Sunlight & Seasons

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!

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)

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:

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:

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."

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?"

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

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

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