The Luna moth (Actias luna) is streamlined and elegant with a beautiful lime green color. Despite inhabiting most of the northeastern the United States, the Luna moth is a rare sight because it favors densely wooded areas like the forests populating Western Pennsylvania. Spotting these moths is also difficult because they only take flight at night.
THE LIFE OF A MOTH
Many people confuse the butterfly with the moth, but the two are actually very different. Butterflies land with their wings together and raised; their antennae are rather thin. When a moth lands, their wings are spread wide and their antennae are normally feathered and actually contribute to their sense of smell—a sense that is key to the moth’s ability to reproduce. In order to find a mate the moth must sense the proximity of odors (pheromones).
The truly impressive part of the moth’s life cycle is the process of complete metamorphosis, The road to adulthood passes through the egg, larvae, pupa, and adult stages. Each stage is fraught with its own dangers. While it might seem odd to attribute risk to the life of an insect since we tend to consider them mindless and directionless, their existence fills such a fragile and vital environmental niche that it is unfair to merely discredit them because we find them “buggy” or “creepy.” Their direction, patterns and innate instincts are so genetically fixed that any substantial change means that the insect dies out. Some species, like the Luna moth, fill very narrow niches, but narrow by no means implies insignificant.
The Luna moth eats specific deciduous trees – the walnut is a particular favorite -- hence its preference for the deep woods. Eggs, roughly the size of pinheads, are laid on leaves in clusters of about 200. Ten days later the young
caterpillars eat through the eggs and crawl out into the forest where they will eat constantly and grow rapidly until their skin becomes taught and splits. Five times before it is fully grown, the caterpillar wriggles off its old skin to reveal a fresh layer beneath it. Once the caterpillar reaches 2-1/2” long, it stops eating and prepares to make its cocoon. The caterpillar winds sticky thread, produced from a hole near the mouth, around the body to form this cocoon. As this nears completion, the caterpillar will pull a leaf into the web to finish the process. Two to three weeks later the Luna moth emerges, its wings wet and unable to fly for at least another 30 minutes.
This expedient reproductive cycle begins in early summer. After the adults crawl out of their cocoons, they really cannot eat (they have no mouth), so in lieu of culinary activities, they find a mate, lay eggs and die within one week The moth’s sole purpose is to reproduce.
THE STRUCTURE OF THE MOTH
Moths have compound eyes (containing hundreds of individual eyes) that are not exactly built for acute vision. They are, however, great for detecting light and movement from all angles. Instead of lungs, they have spiracles, tiny holes in the sides of the body that allow oxygen to pass in and out of the moth. These spiracles process oxygen for the entire insect without requiring a complex circulatory system such as our own. Moths boast two pairs of wings both used for flying. If you’ve ever bothered to take a close look at a moth, you may have noticed some fuzzy looking stuff –actually a set of modified scales that serves as part of the moth’s outer covering called the ectoderm.
There are many examples of modified scales through the animal kingdom. Sharks teeth are scales. Reptiles and fish have scales all over their bodies. Even bird feathers are considered a similar type of modified scale. As that old saying from Comparative Anatomy goes… ontogeny recapitulates phylogeny. That means that species, through the millennia, carry with them consistent genetic traits – in other words, evolution takes place. Over time, evolution discards what doesn’t work and keeps what does. Ever wonder why amphibians lack the aforementioned scales? Without going into a lengthy physiological discussion, the simple answer is that they just didn’t need them any more.
Moths have very tiny brains, which are actually more akin to an enlargement of a group of nerves rather than a brain. In short, calling their mental processes “thinking” may not be appropriate. The moth’s nervous system connects sight, smell and touch through the hair and other organs. These probably function more out of autonomic reflex than through any other means of expression. Their circulatory system consists of a tube that pumps, but there is no defined center such as a heart.
Still you may be wondering, “Really, what’s so important about a moth?” True, they may not seem like they fill much of a role, but the brief life spans of moths and butterflies are indeed quite purposeful in the grand scheme of things. Butterflies pollinate many plants whose flowers attract them to their nectar. The larvae of moths and butterflies influence the shape of plants by browsing their features such as seeds and flowers. And, quite honestly, they are made to be food for other predators and parasitoids.
Though you may not think much of a moth – or really they about you (because, you know, they don’t really have cognitive abilities), these insects play vital roles in our local ecosystems. As a fan of animals and wildlife of all kinds, you can pay them their due respect by merely appreciating the rare sight of a vibrant green Luna moth during their brief, but vital, week-long flight.