They are found in the Americas from the Southwestern United States to Southeastern Brazil.

They are distinguished by the presence of a leaf-like projection from their lips, instead of the nose-leaf found in many other bat species.

In some species, the wing membranes join over the animal's back, making it appear hairless.

The tail projects only a short distance beyond the membrane that stretches between the hind legs.

[1] Their dental formula is: Mormoopid bats roost in caves and tunnels in huge colonies that may include hundreds of thousands of members, producing enough guano to allow commercial mining.