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What Are Lightning Bugs? Are They Different From Fireflies?

Posted by Ashley Robinson | Dec 1, 2019 3:00:00 PM

General Education

 

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If you’re lucky, you’ve had the experience of sitting outside on a warm, summer night and watching lightning bugs blink all around you. It’s a pretty magical feeling, and it’s all thanks to little glowing bugs! 

But what are lightning bugs, exactly? What makes them glow? And why do they only come out during the summer? This article will teach you everything you need to know about lightning bugs, and we’ll answer the questions like: 

  • What is a lightning bug? 
  • What do lightning bugs eat? 
  • Where do lightning bugs live? 
  • Why do lightning bugs light up? 
  • Which term is correct (firefly vs lightning bug)? 

So let’s go ahead and meet our glowy friends! 

 

Feature Image: (John Robinson) 

 

What Is a Lightning Bug?

Lightning bugs are part of the Lampyridae family, which is in the order of insects called Coleoptera. That means that lightning bugs are actually a type of beetle

You might be thinking that lightning bugs don’t look like the types of beetles you’ve seen before. That’s not surprising, since there are more than 350,000 known species of beetles. They’re actually the largest group of animals on Earth.  

There are many different types of lightning bug species all over the world. There are 2,000 known species of lightning bugs, but the most common species in the United States is the Photinus pyralis. These little guys are about 10-14 millimeters long, have antennae, a three-segmented body, and are red and black in color. Oh, and of course: they have the ability to glow through a process called bioluminescence (more on that a little later). They’re also a species with sexual dimorphism, meaning the males and females look different from each other: 

 

Male Photinus pyralis

Female Photinus Pyralis

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(Yikrazuul / Wikimedia)

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(Terry Priest / Flickr



Male and female fireflies or lightning bugs look almost identical, except the male has a larger glowing part (called a lantern) and the female has a smaller one. If you look very, very closely, the male has a protruding genital, like the male of many other species, and the female has an ovipositor (egg-laying organ).

The easiest way to tell males and females apart is by observing their behavior. Males fly higher and brink faster and more brightly, whereas females typically hover near (or on) the ground and blink in response to the males. The brighter and faster a male can blink the more likely he is to attract a female’s attention, so he really goes for it. 

 

Habitat and Diet 

Lightning bugs love to live in damp, warm areas. That’s why they’re so common in temperate, humid regions. But lightning bugs can also be found in dry climates, as long as they have a habitat that remains damp and warm. This is also why lightning bugs are most commonly seen during the summer months. 

You may be asking, “What do lightning bugs eat”? In general, lightning bugs are considered omnivores. That means they consume a mix of plant and animal material. When lightning bugs are in their larval stage and living underground, they eat other insects like worms and slugs. They inject a numbing fluid into their prey and then chow down! (Bet you didn’t realize lightning bugs could be so vicious.) 

Once they emerge as adult beetles, their diets change. Depending on the species lightning bug, they can eat anything from pollen and nectar to other insects. Some lightning bug adults live such short lives that they eat nothing at all! Adult Photinus pyralis (the most common lightning bug species in the United States) eat a mixture of other insects, earthworms, and snails.  

 

Life Cycle

Usually, the lightning bugs you see flying around and blinking are male. They usually blink to communicate and attract potential mates, and once they find one, they mate. 

What do the females do? They, you know, crawl on the ground, looking for an attractive blinking display in the sky, and then they fly up to mate with them (if they’re fliers—not all female lightning bugs fly). Sometimes they blink, too, and the male comes down to meet them, and then they mate. 

Yes, mating is the primary occupation of the lightning bug since they spend only a short amount of time as adults. A lightning bug lives the majority of its life in its larval stage. They can be larvae for several months to several years, depending upon the species, and their whole existence is based on eating and, hopefully, not being eaten. In fact, some species of lightning bugs do all the eating of their whole lives when they are in the larval stage, and don’t even have mouths as adults! 

Once lightning bugs emerge from the ground as adults, they typically only live for one to two months before they die. Then the life cycle of the lightning bug starts again. 

 

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Firefly vs Lightning Bug

So far, we’ve been calling lightning bugs...well, lightning bugs. But what about fireflies? Are they a different species? And which term is correct? 

Fireflies and lightning bugs are the same animal—they just have a different name depending on where you live. If you’re an English-speaker who says either “lightning bug” or “firefly”, you’re very likely North American. Broadly speaking, people who live in the American south and midwest say “lightning bugs,” and people who live in the northeast and the west say “fireflies.” 

But why? There are probably a million reasons, but one very good theory is that there seems to be a correlation between areas that experience common lightning strikes with areas that say “lightning bug,” and areas that experience common wildfires with areas that say “firefly.” 

