirrel for shelter and food, grey squirrels can transmit the squirrelpox virus to red squirrels, to which they themselves are immune but red squirrels are not.
  • Once a red squirrel has squirrelpox, it’ll usually die of dehydration within 2 weeks. The grey squirrel can carry the disease, but their health is unaffected.

Red squirrels are not only protected, but are much sought out because catching sight of them is so rare. Unless you’re around Scotland, Northern Ireland, the Forest of Dean or the Isle of Wight, there’s a good chance you’ve never seen a red squirrel.

In an interesting study titled ‘The enemy of my enemy is my friend: native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations’, scientists have concluded that the rare pine marten could be a key player in curbing grey squirrel numbers.

Signs of squirrels in your home or business

Our figures suggest people have more problems with squirrels during the spring and autumn when they’re looking for food.

These are the seven signs easiest signs to spot when looking for evidence of squirrels in your home or loft.

  1. Scratching and rustling sound from your loft or a wall cavity
  2. Spotting droppings in the loft – although you might need a pest controller to identify these droppings (check out our droppings identification guide)
  3. Smell of urine in the loft area might indicate the infestation has been going on some time
  4. Spotting lots of other squirrels around your property, particularly near your roof or on high fences
  5. Fruit and nuts being stolen from bird feeders, or the feeders being disturbed/knocked over
  6. Bark being stripped from trees in your garden
  7. Holes in vents or damage to your insulation foam.

If you’ve noticed a few of these signs, then it might be time to find a pest control company.

Grey squirrel biology, behaviour and habitat


Grey squirrels have a silver-grey (sometimes slightly brown) coat with a white underside and a brownish face.

Squirrels moult their coat twice a year – once after winter and then in the late summer before the weather gets colder again.

They average between 24-26cm in length, with a very bushy tail almost the same length of the body.

They have a pointed nose with long whiskers, big eyes and small ears.

Their hind legs are longer and more powerful than the front, and all paws have very sharp claws which the squirrel uses for climbing.


The drey is a very messy looking, spherical nest which may be found in a hole in a tree or set against the trunk and branches.

hese are easier to see in winter, when there are fewer leaves on the trees.

Alternatively they can make themselves quite at home in an attic or roof space.

The grey squirrel can be found in a wide range of outdoor habitats, including mixed woodland, deciduous woodland, suburban parks and domestic gardens.


They usually have two litters a year, in early spring and summer.

Grey squirrels typically have three to seven kittens.

Pregnancy (gestation) lasts roughly 44 days, with the young weaned at seven weeks and ready to leave the frey at 10 weeks old.

Kittens are born with closed eyes, no teeth and no hair. After about seven weeks they look like small versions of their parents and are ready to leave the drey.

Female squirrels can live up to five years, with male squirrels averaging around two-three years. 


Active during the day, squirrels spend most of their time in the trees, coming down to the ground to search for food.

They are superb climbers, moving rapidly through the trees and leaping between them with ease.

It is one of the few mammals which can climb head first down a tree.

Grey squirrels do not hibernate, so may be seen at all times of the year.

However, in winter they are far less active, sleeping for long periods, sometimes several days at a time, and they are less frequently spotted during this season.

Squirrels are not territorial, often sharing food sources and home ranges.

What do grey squirrels eat?

Grey squirrels are almost exclusively herbivorous.

They eat acorns, hazel nuts, sweet chestnuts, pine nuts, walnuts, berries, fungi, grains, vegetables, buds and shoots, bark and peanuts from bird feeders.

However, if plant food is scarce they will eat insects like caterpillars or crickets, smaller rodents, bird eggs and nestlings.

Squirrels will hoard nuts and seeds in preparation for winter, gathering them and burying them in caches all over.

In spite of their amazing memory, a large number of caches remain uneaten. This helps the seeds and nuts to spread, and allows them to grow.

Treating a squirrel bite

Grey squirrels often associate humans with food, meaning they sometimes approach people. Some people fear being attacked, however it’s very rare for a squirrel to actually attack!

In the rare event you are bitten by a squirrel, you should immediately wash the wound as thoroughly as possible; squirrel bites can be deep, but it’s important to do this even if the skin hasn’t been broken.

Once the area is cleaned, treat it with antiseptic cream and seek medical advice.

Preventing squirrels getting into your property or damaging your trees

Prevention is always better than cure.

Habitat management like as cutting back trees or branches that are overhanging a building, or trimming dense ivy can help prevent squirrels gaining access to a roof in the first place.

Next consider proofing entry points to your roof. For example, block the gaps and entrances holes with tightly wedged mesh or metal plates, wherever possible. A pest control professional should be able to help you with this.

Squirrels are fairly strong for their size and also persistent. If the proofing is not secure then the squirrels may be able to pull it out!

For tree protection, close fitting metal sleeves can protect them from the strong rodent incisors. This should be at least 0.75m deep, and the bottom edge should be at least 1.5m from the ground.

The metal should be a smooth surface to assist in preventing the squirrel from gaining a toehold.


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