The Delaware Department of Natural Resources and Environmental Control is encouraging residents to install bat exclusions before May 15.

Delaware is home to nine species of bats, several of which have begun their annual move from winter hibernation sites to summer maternity colonies. Female bats return to their colonies pregnant and congregate to give birth and raise their pups. In Delaware, these colonies can often take up residence in barns, garages, attics and homes.

Even though bats play an important role in the ecosystem, DNREC notes that they are often unwanted visitors to residents’ homes and outbuildings. If bats are roosting in such a location where they are not welcome, residents can help divert them to a more hospitable roosting spot by installation of a bat exclusion.

DNREC’s Division of Fish & Wildlife notes that in the spring, it is important that bat exclusions be completed before May 15 to prevent trapping flightless newborn bats inside buildings and permanently separating mothers from their pups, which cannot survive on their own.

Bats feed at night on insects, including pest species such as mosquitoes, moths and beetles that damage crops. A study published in Science magazine suggests that bats could be one of the more economically-valuable groups of wildlife to North American farmers, saving farmers at least $3.7 billion annually by reducing the amount of pesticides needed.

For a list of Division of Fish & Wildlife-permitted wildlife control operators who can install bat exclusions, visit To review best management practices for excluding bats, visit