We like to think of our homes as sanctuaries isolated from the outside world, but many types of spiders can live indoors. Some are accidental visitors, while others live for short periods of time.
There are even spider species that enjoy our comfortable indoor spaces all year round, where they happily spend their entire lives and even have offspring. These arachnids are usually stealthy, and almost all are harmless.
Spiders can provide services to control other pests, and even eat other spiders. Of course, if you suffer from arachnophobia, all the benefits that ‘domestic’ spiders provide won’t make you want them to disappear immediately from your surroundings, and we understand that.
Certainly, there are also poisonous spiders, and their bites can cause severe reactions. These reactions are often more severe in children or the elderly, or in people with compromised immune systems.
Whether in the cellar, in a corner of our living room, in the bathtub or hanging quietly from the ceiling, these are the most common spiders in the UK, and ones you’re likely to see without leaving the house.
Common House Spider
The common house spider (Tegenaria domestica) doesn’t get its name accidentally or whim. They are not only the most common spider in UK homes, but also in Europe and North America. They are completely harmless and can be found all year round.
This arachnid is an agile insect hunter that relies on its vision and speed of movement as well as its webbing to catch insects. The body length of females ranges from 7 to 12 mm and males from 5 to 10 mm, not including their legs.
They can be identified by their dark brown colour and long legs. The webs of this species are mainly found in corners, and are shaped like a flat funnel attached to the wall. They move at short intervals, stopping frequently.
Giant house spider
The giant house spider (Eratigena atrica) is among the largest spiders in the UK and Europe, and is also one of the fastest. Its top speed is around 53 cm per second, which is a record in the arachnid world.
They eat insects that fall into their webs, as they have very limited vision for hunting. These webs are funnel-shaped and can be found in the darkest corners of the house such as cupboards, chimneys, and other quiet places.
The size of their legs makes them effortless to identify, as they can reach a length of up to 75 mm. Their bite is harmless to humans, and they are generally reluctant to bite, preferring to hide or escape.
False widow spiders
The false widow spider (Steatoda nobilis) is outwardly very similar to the black widow, with which it is often confused. It is one of the few local spiders that can inflict a painful bite, similar to a bee or wasp sting. They were introduced from the Canary Islands about 150 years ago.
They usually live outdoors in warm weather, but when temperatures drop they are much more likely to be found indoors. Furthermore, they have a bulbous brown abdomen with cream-coloured markings that are often compared to the shape of a skull.
Its appearance and size is very similar to the cupboard spider (Steatoda grossa), another occasional inhabitant of UK homes, and to which it is related. Females range in size from 9 to 13 mm, while males range from 6 to 11 mm.
Juvenile spiders live hidden in small crevices and holes, which can make eradication difficult.
European cave spider
There are two species of spiders that receive this name (Meta menardi and Meta bourneti). Young spiders are attracted to sunlight, so they seek new places to populate. Adult spiders are photophobic and live in dark places, such as basements, caves, or mines.
The behaviour of the two species is very similar. They come out at dusk to hunt small insects using their venom. However, they are not dangerous to humans and the effect of their venom is negligible on large mammals, including humans and pets.
They are large (up to 50 mm wingspan) and glossy satin black to reddish brown. They often have a different coloured back of the body, varying between black, brown, or even olive green. Due to their nocturnal habits, they are not often seen.
Cellar spiders, also known as daddy long-legs, are the common name for several species of the family Pholcidae. However, if you live in the UK you are more likely to encounter a Pholcus phalangioides at home.
As their nickname suggests, these spiders have eight very long, slender legs that are covered in fine grey bristles. On average their legs are 5 to 6 times longer than the spider’s body. Their slender and fragile appearance is unmistakable.
This spider species is considered beneficial because it preys on other spiders. In contrast, it is harmless to humans and the potential medicinal use of its webs has been reported. Their webs are irregular and very loose, making them difficult to see.
The zebra spider (Salticus scenicus) is a jumping spider common in homes and gardens in the Northern Hemisphere. Its common name refers to its vivid black and white colouration. While its scientific name is derived from the Latin words “Salticus” (jumping) and “scenicus” (theatrical).
Female zebra spiders are between 6 and 10 mm long, while males are between 4 and 6 mm. They are well distinguished from other spiders by their particularly large anterior medium-sized eyes. They have excellent binocular vision.
When they detect their prey, which may be other spiders, insects or arthropods, they get as close as they can before jumping on them. Before jumping, they attach a silk thread to the surface, which prevents them from falling if the jump fails.
In homes,they are mainly found in gardens, but can often be found behind curtains. They are completely harmless to humans and pets.