If there is concern for exposure to rabies (bite, scratch or the bat was found in a room with a sleeping person or someone who can not verbalize easily) contact your healthcare provider or go to the emergency room to receive vaccination immediately. Contain the bat securely in a box with airholes and call your local public health office for testing.
There is a single bat in your house…
Open windows or doors where the bat could exit and see if it leaves on it’s own.
Using a small box or trashcan, try to catch the bat against a wall and use a thin piece of cardboard to trap the bat in the container. Release the bat outside on a elevated surface where it could hang upside down and drop into flight (usually they need at least a few feet to do this).
If there is a colony in your house…
If a bat or bat colony is in a non-living space, such as an attic, permanent eviction can only occur from March 15 to May 15 when outdoor temperatures exceed 50° F at dusk, and August 5 through October 30 when outdoor temperatures exceed 50° F at dusk. This guideline is in place to protect pups while they are still unable to fly (Illinois Department of Public Health).
The first step is to figure out how the bats are getting in and out of the house. Typically the best way to do this is to have a few people at different sides of the house at sunset and see if you can identify where the bats are exiting from. This may take a few nights to pinpoint.
Once you know where the bats are coming in and out you can install a “one way door” by securing screen with the bottom open, so the bats can climb out but have a hard time going back in.
If you find a bat outside…
Especially during migration in spring and fall, bats can be found in unexpected places because they are tired from their travels. If the bat is outside and not in the way of human activity, please leave the bat alone. It likely is just resting, potentially in torpor (short period of hibernation) and may not move for a few days. Rehabilitation of bats is currently not legal in Illinois so even if a bat is injured, it is best to leave the bat alone. If it is in the way of human activities, call your local public health department.