Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

 Young girl holds mysterious firefly in the palm of her hand © Steven David Johnson

Unknown to most observers, fireflies are neither flies nor bugs, but rather beetles.
© Steven David Johnson

August 2013

Blinking beetles

Fireflies get glowing reviews from their fans but remain mysterious.

Amanda Laurenzi

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.

Join The volunteer firefly watchers

Tips for tracking the flash dancers

Karely Mendez

Fireflies are a special flashing part of our summer, but they seem to be disappearing. The Museum of Science – Boston has teamed up with researchers from Tufts University and Fitchburg State University to track these bright insects.

They need volunteers to help track fireflies, so they set up a program called Firefly Watch. Anyone can participate and it only takes a fraction of your time. The idea is to track your own backyard or an open field for 10 minutes a day, once a week throughout the summer, and then enter your data in the Field Journal available online. Even if you are not able to collect data every week, any information you can gather is valuable.

So what exactly are you supposed to look for? Basically you will report whether or not you see fireflies, but even if you don’t see fireflies you should still enter that information into your observation sheet. You can also distinguish the type of fireflies out there by flash color, pattern and location.

Their flash color could be a yellow – green flash, bright dark – green flash or other colors. Firefly flash patterns also vary, which is how a firefly identifies its own kind. Flash patterns vary in length, number of flashes, and the number of intervals between them. Location matters too, and distinguishes males from females. Males flash in the air while patrolling an area and females answer by flashing from a perch either on the ground or above it.


  • Wear bug spray

    Since you can find mosquitoes where you find fireflies, it is a good idea to protect yourself from mosquito bites.

  • Dress accordingly

    Wear long pants and long –sleeved shirts to protect yourself against other insects.

  • Watch out for ticks

    Fireflies prefer tall grass neighboring wooded areas, but unfortunately so do ticks. It is a good idea to be on the lookout for ticks as well as to check for ticks when you get home.

  • Bring the observation sheet with you

    Bring a printed copy of the observation sheet with you, then copy the data to the online form when you get home.

  • Shine a blue light

    Since light is the firefly’s form of communicating, shining a flashlight on them disrupts their communication. Fireflies can’t see blue light, though, so turn your flashlight blue by taping a piece of blue acetate over it.

  • Learn their light patterns

    Fireflies look very similar and are difficult to see in the dark, but they do have different flash patterns. Using flash patterns to identify the fireflies is the way to go.

  • Collect with care

    Don’t handle fireflies if you sprayed insect repellent on your hands, and if possible, use a net to catch them instead. Also, if kept in a jar, add a piece of moist paper towel to keep the jar humid.

For more information on the program and fireflies visit Museum of Science Firefyl Watch

Karely Mendez is an editorial intern with Wisconsin Natural Resources magazine. Originally from Green Bay, Karely now attends the University of Wisconsin –Madison.

The cover photo of this issue of Wisconsin Natural Resources magazine was taken by Steven David Johnson of Broadway, Va. His firefly photos will be featured in a new book, Next Time You See a Firefly. The book is part of the Next Time You See book series from the National Science Teachers Association. These books inspire children to experience the natural world. Specially designed to be shared with an adult — be it a parent, teacher or friend — the Next Time You See books serve as a reminder that you don’t have to look very far to find something remarkable in nature.

The book is available for purchase through NSTA Science Store and Amazon.com

Watch us on YouTubeWatch Next Time You See - NSTA Book Trailer  

"That Tree"

Tree at dusk with fireflies © Mark Hirsch
Fireflies share the spotlight with "That Tree" in this image.
©Mark Hirsch

"A one-year iPhone™ photo project captures fireflies in action."

Xin Wang

On the night of July 2, 2012, Mark Hirsch used his iPhone™ and captured this deep indigo sky at dusk gilded with fireflies in a cornfield in southwestern Wisconsin.

Aiming at a bur oak centered by these twinkling insects, Hirsch gasped and anxiously waited for the image to develop on his iPhone™. The result was amazing: the bright yellow brushstrokes that marked the fireflies’ flight paths appeared on the screen, making the image a dramatic scene.

"I stood up and ran around the valley herding fireflies towards my iPhone™, giggling like a little kid," Hirsch said, "I love that photo and the memory." This photo was the 101st from his "That Tree" project, a year-long photo diary of the same bur oak tree. A professional photojournalist, Hirsch never before had much thought about taking a picture of this ordinary tree, which he drove past for 19 years. Nor did he believe his iPhone’s™ camera could ever be used for anything more than a passing snapshot.

Then, one day in January 2012, he stopped during a snowstorm and took a picture of the tree. "It was on the same day that my friend messaged me about my new iPhone™, saying ‘Isn’t the camera great!’" Hirsch recalled.

Hooked by the first photo with his iPhone™, two months later, he accepted another friend’s challenge and officially started this project.

He purchased an app called Camera+ that allowed his iPhone™ to work like a basic single-lens-reflex (SLR) camera, as well as other apps for use in different circumstances.

On the night of the fireflies, finding that the standard camera app could not capture the subtle light of the fireflies, he added an app called SlowShutter. It acted like a timed exposure, capturing an extended time-lapse image. He activated the shutter when the fireflies flew through the scene and snapped this marvelous picture.

"I found it more challenging and therefore rewarding with the iPhone™," said Hirsch. "The limitations of the camera forced me to see differently." Due to the technical limitations of the iPhone™, Hirsch became more sensitive to the subtle changes in light and the angles to achieve his visual goals.

"I could not reach for a different lens, instead I had to reach into my creative reserves and be the human zoom," he said, "I don’t think this project would have had near the depth of creativity, vision or representation of place if I had shot it with my digital SLR cameras."

For the whole year, Hirsch documented the life of the bur oak. Living a mile and a half from the tree, he paid daily visits and took shots. To commit to this project, he did not take his family on a vacation and gave up annual ski trips with friends.

After a few months, the investment in time began yielding rewards. Not only did he learn to tackle the visual challenges, but he also began to appreciate the contemplative nature of "That Tree."

Hirsch completed the year-long project on March 23, 2013. He posted the photos on his website THAT TREE and Facebook (facebook.com/photosofthat tree) and caused a sensation online. He expects the collection to be published in August 2013, in his book entitled That Tree: An iPhone Photo Journal Documenting a Year in-the-Life of a Lonely Bur Oak.

Xin Wang is a graduate student in journalism at the University of Wisconsin-Madison and an editorial intern for Wisconsin Natural Resources magazine.