This time of the year, dusk often finds kids outside in the yard catching fireflies (lightning bugs) of which there are approximately 175 species in North America. They belong to the family lampyridae in the order coleoptera (beetle family).
Adults of most species are readily identified by their brown or black soft bodies, somewhat leathery forewings and a usually red or orange pronotum (shell-like plate) that covers the head from above. The last few segments of the abdomen are pale yellow and can glow yellow, green, orange or sometimes red depending on the species.
Firefly larva live underground during the winter and emerge in the spring and are called glow worms. They don’t blink but glow continuously and can be seen in moist areas near grass and brush. They are voracious predators with jaws equipped with a toxin which helps them overpower snails, slugs, earthworms and other prey.
Adults are nocturnal crepuscular (active during dusk to dawn) nesting in grass during the day and start their flights as darkness gathers staying low at first, flying higher as they scatter.
Adult fireflies eat a variety of foods depending on the species. Most subsist on pollen and nectar. Some species resort to cannibalism and some don’t eat anything at all.
Adult fireflies are rarely preyed upon. When attacked, they shed drops of blood in a process known as “reflex bleeding” which contains chemicals that taste bitter and can be poisonous to some predators. Most animals learn to avoid eating them.
Light produced by fireflies is the most efficient light ever made. Almost 100% of the energy in the chemical reaction is emitted as light; in comparison an incandescent light bulb emits 10% of its energy as light and the other 90% is lost as heat.
Different species of fireflies have their own precise rhythms, flashes and movements all used for courtship. In some species, the females will signal from the grasses because only the males fly. In other species females mimic the courtship signals of other species, luring in prospective “mates” and then eat them. Fireflies are our only bioluminescent insects.
Fireflies use the chemical luciferin and liciferase which interacts with a third chemical, adenosine triphosphate (ATP) to create the flickering light. Because all living cells contain ATP, scientists extract liciferase and luciferin as a diagnostic agent to detect cancer, multiple sclerosis, cystic fibrosis and heart trouble in humans.
Fireflies do not live in the Northwestern United States. I was conducting a toad and frog survey (done during the night) and we had a person visiting from Oregon along who had never before in his life seen lightning bugs. He thought it was the most spectacular thing he had ever seen.
“In every walk with nature one receives far more than he seeks.”
Rachel Carson
