Common Eastern Firefly (Photinus pyralis)

Photinus pyralis, also commonly referred to as the Common Eastern Firefly, Big Dipper Firefly, or Lightning Bug are a species of flying beetles that are one the most common firefly species in North America [1]. These beetles are known for the show they put on in late spring and early summer.

Common Eastern Firefly glowing

Taxonomy

  Kingdom: Animalia 
     Phylum: Anthropoda
        Class: Insecta 
           Order: Coleoptera
              Family: Lampyridae
                 Genus: Photinus
                    

Close up of Common Eastern Firefly with wing covers closed

Description

The average adult beetle is around 9 to 19 mm (0.4 to 0.7 inches) long [1] consisting of three main sections including the head, thorax and abdomen. The overall body of the beetles transitions from red to black to yellow when analyzing from the head to the lower abdomen. The shield like plate covering the beetles head has a black dot in the center surrounded by red and yellow with yellow on the outer most edge of the cover [2]. The wing covers are a black in color and are edged in yellow. Underneath the wing covers is pairs of wings and an abdomen that is black in color with respect to the last segment which is yellow. The last segment is the bioluminescent organ found to "glow". The beetles are have a hard exoskeleton with 6 jointed legs, two antennas, and compound eyes located on either side of the head [3] all of which are blackish brown in color.

Bioluminescence

They create the bioluminescent light with the presence of oxygen, magnesium, and adenosine triphosphate (ATP) producing the complex organic compound luciferin. As luciferin oxidizes, a "cold light" is emitted [4]. The term "cold light" refers to majority of the energy produced is in the form of light with very little released as heat[1]. Each firefly species is found to have different lightning patterns. The male Common Eastern Firefly is found to have a single sustained yellow light while flying upwards forming the letter "J" [5]. The female fireflies are often found on long blades of grass emitting their own flashing signal to find a mate. While most of the bioluminescent is used to attract a mate, it may also be used to warn predators of their toxicity[6].

Habitat

These beetles are nocturnal and crepuscular indicating they are most active at night and during dawn and dusk. The larvae can be found living on damp ground near streams. The adult beetles are typically found in meadows, wetlands, and edges of woodlands typically found in conditions of wet soils and tall grasses [3].

Ecosystem Importance

The Common Easter Firefly acts as both a predator and prey. The larva and adult fireflies can be found eating insects, snails, and earthworms[1]. While not many species eat the Common Easter Firefly, it can be seen that Photinus pyralis species will eat each other. It can be found that females may lure in males by mimicking mating signals as bait[6].

Life Cycle of Fireflies

Life Cycle

The Common Eastern Firefly goes through the life cycle of metamorphous as the beetle transforms from larvae to adult. In the early stages it can be seen that both the eggs and larvae emit a soft glow to warn off predators[1].

Eggs: Are about 1 mm in length and spherical in shape. They are found to hatch 4 weeks after being laid[1].

Larva: The larvae live around 1 to 2 years. The larvae may be found eating insects, snails, and earthworms [7].

Pupa: Pupates are found within damp soil requiring 9 to 15 days to fully mature which is dependent on soil temperatures [8].

Adult: The adult fireflies live around 30 days with female fireflies laying up to 500 eggs in a season.[1].

References

[1] https://www.inaturalist.org/taxa/129350-Photinus-pyralis

[2] https://mdc.mo.gov/discover-nature/field-guide/fireflies-lightning-bugs#:~:text=The%20adults%20of%20most%20species,covers%20the%20head%20from%20above.

[3] https://animaldiversity.org/accounts/Photinus_pyralis/#:~:text=The%20common%20eastern%20firefly%20is,%2C%20thorax%2C%20and%20abdomen).

[4]http://photobiology.info/Branchini2.html

[5] https://www.nps.gov/grsm/learn/nature/firefly-flash-patterns.htm

[6] https://www.fllt.org/firefly-bioluminescence/#:~:text=The%20mostly%20nocturnal%20firefly%20larvae,bats%20that%20they%20are%20poisonous.

[7] https://www.lifeoncsgpond.com/common-eastern-firefly#:~:text=At%20dusk%2C%20a%20flying%2C%20flashing,with%20narrow%20yellow%20side%20margins.

[8] https://www.lsuagcenter.com/profiles/bneely/articles/page1587050468972#:~:text=Larval%20Photinus%20can%20be%20found,to%20mature%20depending%20on%20temperature.