What is an imperial moth?
The imperial moth is a fairly large moth that grows a wingspan measuring an average of 4.5 to 5.5 inches. It is often found in the North American region, including Canada and Mexico and from the Atlantic Coast to the Rocky Moutains. Its scientific name is Eacles Imperialis. In older times, the moth has been recorded in various areas like southern Canada, New England, Gulf of Mexico and the Great Plains. In more contemporary times, the range where it is found has been limited to the northern part of the American region. The population of imperial moth has steadily declined in the northern United States. Factors behind the decline remain unclear.
The imperial moth is nocturnal and can be spotted flying around brightly lit areas like streetlights during the summer months. Its larvae feed on different tree types like elms, sycamore, hickories, pines, oaks, sweetgum, maples, walnuts and willow. It belongs to the Family Saturniidae which also includes giant silk moths like the Luna moth and the Polyphemus moth.
Development Stages
The imperial moth caterpillar usually wanders before finding a spot to eat. The firs instar, or development stage before sexual maturity, lasts for only a few dates. At the end of an instar, the caterpillar spins a small amount of silk on a major vein of a leaf. It then latches onto the silk using its anal claspers and prologs to begin to molt. It starts to become dormant before undergoing apolysis, wherein the cuticula is separated from the epidermis. After a day or two, it undergoes ecdysis, or the molting of the cuitcula. The caterpillar then comes out from its old exoskeleton and hardens as it enters its next development stage. The caterpillar may even eat its old exoskeleton for additional nutrition.
Like most Saturniidae caterpillars, the imperial moth undergoes five instars. Variation between the caterpillars can only be observed by the third instar. Imperial moth is known for having to basic color schemes- black/orange and green/yellow, although variation of colors may also occur on the spines, body, head and feet. At the end of the fifth instar, the caterpillar leaves the tree and crawls along the ground looking for a soft soil patch where it will pupate.
Pupa
After feeding on the trees for months, the imperial moth prepares for its next development stage by climbing down the trees and going to the underground. It pupates by digging itself under the soil. At this stage, the moth is no longer interested in feeding.
Adult
The adult imperial moth emerges once a year to mate. The mating season for imperial moths vary depending on their range, from mid-summer to as late as October. The female moth positions itself in a spot to emit pheromones, a scent which is picked up by the male located even a mile away. After the imperial moths mate, the female moth will lay its eggs on host plants like maples, sweet gums, pines and oaks. The caterpillars will emerge after 10-15 days to feed on the leaves, while the mother moth dies shortly after.
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