The RoVing Naturalist
By Dennis Prichard
Most every child has gone out into the still summer night air and wondered about those flashing specks of light above the bushes and lawns around their houses. Lightning bugs, or fireflies, are almost as much a part of a child’s summer as eating ice cream or going swimming. But if a child inquired of you about how the firefly makes its light, what would you say?
There is no question about it if you could ask a firefly. This beetle is communicating a message to his loved one. The male flies around signaling with a certain frequency and duration of his light. As the female watches from her vantage point among the vegetation, she recognizes each different species by the individual signal. There are nearly 60 different firefly species in North America, and each has their own special sequence.
When the female finds the right light sequence, she flashes her response at the exact time for her species. One kind flashes a short burst of light 5-1/2 seconds after her mate’s, while a different species might flash a long glow only one second after her mate’s “call.” In this way, both genders find each other and different species stay separated.
Generating nearly .02 candlepower, the light of a firefly is much more efficient than an incandescent lightbulb, which uses only 10 percent of its energy to produce light. Fireflies utilize 92 to 100 percent of their lantern energy for light production without all the heat produced by that lightbulb.
Two chemicals, luciferin and luciferase, combine with oxygen to produce this remarkable feat. Adenosine triphosphate, or ATP, which is found in all living plant and animal cells, triggers the complex reaction. Scientists can use this reaction on space flights to other planets to tell if life exists there. Dust is mixed with the chemicals and, if ATP is present, the sample will glow, showing that extraterrestrial life does exist.
The firefly can initiate the flashing process at will, and thus a “rhythm” is established. As the whole yard full of beetles see the light, they all chime in and pulse with their own “lanterns.” If all are the same species, they will be competing for mates, and the flashing soon synchronizes into unison. This sight makes a memory that will last a lifetime.
Answering the question of a firefly’s light may come easier for a child of our computer age than it did for me. To demonstrate this chemical reaction, just go to one of those outdoor specialty shops, purchase one of those chemical lights that come in a plastic tube, then wait until dark. When the fireflies come out to shine and the shining questions start to fly, demonstrate the amazing process by breaking the vial, mixing the chemicals and having fun with the light. Learning always sinks deeper into a youngster’s mind if it is accompanied with a dose of fun!
Dennis Prichard is a retired park ranger. He’s worked and studied wildlife at many National Parks and Wildlife Refuges including Carlsbad Caverns, Mammoth Caves, the Everglades, Sequoyah NWR in Oklahoma, Sevilleta NWR in New Mexico, and Isle Royale National Park, to name a few. He travels in a fifth wheel with his wife and dog, a Labrador named Cricket.