Indiana warm summer nights that follow the summer solstice – the shortest night of the year and the official beginning of summer – mean its prime time for aerial displays of luminescent insects. These insects are beetles that are classified scientifically in the insect family Lampyridae.
Of course, few people use the term Lampyridae in reference to flashers of the insect type, except maybe an old entomologist or two. Most folks refer to the aerial showoffs by using a common name: either firefly or lightningbug.
Before the linguists among us dash off to check the spelling of the words "firefly" and "lightningbug," let me explain. In spite of what dictionaries, some newspaper editors and my computer spell checker maintain, "firefly" and "lightningbug" are scientifically the correct spellings. The reason is that if the common name of an insect includes the common name of an insect order it is appropriate to indicate whether or not the insect is really classified in that order.
How does this work? By spelling the name as one or two words. In this case the insects in question are beetles, members of the insect order Coleoptera. So a scientifically correct common name would be "fire beetle" or "lightning beetle" written as two words.
Because the insect is not a fly – a member of the order Diptera – that common name is correctly written as the single word "firefly." It is also not a true bug in the order Hemiptera, thus lightningbug would be the correct way to spell that name.
As it turns out, both lightningbug and firefly are widely used names for these light-producing beetles. OK, hold up your hand if you use the word "firefly" for these insects. Based on my experience with students in my classes over the years, a little over half of you have your hands in the air.
The rest of you, well, you use the term "lightningbug."
Exactly how these terms for the same group of insects came into existence is a matter of speculation. The word "fly" shows up in several insect names such as butterfly and dragonfly mainly, because of the flying ability of the insects. The term "bug" has been widely applied, incorrectly to be sure, to lots of insects. A common example is a ladybug, an insect like the lightningbug that is a beetle, not a bug.
A person I know who studies word origins and who suggested that the term "firefly" probably originated in New England states and that lightningbug originated in Southern states back in the early days of our country.
Either way, as people moved around the U.S. they carried the common names with them, and today we have both terms in use throughout the United States.
Regardless of whether you favor the "firefly" name or the "lightningbug" name for Lampyridae, these insects fascinate almost everyone. As is widely recognized, the insects produce their light to attract mates.
Each species has its own unique flashing pattern – sort of a Morse code of the firefly set. Male fireflies fly about flashing their lights. Females sit on vegetation and watch until they spy a fellow that they like and respond with the same flashing signal.
Firefly light is a cold light in that very little heat is produced. In general terms, the insect produces light by using a substrate called luciferin and an enzyme named luciferase.
In the presence of oxygen the chemical mixture burns much as a fire burns. These two chemicals are present in the photocells of the firefly, and when the insect injects oxygen into the photocells, light is produced.
So when the photocells have oxygen, light is produced. When oxygen is absent, the system goes dark. So alternatively injecting and removing oxygen from the photocells accomplish the flashing displayed by fireflies. Those of you who have intentionally or accidentally smashed a firefly have probably noticed that the light glows constantly.
That is because oxygen in the air continually enervates luciferin and luciferase in a chemical reaction that continues until the chemicals are consumed.
That is also why a firefly that gets smashed on the windshield of an auto produces a bright and continuous glow for a moment or two. The air moving over the windshield fans the chemical fire in the smashed photocell of the firefly.
Lightningbug or firefly, by either name these chemical wizards of the insect world put on an amazing summertime show.
The views and opinions expressed in this column are those of the author and not necessarily those of Farm World. Readers with questions or comments for Tom Turpin may write to him in care of this publication.
