At this point, it’s a losing battle. Bats with noses dusted by the Geomyces destructans fungus that causes WNS were seen for the first time in early 2006, in upstate New York. One year later, biologists realized that WNS could kill bats in large numbers. By 2008, mortality in major New York and Vermont hibernacula, caves where tens and hundreds of thousands of bats had wintered, was more than 90 percent. Biologists wore gas masks against the stench of rotting bodies. Bones cracked like popcorn under their feet.