The luna moth (Actias luna) can be found throughout much of the eastern half of the U.S. It is one of our larger native moths with a wingspan of approximately 4 – 4.5 inches, or about as wide as one and a half post-it notes from the widest point on one wing to the widest point of the other wing. Luna moths are a beautiful pale green with eyespots that are visible when the wings are stretched out. However, perhaps the most distinctive feature of a luna moth is the long “tail” that extends off of each hindwing.
Despite their large size, luna moths aren’t seen as often as you might think they would be. Part of the reason for this is that they spend so much time up in the trees. Sometimes the best evidence that they are around is when you find a pair of wings on the ground under a tree after an owl, bat, flying squirrel, or other predator enjoyed a meal the night before. Your best chance of finding a live luna moth is to look around bright street or porch lights. Luna moths are highly attracted to bright lights and can sometimes be found perching on the sides of brightly lit buildings or on nearby trees or even sidewalks.
Adult luna moths only live for about a week. During that week, their sole purpose is to reproduce. They don’t even eat as adults and instead live off of the fat reserves that they stored as caterpillars. Adult females will fly to the top of a tree and sit on a leaf while giving off pheromones that are designed to attract a mate. The adult male luna moths fly around using their antennae to “smell” for the pheromones. Once a male detects the pheromone, it follows the pheromone trail until it finds the female. Female luna moths only mate once, while male luna moths can mate multiple times.
After mating, the female will lay between 200 and 400 eggs either singly or in small groups on the leaves of persimmon, sweet gum, walnuts, sumacs, or hickories. In the northern part of its range, white birch also frequently serves as a host tree. Some research indicates that luna moth caterpillars from different regions may prefer, or even require, different host plants.
The eggs will hatch after about a week and the caterpillars will begin eating the tree’s leaves. Even though the luna moth caterpillars stay on the same tree where they hatched and eat the tree’s leaves, they don’t cause any noticeable harm to the tree. Luna moth caterpillars are solitary and never form big groups like the groups formed by tent caterpillars.
If an ant or mouse or other potential predator messes with the caterpillar, then the caterpillar can make a clicking sound with its mandibles. If that doesn’t scare the potential predator away, then the caterpillar will puke on the predator, which has been shown to be an effective deterrent for many predators.
After a little more than a month, the caterpillar will be ready to spin its cocoon. However, before spinning its cocoon, the caterpillar will wrap itself in a leaf for camouflage. In the northern part of its range, luna moths only complete one life cycle per year. In those parts of the country, the luna moth will remain as a cocoon throughout the winter. This means that when the tree sheds its leaves in the fall, the cocoon will fall to the ground with the leaf that is wrapped around it. The cocoon will then spend the winter on the ground in the leaf litter. Further south, luna moths may complete two or three life cycles in a year. However, the last life cycle always has the cocoon overwintering in the leaf litter after the tree sheds its leaves, including the leaf surrounding the moth’s cocoon. This is one of the reasons why it is a good idea to leave fall leaves on the ground instead of burning, mulching, or throwing them away.
This article was part of Shannon’s original Kentucky Pollinators and Backyard Wildlife blog which evolved into the blog for Backyard Ecology.
Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.