Luna Moth Mysteries

Sallie Satterthwaite's picture

They looked like leaves, two lime-green leaves in a jumble, caught on the outside of the screenporch that allows us to have doors open at night. When I looked at them more intently, they transformed from tangled leaves to two large moths with wings tightly folded together.

The large insects appeared to be still in the process of extending their wings and legs, inflating them from weeks in pupae, making ready to take to the air.

I needed to start our dinner, but I decided to keep watch over the moths lest a bird or other predator decided to take them out for dinner.

I was being held captive by two luna moths, among the largest moths in North America, as big as a small bird, rarely reported because they are nocturnal. Various sources portray them as measuring upwards of 10 inches in wingspan. The two I was admiring were about five inches from wingtip to wingtip.

They were exquisite. Fresh new wings look as though they were shaped from delicate porcelain, decorated with four large “eyespots” to scare predators, and rimmed with purple satin.

As I watched, they straightened those wings, stretched out little legs, and two tiny “sticks” slowly turned into fern-like antennae. Meanwhile the bottom inch of each hind wing straightened into a small tail.

As they began taking form, I realized that I was not seeing them move. There was only the slightest movement, yet while I watched they went from caterpillar to half extended wings, little legs (six, the normal allotment to insects). They held me enthralled, changing into new beings without (apparently) moving.

I marvel at such beauty, and warned Dave dinner might be late. Finally I brought a deck chair to a spot about two feet from the moths, trying to shelter them from predation.

Let Nature be Nature, goes the philosophy, but I have a role in Nature too. Curious Homo sapiens, I guess, trying to learn something from Actias luna.

When we finished eating, it was nearly dark. I couldn’tbe sure they were still out there because I did not want to rush them with a flashlight. They fly only at night, seeking a mate, and I didn’t want to foul up this stage of their lives. When I looked next morning there was not a sign of them. So I did what any curious Homo sapiens would do, and searched on-line to broaden my understanding of these amazing creatures. There’s a lot to be had. Just do a search on Luna Moth. (NOT “lunar” moths).

What I learned on-line was that in our climate there may be three generations hatched each year, transformed into a caterpillar until at last doing time in a pupa, then emerging as this wonder of the dusk.

Sweetgums and willows are among the trees favored by a luna moth laying eggs. She secures about 200 eggs to the bottoms of leaves, a dozen or so at once. They hatch in about a week, voracious caterpillars, then build another pupa case, repeating this phase four times in about three weeks.

Even the caterpillar is spectacular. He’s a chubby fellow, about two and a half inches long, in colors that very somewhat from pupa to pupa, solid green with some pink or orange decorations and a white fuzzy belly. He’s also an eating machine, but there are so few of these big bugs that damage to trees is miniscule.

Now here’s another bit of mystery. The adult moth has no mouth, no vestigial jaws or teeth. She goes from egg to a series of five pupa caterpillars, to a paper-thin cocoon, to a breathtakingly beautiful moth, to a bird’s idea of fast food. And dies in about a week, “naturally” or by predation.

If you decide to keep her captive, know that in some areas Luna moths are protected by law, but I don’t see that as a problem as long as she has lived at least long enough to mate and lay eggs. And that takes only about a week.

Some mysteries give up their secret faster than others. Why? Why go through these changes only to live a week?

Because in Nature the sole intent of any organism is to ensure that its genes are carried forth to take their part in propagation of its own species. That’s all. No glamour, no soaring angel choirs.

Just one more bug that has figured out the most efficient way to ensure its own place in eternity.

[Sallie Satterthwaite of Peachtree City has been writing for The Citizen since our first issue Feb. 10, 1993. Before that she had served as a city councilwoman and as a volunteer emergency medical technician. Her email is SallieS@Juno.com.]

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