Adult male fireflies are very focused animals. And what’s their focus? Reproduction. Mating is the reason for their night flights, and mating is behind the brightness and patterning of their flashes.
Finding the right mate is the best-understood function of a firefly’s glow. But light is about more than looking for love. In many of the bioluminescent species, including fireflies, light may discourage predators by signaling that the animal they are about to eat will taste very, very bad. Even stranger, females of several species in the firefly genus Photuris flash to lure males of other species to their deaths.
When female fireflies prey on males of other species, they sometimes attack flashing males in midair like a predatory bird. Firefly scientists call this phenomenon “hawking.”
Fireflies Around the World
Festivals celebrating firefly season are common in the countryside around Tokyo. Traditionally, fireflies symbolize silent yet passionate love in Japanese poetry. And today, they have become a symbol of environmental conservation.
One of the most common insects shown in the art—especially the ceramics—of ancient Mayan civilization is the firefly.
For reasons not fully understood—and with a few rare exceptions—there are no flashing fireflies west of the Rocky Mountains. Nonflashing fireflies communicate with chemical signals called pheromones.
In some states in the southern U.S., as well as in locations in Asia, tourists come to watch the spectacular display of male fireflies flashing to the same rhythm. This timing increases the visibility of the light, which may increase a male’s chance of finding a mate.
In much of Europe, female fireflies don’t fly, have a somewhat wormlike form as adults, and glow steadily rather than flash.
Worldwide, the greatest diversity of firefly species is in the tropics—the region about 800 miles (1,300 kilometers) north and south of the equator.