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.

The False Widow Spider Ireland distribution

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.

Identify the three false widow species in the UK & Ireland

False widow spider fun facts

False widow spider Ireland lifespan

Years average lifespan

False widow spider poisonous venom

%

As potent as the black widow

False widow spider reproduction rate in Ireland

Offspring per year

False widow bites in Irish homes

%

Of bites occur in beds & clothing

Gathered from data recently published by the Venom Systems Laboratories at NUI Galway.

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.

Large female noble false widow spider Ireland image
Steatoda nobilis
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.

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.

Image showing family, genus and species relationship between false widow and black widow spiders

False widow spider species in Ireland

The three most common false widow spiders in Ireland and Britain are Steatoda nobilis, Steatoda grossa, and Steatoda bipunctata.

Noble false widow spider

Steatoda nobilis

Cupboard spider

Steatoda grossa

Rabbit hutch spider

Steatoda bipunctata

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.

Learn more about Noble false widows

Image of a female noble false widow spider size compared to 2 euro coin

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.

Male Noble false widow spider in Ireland

“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.”

Dr John P. Dunbar, Aiste Vitkauskaite, Sean Rayner and Michel M. Dugon
Venom Systems Laboratories, NUI Galway
Article: RTE Brainstorm

leaves left large
Large leaf right
leaves left loose

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.

Dr John Dunbar
Venom Systems Laboratories, NUI Galway

The false widow spider is not aggressive and will usually only bite a person when it feels threatened.

“The False widow spider is a new addition to Irish ecosystems and it is here to stay. It is therefore important to learn about its ecology and the potential risks associated with its bite.”

Dr Michel Dugon
Venom Systems Laboratories, NUI Galway

False widow spider lookalikes

Native spiders to Ireland that are often mistaken for false widows.

Lace-weaver

Amaurobius similis

Black lace-weaver

Amaurobius ferox

Missing sector orb weaver

Zygiella x-notata

False widow spider in Ireland stories

Met my first false widow today!

Met my first false widow today!

This morning, a fresh sunny day in April in coastal Galway, just as we were getting the kids ready to leave for school, a false widow spider started making it's way from the front door across our hallway. It wasn't moving too quickly so I was able to get an envelope to put under it and then take it outside. Once outside, I immediately noticed it shot...

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False widow spider in my pajamas!

False widow spider in my pajamas!

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...

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False widow spider in my house

False widow spider in my house

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...

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Baby false widow spider bite?

Baby false widow spider bite?

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...

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