In Japan, fireflies are associated more with early summer than with the height of summer. That is when adult fireflies are most visible, flying and glowing at night. The exact timing varies by region and from year to year, but going to a river on a slightly humid night around the beginning of the rainy season feels very natural.
Fireflies are also strongly linked with rivers, rice fields, and places where the water is clean. When people hear that fireflies still live somewhere, many imagine that the area has kept at least some of its natural environment. In reality, fireflies need more than clean water. They also depend on suitable soil, vegetation, darkness, and other conditions. Even so, in the Japanese imagination, they remain closely tied to clean rural waterways.
That is why hearing someone say, “There used to be fireflies around here,” can sound like more than a comment about one insect disappearing. It can suggest that the landscape itself has changed. On the other hand, seeing fireflies still flying in a place can make it feel as though some part of the older natural environment is still there.
A night spent watching fireflies is very quiet. Beside a dark river or rice field, small lights appear and disappear, then appear again. Because everything around them is so dark, it can be difficult to tell how near or far away they are. The lights seem to float in the air by themselves. Around them, you can hear insects and running water, and there is the smell of the countryside at night. When all of that comes together, the feeling is not simply that the fireflies are beautiful. It can bring a quiet sense of nostalgia that is difficult to put into words.
So fireflies are associated with early summer not only because of when they appear. The darkness by the water, the humid night air, the rice fields and rivers, and the atmosphere of the whole scene have become part of what “firefly season” means in Japan.
