<p>Fireflies use their light, called bioluminescence, to light up the ends of their abdomen to communicate with their fellow fireflies.</p>

Fireflies use their light, called bioluminescence, to light up the ends of their abdomen to communicate with their fellow fireflies.

Photograph by higrace photo / Getty Images


It’s a quiet, warm summer evening with no human in sight for miles in the woods. As the sun sets, tiny flashes of light start to flicker throughout the trees. At first there’s just a few, but soon hundreds of blinking lights are floating in the forest. Fireflies have come out for the evening.

Common Name:
Scientific Name:
Average Life Span:
About 2 months
Up to 1 inch


Also known as lightning bugs, fireflies are beetles. Most fireflies are winged. That’s different from other light-producing insects of the same family, called glowworms. (Animals that produce light are called luminescent.)

There are about 2,000 firefly species. These insects often live in humid regions of Asia and the Americas, where they mostly feast on plant pollen and nectar. Firefly larvae—recently hatched worm-like fireflies that haven’t fully developed yet (including their wings)—feed on worms, snails, and insects.


Fireflies mostly use their light to “talk” to other fireflies and find a mate. They have special organs under their abdomens that take in oxygen. Inside special cells, they combine the oxygen with a substance called luciferin to make light with almost no heat. They use this light, called bioluminescence, to light up the ends of their abdomen.

Each firefly species has its own unique flashing pattern. When a male firefly wants to communicate with a female firefly, he flies near the ground while he flashes his light every six seconds. Once he’s near the ground, a female can more easily tell if he’s from the same species as she is. (Most female fireflies can’t fly.) She answers his flashes by turning on her lights. Then the male finds her.

Predators, such as birds or toads, get a different message from these lights. Although they can easily spot fireflies by their glow, they rarely eat them. That’s because fireflies release drops of toxic, foul-tasting blood. Their flashing is a warning light to predators to stay away.


Fireflies aren’t endangered, but scientists are worried about them. In recent years, fewer of the insects have been spotted during the summer. Pesticide use and loss of habitat have likely impacted the population, as has light pollution. Too much nighttime light can be harmful to wildlife, affecting their migration patterns and hunting abilities. For fireflies, light pollution interferes with their attempts to signal each other.

Scientists aren’t sure how much the firefly population has dropped since their small size makes them hard to tag and track. Plus an adult firefly's life span is just one to three weeks, which makes counting them difficult. Scientists are working on ways to better track and protect these insects.