Country diary: the spiderlings are under wraps

Country diary: the spiderlings are under wraps

Country diary: the spiderlings are under wraps

Bishop Auckland, County Durham: This nursery web spider has woven a protective nursery around a folded burdock leaf

Pisaura mirabilis weaves a silken nursery for her spiderlings and guards them until they can fend for themselves

Wed 7 Jul 2021 00.30 EDT

Last week I spotted a nursery web spider crouching in a fleck of sunlight in the undergrowth. Motionless, camouflaged in shades of brown, she was well hidden among the dead leaves. Only her pea-sized white egg cocoon – carried under her jaws, forcing her to stand on tiptoes on her long legs – gave her away.

Since then, motherhood has progressed. Sensing the stirring of spiderlings in the ball of eggs under her body, she had woven a protective nursery around a folded burdock leaf. Now she sits on top of the silken tent, defending her brood in characteristic pose, front pair of legs on each side held close together, so at first glance she seems to have only six limbs.

Before she deposited her cocoon, she bit through its outer coat, allowing her spiderlings to escape into their nursery tent. There they’ll stay, under her protective gaze, until they’ve moulted twice and have a fighting chance of fending for themselves. A gentle finger poke sends her scurrying away, but she’s soon back, standing guard against smaller threats, like parasitic wasps.

A female nursery web spider carrying her egg cocoon under her body,.

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.

The species is uncommon hereabouts, but this sheltered site, beneath a sun-warmed wall, clearly suits it perfectly. When the brood disperses and she’s ready to breed again, I’m hoping to witness that fascinating high-stakes courtship. Her prospective mate had better arrive bearing a substantial gift because, preoccupied with motherhood, she may not have eaten for several days.

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