Tuesday 20 August 2019

False Widow spider: What to do if you find one, how to get rid of them and what to do if you've been bitten

Researchers from Venom Systems Lab, NUI Galway, Dr Michel Dungon and John Dunbar say a bite from a False Widow spider could lead to Steatodism syndrome
Researchers from Venom Systems Lab, NUI Galway, Dr Michel Dungon and John Dunbar say a bite from a False Widow spider could lead to Steatodism syndrome

Aoife Walsh

The Nobel False Widow spider has made its presence in Ireland known after reports emerged that two Waterford women had been hospitalised after being bitten by the insect.

Maria Condon from Ferrybank, Waterford was hospitalised for six days in University Hospital Waterford after blisters formed on and underneath her leg within minutes of having been bitten by a spider which ran up the inside leg of her jeans.

Speaking on WLR FM's ‘Deise Today’ to Damien Tiernan, Ms Condon said she was told by hospital staff the bite was from a Noble False Widow spider.

However, Waterford is not the only place that the creepy crawly has been spotted. With reports of sightings in Dublin, Laois, Sligo and Galway, it is likely that you could come across one over the coming weeks.

The False Widow is a recent addition to Ireland's wildlife
The False Widow is a recent addition to Ireland's wildlife

Researchers from Venom Systems Lab, NUI Galway, Dr Michel Dugon and John Dunbar explain how to spot a False Widow, the best way to get rid of them, how to know if you've been bitten and what to do if you have. 

What does a Nobel False Widow spider look like?

The Nobel False Widow spider bears a strong resemblance to the Black Widow, but they are very different. Dr Dugon and Mr Dunbar explain that “true” and “false” widows belong to the same main family of spiders called the comb-footed spiders. These spiders use little combs on their back legs to spin their silk.

The spider researchers say that the spider is about the size of a two euro coin in leg span, and have a shiny black back with cream coloured designs, but do not have the red hourglass shape present on the belly of almost all black widows.

It is more likely that you will come across a Nobel Black widow spider as the Black Widow has not settled in Northern Europe.

 

What should you do if you spot one?

If you happen to come across a Nobel False Widow, Dr Dugon and Mr Dunbar advise that you keep it and contact them: "We recommend that victims keep the spider - even if it is dead, and to contact us at NUI Galway Venom System Lab and to go and see their GP if they develop swelling, extensive redness or if they feel “ill”.

If you don't fancy holding on to your new eight-legged friend, the experts say you can "safely put them into a glass and throw them outside."

"I would recommend this over killing them, as people can easily mistake them for other, harmless native spiders. It’d be a shame to kill a bunch of useful native spiders thinking that they are invasive false widow," said Dr Dugon.

The most important thing is not to panic as Dr Dugon says the False widow is not a  "particularly aggressive" species, and "usually bite only when they are squeezed between the skin and clothes or a bedsheet.

How to know if you have been bitten

A False Widow bite can lead to Steatodism syndrome, which causes symptoms such as:

  • A very fast onset of a moderate to intense pain around the bite site quickly expanding to the whole limb
  • Redness of the skin - first around the bite, quickly expanding to the whole limb
  • Swelling first around the bite, and sometimes expanding to the whole limb
  • Goosebumps, chills, sweat, fever, malaise and a cramping sensation as venom affects the central nervous system

Dr Dugon added that in rare instances, "small dermonecrosis" can appear around the bite site. This causes the skin to blacken and die at the bite site.

In the case of Ms Condon, the experts said: "The victim suffered first the symptoms expected from the venom: redness, swelling, pain. But then, as the effect of the venom was subsiding, she suffered a bacterial infection which developed into a cellulitis. Cellulitis is a serious pathology that requires hospitalisation.

"We can’t know for sure where the bacteria responsible for the cellulitis came from, but it is possible and likely that the bacteria were present on the fangs of the spider and were transferred to the wound during the bite."

Read more here: Spider's bite: False widow warning after woman spends days in hospital

 

What to do once you identify a bite

If you have developed any of the symptoms, the experts urge that you contact your GP straight away and monitor the injury. Dr Dugon said: "Get the spider, even if you kill it in the process, take a picture of it, and take a picture of your wound. If you experience anything more than pain and redness, contact your GP and contact us by email or via Facebook with the picture of the spider. The more solid cases we have, the better as we will then be able to inform and advice medical practitioner on how to recognise and treat false widow bites."

It is recommended that you draw a circle around the bitten area with a marker in order to keep track of where you have been bitten, and to monitor how much the swelling and redness grows.

How to avoid an infestation

Dr Dugon says that female False Widows have the ability to produce one egg sack containing up to 200 eggs every 3 to 4 weeks from March until October. This means these spiders have a longer lifespan than most native species, which is generally 5 to 7 years versus 1 to 2 years for native spiders. Their high fertility and longevity means that they have an advantage over native spiders.

"This means that at the moment, getting rid of Steatoda nobilis is near impossible. They are too numerous and too fertile to be exterminated efficiently. There are however, preventive measure that can be taken to limit their presence, " he said.

Dr Dugon's tips for getting rid of the creatures are:

  • Steatoda nobilis always make their webs in tight corners, behind furniture, in cracks in outside walls or around timber frames. Inspect these areas and get rid of them if found.
  • Steatoda nobilis are photophobic - meaning they don’t like light, so they will come out mainly at night. Go around and look for them after night fall, not during the day.
  • Try and limit their source of food within the house: try and limit the presence of woodlice, flies, wasp or other creepy crawlies within your house. If no food is available for them, false widow will move out in search of food.
  • Use a spider hoover to get rid of them. Search online for spider hoover. These are cheap (about 15 euros) small hoovers that allow you to “suck up” spiders hiding on corners without killing them. This way, you can dispose of spiders (by putting them outside) without harming them - which is important if you are not sure what species you are dealing with.
  • Avoid fumigation and insecticides: fumigation and insecticides are efficient in the short term, as they get rid of all bugs. In the longer term, spiders will make a swift come back in, filling up They also contain harmful chemicals for that can kill / hurt beneficial organisms and small pets (if you have a pet tarantula for example).

The Noble False widow spider, who were first spotted for the first time in Bray, Co Wicklow in 1997, originates from the Canary Islands and Madeira, and have been brought to Ireland and the UK through imported goods.

They are now found in all major towns, from Dublin, where they occur in very large numbers in and around houses, to Wexford, Cork, Galway or Sligo.

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