Family: Vespertilionidae, Vespertilionid Bats view all from this family

Description The smallest bat in the East. Reddish to light brown. Hairs tricolored: dark at base, pale in middle, dark at tip. Calcar not keeled. Tragus blunt. 1 tiny premolar behind canine. L 3 1/8–3 1/2" (81–89 mm); T 1 3/8–1 3/4" (36–45 mm); HF 1/4–3/8" (7–10 mm); FA 1 1/4–1 3/8" (31–35 mm); Wt 1/8–1/4 oz (3.5–6 g).

Warning Bats are susceptible to rabies, a serious viral disease that results in death if untreated. Rabid bats rarely attack humans or other animals, but bats found lying on the ground may be rabid. Never touch or pick up any bat. Stay away from any animal that seems to be acting strangely and report it to animal-control officers. If you are bitten by a possibly rabid animal, you must immediately consult a doctor for a series of injections; there is no cure once symptoms emerge.

Similar Species Myotises lack distinctly tricolored hairs; most have longer, thinner tragus, and have 2 tiny premolars behind canine. Western Pipistrelle also lacks tricolored fur.

Breeding Maternity colonies start forming late April– early May. Gestation about 44 days; 2 young born June– early July.

Habitat Primarily woodlands. Hibernates in caves, mines, or crevices. Summer colonies may be in buildings or hollow trees; there is at least one record in a cave.

Range Eastern U.S. from se Minnesota, Iowa, s Kansas, Oklahoma, and Texas eastward.

Discussion Emerging early from its daytime hiding place in a building or hollow tree, the Eastern Pipistrelle feeds on tiny insects, especially leafhoppers, plant hoppers, beetles, and flies. Maternity colonies are often found in buildings, but the great majority are probably in tree hollows. The number of bats in these colonies is very small, usually not more than 30 or 35 individuals. Each colony appears to use several alternate roosts, moving from one to the other during the season, even when young are present. In fall, pipistrelles migrate to a small mine or cave to hibernate. During hibernation they are often covered with water droplets, which sparkle and give the bats a whitish appearance.