I have watched tons of dramas and movies until now but I can't recall a single movie or drama, Korean or foreign, where there is a scene of fireflies. Except two movies and one drama I have seen recently. All three star Son Ye-jin. Pretty weird, huh?
The drama is, of course, "The Summer Scent." The movies are "Lover's Concerto" and "The Classic." both starring SYJ. Especially in "The Classic" the firefly plays an important role: At an early part of the movie Cho Seung-woo(the mother's beau) catches a firefly and gives it to her as a gift, perhaps as a memento to a most wonderful day they spent together in the countryside, not knowing that tragedy is waiting for them in the future. At the end of the movie the daughter's beau also catches a firefly for her, which leads to the mesmerizing kissing scene.
Fireflies are pretty common in the Korean countryside during the summer. I haven't seen any in the U.S. or any other countries I have visited. Makes me wonder.
Korean children living in the countryside love to catch fireflies and put them in a glass bottle, using them as a kind of lantern during the dark summer nights. Usually they are set free next moring or so.
We have fireflies where I am (in the U.S.) You can only see them at dusk and only within a 2 week span in the summer.. So, I think if you weren't outside during that time you may not have seen them but I assure you they exist outside of Korea. They are alot of fun to catch.. very slow moving. I let them go of course.