Secrets of Lightning Bugs

By Amber Mabe

It is finally here – the time of year when lightning bugs put on nightly performances of dancing, glowing, fairy-like lights. As a child, I never considered it to be truly summertime until the lightning bugs came out. We chased their blinking forms through the yard just after dusk, trading tips on how to track them and catch them for our lightning bug jars. My parents taught me what most of us know: lightning bugs use chemical reactions in their abdomens to send signals to one another during mating season. But it turns out, there is a lot more to lightning bugs that most of us probably do not know.

Lightning Bugs are masters of energy efficiency. They produce what scientists call “cold light” which means they use their energy to create light without losing energy in the form of heat. In comparison, an average incandescent lightbulb works at a 10% efficiency, meaning the other 90% of its energy is released as heat. Modern LED lights are much more efficient, producing around 80-90% light and wasting much less energy on heat. Lightning Bugs leave everyone else in the dust, however, operating at nearly 100% efficiency. Not one percent of their light-making energy is lost by creating heat.

Lightning Bugs might not eat what you think they eat. When I was a kid, I remember collecting grass to put in my lightning bug jar, mistakenly believing that they must be eating the grass they were landing on. In reality, lightning bugs have a diverse diet, depending on the species. Most are actually carnivorous, eating worms and other insects while in their larva stage. Some species even eat other lightning bugs, temporarily changing their light patterns to trick smaller species of lightning bugs into believing they are a potential mate. While it is generally assumed that most adult lightning bugs dine on pollen and nectar from plants, some scientists believe that certain species of adult lightning bugs do not actually eat, since the adult lifespan is a mere two months and is mostly spent looking for mates and laying eggs.

Lightning Bugs contribute to cutting-edge research. The chemicals and enzymes in a lightning bugs body that produce light, Luciferin and Luciferase, are key players in several areas of scientific research. Luciferase reacts with a chemical that is found in all living things, called ATP, producing the glow we see in their abdomen. This chemical reaction and the information it provides is useful in forensics, cancer and other disease research, and even food safety tests.

Every species of lightning bug has a unique blinking rhythm. These rhythms are used to find and identify other lightning bugs by species and by gender, in order to find mates. One particular species, the photinus carolinus, is found only in the Great Smoky Mountains of North Carolina, and each year puts on a spectacular display of synchronized flashing. This is one of the few species that synchronizes their rhythms at certain times. Lightning Bug glows also vary in color by species, including yellows, oranges, greens, amber, and even blue. “Blue Ghost” lightning bugs do not blink, but instead glow with a steady, eerie blue light. These rare lightning bugs can be seen just a few weeks out of the year (usually late May to early June) in the Pisgah National Forest. Surprisingly, there are even species of lightning bugs that do not light up at all.

Lightning Bugs are on the decline. Loss of habitat, pesticides, and light pollution are a few of the factors that have caused lightning bug numbers to decrease around the world. So how can we help? Lightning Bugs are natural pesticides, feeding on the larvae of harmful insects. Consider not using broad spectrum pesticides on your lawn, and even be conscious of whether you are using harsh chemical fertilizers. If you can maintain a natural portion of your property that contains trees, long grasses, and even a water feature, these are all things that create a habitat for lightning bugs and will draw them to your yard. In return, you will enjoy a spectacular summer show.

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