Little Brown Bats

July 18, 2025

The little brown bat lives throughout much of the United States and Canada, but is most common in the northern part of United States and southern Canada. Male little brown bats can be found at the most northern boundaries and occasionally a nursery roost has been found as far north as the Yukon. They have been found in Iceland and Kamchatka, but are not native to these countries. These findings are most likely due to accidental ship transportation by stow away bats.

The little brown bat is also known as little brown myotis (Myotis lucifugus), related to the genus Myotis or mouse ear bat. Other then the little brown bat the mouse-ear bat is one of the most common bats in North America, but the little brown bat is the model used for studying bats and bat behavior.

Little brown bat gets its name from its uniformly dark brown fur, its back and upper parts are a dark glossy brown with a slightly paler grayish fur underneath. Little brown bat wings have a membrane which is also a dark brown and its wing span is typically 8.7″ to 11 inches. Its ears black and small with short rounded points at the upper tip. Also its fore and hind limbs have five metapodials or bones and a mouth consisting of 38 teeth with molars that are relatively sharp. They use these sharp teeth to grasp insects with hard bodies in flight.

Adult little brown bat ranges from 2.4″ to 3.9 inches with the female typically running a little larger than the male. The average weight of a little brown bat is 0.2 to 0.5 oz. The average life span of a little brown bat is 6 to 7 years, and in some cases living beyond 10 years.

Roosting for the little brown bat is broken is three categories, day roost, night roost and hibernation roosts. During the spring, summer and fall little brown bat uses the day and night roost while hibernacula are used during the winter. Typically found in buildings, trees, bat houses, rocks, wood piles and sometime caves are day roost sites. Roosts concerning bat nurseries are found inside buildings, bat houses, tree crevices, metal roofs and attics. Night time roosts are basically the same as day time roosts but with one difference, the night time roost tends to be confined spaces and are packed with many bats packed tight to increase the roost temperature. This is done usually after the feeding in the evening.

With the large gathering of bats at the night roost there will be a large accumulation of feces (bat guano) under the night time roost. For the bats this could be a plus because with the large presence of feces under the night roost it would make the day roost less noticeable to predators.

As for the winter months little brown bats hibernate in mines and caves. The northern bat population entering their hibernation in early September and starting to come out in mid-May. The southern bat population enter the winter hibernation in early November and start to come out in mid-March.

Little brown bats are known for their taste for mosquito’s but they also like to feast on moths, wasps, beetles, gnats, midges and may flies. Eating up to a 1000 insects a night this makes the little brown bat one of the largest consumers of night time insects. Consuming over 100 metric tons of insects a year, when you think the average insect weighs .00625g or .0000325oz that’s a lot of bugs! Not only is the little brown bat beneficial to home owners who like to spend their time out side during the summer months, but the benefits to the farmer are even greater. With the presence of bats the use of chemicals to control the insect population is wildly reduced cutting down on extra costs to the farmer and harmful use of pesticides that can hurt the environment.

Little Brown bats like to roost around water which is where most of your insects prefer to live making them more abundant and easier for the bats to find and catch. Usually you will see them in a zig-zag motion above the ground or water as they hunt their prey in groups, staying 6 to 12 feet above the ground or water. Little brown bats can been seen in large swarms at times especially if there is a large presence of a single type of insect, or you can see them is smaller groups when large swarms are less prevalent.

read more at http://en.wikipedia.org/wiki/Little_brown_bat

Categories: Bats