The Emerald Ash Borer has spread from its point of introduction in Michigan to the East Coast in less than 2 decades. It is now spreading west at a rapid rate. In Boulder, CO this month, I observed first hand the dead and dying ash trees, victims of Emerald Ash Borer. So far, Boulder is the only Colorado location to report Emerald Ash Borer. In spite of quarantine efforts it will probably soon spread.
Ash is not native to Colorado, but has been planted (over planted?) as a tree that tolerates parking lots and accompanying pollution reasonably well. Emerald Ash Borer in Colorado affects urban and suburban areas. Unlike Eastern North America where ash is common, EAB will have little effect on Colorado’s native forests.