Lightning bugs also have different names around the world! In Great Britain, for instance, lightning bugs are usually called “glow worms” because the most common subfamily that lives in Great Britain is Lampyris. Male Lampyris fly but don’t glow, and female Lampyris glow but don’t fly—so people don’t think of them as being the same thing, and call them “glow worms” because the only glowers look more like worms than flies or bugs.

Here are some other names for lightning bugs that you’ll hear in other regions and countries: 

 

Place
Lightning Bug Names
North America
Firefly (Bug) 
Lightning Bug 
Moon Bug 
Glow Fly 
Golden Sparkler 
Fire Devils 
United Kingdom 
Glow worms 
Japan 
Hotaru
Jamaica 
Blinkie 
Peenie Wallie 
Puerto Rico and Cuba
Cucubanos 
Portugal and Brazil
Pirilampos
Germany 
Glühwürmchen
France
Luciole 
Netherlands
Glimworm
Italy 
Lucciola 

 

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In this time lapse picture, you can see how long lightning bugs blink. The longer the blink, the longer the tail!  (Bernd Thaller / Flickr

 

A Year in the Life of a Lightning Bug

Imagine you are a lightning bug. This is your life:

You begin your life as an egg, and you are laid in mid-summer. Around June, you hatch out of the egg and grow six legs. You crawl around in rotting leaves and undergrowth eating other insect larva, as well as snails and slugs. 

After eating a few snails, your top side hardens into a nice, camouflaged armor, but your underside stays soft and white. Eventually, you look kind of like a beetle, just as summer is about to end, your light organs in your tail develop and you start to glow a bit. In this stage you are called a glow worm, but you share that name with many other species of crawling things that glow. 

This is a dangerous time for you, because glowing attracts the attention of predators, but not being able to fly makes it difficult to escape. Well, luckily, you taste terrible! The chemicals that make you glow also make you taste bad to predators, so they’re likely to leave you alone.

As summer ends and the weather cools off, you will probably go underground and hibernate until spring. You either sleep or you burrow underground looking for more food. Then summer rolls back around again and it’s your time to shine! 

Around mid-June of Year Two, you pupate briefly and then you turn (like many beetles) into a wild, flying creature that spends the rest of its (short) life trying to find a mate. As an adult lightning bug, you eat a little bit (unless you’re the kind that doesn’t have a mouth), you sleep (or at least sit dormant for most of the day, waiting for nightfall), but mostly you mate, mate, mate until your death after a few days or weeks of adulthood! What a party!

 

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Unfortunately, humans don't have bioluminescence...no matter how hard we try.
(Bill Waterson / gocomics.com)

 

Lightning Bugs: Why Do They Glow?

So much of lightning bug survival depends upon the fact that they glow. It is, quite simply the thing that makes lightning bugs lightning bugs. But how and why do they glow? If glowing is so great, why don’t more animals glow? What is up with the glowing?

 

How Do They Glow?

The short answer is chemistry. The specific chemicals are calcium, adenosine triphosphate (ATP) and something called luciferin. The word “luciferin” comes from the Latin phrase meaning “light-bringing,” and is related to the alternate name for Satan: Lucifer (bet you didn’t expect him to show up in this article!) As you can imagine, luciferin is the essential ingredient in this glowing cocktail.

When these three chemicals come together in the presence of oxygen, they glow in a process called bioluminescence (the emission of light by living organisms). The lightning bug can turn the glow on and off by controlling the flow of oxygen into the lantern. Now, fireflies don’t have lungs, so they don’t breathe in and out like we do, but rather have organs called tracheoles that channel oxygen from the exterior through the walls of their exoskeleton. Weird!

So, do they control their flashes consciously? Scientists believe lightning bugs are able to control their flashing intentionally as a means of communication.  

 

Why Do They Glow?

But if lightning bugs blink intentionally, that begs the question: why? The short answer is mating, mostly. They blink in order to attract mates, which allows them to continue their species. 

Each species blinks a little differently, and these displays can change depending on the time of year. Lightning bugs are not segregated by species, and a single meadow can have dozens or more species which cannot mate with one another. How do you tell who is who in the dark? You blink out morse code that says, “Hey! I’m this certain kind of lightning bug—and if ur2, hmu!”

Lightning bugs also blink to signal to predators that they don’t taste good. Their glow lets everyone know that eating them would not be a great idea. That helps keep them safe, especially before they grow wings. 

 

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The Photinus pyralis, pictured here, is the most common firefly in the United States. 
(Katja Schulz / Flickr)

 

Types of Lightning Bugs

So, what are all these different species (to be more technical, subfamilies) of lightning bugs? One way to distinguish them is by color. Different subfamilies of lightning bugs come in several colors, and these are the most common ones.

