Along the lower Virgin River in the American Southwest, the breeding grounds of an endangered songbird all but disappeared in just five years. The cause wasn't drought or bulldozers, but a small leaf-eating beetle the U.S. government had deliberately introduced to control an invasive tree.
The beetle did exactly what it was released to do: defoliate the tree. The trouble was that many flycatchers had come to depend on that same vegetation for nesting.
