Tag Archives: “False Widow”

False Widow Spiders

Unfortunately this week I have been a bit slow on the draw when it comes to posting, but here at last are photos of False Widows to help you identify them. It seems they have been in the south of the country in small numbers for over a century, but with the mild winters of the 1990s and 2000s they spread about the island of Ireland rapidly, aided greatly by the sheer amount of activity of  the Celtic Tiger.

A classic example of a female Steatoda nobilis, the larger of the two common False Widows found in the British Isles. She is very similar to the female Missing-sector Orb-weaver spider, but much larger.
A classic example of a female Steatoda nobilis, the larger of the two common False Widows found in the British Isles. She is very similar to the female Missing-sector Orb-weaver spider, but much larger.

Anyhow, the first thing you need to know is that they get their name because of their resemblance to the true widow spiders, the Lactrodectids, They are identical in size and shape and sometimes in colour, depending on the species.  And, most importantly, they are also venomous to humans, but much less so than the true widow spiders. However, if you have an allergy to their bite then it might as well be a true widow spider, and you immediately need medical help. How do you know if you are allergic? Simple, you will also be allergic to bee stings. The acid in bee stings is almost identical to the acid in the venom of these spiders, and to the acid in nettle stings. Crushed leaves of the Dock plant are very effective at treating all three stings if you are not allergic, as is a little baking soda dissolved in water, as these things are alkalis. If you are allergic or get any sort of large swelling after a bite, whatever the biter was, always seek medical help immediately. Don’t try to tough it out.

A dark female specimen of Steatoda nobilis.
A dark female specimen of Steatoda nobilis.

The female Steatoda nobilis can be very dark, as in the photo above,  but the slightly smaller Steatoda grossa can be as shiny and black as a black currant, and is much more easily confused with the infamous Black Widow. The usual patterns that distinguish the species can often only be seen under a strong light, such as from a flash bulb. False Widows spend almost their entire lives hanging upside down and are very slow-moving. If they are attacked they normally pull their legs in tight to their bodies like a tortoise and drop to the ground to wait until the danger has passed. They mostly get onto humans (a rare enough event) when they are accidentally carried away in items from sheds.

A male Steatoda nobilis trying to convince a female to mate having blocked her retreat into the hollow rung of an upturned ladder. He has very red legs and is as large as she is although his abdomen is much smaller. Pregnant females will have swollen and shiny abdomens about the size of a black currant or a little larger.
A male Steatoda nobilis trying to convince a female to mate having blocked her retreat into the hollow rung of an upturned ladder. He has very red legs and is as large as she is although his abdomen is much smaller. Pregnant females will have swollen and shiny abdomens about the size of a black currant or a little larger.

Unlike true widow spiders, the males of False Widows can be almost as big as the females, and well capable of bullying a female into mating. The true widows don’t stand for that behaviour, which is why they become widows so soon. But their males are much smaller than them. Right now, in Autumn the male Steatoda nobilis spiders are roving around still looking for females. They climb walls outside houses where the females usually wait quietly under the eaves. Some males do get eaten, but this year every male I’ve seen successfully mated and escaped to mate again. That’s probably why they grow as large as their females.

A magnificent example of a male Steatoda grossa False Widow, seen not now but in the spring, their time to wander round. they don't get very big though, but big enough if you don't like spiders.
A magnificent example of a male Steatoda grossa False Widow, seen not now but in the spring, their time to wander round. They don’t get very big though, but big enough if you don’t like spiders.

Although the female Steatoda grossa is very similar in habits to the larger S. nobilis, they much more readily enter houses, particularly sheds and quiet and cool attics. They arrive as tiny spiders and stay put only if they are not disturbed. The male S. grossa is completely different to the female. He seeks her out not in autumn, but in the springtime. Larger ones can resemble the long-legged running House Spiders that terrify people every autumn but they are not nearly so big and can be very brightly coloured. Above is a classic example of a male Steatoda grossa, which prefers running along the ground to climbing around upside down, until he finds a mate. He is clearly built for running.

Now, that mostly takes care of False Widows but I will be uploading a video soon which some people will probably find more useful as the behaviour of various spiders is more obvious.

How to recognise a False Widow

The photo of Steatoda nobilis in the previous entry shows a female with the classic pattern of this species. However, here is the other, smaller False Widow, Steatoda grossa, which has a similar pattern, but with a row of triangles in the middle rather than a big pale patch.

A classic example of Steatoda grossa, a female.
A classic example of Steatoda grossa, a female.

