The Atlas moth is one of the largest lepidopterans with a wingspan measuring between 25–30 cm (9.8–11.8 in) and a wing surface area of about 400 cm2 (62 in2). It is only surpassed in wingspan by the white witch (Thysania agrippina) and in wing surface area by the Hercules moth (Coscinocera hercules). As in most Lepidoptera, females are noticeably larger and heavier than males, while males have broader antennae.
The body is disproportionately small compared to the wings. The upperside of the wings are reddish brown with a pattern of black, white, pink, and purple lines and triangular, scale-less windows bordered in black. The undersides of the wings are paler. Both forewings have a prominent extension at the top.
The atlas moth has no mouth, every flight takes valuable energy and can take days off their already short lives, as it has a very short life span of only one week. They conserve energy by flying as little as possible. A female will wait for a male to come along and be fertilised, lay eggs and die.
Atlas moths are named after either Atlas, the Titan of Greek mythology (due to their size), or their map-like wing patterns. In Hong Kong, the Cantonese means "snake's head moth", referring to the prominent extension of the forewing which bears resemblance to the head of a snake.
|Holometabolism (complete metamorphosis)|
|Eggs||Larva||Pupa within cocoon||Emerging from pupa||Imago|
Females release powerful pheromones through a gland on the end of the abdomen to attract a mate. The female does not stray far from the location of her discarded cocoon. She seeks out a perch where the air currents will best carry her pheromones. Males can detect and home in on these pheromones from several kilometers away using chemoreceptors located on their feathery antennae. Once fertilized, the female lays a number of spherical eggs, 2.5 mm (0.098 in) in diameter, on the undersides of the leaves of food plants.
Dusty-green caterpillars hatch after approximately two weeks and feed voraciously on the foliage of citrus, cinnamon, guava, and evergreen trees. The caterpillars can grow to 11.5 cm (4.5 in) in length and 2.5 cm (0.98 in) in thickness. They are adorned with white, waxy, fleshy spines along their backs, which become more prominent at later instars. Beside the prolegs on the last abdominal segment, there is a large green spot surrounded by an orange ring.
After reaching a length of about 11.5 cm (4.5 in), the caterpillars are ready to pupate. They spin a 7–8 cm long papery cocoon interwoven with desiccated leaves and attach it to a twig using a strand of silk. The adult moths emerge from the cocoon after approximately four weeks depending on environmental factors.
Adult Atlas moths are weak, unsteady fliers. To conserve energy, the moths rest during the day and fly at night. As they lack fully formed mouthparts, the adults cannot eat, subsisting entirely on fat reserves accumulated during the larval stage. As a result, they live for only a few days during which their sole objective is seeking out a mate. Adults may be found on wing throughout the year but are most abundant between November and January.
Relationship with humans
In India, Atlas moths are cultivated for their silk in a non-commercial capacity. Unlike silk produced by the related domestic silkmoth (Bombyx mori), Atlas moth silk is secreted as broken strands and is therefore less desirable. This brown, wool-like silk, known as fagara, is thought to have greater durability. Atlas moth cocoons are sometimes used as small pocket change purses in Taiwan.
The term "Atlas moth" is sometimes used mistakenly as a name for any species in the genus Attacus, of which there are over 20 named species and subspecies. Attacus taprobanis native to southern India and Sri Lanka is very similar in morphology to the much more widely distributed Attacus atlas. It was once considered a subspecies of A. atlas. A few New World species can be mistaken for Atlas moths, specifically members of the genus Rothschildia. Very similar in appearance to the Asian Atlas moth, Rothschildia aurota is one of the largest members of its genus and a Neotropical relative.
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