Photinus pyralis

The common eastern firefly, or North American firefly, ranges throughout the United States east of the Rocky Mountains. ("World Book", 2001)

Larvae of the common eastern firefly most often inhabit moist places such as on the ground, under bark, and near streams. Adult fireflies can be found from late spring to early fall in meadows, woodland edges, and near streams. (Milne and Milne, 1980)

The common eastern firefly is, in fact, not a fly, but a type of beetle. The average adult is dark brown and 10-14 mm long. Like all insects, it has a hard exoskeleton, six jointed legs, two antennae, compound eyes, and a body divided into three parts head, thorax, and abdomen). Its head has a rounded cover outlined in yellow and accented with two orange spots. Photinus pyralis also has two pairs of wings. The first pair, the elytra, form a cover over the second pair and is dark brown with narrow yellow side margins. Only males use the second pair for flying; females usually have short wings, and do not fly. The last segment of the abdomen is the section that lights up, flashing bright yellow-green.

Common eastern firefly larvae are characterized by six legs, a pair of antennae, and a flattened segmented abdomen. Upon emerging from the egg they are generally about 1.6 mm in length. By the end of its larval stage it will have grown to about 10.3 mm. Firefly larvae are often referred to as "glow worms" because, like the adults, they emit a glow of light. ("Firefly or Lightning Bug: Photinus pyralis", 1999; Arnett, 1985; Grzimek, 1972; Milne and Milne, 1980; Tweit, 1999)

Firefly eggs, which also emit a slight glow, hatch after four weeks into flightless larvae, the longest stage of the firefly life cycle. Larvae live one to two years and can be seen glowing on damp ground and near streams. After passing through the larval stage, the developing firefly moves into chambers in the moist soil and pupates. While pupating, it undergoes metamorphosis, emerging from the pupa as an adult. ("Firefly or Lightning Bug: Photinus pyralis", 1999; "World Book", 2001; Milne and Milne, 1980; Pesson, 1959)

Adult Photinus pyralis live 5 to 30 days. (Grzimek, 1972; Milne and Milne, 1980)

Firefly larvae spend winter and early spring burrowed into the soil. In late spring, they emerge to feed. Adult fireflies use their glow to both ward off predators and attract mates. It was originally thought that the light signals of the firefly would attract predators; however, the common eastern firefly contains a steroid that is poisonous, and this deters potential predators such as birds and frogs.

The light signal benefits P. pyralis most during mating. At dusk males take flight while females wait perched on the ground or in bushes. While in flight, the male emits, on average, a 0.3 second flash every 5.5 seconds. This particular signalling sequence is specific to P. pyralis; however, it is the females's response that enables the male common eastern firefly to find a mate of the same species. The female flashes a response approximately two seconds later, a specific and crucial interval for this firefly species. Once the male recognizes the female P. pyralis, it flies down to the ground where mating takes place. ("Firefly or Lightning Bug: Photinus pyralis", 1999; "World Book", 2001; Grzimek, 1972; Tweit, 1999)

Both adult and larval Phorinua pyralis are carnivorous. They feed on other insects (including other fireflies), earthworms, and snails. When feeding, they inject poison to immobilize and liquefy their prey. This allows the fireflies or larvae to suck up their meal. ("Firefly or Lightning Bug: Photinus pyralis", 1999)

An interesting predator of Photinus pyralis is the female Photuris pyralis. This firefly mimics the signal of the female Photinus pyralis and lures male Photinus pyralis that are expecting to mate. However, when the male common eastern firefly reaches this mimicking species, he quickly becomes the female predator's meal. (Milne and Milne, 1980)

There is no known negative economic importance for humans.

The chemical utilized by the common eastern firefly for bioluminescence is a complex organic compound, luciferase. Fireflies have recently been harvested by the biochemical industry for this important compound. Researchers discovered a technique to splice the gene containing luciferase into the DNA of other plants and animals. They use this in tracing the inheritance of a particular disease-resistant gene by splicing the bioluminescence gene into the disease-resistant gene in a parent plant or animal. The disease-resistant gene can then be traced in the offspring, because if it is inherited, it will glow. ("Firefly or Lightning Bug: Photinus pyralis", 1999; Tweit, 1999)

This species does not require any special status.

Photinus pyralis is the most common of 1900 species of fireflies.

The firefly produces light in the presence of oxygen, magnesium, and adenosine triphosphate by using an enzyme, luciferase, to oxidize a complex organic compound, luciferin. The light produced is often referred to as "cold light" because almost all the energy is released in the form of light and very little is wasted as heat. The wavelength range of this light spans from 520-620nm, and its brightness reaches 1/40 that of a candle. This bright light is what attracts most of the common eastern firefly's popularity. ("Firefly or Lightning Bug: Photinus pyralis", 1999; "World Book", 2001; Arnett, 1985; Grzimek, 1972; Milne and Milne, 1980)