A preservative used to cure bacon is being tested as poison for the nation's estimated 5 million feral hogs, which cost the US about $1.5 billion a year—including $800 million in damage to farms. Hunting and trapping won't do the trick for these big, wildly prolific animals. "It looks like a bulldozer has been through your field," says one Mississippi farmer of the damage wrought; in addition, feral pigs' feces was likely behind the 2006 E. coli outbreak in California that killed three people. So, the US Department of Agriculture kicked off a $20 million program this year, and it's focusing on a somewhat unlikely poison: Sodium nitrite, used as a salt to preserve meat, including bacon, is far more toxic to pigs than people and is used in Australia and New Zealand to kill feral swine. USDA scientists say it may be the best solution in the US, but they're not yet ready to ask for federal approval as pig poison.
To stay even, at least 70% of an area's feral pigs must be killed each year, says a USDA biologist. "The problem will never, ever end until they find a way to poison them," says a weekend hunter who estimates he has shot 300 to 400 a year. But baits so far haven't hit the 90% kill rate needed for EPA consideration. Once it does, approval could take up to five years. However, there's another big hurdle: making a bait dispenser other animals can't break into. A solar-powered machine designed to open only when pigs grunt and snuffle is being tested at the Kerr Wildlife Management Area in Hunt, Texas. The HAM (Hog Annihilation Machine) delivers a 15,000-volt shock to animals that touch it when its hoppers are closed—not enough to faze a pig or injure other wildlife but enough to send a bear or raccoon running. (Read more feral pigs stories.)