|A firefly about to start its nightly light show|
|The light organs on a male firefly, females have smaller organs and eyes.|
The most common species locally, indeed in all of North America, is the Eastern or Big Dipper Firefly (Photinus pyralis), the state insect of Tennessee. It gets its common name because the males use a signal that dips, almost in an upwards forming "J" shape. A neat naturalist trick is to call them in by mimicking a female of the species using a penlight. The trick is to flash a response back to them from ground level 2 seconds after they flash and hold it for a 1/2 second. The males will often respond if they're within 15' or so. Keep calling back to them but point your penlight down as any approach so it is not too bright. You will be amazed at how close you can get them to come sometimes.
Whether you choose to call them in or catch them in a jar, do not hold them for long. Their adult lives only last about 2 weeks and they dehydrate quite quickly. Make sure to have a moist piece of paper in their jar if you intend to contain them for any extended period of time, say overnight.
Keeping your lights off to reduce "light pollution," not mowing your lawn right before dark, and not using pesticides/herbicides to treat your lawn, you can ensure there will be these natural light shows for generations to come.