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Monday 16 September 2019

False widows 'are only a threat to other spiders'

Web of influence: A false widow spider
Web of influence: A false widow spider

Ralph Riegel

They're the stuff of childhood nightmares and have been the villains in everything from 'Lord of the Rings' to 'Harry Potter'.

Spiders rank as probably the most feared yet vital part of Ireland's eco-system.

However, a leading Irish researcher warned the near-hysteria in the media which followed a Waterford woman being hospitalised for a severe reaction to a bite from a false widow spider has masked the fact the foreign interloper poses a greater threat to native spiders than to humans.

The false widow, or Steatoda nobilis, is believed to have arrived from its natural habitat in the Canary Islands sometime over the past 30 years.

The species was first detected in Bray, Co Wicklow, in the early 1990s and has since spread to most other parts of Ireland.

"It is an age-old thing with spiders that people tend to be afraid of them," explained Collie Ennis, a researcher in Trinity College Dublin (TCD) Zoology Department. "But they are an absolutely vital part of our eco-system and usefully control a lot of the pests around the house.

"Headlines in the media like 'Killer Spider' certainly don't help.

"In fact, they may prove dangerous because it is generating an irrational fear of spiders that could, for instance, result in people getting such a fright if they see a spider that they fall down the stairs."

The TCD researcher pointed out the false widow spider is a cause for concern - because of its impact on native spiders.

Ireland's two largest spiders - the giant European house spider (Eratigena atrica) and the daddy long legs spider (Pholcidae) - are harmless to humans.

Both are lethal to a range of pests from flies to mites that can plague homes.

"Unseen they do a vital job of getting rid of the pests in your home," said Mr Ennis.

The daddy long legs spider - responsible for the cob webs on the ceilings of most Irish homes - also plays a valuable role in hunting other spiders and controlling their numbers.

However, both Irish species are effectively powerless when it comes to the false widow and its venom. "That is really the concern - the manner in which this spider might displace our native species.

"It is an ecological concern," he added.

But the TCD expert stressed people also have to consider the incredibly small threat posed to humans.

"It is not an aggressive spider. Far from it.

"While it tends to like living near human habitation because it gets both shelter and warmth, it also tends to avoid humans if it can," he said.

The spiders - usually the males - tend only to be seen when they are moving around in late summer or autumn.

People are only bitten when direct pressure is exerted on the creature, either by someone accidentally standing on it or getting it caught in their clothing and crushing it.

No one has ever died from a false widow bite.

It doesn't even rank on the same scale as the world's major spider threats, the highly venomous Sydney funnel web, the black widow and the red back.

Irish Independent

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