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 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 will stay in their cocoons, even if their metamorphosis is complete, until they receive certain biological signals, i.e. light changes, temperature changes, or hormonal signals. When the adult luna moth eclose, or emerges from its cocoon, their abdomen is swollen and the wings are shriveled. The first few hours of the moth's adult life, will be spent under a leaf pumping hemolymph (invertebrates equivalent to blood) from the abdomen into their wings. During this time, the moth is much more vulnerable to predators. Their wings will be soft and wet, the moth will have to wait for their wings to dry and harden before they will be able to fly away. This process can take 2–3 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 hind wings, which have eyespots on them to confuse potential predators. Luna moths are common, although rarely seen due to their very brief (1 week) adult lives. As with all Saturniidae, the adults do not eat or have mouths. They emerge as adults solely to mate. They are more commonly seen at night. You can distinguish male luna moths by their larger and wider antennae. Their wing "tails" are expandable decoys that trick hungry bats; they are the moth's anti-predator deflection strategy. As the echolocating hunter comes in for the kill, the moth's moving tails distract and fool the bat, knocking the attacker off target and allowing the moth the split second it needs to get away, alive.