Fireflies: The Real Tinkerbells

One of the most enchanting sights of the season is the delicate light of Fireflies blinking in the night. Found on every continent around the world except Antarctica, these graceful little stars put on a magical show each year that would make even Tinkerbell jealous!

What's really going on in the dark?

Credit: Dr. Patrick C. Hickey
University of Edinburgh, Scotland, UK.

If you've been lucky enough to see them, you'll know that fireflies or lightning bugs can be seen in meadows, near marshes, fields and backyards in the eastern U.S. and parts of Canada. Unlike some other insects, fireflies are no bother to us humans. They don't sting, bite, attack or carry disease.

But what's really going on out there in the dark? What do all the blinking lights mean? And how do fireflies generate the light we see? There's so much more to learn and admire about fireflies than just a mini-Fourth of July light show. Read on--you'll be amazed!

Firefly Morse Code: "I'm Your Love Bug!"

Credit: J.E. Lloyd,Univ. of Florida

There are over 2,000 species of fireflies in the world and approximately 200 species in North America. Some species of firefly actually don't flash. But among flashing fireflies, each separate flashing species has its own unique, distinguishing flash pattern or signal.

But just who's doing the flashing? Who's watching? What are they watching for? And what do the flashes mean? Well, one purpose of the flashing is thought to be a signal system for attracting mates--a sort of Firefly Morse code for "Hey, baby! I'm the light of your life, check me out, let me be your Luvvv Bug!"

Entomologist Susan Weller, from the University of Minnesota, tells us that male and female fireflies have different roles in this flash dance:


"Males and females find each other by exchanging light flashes called bioluminesence, or by emitting chemicals called pheromones. In flashing species, males cruise and flash at or above the tree line at the edge of meadows. Females usually sit on bushes and other low plants, and wait for the right male before flashing a return signal."

The firefly's light source is not located where you might think. In fact , the light source on these tiny lanterns is located on their behind or posterior--close to the tip of their abdomen. Poet Ogden Nash seemed to have noticed this when he wrote this limerick .

The firefly's flame
Is something for which science has no name.
I can think of nothing eerier
Than flying around with an unidentified glow on a person's posteerier.

-Ogden Nash
(Illustration: Arwin Provonsha,
Purdue Department of Entomology)

Marc's A (fire)Fly On the Wall

Click on image to see the firefly flash
Credit: Dr. Patrick C. Hickey
University of Edinburgh, Scotland, UK.

What is it in a male firefly's flash that leads a female to respond to his flash pattern instead of that of another male? What tells a female that "he's the right male?" Firefly expert Marc Branham of New York's American Museum of Natural History studied this question by videotaping and analyzing fireflies' flash patterns. Learn more about his fascinating research on the linked page below. But before you go to that page, put yourself in the place of the female and the male firefly surrounded by all this flashing, and think about these questions:

Journaling Question :
"If you were a FEMALE firefly, what type of a male flash pattern would be more attractive to you? Do you think there would be some strategy in a male's flash? What information might the flash rate tell you about the male? Think about what information you might want to know about the male."

Journaling Question:
"If you were a MALE firefly, what kind of night conditions would you want so that female fireflies would be sure to notice your flashes? What conditions, both natural and man-made, could enhance or impair a female's ability to see your signals?"

Take a closer look at Marc's research, and see if he has unlocked the code behind the fireflies' signals:

A "Light" Goes Off in a Scientist's Head

Credit: Mike Lee

How do you think Marc Branham's theories about male firefly flashes first developed in his mind? Marc tells us how he came to think about this question, and how he thought through the testing and experiments he conducted to explore his theories.