 

Photinus pyralis

Photinus pyralis is the lightning bug most people in the United States are familiar with. Their light is yellowish-green and they cover more or less the whole of North America. One photinus that is a little rarer is Photinus carolinus, which only lives in four U.S. states: Tennessee, Georgia, Virginia, and Pennsylvania. You can tell Photinus carolinus apart from Photinus pyralis because their flashes are synchronized! So, instead of random blinking on and off, the whole swarm blinks in unison! 

 

Phausis reticulata

Phausis reticulata have a blue glow. Additionally, they don’t really flash like Photinus pyralis, but rather glow with a dim, ghostly light. This leads them to be called Blue Ghosts, since the males eerily flit along in the night sky. The females of this species do not fly, they just crawl on the ground. Phausis reticulata are most often found in the southeastern United States. 

 

Photuris versicolor

These are the trickster lightning bugs! As their name “versicolor” implies, they can change color. Usually, they are a little bit more green than Photinus pyralis, but it can be difficult to tell them apart by their light (even if you’re a lightning bug). The males fly and flash just like our buddy Photinus pyralis, but the females respond in two different ways: a) just as Photinus pyralis does, they respond back with mating patterns, and b) they mimic the color and flashes of the female lightning bugs of different species and eat the males who are lured in. Lightning bugs are so metal!

 

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(Jessica Lucia / Flickr)

 

Are Lightning Bugs Endangered?

Now that you know all about lightning bugs, you probably want to see some of your own. But finding your own lightning bug light show might be a little trickier than you’d think. 

Unfortunately lightning bug numbers are diminishing, both in total numbers and in numbers of species. Many of the common species described by entomologists in the early twentieth century are now very uncommon, if not altogether extinct. So while lightning bugs aren't on the endangered species list, the number of lightning bugs today has declined. 

There are a number of possible reasons for the decline in lightning bugs, including the increased use of pesticides. But the number one reason is development. There simply aren’t as many marshes, wetlands, and meadows as there once were, and the fireflies don’t adapt well to urban environments.

Why not? The answer is simple: a species that relies on blinking lights to reproduce needs a certain amount of darkness. As more of the world gets developed, light pollution in developed areas causes it to never be quite dark enough for our friends to see each other blink their lanterns. Just as their survival is linked with light, so is their extinction. That’s why environmentalists have started the Dark Sky Movement, which hopes to reduce light pollution to make the world safer for all nocturnal species, including lightning bugs. 

 

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(John Brandauer / Flickr)

 

7 Frequently Asked Lightning Bug Questions

Let’s recap with a list of the seven most common lightning bug questions you’re most likely to have. 

 

#1: What Is a Lightning Bug?

An insect of the order Coleoptera (beetle) and family Lampyridae that is most commonly known for the ability to emit light from their anterior segment called a lantern.

 

#2: What Is a Lightning Bug’s Life Cycle?

A lightning bug hatches in mid-summer, enters a larval state for about a year, most of which they spend underground. Then they turn into a flying insect with a glowing lantern (their adult stage) in order to mate. Adult lightning bugs usually live for a few days up to two months. 

 

#3: What Is the Difference Between a Male and Female Lightning Bug? 

Physical differences are difficult to see, but a male is more likely to fly high in the air and flash brightly and rapidly. A female is more likely to crawl or fly at ground level and flash more slowly in response to the male.

 

#4: How Do Lightning Bugs Glow? 

They glow in a chemical process called bioluminescence that lightning bugs can control by regulating the amount of oxygen that enters their lanterns through their exoskeletons.

 

#5: Why Do Lightning Bugs Glow? 

They light up for three reasons:

  1. Most importantly, they light up to attract mates.
  2. They light up to signal to predators that they don’t taste good.
  3. The predatory females of some species mimic the flashes of the females of other species so they can lure in and eat the males.

 

#6: Where Do Lightning Bugs Live? 

Basically, everywhere. But they favor marshes, wetlands, and forest meadows. You’ll see them in  your backyard if you don’t live in a very urban area because your backyard is basically a meadow as far as lightning bugs are concerned.

 

#7: Are Lightning Bugs Disappearing? 

Lightning bug populations are declining due to development of their natural habitats and light pollution making it more difficult for them to see each other’s glow.

 

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What’s Next? 

If you’re fascinated by animals like lightning bugs, you may be a good fit for a STEM major. Learn more about what a STEM major is and what careers are available for STEM majors.

Another good way to learn more about creatures like lightning bugs is to take high-level biology courses in high school. Before you make a decision to enroll in an AP or IB class, it’s a good idea to learn more about them! Here’s an overview of AP Biology, and here’s a guide to IB Biology.

If you’re applying to competitive colleges in order to major in biology, they may require you take the SAT Biology exam. Here’s everything you need to know about the SAT biology test. 




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Ashley Robinson
About the Author

Ashley Sufflé Robinson has a Ph.D. in 19th Century English Literature. As a content writer for PrepScholar, Ashley is passionate about giving college-bound students the in-depth information they need to get into the school of their dreams.



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