When do the fireflies come out?

I was wondering at what time of year one can expect to see fireflies, though I understand that it probably varies depending on where you are in the country. I am planning to be in Japan for most of April and I was wondering if it would be worth seeking out places I might find them.

Apologies if this seems like an odd question.

What a beautiful question!

Just like the "cherry blossom front" that moves from south to north of Japan during spring, there is a "firefly front" moving through Japan from south to north.

The dates vary from year to year (probably ahead of the average year this year due to the warm temperatures).

Typical dates are early May for Okinawa (April for Yaeyama) late May for Kyushu, early June around Tokyo, Osaka and Kyoto. Mid June in much of the Chubu region. And late June to mid July in the Tohoku region.

I am not sure where there are good spots to see fireflies. They have become quite seldom these days. I have never seen them.

Thank you very much for the information! I guess that means I shouldn't go out of my way to track them down in April. The reason I asked was because a hiking book that I've been reading mentioned that they could often be seen along Kiyotaki-gawa, just northwest of Kyoto. It does say that June is the most popular time for this, but I wanted to make sure. Thanks again!

Note that the dates refer to the average date of the year when the fireflies are FIRST seen. I am not sure about the lenght and characteristics of the firefly season that follows the first sighting.

In one of my night photos there are 6 little fluorescent green spots. What could these be? Fireflies? But it was in mid April, too early? It had just rained and was sort of warm. Thanks for any ideas.

" In one of my night photos there are 6 little fluorescent green spots. What could these be? Fireflies? But it was in mid April, too early? It had just rained and was sort of warm. Thanks for any ideas."

When I was younger (5-8) I would spend every Summer up in New York playing with the fireflies at night, and to answer your question, yes those were fireflies. They range from yellow to green depending on heat and the atmosphere.