Bats eat insects that damage crops and mosquitoes that are vectors for disease. One million bats can eat several tons of insects per night, saving billions of dollars in pesticides yearly. Agricultural and public health scientists are concerned about the spread of white-nose syndrome (WNS). WNS is a result of a fungus that can infect cave-dwelling bats. While bats hibernate during winter months, the fungus covers the bats’ face and wings. WNS has a near 100% mortality rate, and 5.7 million bats have died since the discovery of the fungus in 2006. Many scientists are searching for ways to protect these bats. The relationship between this fungus and bats can best be defined as