As I recall, the first time I ever saw fireflies was on the United Nations Pilgrimage for Youth. We were at Gettysburg at a motel almost right next to the national park, and for once not only did the chaperones let us stay up late, the bus driver gathered use up at midnight to go out to the battlefield. He led us to a spot and had us stand quietly, and then all of a sudden there were the fireflies, flitting about like so many miniature lanterns bobbing in the breeze. Amazingly enough for a bunch of teenagers we stayed quiet long enough that they started blinking in sync!
Somehow watching that for ten minutes or so enriched our official tour of the grounds the next morning.