By Staff
Have you noticed all the fireflies out in the last several weeks?
At least around my place it is a banner year for them. As the evening's shadows along the creek fade into the dim twilight the show begins. First a blink here and another there, then a few more and within just a few minutes the whole yard is blinking on and off like a giant Christmas tree. Fireflies, or lightning bugs, whatever your preferred nomenclature, are one of nature's more wondrous phenomenons.
We associate light with electricity or fire but the firefly resorts to a different trick, biolight. The fireflies’ glow comes from a chemical reaction. Without getting too technical (which quickly gets over my head), enzymes called luciferase and luciferin are contained in special light emitting organs, usually located in the abdomen. These are the same enzymes that produce the glow in a variety of light emitting life forms from Jack-O-Lantern mushrooms to a number of marine creatures.
The lightning bug can control the light emitting reaction at will. This is important as in most cases the blinking is done to find mates of their own species. There are some two thousand species of fireflies. Not all emit light but of those that do each species has its own unique combination of blinking and flight pattern. For instance, species A steadily flies high above the ground producing three slow flashes in a series. Species B flies lower emitting single flashes. Species C emits long flashes while executing a lateral curve and yet another species makes a J curve while flashing. These various combinations of flight and flashing continue on to near infinitum. In some locations, most notably in areas of Tennessee and South Carolina a phenomenon occurs where they all blink in unison. We've yet to discover why.
In most species it's the male that does the cruising while the female just hangs out on some vegetation and blinks back with a tantalizing smile. Not all is wine, roses and chocolate, though. There are some predatory species of lightning bugs in which the females mimic other species’ light. The targeted male thinks a hot chick is giving him the come on and when he moves in on her he's pounced upon and eaten. The dreaded "femme fatale." There's always a hitch, isn't there?
Most species of fireflies prefer wetlands or damp woodlands, which explains why we have so many at our place on the creek. These moist areas provide abundant food sources for the larvae, most of which are predatory. The larvae is the familiar glow worm, which obviously also emits light. In fact, even firefly eggs give off a dim glow. You would think a little worm wandering around all aglow would be suicidal. It actually works just the opposite. Most glow worms are distasteful or toxic to other predators so the light serves as a warning signal. The larvae over winter either underground or under the bark of trees. In some of the more northerly species the larval stage continues for two years before transforming into short lived adults.
Most firefly species are what's called crepuscular, meaning they are most active at dusk or when there is a lot of moonlight rather than flying all night long (nocturnal) or daytime only (diurnal). Other than the aforementioned femme fatales, the adults of most firefly species feed on pollen and nectar, if they feed at all. The glow worm larvae feed on a variety of deleterious larvae, snails and slugs so fireflies are good things to have hanging around.
We have also found other uses for lightning bugs. The ancient Chinese reportedly collected quantities of lightning bugs in transparent containers for use as lanterns. If you can figure out what they had back then that was transparent let me know but that's what I read. We've also found the light producing luciferase enzyme to be pretty handy stuff. It's sometimes used in forensics to detect blood residue. The medical community introduces it into cells to better see and identify specific cell types. It also lights up in the presence of certain diseases, making it a useful diagnostic tool. Carpe diem.