Spiders: Should I be worried about being bitten by a fake widow?
You could be forgiven for thinking the UK is in the throes of a spider emergency. With “the increase in the number of spiders” and the “dangerous bite warnings” broadcast in the media, people are “terrified” and even hospitalized.
These headlines have been piling up for a few years, and the species behind the media obsession with arachnids is the noble fake widow spider. Steatoda nobilis.
Relatively new to the UK, the species is native to the Canary Islands and Madeira. First reported from a site near Torquay in 1879, it spread across southern England, accumulating from the 1980s to become quite abundant, especially in urban areas.
It has also extended its range northward over time. So although the headlines are recent, the species has been present in many parts of the country for some time.
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If we are to uncover the truth behind the headlines, there are several questions we need to answer. First, can noble false widows really bite? There aren’t many species of British spiders with fangs that can pierce our skin, but the fangs of the noble false widow certainly can.
However, like most spiders, they are not aggressive. The bites appear to occur when spiders are trapped in clothing or when people are sleeping and possibly turning around, trapping a spider. This is of little comfort to anyone who has been bitten, but it is important to keep in mind that these animals are not there to catch us.
The second question we have to answer is: are bites more and more frequent? Given that spiders are increasingly abundant and are found where people live, it certainly seems likely.
It is also supported by evidence far from the headlines. The number of false noble widows has increased in Ireland, and a study was recently conducted at the National University of Ireland, Galway, on their bites.
Aiste Vitkauskaite, a masters student in toxicology and co-leader of the study, reported: “About 10 species of Irish spiders have fangs large enough to bite human skin, but in the past five years we haven’t have never heard of anyone bitten by native species. During the same period, we recorded dozens of confirmed or probable cases fake widow bites. “
Vitkauskaite went on to confirm that: “These spiders will become more and more common, as will their bites.”
The last and perhaps most important question is: Are bites medically important? This is a difficult question to answer. It can be difficult to confirm that a bite was caused by a spider, and if so, which species was the culprit. The Irish study bypassed the misidentification of species (and false noble widow spiders are easily mistaken for similar species) by using DNA extraction and genetic profiling.
This allowed them to confirm “envenomation”, when spider bites lead to the injection of venom, in 16 cases. Symptoms included debilitating pain, tremors, fatigue, nausea, and low blood pressure. Bites could also cause bacterial infections, including cellulitis and dermatitis.
While many bites likely only result in mild symptoms, in some people the bites can cause more serious reactions and, according to the study, hospitalization was required in some cases. The study warns that false noble widows may pose a potential threat to public health.
While this new study shows that in some cases, bites from false noble widows can cause problems, we need to keep it in perspective. No one has died from spider venom in the UK, as around five people a year are killed by wasp and bee stings, and several people die from dog attacks each year. Spider bites seem to exploit our deepest fears, but remember many of us have lived and will continue to live with noble false widowed spiders around our homes without ill effects.
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Indeed, I doubt most people are even aware of it. I have been sent many photographs of spiders considered noble false widows and very few have been. As with all risks, we should keep things in perspective and perhaps be grateful that the UK has very few animals that can harm us.
If you’re unlucky enough to get bitten by a fake widow spider, then don’t panic. Try to get a photo of the spider or, if it is safe to do so, capture it for later identification. Like a bee sting, there may be pain and swelling, but if you develop other symptoms or the pain becomes more severe, you should see a doctor.
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About our expert, Professor Adam Hart
Adam is an entomologist and professor of science communication at the University of Gloucester. In addition to research and teaching, he is a regular broadcaster for BBC Radio 4 and BBC World Service, and has also co-presented several television documentary series for BBC2 and BBC4. His latest book, Unsuitable for use (£ 16.99, Bloomsbury Sigma) is out now.