So here are the best ways of recognising False Widows:

1. The spider’s abdomen is generally very shiny, like a berry. The spider is hairless.

2. False Widows don’t just hatch out of an egg fully grown. They can be very large, up to 2.5 cm (just short of an inch) when pregnant, and any size under that.

3. The web is a hammock-type web, but unlike the similar Hammock-web Spider, the web of the False Widow is EXTREMELY strong.

4. The spider always hangs upside down from its web.

5. Apart from the male Steatoda grossa, which is a fast runner often wandering into houses in spring (he doesn’t bite for some reason and will happily let you handle him) the female S. grossa and both male and female Steatoda nobilis are extremely slow and clumsy on the ground and actually slip when they walk on smooth surfaces.

6. The False Widow pulls its legs in tight, forming a ball, if knocked from its web or handled. Biting is the very last resort.

7. Both species have two very shiny eyes located at the top front of their heads which virtually glow in torchlight and are among the first things you will notice.

False Widows rest under crevices, usually only coming out at night when birds won’t see them. Birds have no difficulty eating any spider that will fit in their mouths. Anything resting against a wall, or in a sheltered area, or on the outside of a house especially under the eaves will be an attraction to a False Widow. They will enter sheds too, but outside if their preference.

8. False Widows are not afraid to be outside on even the coldest, frostiest nights. It was assumed, because they originate from the Canary Islands that they would fear the cold, but I have seen them outside in their webs when the temperatures were below freezing.

A big female Steatoda nobilis. This is one of the darker ones, with only a white crescent to the front of the big abdomen. They can be all black too, as can Steatoda grossa.
A big female Steatoda nobilis. This is one of the darker ones, with only a white crescent to the front of the big abdomen. They can be all black too, as can Steatoda grossa.

 

False Widows

A good few people have been in touch yesterday and today due to concerns over False Widow spiders being in Ireland.  I’m doing this post just to give you the facts. For anyone who is generally concerned about spiders and how to identify them, here is a link to my e-book about spiders, which you can download and read whether you own a kindle, or not, as it works on pc, laptop or Mac automatically when you download:

http://www.amazon.co.uk/Irish-Spiders-ebook/dp/B00ALJ8JTE/ref=sr_1_1?ie=UTF8&qid=1381702822&sr=8-1&keywords=sam+connolly+irish+spiders

A female Steatoda nobilis False Widow eating a woodlouse.
A female Steatoda nobilis False Widow eating a woodlouse.

Firstly, they’ve actually been recorded in Britain since the 1870s and here since the early 1980s. Firstly, they’ve been well established in Ireland since the 1990s. I found my first one in 1996. Secondly, they are called False Widows because they are not in the same genus as the true Widow spiders, but they are related. They are also much less venomous, and many False Widows are not venomous to man at all. They are virtually identical though, in size shape and colour.

Both Steatoda grossa and S. nobilis can be all black, looking identical to true Widow spiders. This one on my hand is an all black S. grossa.
Both Steatoda grossa and S. nobilis can be all black, looking identical to true Widow spiders. This one on my hand is an all black S. grossa.

False Widows also don’t actively bite and they don’t wander around very much either. They are not nearly as large as the House Spider, and are smooth rather than hairy. The body is the shape, size and texture of a black currant. I have frequently handled them and so far have never been bitten. However, if you are bitten the alkalic juice of the Dock leaf is very effective at neutralising the venom. Baking soda diluted in water is also very good but be careful as some people suffer burns to their skin from baking soda.

The bite my brother received when he accidentally crushed a False Widow beneath his hand. The spider lived, as did my brother. He described the pain as a numb ache that lasted about half-an-hour.
The bite my brother received when he accidentally crushed a False Widow beneath his hand. The spider lived, as did my brother. He described the pain as a numb ache that lasted about half-an-hour. I originally thought this might have been the bite of the Walnut Orb-weaver, an indigenous Irish spider which also delivers painful bites, as it was not quite as painful as we expected it should be. However, Trevor was 100% certain of his identification, and he knows his stuff.

Finally, the bite: the effects you suffer, if any, very much depend on your skin pH, and specific biology. My brother, Trevor, accidentally leaned on a False Widow when he rested against a bust stop bin while waiting for a bus a few years ago. It was a fully grown spider. Trevor says that the average bee-sting he has suffered was about twenty times more painful. However, some people could be allergic and suffer anaphylactic shock, but a peanut is potentially as much a threat to any person as a False Widow in that case.

Anyhow, the two most common spiders False Widows are confused with are the Missing-sector Orb-weaver  (Zygiella x-notata) and the Windowsill Spider (Amaurobius similis, both of which are very different to each other, but somewhat like False Widows.