The truth about Steatoda nobilis - is it the UK's most dangerous spider?

The truth about Steatoda nobilis - is it the UK's most dangerous spider?

The Daily Mail today squeaks a warning about the inexorable rise of what it describes as "the UK's most dangerous spider":

Somehow avoiding a link the the forthcoming Spiderman movie the article begins:

Global warming has led to the rapid rise in numbers of a poisonous spider which is a close relative of the deadly Black Widow and is now thriving in Britain. Although the false widow spider accidentally came into this country 200 years ago after it arrived in a bunch of bananas from the Canary Islands, it is rare to find one. But our mild winters and have sent numbers rocketing.

Experts are now warning gardeners to be alert after a couple stumbled across two of the biting black spiders, known as Steatoda Nobilis in Latin... Stuart Hine, insect expert at the Natural History museum, is now warning all gardeners to be on alert. He said:
"Numbers of the Steatoda Nobilis have whipped up in the last ten years. There is no doubt in my mind that this is due to the milder winters caused by global warming."

Now apart from the oddities in this text (would the eminent Mr Hine really have said 'the Steatoda Nobilis'? The definite article is erroneous, as is the capitalisation) its really no more than a tired old story whipped up for the season (and an apparent rewrite of a 2006 story in the Daily Telegraph).

If someone had actually been bitten by the spider and suffered ill-effects (a malaise known as steatodism) that would probably be news - as such an event is pretty rare in this country. There is one reported case in which Steatoda was confirmed to be the cause in Worthing in 1991, but the only other well-known incident was in 2006 in Dorchester, and of this the same Mr Hine says, in a Natural History Museum page on the subject:

In this case, the spider ran off and couldn't be captured, so it wasn't formally identified. The culprit spider was described as looking very much like one of the false widow spiders, Steatoda nobilis , but there are a number of similar looking species such as the black widow. The incident happened in a market, so it is possible that the culprit may have been an exotic spider accidentally shipped over in a fruit container from overseas.

It's quite possible it was an exotic spider, and if indeed these severe symptoms were wholly attributed to the spider then I would say they are a bit extreme for the bite of S. nobilis in a healthy adult.

So not much to worry about there then. Many other cases of reported spider bites turn out to be unproven, and as an adverse reaction is in itself unusual it's hard if not impossible to say what species was involved after the fact - especially as the specimen responsible is usually a jammy smear by that time.

As with nettles, bees wasps, and even peanuts and PVC, some people unfortunately are sensitive to spider bites and will suffer reactions such as flu-like episodes, palpitations and hot/cold sweats. But for almost everyone, the effect of spider bite in this country is an itchy lump for a day or so at worst.

So actually, there's almost no evidence of Steatoda nobilis or any other UK spider causing anything more than temporary discomfort to anyone. [Edit: Stuart Hine reads The Ranger's Blog - he gives more detail of actual statistics in a comment below. Thanks Stuart!]

What is clear, however, is that there are a good many people terrified of spiders, and this sort of alarmist populism serves only to reinforce this terror without any benefit to them. For example, the Daily Mail continues:

Michael Willis and his wife Pam, both 62, were terrified after spotting the shiny black creatures crawling up their garden wall of their home in Verwood, Dorset.

Unsure what to do, Mrs Willis captured one in a jam jar and took it to an environmental health expert who confirmed it was a female Steatoda Nobilis.

Poor old Mr and Mrs Willis - terrified by a more-or-less harmless spider in their garden. There are probably thousands of the spiders there, and they've probably been there for decades. And yet nobody has been bitten, certainly not Mr and Mrs Willis. Despite this lack of notability, they were obviously upset, as this creeping menace merits the attention of the local Environmental Health, the Daily Mail, the Natural History Museum, and now us.

So Steatoda may well be the UK's most dangerous spider, but that position is only slightly more odious then being the UK's most dangerous kitten. Far better, and more accurate, if the headline had been 'Worried householders reassured to know that spiders are safe and good for your garden'. Doubtless the sensible reassurance that Stuart Hine added to his statements was edited out along with his grammar and punctuation. Perhaps we should wait for the 'Beware of Water Boatmen' story!