Kansas City Star | 09/19/2002 | `Alien species' are everywhere

Well, technically humans are an alien species, in the Americas and Australia anyway. You think snakeheads are voracious! Anyway, this is a nice summary of the whole situation. It's getting a lot of attention because of the DCSWF, but as a problem for North America it goes back to the European conquest. Unless you're including humans, in which case it goes back much further...