The false widow spider is now widespread throughout Ireland.
And they’re here to stay!
Originally from the Canary Islands, the false widow is an invasive species that can now be found in many countries across Western Europe.
What is a false widow spider?
The name ‘false widow’ applies to several different species of spider that bear a resemblance to the true black widows. Three false widow species can now be found in Ireland with the Noble false widow being the most commonly observed.
False widow spiders belong to the genus Steatoda, a group that shares many traits and characteristics with the more infamous black widow spider, which belongs to the genus Latrodectus. These spiders could be seen as “distant cousins” and share many visual traits such as a two elongated front legs, a dark shiny body, and a large bulbous abdomen.
The name “false widow” highlights the superficial similarity while emphasising the distinction between these two spider groups. Despite their visual resemblance, false widow spiders are less venomous than their true widow counterparts and are generally not as dangerous to humans.
The name “false widow” is sometimes used very generally when referencing the three primary species often found near human populations; Steatoda nobilis, Steatoda grossa and Steatoda bipunctata. These three species can now be found throughout Ireland and the UK, where the name ‘false widow’ is usually used in reference to the most notorious and widespread of the species; Steatoda nobilis – the Noble false widow.
The spider genus Steatoda, in the family Theridiidae, includes about 120 recognised species distributed around the world. Three of these false widow species can be found in Ireland and the UK.
False widow spider fun facts
Years average lifespan
As potent as the black widow
Offspring per year
Of bites occur in beds & clothing
The Noble false widow spider
While not as infamous as the black widow, the Noble false widow spider is by far the most notorious of the false widow species and accounts for the majority of recorded bites.
Noble false widow
Noble false widows in Ireland
The first documented record of a false widow in Great Britain dates back to the 1870s. It is believed to have arrived in the country via imported goods, most likely from the Canary Islands or Madeira. The false widow was first reportedly seen in Ireland in the late 1990s in Bray and it is now the most common urban spider found in Dublin.
The false widows have settled in quite well, successfully taking over habitats and displacing many of our native species. In time, this may have a detrimental effect on our ecosystems.
While false widow bites are extremely rare and usually no more harmful than a wasp sting, its venom has the potential to pack a punch that’s 66% as strong as that of the black widow. The bite has recently been classed as “medically significant” by the team of researchers at NUI Galway who have been studying the spider over the last six years.
False widow spider species in Ireland
What does a false widow look like?
There are several species of false widow spider in the UK and Ireland. While they closely resemble the black widow in appearance and characteristics, the false widows tend to be more brown in colour with reddish-orange legs, although some may be very dark brown or almost completely black.
False widows have distinctive markings on their abdomens but the marks can vary, be faded, or even missing, especially in the adult females. All have a white or cream coloured band around the front of the abdomen near their head. Other markings will vary by species but are often described as being skull shaped, especially with the Noble false widow spider (Steatoda nobilis).
Females have a larger and more globular, shiny abdomen while the males are smaller and less rounded, but their markings are usually more clear.
Female Noble false widows average in size from 9.5 to 14mm, while males are usually between 7 to 11mm. The larger specimens can span about the size of a two euro coin.
Male and female baby false widows are indistinguishable.
Where you will likely find them
False widows in the United Kingdom and Ireland are generally found in and around houses and other buildings. They prefer elevated positions such as the top corners of rooms, sheds, rafters and garages. During colder months they will venture inside for the warmth of bedrooms and living areas.
Outside, they are often found around window frames, wall crevices, gutters, and trees. You may even have noticed their messy webs around the lids and handles of your wheelie bins.
The spiders are usually more active at night and the female Noble false widow is usually seen hanging upside down in her web. It is also common to see their legs poking out from a hole or crevice during the day.
“Some 23 years after being first spotted in Ireland, the Noble false widow is now established in almost every county on the island. In east coastal counties such as Dublin, they are one of the most common urban spiders.”
Colder temperatures will drive many false widow spiders into the warmth of our homes this Autumn.
The chances of finding a false widow spider in your home will increase dramatically as the weather cools and they seek out warmth and a mate.
“Although our study shows that the venom of false widow spiders may be more potent than previously thought, it does not mean we need to fear them. In many parts of the world even “true” black widow bites rarely require medical attention.“
False widow spider lookalikes
Native spiders to Ireland that are often mistaken for false widows.
False widow spider in Ireland stories
A Close Encounter in Cork Hey there! Hope you're keeping well, I actually stumbled across my first false widow spider earlier today and identified it with the help of the internet. I have nothing but good things to say about it honestly! I typically tend to keep my pajamas on if I know I'm not going out for the day, so I had them on for quite a while. I...
Lots of false widow spider webs Over the past year I have noticed a lot of false widow spider webs in my back garden around my shed. I recognised them due to their messy box/sail like shape - as opposed to the traditional neat patterned web of a typical garden spider. The spiders are only active at night so I wasn't too concerned. But I was very...
Was it a baby false widow spider bite? I'm pretty sure I sustained a baby false widow spider bite this summer but I'm not 100% sure. I have seen loads of the adults recently, really for the first time too. A neighbour told me last year that they had a lot of false widow spiders in their back garden. That year I started to notice a few around the outside...