Wolf spider in Collserola – Hogna radiata

Written by Lucy Brzoska

Something scurried across the ground in fits and starts: a spider with a bristling brown back.  I approached and found the bristles were a cargo of spiderlings.  Their mother, a Wolf Spider, was moving her brood in broad daylight along a track in Collserola.

wolf-spider-hogna-radiata-and-spiderlings

At first I thought it was a Mediterranean Tarantula (Lycosa tarantula), but the radial pattern on the thorax should have led me to Hogna radiata.  Another difference between the two species is that H. radiata doesn’t build a burrow, instead roaming to hunt its prey and using stones for shelter.

Looking at the tightly-packed brood, it was possible to make out rounded bodies and a tangle of spiky legs.

wolf-spider-hogna-radiata-spiderlings

Wolf spiders are dutiful mothers who carry the egg sac attached to their spinnerets, quite a burden for an active hunter.  The abdomen has to be kept raised so the egg sac doesn’t drag on the ground.  The mother spider will sit in the sun to warm the eggs, and when the time is right, chew open the silk case to free her brood.  She’ll wait until all the spiderlings have climbed on board and are clinging to her bristles.

Maternal care doesn’t go as far as feeding the young (as in other species, like the Mothercare spider).  Wolf spiderlings survive on nutrients stored in their abdomens and usually after a week they moult and scatter.

Wolf spiders are among the largest spiders in Europe.  H. radiata is only slightly smaller than the Mediterranean Tarantula, the female measuring up to 2.5 cm long.  Out in the open, the spider struck me as vulnerable and defenceless.  But the view from the front was quite different.

wolf-spider-hogna-radiata-with-young

The prominent dark eyes – which gleam in the dark if you go searching for it by torch-light – and strong hairy legs – the sprinting spider pounces on its prey like a wolf – warned me I was facing a formidable hunter.

Wolf spiders have far better eyesight than other spiders, and the eyes are arranged in a distinct pattern: a row of four at the bottom, two on top, and two enormous ones in the middle, all visible from the front.  Look at this fantastic close-up.