Nursery web spider

 The rough grassland on the old Brancepeth  colliery site, never grazed or mowed, is perfect habitat for the nursery web spider Pisaura mirabilis. This female had recently enclosed her egg cocoon inside a silken tent woven around grass stems - a nursery where the vulnerable spiderlings can hatch and grow in safety.

Over 250 years ago, the Swedish taxonomist Carl Alexander Clerck gave this species the scientific name Pisaura mirabilis, the marvellous Pisaura. Its fraught courtship ritual has been a source of wonder for arachnologists ever since. Males pacify females, which are notoriously prone to cannibalism, with the gift of a fly wrapped in silk. The larger the fly, the longer it will take to unwrap and eat, extending the opportunity to copulate before her hunger turns to aggression. So, there is a premium on males who are good hunters, though deceitful suitors sometimes wrap and present small twig fragments, risking death mid-copulation when she uncovers the fraudulent offering.

If she does accept his advances she'll eventually produce a ball of eggs wrapped in white silk that she carries in her jaws, slung under her body, until they are almost ready to hatch. The egg cocoon is so large that she is forced to walk around on tip-toe, to keep it clear of the ground.

 These pictures show what happens next - a remarkable example of spider maternal instinct. Her eggs have matured and the grasses have grown tall, so she climbed to the top and bound a few together with silk. Then in the space below she wove a tent, deposited her eggs inside, nibbling through the cocoon so that the spiderlings could hatch and then finally sealed them inside their silken nursery. 

Now, she’ll stand guard until they grow large enough to bite their way out of their nursery and take their first steps into the outside world. In the photographs below you can see her yellow egg cocoon, safe inside the nursery she has woven, with spiderlings beginning to hatch.