What’s a country to do with a millions-strong plague of crop-munching rodents? Ideas abound for Spain’s Castille-Leon region to quell its infestation: Burn them. Drown them. Choke them with engine exhaust. Squish them with a rolling pin attached to a plow.
Then there’s this high-tech doozy from a government veterinarian: Zap these mouse-like animals called voles with earsplitting ultrasound, using a cross between the Pied Piper ploy and a military pincer movement to herd them together for a collective death blow with water or fire.
The government of Castille-Leon, a northern region that is one of Spain’s agricultural heartlands, began burning harvested farmland last week to try to wipe out an invasion that had been brewing for months but has now mushroomed into an agricultural nightmare.
Farm organizations initially estimated the mysterious vole infestation at 7.5 million wee intruders. But Jose Carlos Pinero, a veterinarian with the Castille-Leon regional health department and proponent of the ultrasound eradication idea, said Tuesday that scientists now believe there are hundreds of millions of the pests — perhaps as many as 700 million.
Voles give off a characteristic odor and the plague is so intense you can smell the critters — live ones, not rotting bodies — as you drive around, he said.
“The other day I was driving along the highway and the smell was overpowering,” Pinero said from Valladolid, the regional capital.
Grain crops have been devastated and the voles are now turning their appetites to summer crops like potatoes, grapevines and beets.
The government says it is flummoxed as to what is causing the infestation, although Pinero blames it on a mild winter — freezing temperatures kill off many voles — and an abundance of spring rain that led to bountiful harvests and a rodent feast.
Pinero presented his ultrasound plan to the government on Monday and said he expects an answer soon because the infestation is at crisis level.
It would work like this: zap the animals with ultrasound devices — they are inaudible to humans but excruciating for voles — from two directions, shooing them toward a designated point where they could be drowned or burned.
Pinero likened it to the Brothers Grimm tale of the piper who lures a plague of rats out of a town with irresistible music.
Other weapons are being considered as well.
From cyberspace, Internet contributors offer up ideas like piping motorcycle exhaust fumes into vole holes, stuffing the holes with rags soaked with gasoline or even electrifying them.
Pablo Villar, mayor of the town of Villalar de los Comuneros, population 500, tried out a makeshift extermination device Tuesday: a huge iron tube tied the back of a farm plow. The idea is to loosen the soil and uncover the voles’ hideouts, then crush them with the roller.
The result was so-so. “The roller did not kill as many animals as we thought it would,” he said in a telephone interview, adding that he will try again with a heavier one. The streets of his village used to be crawling with voles, until he set up a perimeter of poison.
“I am simply not going to allow voles to live here with me,” he said.