The Atlas Moth Is a Behe-moth, Plus 5 Other Facts

The Atlas moth is probably best known for its size. The Atlas moth (Attacus atlas) is a species of moth in the giant silkworm family Saturniidae and it has one of the largest wing spans — and wing surface areas — among its kind. The average female Atlas moth is usually larger than the male Atlas moth, and has a wingspan up to 12 inches (30.5 centimeters) with a total surface area up to 62 inches (1.5 meters).

An Atlas moth that is perched on a branch with its wings closed may seem like an easy target to any of its natural predators, but by making just one move — opening its wings — the Atlas moth can flip the script. The upper corner of each Atlas moth wing mimics the distinctive profile of a cobra's head, acting as an immediate deterrent (times two!) to the birds or lizards that would otherwise consider it a readily available meal.

When the Atlas moth becomes frightened, it opens its wings and shakes them to imitate the movements of a snake, and in doing so, may fend off its attacker. In addition, the pattern on the wings of the Atlas moth will sometimes resemble the pupils of watching eyes. These “eyes” may also deter predators.

The Atlas moth lives in forested areas of Asia, ranging from India to the Philippines and south to Indonesia. It has adapted to life in a variety of forested climates, from tropical and lowland to upper mountain forests. The female Atlas moth lays eggs on the underside of a leaf and after seven to 14 days, the eggs hatch into large caterpillars.

These Atlas moth caterpillars, which can grow up to 4.5 inches (11.5 centimeters) long, eat the leaf on which they were born and then make a meal out of any other leaves they can reach. The caterpillars will continually gorge and grow on leaves as they prepare for the next stage of life, during which they will entwine themselves in a self-woven silk cocoon.

The caterpillar that eventually emerges from a cocoon as an Atlas moth has gotten to this point by storing up food reserves. As an adult, it won't taste another bite. "The adult form of the Atlas moth no longer eats food because it has an underdeveloped mouth with a tiny and non-functioning proboscis," says Craig Miller, co-founder of Academia Labs, in an email. He has taught courses about the Atlas moth, collaborated with Atlas moth researchers and witnessed the moth in its natural habitat during a visit to Southeast Asia. "The adult Atlas moth mainly relies on the reserves it stored when it was still in the caterpillar stage." These reserves are designed to offer about a week of energy to an Atlas moth, allowing it to survive long enough to mate.

If these giants-among-moths were starring in a new reality series, it would probably be titled "Atlas Moths: After Dark." The male Atlas moth waits until the sun goes down to seek out a female and will locate her, not by sight, but by following the heady scent of the mating pheromones she releases. Once united, male and female Atlas moths will mate (sometimes for up to 24 hours) and then the female will lay more than 100 eggs on the underside of a leaf. This life cycle — from moth to mate to mother — will take place in a single week and will end in death. Likewise, the male Atlas moth dies after mating.

The cocoons of the Atlas moth caterpillar are composed of broken strands of light brown fagara silk, a durable silk spun by the caterpillar as it prepares to pupate. Cocoons of the Atlas moth are typically about 2 inches (6 centimeters) in length. The name for the silk, 'fagara silk,' is believed to have originated from an archaic generic name for a genus of trees upon which Atlas caterpillars are known to feed, the Zanthoxylum genus. When harvested commercially, the silk of the Atlas moth is used to make purses, light coats, shirts, scarves and other wearable items.