Tag Archives: Steatoda

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.

 

A few more notes on Autumn Spiders

Some people are worried that the spiders that start appearing in autumn are banded together into small gangs hell bent on mischief. That couldn’t be further from the truth, and the reason the numbers get smaller is largely due to the effects of these big spiders on each other. They are often extremely territorial, and in the photo below you can see a female being driven from her web in an old shed by another female of roughly the same size.

The Tegenaria on the left is still sitting in the extremities of her web, but the intruding spider on the right is much closer to the entrance, preventing her from returning.

The spider left her home and fled while the newcomer decided to set up camp, and made the fatal error of straying to close to a neighbouring False Widow (Steatoda nobilis) which made short work of her. Almost all spider species will prey on each other, and sometimes members of the same species (cannibalism) but it is important to realise that the difference between one spider species and another can be as vast as that between a human being and a cow or any other mammal, and maybe even more so.

A large and dark female False Widow, Steatoda nobilis, with a large House Spider as prey. Spiders are an important part of many spiders prey.

Despite the massive appearance of large Tegenaria duellica House Spiders (the legs would easily span the palm of my hand) the bodies are never quite so large as they appear to be. The largest House Spider I ever saw appeared to have an abdomen of three centimetres in length (an inch) but when I measured it accurately with a scientific ruler I was very surprised to discover its body measured exactly 23 centimetres. And, of course none of these species are the largest in Ireland. That honour falls to a much more impressive creature, the Raft Spider, Dolomedes, which lives in swamps and bogs and hunts frogs and small fish among many other things. When I get a good photo ( I have a bad one) I’ll post something about that very handsome monster.