Three stories about human impact on the natural world -- the emerald ash borer, an invasive beetle from Asia that is killing ash trees in Maryland; the monarch butterfly, whose population is threatened by herbicides; and the osprey, whose population in the Chesapeake is on an upswing. Our guests: Mike Raupp, an entomologist from the University of Maryland; Joel Dunn of the Chesapeake Conservancy; and Paul Spitzer, ornithologist and naturalist.