The Beautiful, Endangered Luna Moth Is Not a Pest

Luna Moth on Geraniums

Michael Crowley/Moment/Getty Images

If you have seen a live luna moth, count yourself lucky. This large, beautiful moth is of the Saturniidae family. It is sometimes called the giant silkworm moth or the American moon moth. Once a very common sight, the luna moth is considered to be endangered in some areas, although it is not officially on any endangered species list.

Identifying the Luna Moth

The luna is one of the largest of moths in North America with a wingspan of 4 1/2 inches, and can be identified by its physical characteristics:

  • Its body is white, its long legs are pinkish, and its large wings are translucent lime green. Its hind wings have eyespots and long tails to confuse predators.
  • The male's antennae are larger and bushier than the female's.
  • It is found in forested areas in the Northern hemisphere. In southern Canada, it can be found from Nova Scotia to Saskatchewan. In the United States, it can be seen in every eastern state from Maine to Florida as far west as Texas.
  • Luna moth larvae feed on plant leaves including hickory, walnut, sweet-gum, persimmon, birch trees, American beech, red maple, white oak, black cherry, willows, American chestnut, and smooth sumac.

The Luna Moth Lifecycle

Seen primarily in spring and early summer, the moth will generally produce two generations in a year. In early spring, a luna moth will emerge from a cocoon in which it spent the winter in.

Generally emerging in the morning, the moth will rest and hang through the day to allow its wings to inflate with its blood before flying off at night to seek a mate.

Male luna moths are particularly strong fliers and may fly over relatively long distances. Female luna moths release a sex-attractant pheromone that is used to attract the male moth from a great distance. The mating usually occurs during the first couple of hours after midnight.

Once the moth mates and lays its eggs, it will die. In about 10 days, the eggs will hatch into caterpillars and immediately begin to feed, grow, and molt. The luna moth caterpillar will feed, grow, and molt about five times for three to four weeks until it is about 2 1/2 inches long. At this time, it will spin its silken cocoon wrapped in a leaf. It will cocoon for two to three weeks, then emerge as an adult moth to begin the lifecycle again.

This second generation will go through the same process. However, because it will cocoon late in the season, it will stay cocooned over the winter to emerge as an adult moth in the spring. Once it becomes an adult, the moth no longer feeds at all, nor even has a mouth by which it could feed. It will live for only about a week as an adult, during which time it will mate, and the female will lay her eggs. Most female luna moths lay about 200 eggs in small batches on the underside of leaves.

A Beautiful, Unique Moth

Although the luna moth larvae are large caterpillars that feed on the leaves of many shrubs and trees, their populations don't grow large enough to cause significant damage or destruction. Because there are so few, and they are a nocturnal insect, it is very rare for people to see this unique moth. Its name, "Luna," meaning moon, is attributed both to its nocturnal nature as well as the crescent in the eyespot of its wings that resembles a crescent moon.

The Luna Moth's Predators

The moth's natural enemies are owls, bats, bald-faced hornets, Fiery Searcher ground beetles, and parasitic wasps. The caterpillar stage deters predators by rearing its front end in a "sphinx-like" stance, making a clicking noise with its mandibles, and regurgitating a distasteful fluid. Additionally, the luna caterpillars get protection from predators by their green coloration which often camouflages them into their natural surroundings.

Moth Control

Due to its beauty, the luna moth is not considered a pest, and control efforts are not needed or desirable. In fact, the use of pesticides, loss of habitat, and pollution are some of the reasons it is endangered. If you see a lunar moth in its natural habitat, consider yourself lucky for seeing an endangered species.