Luna Moth, Actias luna

Habits and Traits of Luna Moths

Luna moth.
Luna moth. Flickr user ggallice (CC license)

Readers often email me photos of this beautiful creature, and ask me to identify the unusual butterfly they found. Although it's colorful and large, this is no butterfly! The luna moth (Actias luna) is a giant silkworm moth, and although common throughout most of its range, it's still a thrill to find one.

Description:

The name luna means moon, apparently a reference to the moon-like eyespots on its wings.

These night-flying moths are also most active when the moon is high in the sky, so the name is doubly apropos. Luna moths are strongly attracted to lights, so you may see them flying around your porchlight during their breeding season (spring to early summer in the northern part of its range). When the sun rises, they often come to rest nearby, so look for them around your home in the morning.

Both male and female luna moths are pale green, with long, curving tails trailing from their hindwings and light eyespots on each wing. Early season broods in the south will be darker in color, with an outer margin marked in deep pink to brown. Later southern broods and all northern broods tend to be paler in color, with an almost yellow outer margin. Males can be differentiated from females by their prominent, feathery antennae.

Luna moth caterpillars are lime green with magenta spots and sparse hairs, and a pale stripe running lengthwise just below the spiracles.

They reach a length of 2.5 inches (65 mm) in their final instar.

Classification:

Kingdom - Animalia
Phylum - Arthropoda
Class – Insecta
Order – Lepidoptera
Family - Saturniidae
Genus – Actias
Species - luna

Diet:

Luna moth caterpillars feed on the foliage of a variety of host trees and shrubs, including walnut, hickory, sweetgum, persimmon, sumac, and white birch.

Adult luna moths live only a few days, just long enough to find a mate and reproduce. Because they don't feed as adults, they lack a proboscis.

Life Cycle:

The luna moth undergoes complete metamorphosis with four life stages: egg, larva, pupa, and adult.

Egg – After mating, the female luna moth oviposits on leaves of the host plant. She may produce as many as 200 eggs in total. The eggs hatch in about one week.

Larva – The solitary luna moth caterpillars feed and molt through five instars in 3-4 weeks.

Pupa – Once it's ready to pupate, the caterpillar constructs a simple cocoon of leaves. The pupal stage lasts about 3 weeks in warmer climates. The luna moth will overwinter in this stage in colder regions, usually hidden under the leaf litter near the host tree.

Adult – The luna moth usually emerges from its cocoon in the morning, and is ready to fly by evening. As adults, luna moths live just one week or less.

Special Behaviors and Defenses:

Luna moth caterpillars employ several defensive strategies to fend off predators. First, their coloration is cryptic, so they blend in with the foliage on the host tree and make it difficult for predators to see them. Should a bird or other predator approach, they will often rear up and attempt to scare the attacker away.

When that doesn't work, the luna moth caterpillar may snap its mandibles to make a clicking sound, thought to be a warning of what's coming – vomit. Luna moth caterpillars will regurgitate a foul-tasting liquid to convince potential predators that they are not at all tasty.

Adult luna moths find their mates using sex pheromones. The female produces the pheromone to invite males to mate with her. Males will travel considerable distances to locate a receptive female, and mating typically occurs in the hours just after midnight.

Habitat:

Deciduous hardwood forests.

Range:

Eastern North America, from Canada south to Texas and Florida.

Other Common Names:

American moon moth.

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