Bats can survive up to 24 hours without food or water. The exact amount of time depends in part on the bat's size, species, the time of year and whether it is nursing its young.
Flight is an energy expensive form of movement, which means bats must consume up to 110 percent of their body weight in food every night. Some species of bats hibernate, which greatly reduces their metabolism. In this case, it can survive for up to six months without hunting. Many bats are insectivores and have proven useful to farmers by eating insects which prey on their crops.