Saturday 21 July 2018

False Widow spider is taking over Ireland and is a potential health risk - Irish experts

False Widow. Photo: NUIG
False Widow. Photo: NUIG
Geraldine Gittens

Geraldine Gittens

Researchers at NUI Galway have published research which shows that the False Widow spider is taking over Ireland and is an invasive species with a detrimental effect on native species.

In Ireland, False Widow spiders live close to buildings and houses inhabited by people. They only survive in cities and not in rural areas.

Dublin, Cork and Wexford have the highest number of False Widows to date.

“While it is extremely unlikely that a bite will ever be fatal, we do need to consider bites from False Widows as a potential health risk given the increase of this species not just in the UK and Ireland but also mainland Europe and the US,” Dr Michel Dugon, lead author of the study from the Ryan Institute at NUI Galway.

“We hope that our study will help to address some of the public’s concerns about these spiders and will provide healthcare professionals with the information required to accurately diagnose and report bites associated with the False Widow.”

The researchers from the Ryan Institute in NUIG published their research papers in the journal Biology and Environment, and the journal Clinical Toxicology.

The False Widow is competitive, and fast-breeding, they found.

Have you seen any spiders? Send your photos to

Photo: Paul Harper
Photo: Paul Harper
Photo: Florencia Saluzzo, Dublin 12

The spider arrived in the UK about 100 years ago and has steadily invaded Ireland over the past 20 years through human transport of goods, a by-product of globalisation.

It lives for five to seven years whereas most other spider and bug species in Ireland only lives for a maximum of one year.

"False widow spotted." Photo: Louise Cribbin, Leopardstown

The first true case of a False Widowspider bite was identified in the UK in the 1990s and in Chile last year.

There has since been five additional reported cases, three in Ireland and two in the UK, leading to the NUI Galway study being the most intensive research carried out on this species to date.

"We’ve been getting them here for years now. Here’s one I found a few weeks back coming out of my airing cupboard." Photo: Mary Kelly, Cashel, Tipperary

Bites from a False Widow spider are not fatal with identified symptoms resulting in a large swelling within three minutes of being bitten, sometimes followed by the formation of a dry necrotic wound when the swelling subside, and inflammation for a few days afterwards, the scientists say.

The venom from a False Widow spider is a lot more powerful than the researchers expected, producing about one tenth of a millionth of a litre of venom.

Photo: John, Monkstown, Dublin
Photo: John, Monkstown, Dublin

The NUIG laboratory is the only one in the world currently working on extracting venom from The False Widow spiderfor potential therapies.

Photo: Ciaran Patrick Doyle
Photo: Ciaran Patrick Doyle
"We have a false widow at work that we leave alone and has been there for 3 years now, she leaves us alone and we leave her alone." Photo: Peter Durnin
"Found in my shed in Wicklow last week." Photo: Andrew O'Toole
"This one fell from a velux window in my kitchen last year. Photo: Paul Harper, Raheny, Dublin
"This little lady has set up home outside the kitchen window." Photo: Jacinta Moore
"This was in my back garden and have gotten rid of three more since." Photo: Emma Crowe
"Not the cutest of critters". Photo: Eleanor
Send us your photos:
Send us your photos: "Saw it in the garden about a week ago, and it’s not the first time I’ve spotted one with the markings on its back. Petrified!" Photo: Sam Mockus, Dublin
"Cleaned out the garage and the decking this week and found so many of these guys. All HUGE. Are these false widows? Are they dangerous to small kids?" Photo: Hugh O'Keeffe
Reader Vanessa Tucker sent us this photo to
Photo: Maria Galvan, Cork
Photo: Maria Galvan, Cork
"This spider has been on my garden shed for months now. It only comes out at night. Over the last year or more I have noticed an increase of spiders that look like this one in my garden." Photo: Lorna Cullen, Dublin
Photo: Louise Coyne, Galway

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