Most commonly called fireflies or lightning bugs, these interesting insects are in fact a beetle and members of the family Lampyridae, Greek for “shining ones.” The familiar luminescent beetles are recognized for their nighttime display of flashes in the summer. Most of us have fond memories of catching these gentle and harmless beetles as kids and still find joy in admiring their light show as adults. The flashes that make this insect so famous, called bioluminescence, derive from a chemical reaction inside the insect’s abdomen. Bioluminescence in fireflies is nearly 100% efficient, meaning that almost no energy is wasted as heat to produce their light!
There are about 2,000 species of fireflies worldwide. One of the most common in Ohio is Photinus pyralis known as the “Big Dipper Firefly.” The name comes from the “J” swoop the males make mid-flight when they light up at night. P. pyralis may be found in fields and forest edges, where flightless females wait on the ground or on vegetation. The males of this species flash a yellowish light for a half second and repeat about every seven seconds. Interested females return the male’s flash about three seconds later. The males then land and mate with the female. The flash colors and pattern vary depending on the species. The flashes of light are messages sent to the females revealing characteristics of the flashing male such as age and health.
Another common genus of fireflies is called Photuris. Females of this genus, the so-called firefly “femmes fatales,” prey on male fireflies of the similarly spelled genus Photinus. The males are drawn to them by mimicry, where they are then captured and eaten! Photuris females receive more than just nutrients from their unfortunate mates. These males also contain defensive chemicals that the females incorporate into their own bodies and use to repel predators, such as spiders and birds. How cool is that!
And of course there are always exceptions. The fireflies of the genus Lucidota are diurnal lightning bugs without lights. Adults of this genus do not luminesce and communicate instead using pheromones. The larvae of this genus and all other species of fireflies are sometimes known as “glowworms” and actually do glow! Like all beetles, fireflies undergo a complete metamorphosis with four stages in their life cycle: egg, larva, pupa and adult.
Evidence suggests that firefly populations may be on the decline. Great Parks’ Stewardship Department manages natural habitats that fireflies thrive in. These areas are becoming scarcer, which makes it more important to welcome these amazing creatures into your backyard! So turn off your porch lights, limit the amount of pesticides you use in your lawn, plant some trees and shrubs and kick back and enjoy the silent symphony.
Olivia Espinoza, Stewardship Technician