Why Do Fireflies Glow?
by Tsai Ming-hao · Oct 2026
On warm spring nights in the mountains of Taiwan, you may see hundreds of tiny lights in the dark. They are not stars. They are fireflies. Many people have watched them, but have you ever asked yourself why they glow?
Fireflies are a kind of beetle. Their light is made inside their bodies by a special . Unlike a light bulb, a firefly's light is almost cold. Its stays low, so the insect doesn't get hot. Scientists have studied this light for many years because it uses energy so well.
The main reason for the glow is . Fireflies use their lights to talk to each other. A male flies through the air and flashes his light in a special pattern. A female waits on a leaf and answers with her own flash. Each has its own pattern, so fireflies can find the right partner in the dark. The light also sends a warning to birds and frogs: "I taste bad. Don't eat me!"
Sadly, fireflies are getting harder to find. Many of their have been turned into roads and buildings. Bright lights from cities are a problem, too. When the night is too bright, fireflies can't see each other's signals.
If you want to see fireflies, go to a quiet place with clean water and lots of plants. Turn off your flashlight, keep your voice low, and never catch them. With a little care, these little lights will not disappear. Then our children will be able to enjoy them, too.