Photinus pyralis

Common Eastern Firefly

Photinus pyralis, Firefly Beetle photo






Family: Lampyridae

Subfamily: Lampyrinae

Length: 10-14 mm

Photinus pyralis, Firefly Beetle image



Some have suggested this is the most common Firefly in North America, and certainly it is widespread in West Virginia. It is easy to find them early in the evening, flying low over grass. The species is also attracted to lights.

Photinus pyralis is one of the largest members of the genus Photinus, typically measuring 10-14 mm in length.

Larvae live in the soil and are earthworm hunters.

Many chemists are fascinated by Fireflies, because the glow is produced by a chemical reaction and, although bright, it produces essentially no heat.


Photinus pyralis, Firefly Beetle with light organ


Right: A Photinus pyralis, showing off its light organ. In flight, the male's light organ traces the letter "J," a signal that is of interest to the female Photinus pyralis but not to females of other species. The female Photinus pyralis has a light organ too, and she uses it to send a response to the flying male.

The light of Photinus beetles are generally yellow, while the lights of fireflies in the related genus Photuris are green to yellowish-green.

Photinus pyralis fireflies are noted for doing their signaling earlier in the evening, compared with fireflies in other species and genera who signal later in the night.

Insects of West Virginia