Actias luna, the luna moth, is a lime-green, Nearctic Saturniid moth in the family Saturniidae, subfamily Saturniinae. It has a wingspan of up to 114 mm (4.5 in), making it one of the largest moths in North America.
This moth is found in North America, from east of the Great Plains in the United States to northern Mexico and from Saskatchewan eastward through central Quebec to Nova Scotia in Canada. Luna moths are common as far south as Seminole County in central Florida.
Based on the climate in which they live, luna moths produce differing numbers of generations. In Canada and northern regions, they can live up to seven days and will produce only one generation per year. These reach adulthood from early June to early July. In the northeastern United States around New Jersey or New York, the moths produce two generations each year. The first of these appear in April and May, and the second group can be seen approximately nine to eleven weeks later. In the southern United States, there can be as many as three generations. These are spaced every eight to ten weeks beginning in February.
Each instar generally takes about five days to a week to complete. After hatching, the caterpillars tend to wander around before finally settling on eating the particular plant they are on. These caterpillars tend to be gregarious for the first two to three instars, but separate and live independently after that. These caterpillars go through five instars before cocooning. At the end of each instar, a small amount of silk is placed on the major vein of a leaf and the larva then undergoes apolysis. The caterpillar then undergoes ecdysis, or molts from that position leaving the old exoskeleton behind. Sometimes the shed exoskeleton is eaten. Each instar is green, though the first two instars do have some variation in which some caterpillars will have black underlying splotches on their dorsal side. Variation after the second instar is still noticeable, but slight. The dots that run along the dorsal side of the caterpillars vary from a light yellow to a dark magenta. The final instar grows to approximately nine centimeters in length.
The luna moth pupates after spinning a cocoon. The cocoon is thin and single layered. Shortly before pupation, the final, fifth-instar caterpillar will engage in a "gut dump" where any excess water, food, feces, and fluids are expelled. The caterpillar will also have an underlying golden reddish‐brown color and become less active. As a pupa, this species is particularly active. When disturbed, if it feels threatened the moth will wiggle within its pupal case, producing a noise. Pupation takes approximately two weeks unless the individual is diapausing. The mechanisms for diapause are generally a mixture of genetic triggers, duration of sunlight or direct light during the day, and temperature.
Adults eclose, or emerge from their cocoons, in the morning. Their wings are very minute when they first emerge and they must enlarge them by pumping bodily liquids through them. During this time, their wings will be soft and they must climb somewhere safe to wait for their wings to harden before they can fly away. This process takes about 2 hours to complete. The luna moth typically has a wingspan of 8–11.5 cm (3.1–4.5 in), rarely exceeding 17.78 cm (7.00 in) with long, tapering hindwings, which have eyespots on them in order to confuse potential predators. Although rarely seen due to their very brief (1 week) adult lives, luna moths are considered common. As with all Saturniidae, the adults do not eat or have mouths. They emerge as adults solely to mate, and as such, only live approximately one week. They are more commonly seen at night. The males are distinguished from the females by their larger and wider antennae. Their wing "tails" are expandable decoys that trick hungry bats; they are the moth's antipredator deflection strategy. As the echolocating hunter comes in for the kill, the moth's moving tails distract and fool the bat, knocking its attack off target; it may nab a bite of an extremity but seldom the whole insect.
Images of life cycleEdit
The highly polyphagous caterpillars feed on the following host plants, with different localities specializing in certain hosts that cannot be used by populations elsewhere:
- A Field Guide to Moths of Eastern North America, Special Publication 12, Virginia Museum of Natural History, 2005.
- "Luna Moth". Fcps.edu. Retrieved 2011-10-18.
- "luna moth - Actias luna (Linnaeus)". Entnemdept.ufl.edu. 2010-08-19. Retrieved 2011-10-18.
- "Map of Actias Luna - Discovery Life".
- "Species Detail: Luna moth – Actias luna (Linnaeus, 1758)".
- "Species Detail: Largest and smallest butterfly and moth".
- Luna Moth, Northern Virginia Ecology
- National Geographic magazine, June 2016, page 20. Article by Catherine Zuckerman. Cited biologists: Jesse R. Barber (Boise State University) and Akito Y. Kawahara(Florida Museum of Natural History).