The U.S. Agriculture Department is known for its army of statisticians packing yardsticks and calculators to measure wheat and count soybeans. But the agency needs more firepower for another kind of rural reckoning and is gearing up with thermal imaging weapons. In its crosshairs are aggressive feral hogs that can weigh more than 400 lbs (180 kg) and have been known to carry off newborn calves. They cause about $1.5 billion of damage every year to farm communities and fields, say department officials, and now there are worries they may help spread a deadly pig virus. So the USDA wants...
