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  Thursday, October 2, 2014  
   
 

 
Fireflies
Nature's Lanterns
 

Darkness fills a damp summer night,
Nature’s lanterns begin to take flight,

Crickets chirping, the nocturnal awake,
Nightfall in action until the day breaks,

Fireflies staging a brilliant show,
Festival of lights in a grassy meadow.

Children rush to this sacred place,
Wondrous looks on each little face.

Searching ever carefully for a twinkle and flash,
snatching beetles from mid-air, away again they dash.

Catch them, count them, one, two, three...
Flickering in a jar for all to see.

A call in the distance, time to fly,
Release the luminaries back to the sky.

Do you remember the lazy days of summer when we were still children? Without the bells of school and deadlines to meet, one day seemed to melt into the next. After dinner our parents would often tell us to “skedaddle” and play outside. For many of us, catching fireflies (often referred to as lightning bugs in the South) became a favorite evening pastime.

When I see fireflies today, memories of visiting my grandparents in North Carolina resurface. Their backyard was bordered by acres of woods with mostly hardwood trees — chestnuts, maples, oaks, and dogwoods. Sitting on their screen porch we’d gaze at hundreds of twinkling lights in the woods. My grandparents would bring us an old mayonnaise jar and poke holes in the lid for us. After catching several lightning bugs we’d set the jar on our bedside table and wait for the room to glow in the dark.

Wanda Musselman, who was raised in the Piedmont of rural North Carolina, shares her childhood experience catching lightning bugs. “I was an only child and often had to create my own fun. After supper my parents would tell me to go play with Gene, which was my middle name. I would often go and get my jar with holes in the lid and run outside to catch them.”

Lena Sickle grew up in Tidewater Virginia in the 1940s and remembers standing in her backyard watching lightning bugs with her siblings. To Lena it seemed the entire yard was illuminated. She remarks, “Today it’s very different because only a few lightning bugs are in that same spot.” Lena remembers her father buying a small battery operated TV at a time when programming was so limited. “There were very few distractions keeping us indoors,” she reflects, “so we’d spend many evenings catching lightning bugs.”

Throughout history people from different cultures have been fascinated by fireflies. European sailors returning from the South Pacific talked of “fields of fairies” they had seen in the islands. Many Native Americans believed they were magical. The Cherokee told a legend of fireflies leading a young brave to his lost daughter after a terrible storm. And today the Japanese, having a deep respect for nature, hold firefly festivals — hotari matsuri — in their honor. Aside from the romantic myths that surround these luminous insects there are numerous scientific discoveries that we can share as we engage in chasing fireflies.

Chasing fireflies is a wonderful way to introduce children to a fun outdoor activity with one of nature’s most fascinating insects. Not to mention they will get the benefit of exercise. Children are not only intrigued by the glow on the tails of these beetles (order Lampyridae), but overall they do not feel threatened by their slow flying speed and soft bodies. “I like the way they tickle your hands,” says Nan (age 6). “I’d like to use them as lanterns I think,” suggests Freddie (age 10).

Cool Light
The name firefly is actually a misnomer. These insects are not related to flies but actually belong to the beetle family Lampyridae. Characteristic of beetles, they have elytra, which are hard fore-wings that protect the larger hind wings. The hind wings are used for flying. The leathery elytra of the firefly are separated by a line (also a feature of the beetle) that runs straight down the middle of the body. Their soft bodies are dark brown or black, often marked with yellow or orange. The common eastern firefly, native to Virginia, is known as the Photinus Pyralis, distinguished by a round black dot on its head.

Fireflies produce a cool light — not what you’d expect from the name “firefly.” Their ability to make light is known as bioluminescence. Both males and females have light producing organs composed of cells called photocytes, which contain a chemical called luciferin. An enzyme known as luciferase acts on luciferin that combines with oxygen to generate light in the firefly’s tail.

When emitted, the firefly’s cool light tops the standard 100-watt light bulb in energy efficiency. In the average electric bulb, about 97% of energy is turned into heat while 3% is released in the form of light. Most fireflies are more than 90% efficient.

So why not tap into this light source for our own use? In the dark of night one can easily be fooled by their radiance. In fact, the light produced by the most luminous animal known, the cucujo beetle, is only 1/40th of a candlepower. Strange as it may seem, fireflies have served as cheap lights in some countries, such as China and Japan, where students once used them as reading lights. The Brazilians made gourd lanterns from them and tied them in their hair and around their ankles to guide them at night.

