Owls and hawks take some, as do housecats, raccoons and foxes. Rat snakes occasionally eat roosting bats. Other causes of mortality include cave floodings and accidents. The greatest threat to bats comes from humans. Caves may be flooded by dams, or dynamited shut.
Some scientists suspect that widespread use of pesticides also harms bat populations.
Pennsylvania's most common bat, the little brown, is found statewide. Females are slightly larger than males. This bat eats a wide variety of flying insects, including nocturnal moths, bugs, beetles, flies and mosquitoes. Insects are regularly caught with the wing or tail membrane, and transferred to the mouth. An individual emerges from its day roost at dusk, and usually seeks a body of water, where it skims the surface for a drink, and then hunts insects.