Humans have destroyed natural habitat in so many places that local extinction is rampant and global extinction accelerating. This is a growing problem because it is the ecosystems around us that support us. Doug Tallamy is a professor of Entomology and Wildlife Ecology at the University of Delaware, where he studies the many ways insects interact with plants and how such interactions determine the diversity of animal communities. His new book, Nature's Best Hope, lays out a new approach to conservation that everyone can employ at home in their own yards.