Deadly white-nose syndrome is striking more bats over a larger area this winter, reaching south into New Jersey and Pennsylvania and emptying caves in hard-hit areas like New York.

Two winters after it was first observed, bats in at least a half-dozen states have been infected by white-nose and a suspicious sighting has closed a cave preserve in West Virginia as a precaution. While researchers recently identified the fungus that creates the distinctive white smudges on hibernating bats, they are scrambling to find a way to stop the scourge.

Bats with white nose burn through their fat stores before spring. The syndrome poses no health threat to humans, though some scientists say that if bat populations diminish too much, the crop pests they eat could flourish.