Country diary: Leeches are sinister, insatiable – and more common than you’d think

Who loves a leech? Not me, for sure. Neither the black (in reality a speckled olive-green) horse leeches that undulate, swift and purposeful, across the muddy bottoms of ponds, nor the paler fish leeches that plague the carp that rise out of the green depths of Llandrindod Lake. Here, a water bailiff transfers the carp to his keep-net and with a flick of his fingernail rids them of their unwanted parasites. There’s even a word, hirudinophobia, for that shuddery psychological dislike of these miniature vampires, about which the Book of Proverbs had this to say: “The horse leach hath two daughters, crying, ‘give, give’. There are three things that are never satisfied, yea, four things say not, it is Enough!”

A medicinal leech sucks several times its own weight in blood before it falls off, returns bloated to its muddy home and does not need to feed again for weeks. They’re surprisingly common, present year-round, yet seldom seen. The first one I saw, when I was 12, was in Cheshire’s Dunham Park Lake. I looked down, appalled, into murky water at this dark, flat thing, a toothed mouth at both ends, speeding purposefully across the bed of the lake. The way leeches move is so sinister.

Years later, travelling by dugout canoe up the Rejang river in Sarawak, Malaysia, to the headhunters’ village of Long Singut, our guide took us into a shop to buy women’s tights – “Best thing to keep the leeches out,” he explained. Other travellers told tall tales of limbs rendered invisible under a waving curtain of leeches, of socks filled with blood, of leeches dropping like rain out of the trees on to any bare flesh. I didn’t get bitten once.

This Llandrindod leech was a different matter. It crawled up the bank with that looping gait and headed into the grass. A silvermew, or herring gull (Larus argentatus), inland from Storm Gerrit, was doing its worm-dance, luring them to the surface. Worms galore popped out of the ground. The leech latched on to a particularly juicy specimen, and commenced to suck. The bird cocked its head, seized both leech and worm, and wheeled away in strident delight. The moral: if you’re anywhere near leeches, take a herring gull along with you.