Eastern Pipistrelle Bats of Maryland

The Eastern Pipistrelle has a body length of 3 ½ inches with a wingspan of 9 inches. Its bodyweight is about .17 to .28 ounces. This bat is easily distinguished by its tri-color dorsal fur. It has dark brown tips at the base with a yellowish-brown coloring in the middle. This is considered the smallest bat in the Eastern states. The nickname for this bat is the Butterfly bat because of its moth-like flight pattern.

Physical Description

  • Weight – .17 ounces to .28 ounces
  • Wingspan – 9 inches
  • Body Length – 3 ½ inches

its and Habitat

This bat typically spends its summers in the same general area where it hibernates for the winter. They do not travel more than fifty miles to a winter hibernation site. They roost in caves more than any other bat in the eastern United States. They will sometimes hibernate in rock crevices and quarries but prefer to hibernate in abandoned mines and caves. In the summer they will roost in hollow trees, rock crevices, and sometimes buildings. This bat is one of the first to start hibernating usually in September or October and they are one of the last to emerge from hibernation in the spring. Males are usually solitary and the females will roost with populations of 35 or less. The average life of these bats is 4-8 years.


The Eastern Pipistrelle is found in the eastern part of the United States ranging as far west as Kansas, Oklahoma, Nebraska, and Texas. They also range northward from southern Canada and southward to Honduras. The Eastern Pipistrelle does not travel more than 50 miles from their summer roosting site to their winter roosting site. This bat will spend 6 to 9 months out of the year hibernating in caves and abandoned mines that are between 46 degrees and 55 degrees. They will hibernate individually in an area of a cave or mine that is quiet and does not have any activity. These bats will hibernate in the same cave or mine throughout their entire life. In the summer up to 35 females will roost in maternity colonies in tree cavities, rock crevices, and even buildings and attics. The males will roost solitarily in tree cavities and rock crevices.

Mating and Reproduction

The Eastern Pipistrelle mates during their fall migration to their hibernating roost. The females store the sperm through the winter hibernation and become pregnant in April or May when they emerge from hibernation and migrate back to their summer roosting place. The females are pregnant for approximately 44 days at which time they give birth to two pups. The pups are born blind, hairless, and weigh about 1.6 grams. The pups are able to fly at about 3 to 4 weeks old and are weaned from their mother’s milk at about 4 weeks old. As a side note, this is one of the few bats that give birth to twins, probably because of the high mortality rate of the young.


The Eastern Pipistrelle emerges from its roost earlier than other bat species due to making its first of two feeding runs for the night. The second run for food usually happens around midnight. They search for food over waterways and the edges of tree lines feeding on moths, beetles, mosquitoes, midges, ants, and a variety of other insects. This bat will eat 25% of its body mass in the first 30 minutes of hunting in one night. If bats are in your crawl space or attic give us a call or contact us online to schedule an appointment for an inspection with one of our professional Bat Control Technicians. We can humanly evict the bats from your home and seal your rooftop to prevent bats from entering another area.