Mating Signals
Entomologists have discovered about 2,000 firefly species worldwide. Both nocturnal and diurnal species exist. Those in the luminescent category either glow steadily or flash. Those that are diurnal are typically non luminescent; however, certain species may glow in shadowy areas. In North America those that flash are grouped in three main genres: Photinus, Photuris and Pyractomena.

Research suggests that fireflies come together to mate through one another’s luminescent flash patterns. Fireflies can identify both the species and sex of others through these light signals, which can vary according to pulse rate, duration, and number of pulses in a pattern. The adult males typically fly between three and six feet above the grass while the females remain perched on blades of grass or weeds.

Recent studies have found that females are selective in their choice of males. Some species are partial to a male’s flash that lasts the longest, while other female species prefer males who flash the fastest. Therefore, the “flashiest” bachelor wins in the dating game of fireflies.

Not all females are choosing males for the “right reasons.” The female Photuris Pennsylvanica will sometimes act as a decoy and mimic the desired signal of the female from a different species, the Photinus scintillans. She then lures the Photinus male to her as he responds to her false mating signal, and he becomes her next meal! This phenomenon is known as aggressive mimicry.

Scientists believe that the female Photuris may also benefit from this trickery by ingesting a bad tasting chemical called lucibufagens. This chemical is a natural defense that can be very toxic if eaten by predators. Research suggests that their glow is not only for the purpose of signaling a mate, but also to warn predators such as frogs, spiders and birds, that they are dangerous to eat.

Life Cycle
Most of the firefly’s life is spent in the larval stage. The North American adult lives no longer than a few weeks. Females lay their eggs in moist soil or moss. After about two weeks, the eggs hatch into larvae, commonly called glowworms, which have photic organs and produce glowing light. During the larval stage, glowworms live under tree bark, leaf debris, or burrow underground. Surprisingly, they spend between one and three years as larvae, they feed on snails, slugs, and earthworms. Once reaching adulthood, the firefly is no longer concerned with food, but instead turns to finding a mate.

Habitat
Where are the best places to look for fireflies? You can start by searching near streams, marshes, wooded areas and open grassy fields. They are found in warm, humid areas of the world and exist on every continent except Antarctica. A few of the species live in arid climates but are often found following the rains. In tropical climates, fireflies can be seen year round while in temperate zones they usually appear in the late spring. Adults do not stray far from the nest, flying in the same areas that they lived in as larvae. During the day, these insects hide out in the long grass on the ground. At night they crawl up the blades of grass to fly in search of a mate.

Fireflies in Research
Fireflies are important! Scientists have used luciferase in the analysis of cells. By injecting luciferase into specific cells within an animal’s body, they are distinguishable from other ones because of their glow. For instance, by injecting cancer cells with luciferase, researchers can monitor progress in treatments, as cells begin to disappear. Apart from cancer research, firefly luciferin-luciferase has played a significant role in the areas of muscular dystrophy, heart disease, urology, antibiotic testing, and wastewater treatment. Furthermore, blood banks have used the luciferase enzyme to test the quality of red blood cells within their stock.

Fewer Fireflies
Some experts worry that firefly populations may be dwindling, although very little research has been done in this area. With rapid development, on going pollution, the logging industry, and use of pesticides, to name a few environmental factors, much of their habitat has been destroyed. The firefly is site specific. If its habitat is disturbed, it is not likely to move to another and becomes extinct in that area. Another proposed risk factor is light pollution. It is believed that bright lights from cars, stores, streetlights, and homes confuse firefly flash patterns and interrupt the mating process.

Tips for Catching Fireflies
As adults, we can practice good will in the area of firefly conservation by teaching our children to catch fireflies with care. The safest technique is to use a net and work as a team, one holding the net while the other holds the jar. Once you catch them, place them into a jar with a moistened paper towel to keep them from drying out. Be sure to give them plenty of air. After a couple of days, release them, preferably at night when they are more likely to have enough energy needed to avoid predators. Once back in the wild they are free to make more fireflies for future generations to enjoy!

We often become nostalgic when we see fireflies, remembering those carefree summer nights. May these wonders of nature continue to shine, and brighten spirits throughout our world.

—Kerry Garrett, Contributing Writer