Little Brown Bats inhabit forested lands near water, but some subspecies can be found in dry climates where water is not readily available. In those habitats, drinking water is provided by moisture on cave walls or condensation on the fur. This species occurs over a wide latitudinal and elevational range, but tend to be more abundant in areas with suitable hibernation sites (Wilson and Ruff 1999). They feed mainly on aquatic insects such as caddis flies, mayflies and midges, sometimes, they eat mosquitoes too. This is a species most commonly found flying around houses in North America.

During the winter, hibernation time depends on altitude and location of the roosts. It usually starts between September and November and ends in March to May. They do not migrate long distances for hibernation roosts. Individuals travel only up to 100 miles. This species does not show territoriality at roosts, and large colonies of as many as 300,000 bats have been reported in a single roost (Barbour and Davis 1969). The lifespan of this species is extended by their ability to find food and inhabit a variety of roosts. These characteristics allow expansion of their habitat to new ranges, but also contribute to their survival. Myotis lucifugus lives approximately 6 to 7 years and often live well beyond 10 years. A 31 year-old male was discovered in southeastern Ontario. Evidence indicates that males tend to live longer than females (Humphrey and Cope 1976).

Myotis lucifugus is found from Alaska (USA) to Labrador and Newfoundland (Canada), south to Southern California, Northern Arizona, Northern New Mexico (USA) (Simmons 2005). Mexican populations usually listed under this name actually correspond to M. occultus, a distinct species (Piaggio et al. 2002). Little Brown Bats are absent from much of Florida, the southern Great Plains regions of the U.S., southern California, and parts of coast Virginia and the Carolinas (Fenton and Barclay 1980).

Natural hibernacula can be managed to encourage bat use. For example, closing but not sealing the entrance to an abandoned mine not only buffers temperature and humidity, but also reduces disturbance from humans and predators. Eliminating disturbance from humans, except for WNS surveillance, is the best management activity for natural cave hibernacula. Therefore, avoid entering hibernacula during winter hibernation (October through May) unless conducting approved and permitted management, surveillance, or research.