(AP) — In this June 8, 2005, file photo provided by the Texas Parks and Wildlife Department a colony of bats fly at sunset in central Texas.
Bats save American farmers at least $3.7 billion a year in pest-control costs by eating insects that feed on crops, a benefit that could be in jeopardy as a disease that has killed more than a million bats in the Northeast spreads to the Midwest, the researchers said in a paper published in the April 1 edition of the journal Science. (AP Photo/Texas Parks and Wildlife Dept., File)