On its own, the beetle can move only relatively short distances. With people moving firewood, the beetles can be moved across town or even across the state in one fell swoop.
You can take the bark off an ash tree and see if (the borers) come to it. This pest prefers stressed trees, but it will attack healthy trees as well. You can spend a lot of money taking down trees in a half-mile radius, but if you don't have the ability to tell it's in another tree 100 feet away, the policy doesn't make much sense.