White-nose syndrome has killed millions of bats in the U.S. since the early 2000s. Since first detected in Wisconsin in 2014, the disease has spread in hibernating sites, decimating bat populations. Learn about these important insectivores and how we can help them. Come prepared for time outdoors. Meet at the Visitor Center. Instructor: Lisa Andrewski, Arboretum naturalist. Fee: $20 (FOA $18). Preregister by Oct. 10.