With around nine or 10 wasp spider sightings reported along the River Avon, Wendy Carter and her partner headed out to look for one themselves. Carter, communications lead at Worcestershire Wildlife Trust, had received just one record in the county the previous year, according to the BBC.
The striped spiders, more familiar in southern England, were now being reported across Worcestershire and neighboring counties. Farther north, Chester Zoo conservationists found a female during a wildlife survey in Cheshire, according to the Guardian.
Warmer conditions are helping wasp spiders spread through Britain, according to the British Arachnological Society. In a recent study published in Ecological Monographs, researchers described northern populations mating earlier in the season and young spiders better able to withstand extreme cold after adjusting to chilly conditions. These changes could help the spiders make a home in colder parts of Europe.
Why Wasp Spiders Are Spreading Through Britain
The wasp spider, Argiope bruennichi, was first recorded in Britain at Rye, East Sussex, in 1922. Successful breeding depends on a long warm season and a mild winter, conditions becoming more common in Britain, according to the British Arachnological Society.
Females have yellow-and-black markings and bodies that can reach about three-quarters of an inch long. Their webs can span nearly a foot, with a bright band of silk running through the center.
Explore All OptionsA female waits there for meals that include grasshoppers, crickets, and flies. She may also eat a male while they mate, though she is unlikely to hurt a person, according to the society’s species profile.
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How the Spiders Cope With Colder Homes
To reconstruct the species’ expansion, Henrik Krehenwinkel and Diethard Tautz compared living populations with museum specimens. They also tested how spiders from different populations handled temperature changes, including whether they could make it through winter away from their home region.
Their study in Molecular Ecology found that the spreading spiders had ancestry from populations that had once lived apart. The researchers think warming allowed those populations to meet and interbreed, giving their offspring a mix of inherited traits that could help them survive in colder places.
More recently, a team collected spiders across a stretch of Europe reaching from southern France to Estonia. They kept females from both ends of that range under the same lab conditions while they laid eggs, then put their young through simulated winters.
Although the northern females were smaller than those farther south, they laid similar numbers of eggs, and a similar proportion hatched. The researchers think these spiders may grow and mature faster, allowing them to reproduce during shorter summers without producing fewer young.
Fewer spiderlings from either region survived the colder simulated winters, with no significant survival difference between northern and southern populations. But in separate tests of extreme cold, northern spiderlings that had already experienced chilly conditions survived better than southern ones given the same winter treatment. The findings point to both inherited differences and an ability to adjust to the cold. The study in Ecological Monographs examined continental European populations, so it doesn’t tell us whether the recent British arrivals have the same adaptations.
Watching for the Next Arrival
In Worcestershire, anyone who spots a wasp spider can help Carter and her colleagues follow its spread. The trust is asking people to send in a photograph and where they found it, according to the BBC.
The search can continue after the females disappear in autumn. They leave brown, flask-shaped egg sacs attached to vegetation, with young that remain inside through winter before appearing in spring. Tucked among the grass, the next generation waits out the cold.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from the BBC: Wasp spiders increasingly seen in West Midlands
- This article references information from the Guardian: Wasp spider seen in north of England latest ‘climate refugee’ amid global heating
- This article references information from the British Arachnological Society: The Wasp Spider, Argiope bruennichi
- This article references a study published in Molecular Ecology: Northern range expansion of European populations of the wasp spider Argiope bruennichi is associated with global warming–correlated genetic admixture and population-specific temperature adaptations
- This article references a study published in Ecological Monographs: Rapid ecological and evolutionary divergence during a poleward range expansion
