A cold-adapted fungus is devastating North American bats. The fungus leaves a trademark smudge of white on the bat’s muzzle. The fungus was discovered in New York bat caves in 2007 and has been steadily moving across the continent since. Initiatives have attempted to slow the spread, but are not working. European bats have developed resistance to this fungus, but so far North American bats are still susceptible. The fungus can live in caves for decades even without bats.