The bad news for arachnophobes in the UK is that they are getting larger because of our warm autumn, warns Luke Creedon

Spiders; for many, already the stuff of nightmares. But this autumn, as spider season begins in earnest, there’s some extra bad news in the offing for arachnophobes — UK spiders are getting larger.

This bombshell is sure to cast a web of woe, the sight of a large, hairy and very leggy arachnid hurtling along the skirting board bringing a shiver to even the bravest of souls.

It seems that the long spell of warm weather has created a glut in spider prey and without waiting for a second invitation, the spiders have gleefully tucked in. This year’s surfeit of flies, midges and mosquitoes has allowed spiders to gorge en-masse, resulting in more arachnids reaching their full potential size.

Professor Adam Hart, from the University of Gloucestershire, said: “We aren’t going to see cat-sized spiders. If there has been a good summer and a kind early autumn then it is quite possible that more spiders are able to reach their potential size wise. Plenty of food means that more of them might become as big as they can be. The fundamental maximum size isn’t changed, but more individuals might be able to get closer to it.”

Reassuringly, nature has put breaks on spider size. Prof Hart adds: “Their body plan and basic biology limits their size — too big and they can’t move as well, or hide out in cracks for example.

“In other places there are other environmental factors that might limit them — perhaps more predators to hunt them.”

Many would prefer if the spiders enjoyed their collective growth spurts out of sight and out of mind, in the solitude of our garden sheds and woodpiles.

But autumn is spider time. As the weather starts to cool, many of these super-sized males abandon their webs and head indoors to a skirting board near you. The males are not fleeing the cold — they are on the hunt for prospective mates.

There are about 660 spider species in the UK, coming in a mind-boggling variety of shapes, colours and sizes. The Society of Biology has released a free smartphone app, Spider in da house, to help the public identify the 12 most common species found in our homes. Tegenaria spiders are large, brown and noticeable. At this time of year Tegenarias are often found in our living rooms, kitchens and hallways. Males sport noticeable appendages that look like boxing gloves, but rather than spider pugilism, these peidpalps or palps are used to transfer sperm into the female. One of the most famous of the genus is the saucer-sized Tegenaria parietina, also known as the Cardinal Spider. Legend has it that the spider’s intimidating dimensions used to terrify Cardinal Wolsey when he came across them during his residence at Hampton Court in the 16th century.

Less noticeable but more fascinating is the rare Scytodes thoracica or Spitting Spider. Pale yellow with black markings, the Spitting Spider, found in older houses, has intriguing yet unwholesome habits. Unlike most of spiders worthy of the name, it builds no web and moves very slowly.

But the spitting spider relies on neither pace nor traps. Its enlarged head contains poison glands that produce sticky glue. This is fired from the spider’s vibrating jaws, producing a zig-zag stream of liquid which pins its prey to the ground.

Less gruesome is the Salticus or jumping spider. With giant eyes they boast the best vision of all UK arachnids.

Found on walls, they leap to catch prey and to avoid being eaten themselves. The most common of these is the Zebra Spider, named after its striking black and white markings.

But one spider regularly found in homes has attracted a bad press. There are six species of False Widow in the UK, but one in particular; the non-native Steatoda nobilis has become the bad boy of the spider world with reports of painful bites in some cases.

Climate change has seen the spider, which first appeared in the UK in 1879, spread across the south coast over the last 15 years.

Bites can produce chest pain, swelling and tingling fingers, but experts stress that bites are rare and that nobody has ever died in the UK from a spider bite.