Eight years into a U.S. program to control damage from feral pigs, the invasive animals are still a multibillion-dollar plague on farmers, wildlife and the environment. They've been wiped out in 11 of the 41 states where they were reported in 2014 or 2015. And there are fewer in parts of the other 30. But in spite of more than $100 million in federal money, officials estimate there are still 6 million to 9 million hogs gone wild nationwide and in three U.S. territories, doing at least $2.5 billion a year in U.S. damages. Estimates in 2014 were 5 million hogs and $1.5 billion in damages. Experts say the bigger figures are due to better estimates, not increases.