Bill Schutt skims the clotted clumps from fresh cow blood with a spaghetti strainer before his vampire bats feed. The biologist begs readers not to think badly of the finicky bats. When they eat in the wild, their prey usually don’t even feel the bite—let alone die—and the bats produce an anticoagulant that could help stroke victims heal. Schutt’s passionate defense of bloodsuckers from the leech to the candiru (a parasitic catfish) will at least leave you glad that you don’t study bedbugs. Those unfortunate researchers let the subjects feed on their own arms.