All Hail the Humble British House Spider

It’s that time of year again. Early autumn is the period in which mature house spiders are desperately seeking a mate, while many mature humans become gibbering wrecks because these tiny eight-legged creatures dare to venture into our homes.

The humble house spider is a timid animal which is completely harmless to human beings. Nevertheless, its appearance seems to strike terror into the hearts of a significant percentage of the British population. Incredibly, a fear of spiders is believed by experts to be the most common phobia in the United Kingdom. Well over a million British citizens are said to be genuine arachnophobes, while millions more are simply scared of spiders.

It’s a peculiar situation when you consider that spiders in the UK are relatively small, they very rarely bite and when they do the symptoms are usually mild. In fact, of the six hundred and forty species of spiders that are native to this country, only twelve are known to have bitten humans. In almost all cases the effects of those bites were less painful than a wasp sting, although there is one comparative newcomer to the British Isles that can provide its victims with a nasty nip.

The False Widow Spider (Steatoda nobilis) originated in the Canary Islands and was first discovered in the UK back in the 1880’s. How it arrived here is something of a mystery, but it eventually managed to establish itself in the areas surrounding the Devon coastline. It remained localised in that region until the 1980’s, when its population began to spread slowly but surely throughout southern and eastern England. Scientists predict this tiny invader will continue to migrate further north in years to come as the effects of global warming lead to milder winters, although it’s likely to be some time before it reaches South Wales.

The False Widow (pictured left) is almost certainly the UK’s most venomous spider and is capable of giving an unpleasant bite by comparison to the majority of species in this country. The effects are reported to include rapid swelling, radiating pain, a numbing of the areas around the bite, nausea and even a variety of flu-like symptoms which can last for a few hours after a bite is inflicted. That’s the bad news, but the good news is that although there have been plenty of False Widow bites recorded within the last decade, none of them have ever proved fatal.

To put the situation into some sort of perspective, the fact is that an average of four people die in the UK each year from anaphylactic shock after being stung by bees or wasps. There is no doubting that the small and exotic False Widow is a spider to be treated with caution, but it should be underlined that the actual dangers it presents to humans have been greatly exaggerated by the tabloid press.

The larger spiders which are often found wandering around our homes and workplaces at this time of year are mere pussycats by comparison to the False Widow. Depending on which area of the UK you live in, they are usually one of two almost identical species. Tegenaria saeva is the house spider that is most common in Wales and the West Country, while Tegenaria gigantea is more widespread throughout the rest of Britain.

Contrary to popular belief, the reason these spiders suddenly start appearing indoors during September and October is not because they are seeking shelter from the colder weather but because it is their annual breeding season. The leggy specimens we see scuttling about on our walls and carpets are almost always mature males who are frantically searching for a mate before the winter sets in. They are easily identified by the distinctive appearance of their pedipalps, which resemble a small pair of arms tipped by miniature boxing gloves.

All spiders have pedipalps, regardless of their sex. Situated between the fangs and the first set of legs, they are sensory organs and are used for a variety of functions, including capturing and manipulating prey, courtship and reproduction. Sexually mature male house spiders have prominent, swollen bulbs at the tips of their pedipalps, as demonstrated by the superb specimen pictured above. These are used to transfer sperm to the female during mating. The males also have slimmer abdomens and considerably longer legs than the females, so spotting the differences between the sexes should be fairly straightforward even for those of us who are unfamiliar with arachnid anatomy.

Male house spiders belonging to the larger Tegenaria species have only a few months left to live once they have reached adulthood. They mature after approximately two years and then embark upon a desperate race against time in a bid to find a suitable partner. Females generally live almost a year longer and tend to remain in the tubular retreats of their large, sheet-like webs for the majority of their lives.

When a male house spider locates a female who is nearing maturity, he guards her web until she has undergone her final moult. The mating process begins shortly afterwards and is usually repeated on a number of occasions before he dies. Unlike numerous other species, the female house spider never kills the male after mating, although she often eats him once he has perished. In doing so, she utilises the nutrients his body provides for the production of their offspring. The female stores the male’s sperm throughout the winter and then produces up to a dozen egg sacks during early spring, with each sack containing between forty and sixty eggs. The tiny spiderlings hatch within a few weeks and immediately disperse from the nest. Mature females frequently survive for several months after producing their offspring but are usually dead by the time winter comes around again.

I should point out that the chances of an errant male house spider finding a female in your living room, bedroom, bathroom or kitchen are virtually zero. As a rule, modern human dwellings are far too warm, dry and bright for this species to comfortably inhabit. Besides which, the food supply they require is at a premium in such surroundings. These spiders eat a variety of insects including beetles, cockroaches and earwigs, so unless your house is infested with creepy crawlies, you have no need to worry about a female setting up residence there. You are far more likely to find her web in the corner of your cellar, garage, garden shed or greenhouse.

Unfortunately for male house spiders, their eyesight is so poor that they occasionally wind up in totally unsuitable locations while they are busily hunting for a partner, with our homes and workplaces being the prime examples. Despite having eight eyes, these nocturnal arachnids are virtually blind and can only clearly sense light, dark and movement. The vast majority enter buildings after dusk through open windows or gaps in walls and ceilings where pipework and wiring emerges. It is widely believed they also travel up bath and sink waste pipes and crawl in through plugholes, but that’s just an urban myth. A house spider is no more capable of swimming through the water in a waste pipe U-bend than any other small animal. These hapless creatures almost always get trapped in baths and sinks after falling from walls and ceilings, although a small percentage end up there during dry spells because they are attracted to the moisture. Either way, they are unable to clamber out again as they cannot maintain a proper grip on smooth surfaces such as stainless steel and enamel.

If you are genuinely concerned about the prospect of spiders entering your home at this time of year, then close all your doors and windows before nightfall and make sure the gaps around your pipework and wiring have been sealed up. Not only will you be keeping the spiders out, but you’ll have the added bonus of reducing your heating bills. Also, if you are worried about finding spiders in your bath, then leave a large towel draped over the sides at night. That will give any clumsy arachnids an immediate escape route and the chances are they will have vanished by the morning.

I’m not going to pretend that house spiders are the most attractive animals on the planet. With their long, spindly legs and hairy bodies, they aren’t exactly easy on the eye and their nasty habit of suddenly appearing when we least expect them can be unnerving even for the most enthusiastic arachnophile. Nevertheless, no matter how squeamish their appearance makes us feel, the fact remains that these interesting little creatures are totally harmless to humans.

The next time you discover a spider in your home, please don’t kill it. Take pity on it instead. Carefully catch and release it if you can, or simply allow it to wander away of its own accord. Remember, the spiders that enter our houses during the autumn do so in error and are far more frightened of us than we are of them. They are only searching for a mate and can do us no harm, so try to ignore any irrational fears and let them live. The likelihood is the poor creatures will perish within a few weeks anyway.