Millions of bats are dying from a poorly understood disease called white nose syndrome. The disease is heading West and scientists fear it could devastate Montana’s bat populations. That would have big consequences ecologically, and also economically, since bats help farmers and ranchers by eating pest insects. A study published in Science estimates that bats in North America are worth at least 3.7 billion dollars per year to the agriculture industry. But little is known about Montana’s bats. Reporter Allison Mills of Science Source took to the field with researchers who are learning more about the nocturnal critters by listening closely to their ultrasonic sounds.