“A bat eats one moth, and that’s 100 more pecans, in theory. If they’re doing that every night, that amounts to something,” Byrd said. “All my life, you can go out at night and there have always been bats. I don’t know how it would be without them.”
A 2006 study found that just in the cotton fields of Texas, Mexican free-tailed bats saved farmers an annual average of $724,000 in pest control costs and losses from insect-related damages. Extrapolating that to the country as a whole, a follow-on study in 2011 estimated that bats are worth around $23 billion in pest suppression services.
Agriculture feeds into many sectors of the nation’s economy, as a whole equaling $992 billion in 2015, or 5.5 percent of the nation’s gross domestic product. Farm output alone contributed $136.7 billion that year, or 1 percent of GDP. In that light, the economic services bats provide is a real and quantifiable sum.
Now, to refine what we know about where the bats are and what insects they’re eating, scientists are looking to the skies. Recent work by University of Tennessee bat ecologist Gary McCracken, his student Jennifer Krauel, and USDA meteorologist John Westbrook are looking at the seasonal movement of insects and how bats track and exploit them. Over three seasons in Uvalde, Texas, they found that bats were eating 44 different agricultural pests, 20 of which were migratory. But that means that bats are having even more of an invisible effect, a big challenge to overcome in helping farmers understand bats’ real-world benefits, even if the bats aren’t flying directly in their fields.
“Part of the issue is that the bats can be removed in distance from the farms because it’s high-altitude,” Westbrook said. “Farmers want to see direct impacts on their farms. But bats are intercepting these vast migrations that are having a great impact on downwind crop areas, places that may never see bats.”