I've told this tale before, but its worth repeating.
The first time our eldest grandaughter saw fireflys in Corfu, she was about 3 or so, she was quite frightened. So one night when they were particularly numerouse, I took her down into the olive groves, and explained that they were fairys looking after the fairy queen.
Now she is 12 I'm not sure she does'nt still beleive a little, after all, since then they have landed on her and her sister many times, and they do have wings dont they?
PS. Yes Orchard it is part of the mateing ritual, but I seem to remember hearing that it was the males that flashed, (no pun intended)