Noticed my first fireflies of the year this past weekend. I usually think of July as firefly season on Long Island, but it's not uncommon to see them a few weeks early. It's always one of those special sights, filled with memories of childhood and warm summer nights. The following is a piece on fireflies I wrote for my column in the Great South Bay Magazine a few years ago. Get out and enjoy them!
Enrico
Lightning
Bugs or Fireflies?
Mark
Twain once said that the difference between the right word and the almost right
word is the difference between lightning and a lightning bug. It’s a good point, but it leaves us
with the question of what is the right word for the insects that make our
summer nights sparkle? Twain
referred to “lightning bugs,” but many of us call them “fireflies.” So which is the right word? Well, as it turns out, both are correct
and are used interchangeably.
Firefly
is the older name; it comes from England and its roots are centuries old. Lightning bug is an American moniker,
coined sometime during the mid-1700s.
A recent poll concluded that one-third of Americans use the name
lightning bug, one-third use firefly and one-third use both names
interchangeably. In Jamaica
they’re called “blinkies” – maybe that’s a name on which we could all agree.
While
the names lightning bug and firefly are both perfectly descriptive, neither is
terribly accurate. Lightning bugs
(which is the term I’ll use since that’s what we called them when I was a kid)
are neither true bugs nor flies.
They are beetles from the family Lampyridea, which translates to “shining ones” in
Greek. There are almost 200
different species of lightning bugs in North America, most of which are found
east of the Mississippi River.
Surprisingly, there are no
lightning bugs to be found west of the Rocky Mountains. Across the world, there are nearly
2,000 species; they’re found on every continent except Antarctica.
The
fascinating thing about lightning bugs, of course, is the fact that they
produce their own light (actually, only two-thirds of the species produce light
as adults; but all lightning bugs do as larvae). It’s one of those amazing aspects of nature that mesmerizes
us as children and puzzles us as adults.
So why do they flash and how do they produce the light? Let’s take the latter question first.
Despite
childhood guesses about tiny lanterns or miniature flashlights, lightning bugs
actually produce light through a process called bioluminescence. It doesn’t involve a spark or flame of
any kind, just a straightforward chemical reaction. The light-producing cells – called photocytes – in the tail
end of the bugs’ abdomens contain two unique chemicals: luciferine and luciferase. When these chemicals mix with oxygen,
magnesium, and a fuel source called ATP, a high-energy reaction takes place
that produces light as its byproduct. Lightning bugs control this reaction by
regulating the amount of oxygen that reaches the photocytes.
One
of the amazing things about this reaction is that it’s almost 100 percent
efficient – almost all of the energy is released in the form of light. There is no heat produced, which is why
bioluminescence is often referred to as “cool light.” Compare this to the light produced by the light bulb above
your head. If it’s an incandescent
bulb, only about 10 percent of the energy produced is in the form of
light. The rest is wasted as heat,
which is why these old-fashioned bulbs get so hot (and why you should switch
that bulb to a more efficient compact-fluorescent!)
The
ability of luciferine and luciferase to create light in the presence of such common substances as oxygen and ATP (which exists in every living cell) has
lead to many practical applications.
They are used for a wide variety of medical and biological tests and
NASA plans to use them to check for extraterrestrial life in space. They also have more everyday
applications – they’re used to create the glowsticks we’ve all seen at concerts
and other nighttime events.
Until
just a few years ago, the practical applications for these chemicals created
quite a demand for lightning bugs.
Chemical companies paid harvesters handsomely for the lightning bugs and
the rare compounds they contained.
I read about one woman in Ohio, known as the “Lightning Bug Lady,” who
collected more than a million each year!
Such predation can put a strain on local lightning bug populations,
especially when combined with the constant pressure of habitat loss. Thankfully, scientists have learned how
to create luciferine and luciferase in the lab, so the lightning bug trade has
been put out of business.
Okay,
so we know how lighting bugs create their wonderful light, but why? Well, like so many other beautiful
displays and rituals in nature, it’s done for mating purposes. In most species, the insects we see
flying around and blinking are males.
They’re trying to locate and attract females, which are usually
flightless, but climb to the top of a bush or blade of grass to do their (less
frequent) return blinking. Males
usually outnumber females by 50 to 1.
If
a male and female are successful in getting together through their blinking
communication, they mate and the female lays her eggs in moist soil. The eggs (which in some species have
their own bioluminescence) will hatch into larvae in a few weeks. The larvae live in the soil and leaf
litter for up to two years before building a mud cocoon and transforming into
adults. All lightning bug larvae have
luminescent abilities, usually in the form of a series of light spots on their
sides (in fact, the larvae of some species are called glowworms). It is believed that this characteristic
is used to dissuade potential predators (in nature, bright colors or showy
displays often indicate toxicity or danger). The lightning bug larvae are voracious predators themselves,
feeding on snails, earthworms and wide variety of other soil inhabitants. They subdue their often-larger prey by
injecting a paralyzing chemical.
For
many, lightning bugs are as synonymous with summer – as much a part of the
season as vacations, swimming, watermelons and fresh tomatoes. Many of us are filled with nostalgia
and joy at the very sight of their blinking light. They bring to mind warm summer nights with friends and
family, chasing the slow-flying bugs around the yard with empty jars in our
hands. Some of us gathered the
insects with plans for bug-powered lanterns; others were just after a few
nighttime companions for the bedside table.
While
the excitement of chasing lightning bugs may wane as we grow up, I’ve
discovered recently that it quickly re-ignites when there are children
around. It’s a special thrill to
introduce a child to these magical insects for the first time, to see the
wonder in their eyes as they try to comprehend the mysterious blinking lights,
and to watch their excitement as they catch their first lightning bug.
So,
if you can tear them away from the TV, computer and video games, take some
children outside this summer as the sun is setting to enjoy one of nature’s
best light shows. Find a
relatively dark place just after sundown, arm them with empty jars, and
introduce them to one of the great joys of childhood. I promise your efforts will be rewarded.
