The 14th annual Muju Firefly Festival (2010 무주반딧물축제) will run from June 12th through June 20th in North Jeolla province's Muju county. I'm pretty sure it was scheduled for an earlier date and pushed back. Anyway, there isn't an English-language website this year, but you can find programs and timetables on the Korean-language version. Saturday the 12th at 8:08 they've scheduled fireworks.
I've written about this festival several times over the last couple years, and you can browse them for more information and user comments:
* June 4, 2008: 2008 Muju Firefly Festival: June 7th - June 15th.
* June 16, 2008: 2008 Muju Festival
* June 2, 2009: 2009 Muju Firefly Festival (2009 무주반딧불축제)
As I mentioned before, it was where my fiancee and I had our first date (awwwww). And as I mentioned before, there were no fireflies, but just huge floodlights that allowed people to mistake moths and other insects for lightening bugs. One poet blamed that on the Japanese
There is a festival of fireflies
in Muju-gun in August
where people pray for firefly prosperity,
in Korea, since the Japanese
exterminated their fireflies
experimenting with insecticides.
though Kim Jong-Gill at the National Institute of Agricultural Science & Technology says environmental changes are to blame, in a 2002 issue of Koreana (.pdf):
Only 20 to 30 years ago fireflies were a common sight, but now they have become a nostaligic rarity, highlighted on television shows. In recent years, their natural habitats have been increasingly destroyed and disturbed through environmental damage resulting from the modernization of rural areas and changes in agricultural methods involving excessive reliance on pesticides and chemical fertilizers, as well as street lights that interfere with the ability of fireflies to communicate with each other. Indeed, with all these challenges to its survivability, it is no wonder that firefly sightings are so infrequent nowadays.
Commenters on this site have said it's hit or miss depending on the weather.
Because the firefly is Pennsylvania's state insect, I feel perfectly qualified to say they generally illuminate themselves at night, which will require you to plan accordingly since the last buses head out of Muju early. Accommodation is scarce in Muju, though Naver says there are 13 motels in town (about 11 more than I remember). That means you'll have to try your luck finding a room that day, try to make a reservation in advance, have your own transportation, or try and get a taxi to take you to another town (Daejeon is the nearest city, 50 kilometers to the north).
As you'll see from this map
the festival takes place just down the street from the bus terminal. If you walk across the Love Bridge (사랑의다리) you'll enter into what is basically the downtown of the county seat. Unfortunately for Jeollanam-do residents, transportation to and from Muju is almost prohibitively difficult because the few buses from Gwangju make several stops---Damyang, Sunchang, Namwon, among others---before arriving three-and-a-half hours later, and as I said the last buses leave at dusk. The last bus to Gwangju leaves at 6:45, according to this timetable, with buses to Jeonju and Daejeon leaving a little later. It would be a great idea if they would arrange for shuttle buses to go from Muju to, say, Daejeon or Jeonju later at night to help people who rely on public transportation, and to cope with the limited accommodation, and I hope somebody brings that up at the meeting next year.