The phenomenon of synchronous fireflies is quite rare and absolutely spectacular. It occurs during some species of fireflies' mating season. Lighting up is a way of communicating for these charming bugs. Their synchronized flashing tends to occur in certain places around the world around the end of May and throughout the middle of June. One of these places is Japan.
Observing fireflies (hotaru) is a tradition for the Japanese. The country boasts over 40 species of these beautiful insects, the most common being Heike and Genji fireflies. Many hotels and parks breed fireflies for the pleasure of their customers so, luckily, there are quite many places where visitors can see them. However, most Japanese fireflies that belong to Luciolinae subfamily make flashes rather than produce a continuous glow. Okinawa in South Japan is one of the few places in the country where you can see rare hime fireflies (Luciola filiformis yayeyamana), which fly lower to the ground and produce a kind of soft glow. Males emit light together attracting females in groups.
The firefly season starts in Okinawa earlier than in the rest of Japan. It runs from mid-March to mid-May. Firefly viewing is available at Iriomote and Ishigaki Islands. Yaeyama Hime Firefly Tours are available through reservations. Banna Park at Ishigaki Island has a Hotaru Path. There are also many fireflies around the Omoto Mountain. In other regions, hime fireflies can be seen on Honshu Island in Hyogo Prefecture. Uchio Shrine offers firefly watching tours called Hikami Dream from June to July.
There are many places in Japan where fireflies live in the wild. Scientists express concern about crowds of viewers in the woods because this may distract the fireflies and interfere in their mating process. So if you want to witness this incredible phenomenon try your best to be careful and respect the nature.