Unknown to most observers, fireflies are neither flies nor bugs, but rather beetles.
Fireflies get glowing reviews from their fans but remain mysterious.
Fireflies. Lightning bugs. Photuris pyralis. Whatever you choose to call them, they are a majestic sight if you can catch them in your palm as the sun sets on a calm summer night. Securing them temporarily in Mason jars is a summertime thrill passed down from generation to generation as kids of all ages gather in yards or on front porches, seemingly hypnotized as they watch the beetles blink in the growing darkness.
The first flight of fireflies signals the beginning of summer, and throughout the rest of the season they can be seen on walks and late night drives in the country. But fireflies also contain chemicals that are being used in researching cancer, multiple sclerosis, cystic fibrosis and heart disease.
These tiny flash dancers are a mystery yet to unfold. Not much is known about fireflies because there are over 2,000 species in the world. Each one has a different lighting pattern, habitat and way of life. Researchers have only begun to delve into the mysterious lives of these creatures; much time has been spent trying to learn more about the aspects which make the firefly famous. The ability of fireflies to produce cold light (bioluminescence) has led to new flashlights and flares on the market today.
Unknown to most observers, fireflies are neither flies nor bugs, but rather are classified as beetles. They reside in habitats such as meadows, wooded areas, streams and lawns. They generally prefer moist habitats for laying eggs. Larvae are carnivorous and eat other small insects in the soil.
Putting on their flashers
During the summer, fireflies use their light to attract mates — backyards and fields become a sort of singles bar for these beetles. Every species has a different light pattern. Males flash their light signals and wait for female fireflies of the same species to flash the same signal back to them. When two fireflies of the same species are paired, they mate and the female lays her eggs. However, some female species will flash a light pattern that is not their own to lure male fireflies in for prey.
The eggs are laid in moist soil a few days after mating. Four weeks later, the eggs hatch and the larvae begin to feed until the fall. When colder weather arrives, the larvae burrow underground and do not surface until summer begins again. When summer arrives, the larvae spend about two and a half weeks in a small, earthen shell before emerging as adults. Then the mating cycle starts all over again.
One of the most significant features of the firefly is the light they produce. Other insects are able to produce light, as well, but the firefly is the only one that can flash it on and off. Even the larvae have a glow; this is where the term "glowworm" came from. Their light is produced by oxygen and the chemical luciferin reacting in the presence of the enzyme luciferase.
While their light is definitely used for finding mates, it is also believed by scientists that it acts as a warning to other insects. Daniel K. Young, a professor of entomology at the University of Wisconsin-Madison, speculates that fireflies do not taste good to predators because of the chemicals that make up their light.
He explains, "It’s telling other species that, ‘Hey, I don’t taste good!’"
The potential for lights out
Researchers have proposed that firefly populations are declining. However, Young suggests that this is impossible to determine without fully understanding each and every species of firefly.
"We don’t really know our fireflies in Wisconsin," Young says. "It’s an incredibly difficult group taxonomically to understand.
"He suggests that one reason fireflies may seem in decline is dry winter seasons. "Some years, like last year and the year before last, when we had a dry winter and we don’t have much moisture, the following year may look like they’re in decline simply because the drought may have knocked the populations back. However, it may not be permanent."
Young adds that because fireflies depend on wetlands and moist habitats, humans can play a crucial role in determining how many fireflies come out for the summer. When these microhabitats are drained for agricultural or development purposes, the moist areas they depend on are lost. This causes a problem for females laying eggs since they need moist soil to do it.
Parasites usually have an impact on a multitude of species, but fireflies are not overly affected by them. "[Fireflies] exude milky looking stuff with chemicals, which protects them," Young says. Firefly.org suggests light pollution also plays a major role in the disappearance of fireflies. The disruption of foreign light has an impact on fireflies being able to communicate through their flashing patterns. According to Firefly.org, research shows that even a car passing by with its headlights on can delay a firefly from finding a mate by a couple minutes. Although seemingly insignificant, less mating occurs and therefore fewer eggs are laid. Even porch lights can have an effect on mating patterns.
How to be firefly friendly
There are a few ways to help protect firefly populations. Firefly.org suggests limiting light pollution by turning outside lights off when they are not in use during the summer. This will give fireflies plenty of space to flash their lights and mate without disruptions. Another tactic is to allow fireflies’ natural habitat to remain untouched. Removing rotting logs or natural litter can take away environments female fireflies need in order to lay their eggs. You can also start planting trees to allow future habitats to be in place.
Along with planting trees, water sources are essential for these insects. Either by building a small pond or redirecting a stream through your property, the long-term effects can have a positive influence on future firefly populations. When gardening, use natural fertilizers and avoid using pesticides. Be sure to reduce mowing your lawn, as well. Fireflies like long grass for mating, so even leaving small patches of long grass around your lawn is beneficial.
Firefly.org also suggests reducing earthworm numbers in your yard. They are not native to Wisconsin and can destroy plants and leave less food for fireflies and other insects.
Although these approaches to preserving firefly populations are relatively general, Young advises that each species differs, and in order to truly understand how to save fireflies, each species would have to be researched and understood fully in order to know what they require to survive.
Doing more than making summer nights sparkle
Firefly taillights contain two rare chemicals — luciferin and luciferase. Luciferin is the light source while luciferase acts as the enzyme or trigger, which is fueled by oxygen. Ohio State University Extension entomologist William Lyon explains in his online firefly fact sheet that a body chemical called adenosine triphosphate (ATP) converts to energy and causes the luciferin-luciferase mixture to light up.
Lyon notes that injecting a firefly’s chemicals into human cells can quickly detect energy problems in those cells and this "firefly technique" is being used to study heart disease, cancer, multiple sclerosis, muscular dystrophy and other diseases.
Will fireflies save lives some day? Time will tell.
But what is known about these tiny pyrotechnicians is that they have a way of lighting up summer nights and stirring a glimmer of goodwill toward the insect world in all of us.
Amanda Laurenzi is a student at the University of Wisconsin-Platteville. She also contributes to Wisconsin Natural Resources magazine and enjoys watching fireflies at her family’s farm house.