Articles
Lighting Bugs: the Beetle Beacons
By Gordon Wilson March 2, 2009
If you ever lived in the eastern United States, you probably witnessed one of those magical ligt shows that bedazzle on summer nights. As darkness settles over the creeks and woodlots, tiny pinpricks of yellow or green lights begin in beautiful randomness. Anyone who grows up watching these magical displays cherishes his childhood memory.
I grew up In Anapolis, Maryland near such a woodlot. I remember my excitement as I lunged about in the darkness trying to catch one of the sources of those eirie Lilliputian beacons. Seeing my delight when I succeeded, you’d think I’d had caught a fairy waving her glowing wand.
No, it was something much more exciting. Instead of something familiar, like the human form of Tinkerbell, I had captured a bizarre little alien.
It had a concealed head with large compound eyes. Strange segmented antennae waved about close by. Six legs protruded from its body. On its back were two transparent wings, protected by two leathery wing covers. And what’s this? A hind end that actually glows in the dark.
This creature was just as incredible as the biblical cherubim, only a lot smaller—it was a lightning bug! Here in my hand, light was radiating from a creature crafted by the Word of God, the Lord Jesus Christ Himself. Of course I should be awestruck.
How Does a Beetle Become a Beacon?
The most amazing things about lightning bugs of course, is their ability to produce light (bioluminescence), which they switch on and off at will. So what mechanism performs this magic? The last two or three segments of the abdomen make up the glow organ. Hence, underneath the exoskeleton, are specialized cells called photocytes (light cells).
These light cells need several ingredients to make light. One is a chemical called luciferm (remember Lucifer, who was the ‘angle of light’). A second ingredient, called luciferase, causes the luciferm to break down and produce light. A third ingredient is the common molecule ATP (adenosine triphosphate), which provides the energy to drive the chemical reaction.
These ingredients are always present I a glow organ. So why isn’t it constantly glowing? How does the firefly turn off its light? The last ingredient is oxygen. The chemical reaction can’t take place without oxygen. No oxygen; no reaction; no light.
One widely held theory of how the firefly turns its light off is that it simply shuts off the oxygen supply (oxygen control theory). Whenever the insect needs the light to glow again, it feeds oxygen to the glow organ and—viola—the reaction begins again.
Another amazing feature is that the light cells are just beneath a transparent exoskeleton so that the light can freely shine from the abdomen. No sense in hiding your light under a bushel!
A Beetle Went a Courtin’
So the next logical question is why an insect would need its bottom to glow in the dark in the first place. Although it has been shown that the firefly glow organs warn predators that they taste bad, the main purpose that entomologists have discovered is that the light serves as a homing beacon for potential mates.
Some species display a unique flash pattern. Lke Morse code, the flying males send out signals beckoning females of the same species who will respond with a corresponding flash pattern, which says, “I’m over here, sweetheart.” When a male sees her flirtatious flickering response, he heads straight toward her, flashing as he goes, as if to say, “Keep flashing my love; your knight in shining armor will be there shortly” (literally shining armor, for his exoskeleton is aglow).The female usually stays put while the male flies toward her. They keep flashing back and forth as they get closer to each other. Once he arrives, they mate. After her eggs are fertilized, she proceeds to lay them in the leaf litter.
Beacon or Death?
Attracting a mate is amazing enough, but that’s not all fireflies use their lights for. The females of one firefly genus (Photuris) lure males of a different genus (typically Photinus) by mimicking the Photunis pattern.
Attracted by the courtship signal of his own species, the duped male flies toward the Photuris female seeking to mate. Upon his arrival the female devours him. Instead of fertilizing eggs of his own species, he bcomes a meal that provides her with the nourishment she needs to make her own eggs.
Lighting bugs are truly fantastical insects, even with their ability to produce light for morbid ends. Fascinating as this strange predatory behavior is, we should be mindful that the world was much different prior to Adam’s Fall. Animals with nepesh (Hebrew for ‘life’) didn’t devour each other and this may have included insects (Genesis 1:30) If so, fireflies originally may have consumed plants or gotten sustenance from the photosynthetic algae embedded in their tissues.
Many examples of non-predators exist today. They give us a glimpse of what it may have been like in Eden before Adam’s Fall and what it may be like in the new heavens and new earth. All creation groans now, but some day that will change.
Class: Insecta Order: Coleoptera (beetles) Family: Lampyridae Genus/species: Over 1700 species worldwide; 125 in the United States and Canada
Lightning Bug or Firefly?
Lightning bugs are also called fireflies, but technically speaking they’re neither true bugs nor true flies.
What are they? They’re actually beetles. Beetles have hard or leathery outer wing covers and belong to the order of insects called Coleoptera (coleos = “sheath” and pteron = “wing”).
TRUE BUGS
You might think any critter encased in an exossssssskelton is a bug (and that’s just fine for nonscientists, but entomologists reserve the term bug for insects with specialized front wings that are partly transparent. These insects belong to the order Hemiptera, meaning “half wing”. True bugs, unlike fireflies and other insects have mouthparts that peircelike hypodermic needles and suck up liquid food.
TRUE FLIES
Fireflies are not flies. True flies have only one pair of wings, hle most flying insects, such as beetles, have two pair of wings. Flies belong to the order Diptera, meaning “two wings”. In place of a second pair of wings, God has provided flies with structures called halteres, small club-shaped organs used for balance in flight.
BEETLES
So what’s a beetle? All 350,000 or so species of beetles share one major feature: front wings that develop into leathery or rigid wing covers called elytra. These non-overlapping sheaths protect the transparent hind wings when not flying. Since lightning bugs have elytra, they are beetles, not bugs or flies.
(Note: Photos available at original source.)
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