Bats for pest control

 from batcon.org:

Insectivorous bats are primary predators of night-flying insects, and many very damaging pests are on their menu. Pregnant or nursing mothers of some species will consume their body weight in insects each night. A single little brown bat can eat more than 1,000 mosquito-sized insects in just one hour.
The 20 million Mexican free-tailed bats at BCI's Bracken Cave in Central Texas eat up to 200 tons of insects each summer night. And a favorite target of Mexican freetails in the United States and Mexico is an especially damaging moth called the corn earworm moth (aka cotton bollworm, tomato fruitworm, etc.) that attacks a host of commercial plants from artichokes to watermelons. Worldwide crop damage from this moth is estimated at more than $1 billion a year, and recent research concluded that freetails are so effective that they save farmers in south-central Texas up to $1.7 million a year in pesticide costs. That, of course, means fewer pesticides enter the ecosystem.