Brown Bats

Bats are very beneficial creatures that feed on a wide variety of insects, including mosquitoes. Nonetheless, we as homeowners do not want them to establish residence in our attics or the walls of our homes.

Identification
Sixteen bat species call Georgia home and all of them are insectivores. The big brown bat is the most common house-infesting species in the Atlanta area and is one of the few that will remain throughout the year. Other species migrate south in the fall.

The big brown bat has broad black ears and thick black wings and is chocolate brown on its back and sides, lighter on its belly, and reaches a length of about 4 to 5 inches. Another species, the Brazilian free-tailed bat, is common in the southern part of the state and forms huge colonies in deserted buildings, sometimes numbering in the thousands.

Biology
Big brown bats mate in the fall, and their young are born the following May or June. During that time, about 40 to 100 pregnant females roost together in nursery colonies. The young are capable of flying in three to four weeks. This species is largely crepuscular, feeding on mosquitoes and other insects. After an initial evening foray, the bats return to their roost. They feed again later in the night before moving back to the roost, where they will remain during the day. Predators of the big brown bat include rat snakes, the barn owl and the great horned owl.

Problems
Bats often roost in attics or other hollow spaces in homes. Bat droppings can build up over time, creating unpleasant odors. They also harbor bat bugs, which can be a problem for humans, especially after the bats have been removed.

Control
The favored method of bat control is exclusion. To be certain all bats are outside the structure, this should be done in the fall, when there are no young. It should also be done after dark, when the bats are out foraging for food. Bat valves are also available that will allow bats to leave, but not to enter.

Building bat boxes is a good way to keep bats out of your house but to keep them in the area.