Green Crab Spider (Diaea dorsata) Photo By André Karwath aka Aka – Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=289458
Dear Readers, after my second fall last week I wasn’t able to go on Sunday’s Invertebrate walk in Coldfall Wood, led by spider expert Edward Milner. It’s so frustrating, but it is what it is, and so I have to enjoy such events vicariously. I was delighted to get an email from Edward this morning, saying that one of the spiders that they’d found was the little beauty above – a Green Woodland Crab Spider (Diaea dorsata). We don’t think of British spiders as being particularly colourful, but this is a splendid spider, a specialist of woodlands – it particularly favours yew, box and oak.
Photo by By André Karwath aka Aka – Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=289462
As is often the case with spiders, the male looks completely different – you can see one in a short film here. They compete for females by standing opposite one another, stretching their (very long) front legs and dancing around one another. Well, it beats fighting. In some species of crab spider, the female can be sixty times larger than the male. One theory is that the bigger the female, the more eggs she can produce, while the smaller males are much more agile and can dash about to find females.
As with all crab spiders, these are ambush predators, hanging about on a flower or leaf or the trunk of a tree with their ‘arms’ wide open and ready to fold a passing fly into their deadly embrace. In the film you can see the spider extruding a line of silk – crab spiders often use this as an ‘anchor’ to prevent themselves from falling off if they grab an over-vigorous prey, and the threads can even act as tripwires, to slow up approaching (or more likely retreating) prey.
Although they can look pretty terrifying, these spiders only grow to about 6mm long, so they are on the small side for crab spiders, though even the giant of the family only manages just over 11mm. In their habitat they are little tigers, though, waiting for passing prey with infinite patience. Our woodlands and gardens are full of drama on a miniature scale. It’s always good to be introduced to one of the actors.