As the sun dips below the tree line and the night sky takes over, a quiet but critical process begins above our heads. Tiny silhouettes flit through the dark, weaving between branches and barn rafters, doing the work of a thousand pesticides—silently, efficiently and for free. These are Pennsylvania’s bats, and despite their bad reputation in folklore and films, they’re some of the hardest-working—and most misunderstood—members of our ecosystem. Bats matter more than most people realize. Thes...