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 synchronised 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.
Sometimes fireflies can light up an entire tree but most of them usually create a carpet of light in the woods. For lots of photographers, it's quite a challenge to capture these little things. Partly because these bugs are nocturnal creatures and are afraid of light and even noise.
Some 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.