On the Big Island of Hawaii, a fungus called ceratocystis is murdering ‘Ōhi‘a trees—at least 1 million in the past eight years. Local forest experts had no idea how to contain the quick-killing pathogen, until an aerial survey from ecologist Greg Asner revealed a pattern they could distinctly see only from above. At the edge of Hawaii Volcanoes National Park, fences drew a sharp line between dead trees and healthy ones. The barriers kept out feral pigs, which, they realized, would gash the trunks with their tusks, enabling the infection. If the scientists could bar the ungulates, the ‘Ōhi‘as might survive.