To the untrained eye, all may appear tranquil and calm in Wisconsin's forests, but the truth is that a war of sorts is underway -- between two foreign species on U.S. soil. For the last several years, a particularly nasty invasive beetle has been ravaging ash trees, and in the latest bid to combat the destructive pests, entomologists have enlisted the beetle-killing prowess of other non-native insects -- tiny parasitic wasps recruited from China. Experts are hoping the wasps will fight the good fight to save the ash trees without causing any problems of their own.
http://www.treehugger.com/files/2011/06/invasive-wasps-released-to-battle-invasive-beetles.php