Vespertilionidae is a scientific term used to describe a family of bats. However, there are several common synonyms for the word, including vesper bats, evening bats, and pipistrelles. These small, insectivorous bats are found in most parts of the world, except for the polar regions and some isolated islands. The vespertilionidae family is characterized by a distinctive tragus, or ear shape, which varies in size and shape between species. Some well-known species of vespertilionidae include the common pipistrelle, the hoary bat, and the little brown bat. Despite their nocturnal habits, these fascinating creatures play an important role in their ecosystems as pollinators and pest controllers.