Bats are the most significant predators of night-flying insects. Most species of North American bats feed on flying insects, including mosquitoes and agricultural pests such as cucumber beetles and cutworm moths. A single little brown bat (Myotis lucifugus) can eat as many as 600 small insects in an hour, and may spend an hour or more feeding each night. Some of the largest colonies of Mexican free-tailed bats consume more than 100 tons of insects during spring and summer nights. Bats normally eat about half their weight in flying insects each night. Lactating females may equal their body weight in insects every night. A relatively small colony of only 500 bats that weigh 1/3 ounce each would consume 2-4 million bugs (5-10 pounds) each summer night. Insects eaten by bats reduces the need for chemical pesticides.

Tropical bats are important seed dispersers, and hence play a critical role in the recovery of forest clearings. Tropical bats are important pollinators of many tropical plants including cashews, mangoes, bananas, figs, balsa wood, avocados, carob, and cloves. In the southwestern deserts of North America, bats are the key pollinators of saguaro and organ pipe cactus. Tequila is made from the agave plant that is pollinated by bats.