Attacus atlas

Attacus atlas, the Atlas moth, is a large saturniid moth endemic to the forests of Asia. The species was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae.

The Atlas moth is one of the largest lepidopterans, with a wingspan often measuring from 250mm to 300mm. and a wing surface area of about . It is only surpassed in wingspan by the white witch (Thysania agrippina) and Attacus caesar, and in wing surface area by the Hercules moth (Coscinocera hercules). As in most silk moths, females are noticeably larger and heavier than males, while males have broader antennae.

Etymology

Atlas moths are named after Atlas, the Titan of Greek mythology (due to their size). The Cantonese name translates to "snake's head moth", referring to the prominent extension of the forewing that resembles the head of a snake.

Description

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Eggs

Atlas moths lay a number of spherical eggs, in diameter, on the undersides of the leaves of food plants.

Larva

After approximately two weeks, dusty-green caterpillars hatch and feed on their egg-shell, and then the foliage of citrus, cinnamon, guava, and evergreen trees. The caterpillars can grow to in length and in thickness. They have white, waxy, fleshy spines along their backs, which become more prominent at later instars. On the last abdominal segment beside the prolegs, there is a large green spot surrounded by an orange ring.

Development takes place over six larval instars, with the first instar ranging from 4-5 days, the second from 8-10 days, and third between 13 & 14 days. The fourth, fifth and sixth instars last 10-11 days, 12-13 days, and 14-15 days, respectively.

Pupa

After reaching a length of about , the caterpillars pupate.

Adult male Attacus atlas moths produce juvenile hormones I and II, with JH II being the predominant form, and at levels significantly higher than in females, highlighting sexual dimorphism in hormone production.

The body is small compared to the wings. The upper side of the wings is reddish brown with a pattern of black, white, pink, and purple lines. There are triangular, scale-less windows bordered in black on each of the four wings. The undersides of the wings are paler. The tips of both forewings have prominent extensions that resemble the head of a snake. The resemblance is exaggerated by movements of the wings when the moth is confronted by potential predators.thumb|left|Atlas moth compared to human handThe Atlas moth has a very short, vestigial proboscis, and they do not eat once they have emerged from the cocoon, relying on fat storage for energy. 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 to two weeks. They conserve energy by flying as little as possible. A female will wait for a male to come along and be fertilized, lay eggs and die.

Habitat

thumb|230px|right|Habitat on [[Mount Kinabalu]]

Their habitat is primarily dry tropical forests, secondary forests, and shrublands across South Asia, East Asia, and Southeast Asia, including Borneo.

Relationship with humans

left|thumb|Japanese stamp featuring an Atlas moth

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. There is ongoing research as to whether the silk of the Atlas moth can be used as a substitute for common silks.

The Japanese subspecies A. a. ryukyuensis, is native to Yonaguni in the Yaeyama Islands.

Threats & Conservation

Climate change, moth trapping, light pollution, pesticides, habitat loss and fragmentation all negatively effect abundance of Attacus atlas and other giant moths. Although not listed on the IUCN Red List due to a scarcity of data, the Atlas moth meets their requirements for a "threatened" species.

Attacus atlas depends on its habitat (tropical & subtropical rainforests, secondary forests, shrublands) and for this reason, "has the potential to be an important flagship species for the conservation of these ecological communities.". 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.

References