British households are being warned about an imminent surge of False Widow spiders, the UK’s most venomous arachnid. Known for delivering a painful bite, these spiders are one of just 12 species in the country documented to have bitten humans. They belong to the same family as the deadly Black Widow spider and are about to begin their annual mating-season migration indoors.

Although their bite is not fatal, the venom can cause swelling, burning sensations, and in some cases, fever. The species is now well-established in homes across Britain, raising concerns as temperatures warm in late summer.

Male Spiders on the Move

Leading arachnologist Dr Tom Elwood explained that “August is when male spiders become active.” During this period, they leave their webs in search of a mate, often entering homes.

“They’re searching for a mate and they’ll wander through open windows, up walls, into bathtubs — anywhere they can,” Dr Elwood said.

Why Dirty Windows Attract Them

Dr Elwood noted that open windows are not the only entry points. Spiders are also drawn to dusty, debris-covered frames and sills.

“Spiders are drawn to dust, insect remains and debris on window frames,” he explained. “Webs cling better to rough or grimy surfaces. That’s why cleaning your windows is just as important as keeping them shut.”

False Widows are often seen moving across floors, along skirting boards, and climbing walls.

A Serious Warning

Issuing a strong caution, Dr Elwood stated: “Spiders are already on the move. You may not see them, but they’re out there — climbing walls, slipping in through vents, and squeezing through the tiniest cracks.”

He stressed that keeping windows closed both day and night is not “paranoia — it’s smart preparation.”

How to Keep False Widows Out

  • Keep windows closed day and night

  • Clean glass and frames weekly

  • Seal visible gaps and cracks

  • Use vinegar-based sprays to deter web-building

  • Tidy corners and dark areas where spiders hide

Dr Elwood concluded: “Do the right things now, and you won’t be waking up to spiders crawling across your bedroom floor.”