The tri-colored bat (formerly call the eastern pipistrelle bat) is Missouri’s smallest bat and one of the smallest bats in North America.

Species: Tri-colored bat

Scientific name: Perimyotis subflavus

Nicknames: Eastern pipistrelle bat

Claim to fame: The tri-colored bat (formerly call the eastern pipistrelle bat) is Missouri’s smallest bat and one of the smallest bats in North America. Despite being common throughout much of the eastern United States, there is still much to be learned about this small mammal, which is sometimes mistaken for a moth.

Species status: Tri-colored bats are common throughout Missouri.

First discovered: The first scientific description of the eastern pipistrelle was written by the French naturalist Georges Cuivier in the 19th century.

Family matters: Tri-colored bats belong to the mammal family Vespertilionidae, a group commonly referred to as the evening bats. They are also sometimes called the plain-nosed bats because they have simple, un-modified muzzles.

Length: Up to three-and-one-half inches

Diet: Tri-colored bats feed on small insects; particularly flies, moths, wasps, leafhoppers and beetles.

Weight: Two to eight grams

Distinguishing characteristics: The color of the back of tri-colored bats varies from dark reddish-brown to light yellowish-brown or gray. In addition to faint squeaks that are audible to humans, they emit ultra-sonic cries like other insect-eating bats that guide them in flight and help them find prey. In comparison to other bats, tri-colored bats appear to be weak fliers. They fly with a fluttering motion in an undulating course.

Life span: Tri-colored bats live up to 15 years.

Habitat: In summer, tri-colored bats roost in trees, crannies of cliffs or buildings, barns and sometimes in high domes of caves. In winter, they hibernate in caves where they select the warmer and more humid parts of the cave.

Life cycle: Tri-colored bats usually enter their hibernating quarters in mid-October and stay until mid-April. Mating occurs in fall before hibernation. Females store sperm over winter and ovulate when they become active in April or early May. Over winter, eastern pipistrelles go into a deeper hibernation and, as a result, are not aroused from their “sleep” as often in winter as other bat species. It is common to see hibernating pipistrelles with droplets of moisture (due to cave condensation) suspended from their fur. If hibernating bats of any species are disturbed, it endangers their chances of making it through winter because bats store just enough energy to make it until the following spring. In summer, females establish nursery colonies. These colonies, which range from a few dozen to up to 50 individuals, are formed in high domes of caves, in the eaves of old barns or in protected parts of cliffs. Females give birth to one or two offspring from late May to the middle of July. The young are able to fly at four weeks of age. It is not known for sure, but it’s presumed they do not mate in the year of their birth.