Roving bands of wild pigs are Feral hogs are invasive species that were brought to North America from Europe by Spanish conquistadors, and ever since, they have multiplied across the country. Millions of marauding wild pigs wreaking havoc through at least 39 states eviscerating crops, gobbling up endangered sea turtles and trampling archaeological sites in a rampage showing no signs of letting up. There are now 6 million of them and they are “rapidly expanding,” according to the Agriculture Department. They move in large groups called sounders. One instance in Ohio met McNabb’s threshold — 30 caught in a single trap. Hogs use their snouts to dig through soil, leaving fields scarred and crops flattened. But they also kill livestock and reptiles.The cost: $1.5 billion a year in damage and control spending, the USDA said in 2014.