Woodlouse spider

Woodlouse spider - Dysdera crocata
Woodlouse spider – Dysdera crocata

The woodlouse spider (Dysdera crocata) is instantly recognisable with its red head, thorax and legs combined with a pale oblong body. Ranging from 10 to 15mm in length this spider has no hair and a shiny appearance. The other identifying feature of the woodlouse spider are the large, immediately visible fangs that project directly forward from the head. In my opinion this is one of the scariest looking of all the British spiders!

Dysdera is known by several names all of which relate to its exclusive diet of woodlice; sowbug hunter, sowbug killer, woodlouse hunter, pillbug hunter and slater spider are all alternate common names.

As woodlice have a tough, protective exoskeleton the woodlouse spider needs to be equipped with strong, large fangs or chelicerae – which it is. Not only are these fangs capable of piercing human skin, they also present somewhat of a problem during the aggressive courtship behaviour of the spiders!

On the rare occasions that people have been bitten by Dysdera the degree of pain has been described as ranging from a nettle sting to a bee sting. The venom is not thought to be particularly significant to humans but local itchiness and marking has been reported.

Although widely distributed across the UK there is less chance of coming across a woodlouse spider as they live outdoors and are nocturnal. They spend the daytime hiding in a silken retreat in crevices or often under logs.

7 thoughts on “Woodlouse spider”

  1. I have been suffering from bites from a mysterious source. Inflamed cluster bites that have happened outside then become infected and turned into large circular blisters like balloons. When I showered yesterday I found a red Woodlouse spider in my bath. Could this be the culprit?

    • No, very unlikely, sounds like allergic reaction to flea or gnat bites. The woodlouse spider will not actively attack you unless it gets trapped beneath clothing etc

    • check out blister beetles. I was getting blisters on my legs that itched.A co worker mentioned her daughter was camping and came home with the same looking blisters. It happened at work where doors are open to the outside.I felt what seemed like something on my legs but was unable to see anything

  2. I just found one on my kitchen sink, in Waterloo, Iowa, USA. I photographed it (because I keep finding large, weird spiders in this very old house I live in but I forgot to photograph the others). Thank you for showing your photo–your photo was the only one on internet I came across that matched my spider.

  3. I suspect I was bitten by one of these last night! Quick, almost nettle-ish pain, two small and very neat puncture marks with localised swelling and numbness with a very faint colour change.

    I was in my greenhouse which is over long grass at night-time, so I suspect I disturbed one and it gave me a good chomp.

  4. yep just came across this beast roaming across my patio tonight whilst my dog did his business! Strolling straight past multiple wood lice clearly not hungry! It was 15mm in size, red legs, body and fangs with pale shiny beige abdomen!


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