The state of Delaware is home to 7 species of bats:
Big Brown Bat (Eptesicus fuscus)
Little Brown Bat (Myotis lucifugus)
Eastern Red Bat (Lasiurus borealis)
Hoary Bat (Lasiurus cinereus)
Eastern Pipistrelle (Pipistrellus subflavus)
Northern Long-eared Bat (Myotis septentrionalis)
Silver-haired Bat (Lasionycteris noctivagans)
Bats are one of the most ecologically useful species of mammals to humans as they eat thousands of insects (primarily mosquitos) per night. If your landscape is plagued with biting insects (mosquitoes, flies, etc.), invite bats in and you will have a much more pleasant yard to live in.
It is very much a myth that bats will "attack" humans. They don't want to have anything to do with you, and most stories of bat interactions are from failed attempts of people trying to remove a bat from an attic space, or a chimney.
If you find a bat "hanging" out in a space where you don't want it, it is best to call an animal control professional and have them remove it without harm or incident.
Additionally, while bats can carry the rabies virus, it is very rare, and even more rare that a human could get rabies from a bat bite.