Elizabeth PennisiAn exotic metallic green beetle is eating its way through North American forests, leaving dead ash trees in its wake.
In the 20 years since this Asian pest, the emerald ash borer (Agrilus planipennis), was first discovered in Michigan, it has killed tens of millions of trees and spread to 35 U.S.
states and parts of Canada. Now, a new analysis predicts ash populations might not recover, because the beetle also attacks young trees that sprout after older trees are gone, blocking long-term reproduction.In some places, ash may disappear completely, says forest ecologist Isabelle Aubin of Natural Resources Canada, who was not involved with the work.