Since the emerald ash borer (Agrilus planipennis) arrived in the U.S. in 2002, it has decimated ash trees, such as this one showing crown dieback resulting from an infestation. Since 2009, organizers of Emerald Ash Borer University have been disseminating critical knowledge about EAB and other invasive forest pests via online webinars, presented live and shared on YouTube. (Photo courtesy of Elizabeth Barnes, Ph.D.)