More spiders

Posted: Wednesday 3 October 2007
by Richard Jones

Moving some bricks around the shed yesterday revealed one of my favourite spiders. There is no mistaking the 'woodlouse' spider, Dysdera crocata.

Richard JonesMoving some bricks around the shed yesterday revealed one of my favourite spiders. With a narrow reddish-pink body 25 mm long and long rather slender legs, there is no mistaking the 'woodlouse' spider, Dysdera crocata. It makes no web, but hunts under logs and stones after woodlice.

Not much eats woodlice, they are incredibly tough. As land-dwelling crustaceans, their shells are hardened with calcium carbonate, the compound that gives us chalk and limestone, and they are much stronger than insects. Dysdera is well-equipped though, with large jaws that articulate up and down as well as left and right. It can open its mandibles, twist them round and skewer the carapace of its prey from above and below at the same time. And if it can't get a woodlouse it's voracious and powerful enough to attack almost anything else, even other spiders larger than itself.

One consequence of having such dextrous mouthparts is that Dysdera is one of only a handful of UK spiders that can deliver a painful bite to humans. Most spiders just cannot open their mouths wide enough to get a purchase on our relatively huge fingers, but Dysdera can. And most spiders do not have long enough fangs to deliver their insect-lethal venom through our thick skin, but Dysdera has.

I've felt the bite. It was a long time ago, but I still remember it clearly. I must have been in my early teens and I was out exploring round the barn of my Uncle's farm near Upchurch, in North Kent. I turned over an old fence post lying on the ground and saw what was clearly a very distinctive spider that I knew I would not have much difficultly finding in an ID guide. I picked it up to have a look under the lens. Ouch. It's not at all human-lethal, but it was as sudden and painful as a wasp sting and enough to make me drop the animal instantly.

So now whenever I see Dysdera it gets my double respect; ecological respect for eating the unpalatable morsels that are woodlice, and personal respect for the very long and very sharp venom-injecting fangs at the serious biting end of its very pretty body.

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Gardeners' World Web User 04/10/2007 at 08:16

I've never seen one of these spiders. Do you have any pictures of one?

Gardeners' World Web User 04/10/2007 at 08:16

katskorner and dawn - click on the link in the first paragraph for a photo of Dysdera crocata. It's very pretty.

Gardeners' World Web User 04/10/2007 at 11:31

I have a large spider in my greenhouse which has a black and white striped body. Do you recognise it and is it dangerous?

Gardeners' World Web User 09/10/2007 at 14:59

I was very pleased to read this article asIi have always had a healthy respect for spiders in my garden. It was good to be reminded of the benfits of these amazing creatures. It is easy to watch the web building ones doing their work in the garden but the ground dwelling hunting types also earn their place. What a pity there isn't a slug eating spider!

Gardeners' World Web User 12/10/2007 at 14:11

whilst watching my spider on his web this morning, i noticed he had a very large ladybird struggling in it. i hastened to rescue it, and then realised it had many, many spots and did not look like a normal ladybird. could this be a harlequin, mentioned on the programme in the summer? unfortunately, he has now been joined by several friends, a kind of mini swarm is now covering my french doors!

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