Take a look at his summary:

Guess Who's Coming for Dinner? You Are!
Fireflies seem to have such a peaceful way of communicating with each other. The male blinks his half of the code and the female answers with her half of the code, and hopefully they find each other and mate. But, sometimes things aren't what they seem.
Fatal Attraction

Credit: J.E. Lloyd,Univ. of Florida

Indeed, flash patterns can also be used for another purpose--luring unsuspecting prey. In a process called "aggressive mimicry", some female species of firefly will actually imitate another species' flash pattern or code in order lure the male of that other species in for a meal--except HE'S the meal! The moral of the story? Be careful who you hold a torch for! Which leads us to this tasty question:


Journaling Question :
"Other than hunger, what reasons can you think of why a female firefly might prey on and eat a male firefly?" (Read more below for some helpful information.)

Got A Bad Taste in Your Mouth?
While scientists believe that the firefly's luminous abilities are a system for attracting mates, some believe that it can also be a protective system for warning off predators.

Scientists from Purdue University believe that the firefly's light tells "birds and other insects that fireflies aren't a good tasting meal. Like the orange color on a monarch butterfly, or the yellow stripes on a wasp, the light end of a firefly lets predators know to avoid eating them."

Marc Branham reports that although the amount varies from one firefly species to another, "as far as we know, all fireflies seem to be chemically protected by defensive chemicals called 'lucibufagins' that are noxious and sometimes toxic to organisms that try to eat fireflies." Lucibufagins in fireflies were discovered by Dr. Thomas Eisner of Cornell University.

However, certain species of fireflies are known to have very low levels of this chemical. And here's where "aggressive mimicry" comes into play. Marc notes that females of the species with low lucibufagin levels are able to gain more of the chemical protection--which they can transfer to their eggs--by attracting and eating other species which have higher amounts of the defensive chemical.

Mmmmm Mmmm, Good! A Warm Glow In My Stomach
Despite the visual warning of the firefly's glow, some predators still have an appetite for a "light" meal. According to Naturalist Jim Gilbert:

"Some frogs have eaten so many lightning bugs that their stomachs shine as though they swallowed a light bulb."

Chemical Action, What's Your Reaction?

Have you ever wondered just what it is that produces the light on a firefly? You're not alone. This same question led scientists to study this over one hundred years ago, and the results of that research continue to help us even now. Would you believe that research about fireflies' bioluminescent glow has played a role in many "glow in the dark" products like toys that you play with?
I Can Fly, But I'm Not a Fly!
Did you know that the name firefly is a misnomer? With common names including firefly, lightning bug and glowworm, fireflies are actually small, soft-bodied beetles, and not flies at all! They are in the family Lampyridae (pronounced lamb-PIER-ri-dee), which comes from the Greek root "pyr" meaning "fire" or "shining fire".

Journaling Question:
"A firefly can fly, so why isn't it considered a fly? How can you tell the difference between a fly and a beetle? Can you name a characteristic(s) that distinguishes them apart?"

Short, but Sweet
Firefly larvae, sometimes referred to as glowworms, are six legged, flattened worm-like creatures. They can live up to two years and live underground, and sometimes in trees and underwater (breathing through gills...Really!). They munch mainly on snails, slugs and earthworms. In contrast, the adult life of these code-blinking beetles is very short--many species live only about two weeks as adults.

Poet Robert Frost seemed to know about the firefly's short adult life in this poem:

Here come real stars to fill the upper skies,
And here on earth come emulating flies,
That though they never equal stars in size,
(And they were never really stars at heart)
Achieve at times a very star-like start. Only, of course, they can't sustain the part.

--Robert Frost, Fireflies in the Garden

Credit: J.E. Lloyd,Univ. of Florida


Try This!

The Lightning Round Quiz

Test your knowledge and try to answer these fun questions about fireflies:

    1. What state in the U.S. has more firefly species than any other?
    2. What city has a firefly festival every year, and has been designated the firefly capitol of the U.S.?
    3. What continent has no fireflies at all?
    4. Which U.S. STATE/city has named the firefly its state insect?

Citizen Science Project

Are you seeing fireflies? Share your observations with scientists trying to study these amazing insects.