Prairie Ridge Ecostation

Common Eastern Firefly

Photinus pyralis

The Common Eastern Firefly (or Lightning Bug) is a regular visitor to Prairie Ridge at this time of year. These nocturnal insects start flying and flashing their bright greenish yellow lights at dusk and continue signaling into the early evening. You'll see many little lights at Prairie Ridge evening programs during the summer!

What is a Common Eastern Firefly? Common Eastern Fireflies (Photinus pyralis) are dark brown beetles with yellow bands outlining the thorax and wings. The thorax has a large pinkish-red spot with a black spot in the center. These beetles have a distinctive light flash pattern at night. They hover about two feet above the ground, drop 6-8 inches, then return to the hovering height, flashing as they loop back upward. The flash is often J-shaped as a result.

common eastern firefly

How do Fireflies generate light? Fireflies have a special chamber in their abdomen where light production occurs. Light is produced when a chemical reaction mixes a chemical (luciferin) with an enzyme (luciferase), oxygen, and energy (ATP). If you’ve ever used a glow stick, they work in a similar fashion by mixing chemicals to form a light-producing chemical reaction.

Why do Fireflies light up? Nocturnal animals are active at night when it's dark, so they sometimes have a hard time finding each other or communicating. One effective way of communicating in the dark is by using flashing lights! In this case, the male Fireflies fly around flashing their lights to advertise their presence to the females waiting in the bushes and trees. If a female wants to mate with a male, she will return the signal to let the male know where to find her. If all goes well, the male and female will find each other, mate, and start a new generation of Fireflies!

Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive.