As Britain enters the peak of the False Widow spider’s mating season, experts are warning residents to keep their windows closed around the clock to avoid unwanted intruders. The False Widow—Britain’s most venomous spider—has been spreading rapidly across the country, thriving in homes, garages, and basements thanks to warmer temperatures and mild winters. Once rare, these glossy brown spiders are now a year-round reality from London to Scotland.

While scientists stress that panic isn’t necessary, they caution that bites can cause pain, swelling, and, in rare cases, infection or flu-like symptoms. Dr. Tom Elwood, one of the UK’s leading arachnologists, urges households to stay vigilant: seal cracks, clear webs, and use natural repellents like peppermint oil or vinegar. “False Widows aren’t hunting humans—they’re just looking for warmth and mates,” he said. Still, with sightings rising daily, Britons are heeding the advice: keep your windows shut and your eyes open.