The big brown bat, Eptesicus fuscus, is found in virtually every American habitat ranging from timberline meadows to lowland deserts, though it is most abundant in deciduous forest areas. It is often abundant in suburban areas of mixed agricultural use. This species ranges from extreme northern Canada, throughout the United States and south to the extreme southern tip of Mexico. Traditionally, these bats have formed maternity colonies beneath loose bark and in small cavities of pine, oak, beech, bald cypress and other trees. Common maternity roosts today can be found in buildings, barns, bridges, and even bat houses. Small beetles are their most frequent prey, yet big brown bats will consume prodigious quantities of a wide variety of night-flying insects.
They are generalists in their foraging behavior and habitat selections, seemingly showing little preference for feeding over water vs. land, or in forests vs. clearings. Like all insect-eating bats, big brown bats contribute mightily to a healthy environment and are vital players in the checks and balances of insect pests. Numerous feeding studies of big brown bats exist indicating that they consume significant crop and forest pests including ground beetles, scarab beetles, cucumber beetles, snout beetles and stink bugs, in addition to numerous species of moths and leafhoppers. Like many bat species, reproductive females often can consume their body weight in insects each night. In fact, a colony of 150 big brown bats can consume enough adult cucumber beetles in one summer to prevent egg-laying that would produce 33 million of their root-worm larvae, a major pest of corn (Whitaker, 1995).
Big brown bats clearly rank among America’s most beneficial animals. And, as they are forced out of traditional forest habitats due to encroaching human populations, logging, and habitat modification, they will move into increasingly close human contact, taking up residence in buildings and other man-made structures. But, humans and bats can coexist peacefully. Sometimes designing bat-specific artificial roosts are the best options to keep bats out of our homes, yet near enough so that we can continue to benefit from their insect-eating capabilities. Though many species, like the big brown, still rank among our most abundant and widespread bats, they nevertheless deserve attention from conservation and education initiatives for healthy environments. (Source: Bat Conservation International)
Sources:Big Brown Bat By U.S. Fish and Wildlife Service Headquarters – Big brown bat Uploaded by Dolovis, Public Domain, Link