LEADING ARTICLE : Revenge of the killer worms

"Alien worms," screamed one headline yesterday. The story of our peace-loving earthworms being systematically wiped out by alien flatworms has all the makings of one of those 1950s schlock-horror sci-fi movies. Squirm, in which mutant man-eating worms terrorise Smalltown, USA, most obviously springs to mind. The fact that the New Zealand flatworm is said to have arrived from a strange foreign place hiding in pods only serves to enhance their sci-fi credibility.

As for the predatory flatworm's eating habits - too lazy to burrow, it loiters with intent to guzzle on the surface of the soil, pounces on the unsuspecting prey coming up for a breather and stuns it with a powerful narcotic juice before spraying it witha digestive enzyme that turns it into earthworm minestrone - well, even the schlockmeister David Cronenberg might balk at putting that on screen.

Of course, worms have long been small objects of disgust in fiction; it's probably something to do with all that slime and unseemly wriggling about. "Give warning to the world that I am fled/ From this vile world, with vilest worms to dwell," runs Shakespeare's 71st Sonnet.

As you might expect, scientists have had a more sober view of your common or garden worm. Charles Darwin devoted his final years to The Formation of Vegetable Mould Through the Action of Worms (1881), which pinpointed the vital role they play in the cycle of life (ie, without our wriggly friends aerating the soil we'd all be dead). The threat to the traditional earthworm is the reason why people such as Dr Brian Boag, of the Scottish Crop Research Centre, are squirming with concern about the revenge of the killer worms and advising gardeners to turn over stones and stamp on the blighters.

Like the North American grey squirrel and the Himalayan rhododendron before it, the New Zealand flatworm is colonising Britain with such success that indigenous species in some areas are under threat of extinction. Not only are they taking over our jobs as barmen, teachers and nannies, species from Down Under are now laying claim to our soil. But it's not all bad news: apparently, there might be a commercial use for the flatworm's digestive enzyme in washing detergents.