Millions of fireflies making whoopee in a dense Japanese bamboo forest during the 2019 mating season, captured by Russian photographer Daniel Kordan, who sez of the sexy swarm, in which males produce flashes of light and females respond in kind:
Fireflies are very sensitive. They need clean water nearby, warm humid air (but not rain), and no lights. Not a single photo can show how beautiful it is—shimmering and blinking forest full of little stars.
Kordan shares more about his process here.