The Hidden World of Fireflies
By Jennifer Meikle, Environmental Educator
Many of us think fondly of fireflies (or lightning bugs) and think back to warm summer nights, the sky dotted by flashes of yellow as they float through the air, searching for mates. There is so much mystery surrounding these bugs, starting with their ability to glow, but there is much more to the hidden world of fireflies than meets the eye. First off, fireflies are actually not flies at all– they are beetles.
There are more than 170 species of light-emitting beetles (Lampyridae) in North America, and over 2,000 species worldwide. Many of these have been around for millions of years, existing on every continent except Antarctica. They spend most of their lives underground or underwater; they can remain in their larval stage for up to two years. During this stage, they are vicious predators and hunt and consume worms, slugs, and snails by giving a paralyzing bite that injects with neurotoxins, and following it up with digestive enzymes that liquifies prey for consumption. After a long period as a larva, a firefly will only spend a couple of weeks as an adult. Many don’t eat during this time. Their goals are to mate and lay eggs, and then they die.
Firefly mating involves the males flashing a pattern to attract a female and back and forth communication through a series of flashes. In addition to communication with each other, their light also warns off potential predators. Fireflies taste bad to birds and other predators, so their light also serves as a warning signal to creatures that have consumed them before. Fireflies produce their characteristic glow through a chemical reaction called chemiluminescence. This efficient process allows them to light up without wasting any heat energy; all of the energy of the reaction goes toward making them glow.
It may surprise you to learn that not all fireflies light up. While all fireflies have glowing larval stages, there are some species that do not use light as a mating signal when they are adults. Instead, they use pheromones to communicate. There is even a species of firefly that is active in winter. The adults of this species do not light up, and instead of standing out in the night they blend in well. They hide in the bark of trees and stay hidden through the winter, finding mates through pheromone signals in spring. They finish their lifecycle by mating and laying eggs before most other fireflies become active.
Firefly populations are in decline due to habitat loss, overuse of pesticides, and light pollution. Artificial light that humans create interferes with courtship signals by interfering with firefly communication. Pesticides also are a detriment to their populations, especially during the larval stage as they spend the majority of their time underground or underwater where pesticide concentrations are usually higher.
Not only is the firefly an almost magical and amazing creature in itself, scientists have also utilized the way they make their light to aid in advances in medicine. Using firefly luciferase, which is the enzyme that creates the bioluminescence in fireflies, scientists have made great strides in detecting blood clots, tagging tuberculosis virus cells, and monitoring hydrogen peroxide levels in living organisms, which plays a part in diseases like diabetes and cancer. Now, scientists have developed a synthetic form of luciferase to do research, but the information that fireflies have provided through their mesmerizing ability to glow is invaluable.
Citations:
https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Fireflies
https://www.thoughtco.com/fascinating-facts-about-fireflies-1968117
https://www.scientificamerican.com/blog/observations/11-cool-things-you-never-knew-about-fireflies/
https://www.smithsonianmag.com/smart-news/study-shines-light-urgent-threats-fireflies-180974127/
https://www.firefly.org/why-are-fireflies-disappearing.html
https://www.usatoday.com/in-depth/graphics/2023/06/02/firefly-lightning-bug-extinction-explained/70257108007/
https://www.fireflyatlas.org/learn/firefly-life-history