The Emerald Ash Borer (EAB) is an invasive insect that has been decimating ash trees throughout the Great Lakes states. It was first discovered in Minnesota in 2009 and is now found in four counties (Hennepin, Houston, Ramsey, and Winona). EAB poses a particularly serious threat to Minnesota because it is home to nearly 1 billion ash trees that occur throughout the state - the second most of any state.