Cows: weapon against mosquitoes. ‘Tis the time of year when you slap legs and arms because of pesky mosquitoes. It seems there’s not much to be done about the nuisance, is there? In Sweden, though, the county administrative board of Gävleborg has taken a decidedly more militant action against the mosquitoes in the area of Nedre Dalälven: 200 cows are to graze the land where the mosquitoes lay their eggs, reports Gävle Dagblad. “We have looked at how mosquito larvae are affected by mowing and grazing and have found that there were fewer mosquito larvae there,” says project leader Ingemar Lindquist at the county administrative board. The cows may be set to work as early as next year, and may, according to scientists, reduce the mosquito larvae by as much as 70 percent.