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Posted by on Sep 2, 2017 in TellMeWhy |

Why Do Lightning Bugs Glow Bright at Night?

Why Do Lightning Bugs Glow Bright at Night?

Why Do Lightning Bugs Glow Bright at Night? Lightning bugs, also commonly known as fireflies are so easy to spot during the night when their lights glow bright. Fireflies aren’t really flies at all. They’re beetles! And there are over 2,000 species of them that can be found all over the world. Not all firefly species glow, though.

In fact, most fireflies west of the Rocky Mountains in the United States do not glow. Fireflies that glow do so when oxygen mixes with a pigment called luciferin, an enzyme called luciferase, and a chemical called adenosine triphosphate. This process is known as bioluminescence.

Fireflies light up after dark in order to attract mates. Fireflies are a classic example of an organism that uses bioluminescence for sexual selection. They have a variety of ways to communicate with mates in courtships: steady glows, flashing, and the use of chemical signals unrelated to photic systems. The signal provides potential mates with information about the species of the signaller or its quality as a mate.

Some species, especially lightning bugs of the genera Photinus, Photuris, and Pyractomena, are distinguished by the unique courtship flash patterns emitted by flying males in search of females. In general, females of the Photinus genus do not fly, but do give a flash response to males of their own species.


Since fireflies are nocturnal insects, they spend most of their daylight hours on the ground amongst tall grasses. Long grass helps to hide fireflies during the day, so you’re unlikely to see them unless you’re on your hands and knees looking for them. Another reason you might not notice fireflies during the day is that they might not be there! Fireflies have very short life cycles. Adult fireflies live only long enough to mate and lay eggs.

Some scientists believe fireflies may not even need to eat during their adult period. Firefly larvae usually live about one year (from one mating season to the next) before they become adults and give birth to the next generation of fireflies. So even though you might not see fireflies once the Sun comes up, they’re hanging around amongst the tall grasses. If you look for them, you’ll find them. Of course, if you’re like most people, you’d rather simply wait for dusk when they come to life and shine their lights for all to see!

Content for this question contributed by Cindy Manning, resident of Allegheny County, Pennsylvania, USA