Attacus atlas

Geographic Range

Atlas moths ( Attacus atlas ) are widely distributed in Southeast Asia, including in Nepal, northeastern India, Bangladesh, Bhutan, southeastern China, Laos, Cambodia, Vietnam, and Taiwan (CAB International, 2020b; Peigler, 1983). They are also widely distributed in Indonesia and Brunei (CAB International, 2020a). There are localized populations reported in the Philippines, Papua New Guinea, and northern India (CAB International, 2020a; Peigler 1983). The primary range of A. atlas is from about 79°E to 121°E in longitude and about 35°N to about 5°S in latitude (CAB International, 2020b).

• Biogeographic Regions
• palearctic palearctic
  • native native
• oriental oriental
  • native native
• australian australian
  • native native

Habitat

Attacus atlas is primarily found in tropical and subtropical rainforests (Peigler, 1983). These forests do not have four seasons, but rather a dry and a wet season. They are characterized by closed canopies, broad-leafed evergreen trees, and temperatures approaching but not exceeding 25°C. The moths spend the majority of their lives on a single tree: laid on the leaves as eggs, eating the leaves as larvae, pupating off the branches, and resting in wait for a male mate as an adult female (CAB International, 2020a).

No formal studies have been conducted to investigate the range of elevation, though A. atlas is widely considered to occupy habitats of elevations from sea level to 1500 to 2000 m.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

Physical Description

The female atlas moths are larger than the males. The body length of Attacus atlas was determined under lab reared conditions to be 39 to 40 mm in females and 30 to 36 mm in males and the wingspan ranged from 240 to 250 mm in females and from 210 to 230 mm in males (Bhawane et al, 2011). The forewing in males is 73 to 125 mm long with a mean of 102 mm, and the hindwing is about 48 to 72 mm long with a mean of 69 mm (Peigler 1983). In females the forewing is 93 to 131 mm long (mean of 119 mm) and the hindwing is 76 to 101 mm long (Peigler 1983). The wingspan is among the top five largest moths in the world. The shape of the wings is rounded, with the forewing having a protrusion from the anterior distal edge. The base of the wing is colored deep orange, soft brown, or deep reddish brown and is patterned with white, black, brown, and pink coloration, with a large white triangular hyaline spot in the center of each wing (Hampson, 1892; Peigler 1983). The protrusions and edges of the wings resemble the head and body of a snake (Hampson, 1892; Peigler 1983). The undersides of the wings are pattered the same as dorsal sides but may be paler in color.

The mouthparts of the adult are non-functioning, with some parts disfigured or completely absent (Britannica 2013). They have two large compound eyes. They have two yellowish brown bipectinate antennae, meaning the antennae are comb-like on both sides (Hampson 1892). The antennae measure 23 to 39 mm long and 10 to 13 mm wide in males and 17 to 21 mm long and 3 mm wide in females (Bhawane et al, 2011). The body is reddish to orangish brown and can vary in shade (Hampson, 1892).

Attacus atlas is distinguishable from other similar moth species in the genus g. Attacus by the presence of a patch of yellow or orange above and below the red dash in conjunction with a prominent white component of the postmedian and antemedian lines (Peigler, 1983). The red dash is longer and thicker in A. atlas than in Attacus mcmulleni , which bear similar resemblance (Peigler, 1983).

The eggs are yellowish white to pale yellow and are oval and flattened consistent with all moths in the family Saturniidae (Bhawane et al, 2011). They are covered in a gummy substance used for attachment to each other and the leaves (Sathe and Kavane, 2014) The size ranges from 2.7 to 3 mm in length and 2.1 to 2.7 mm in width (Bhawane et al, 2011).

The larvae are pale green with orange or brownish speckles and a bright orange ring on the anal somite (Bhawane et al, 2011; Hampson, 1892; Peigler, 1983). There is a white waxy substance on the dorsal side of the larval body which begins developing in the 2nd instar (Bhawane et al., 2011). The first two instars have darker heads and body coloration between the scoli. The body length varies from 8 to 10 mm in the first instar to 88 to 92 mm of the fifth and sixth instars (Bhawane et al., 2011). The 1st, 2nd and 3rd somites have dorsal protrusions (Bhawane et al, 2011; Hampson, 1892). The 4th through 11th somites have dorsal and subdorsal blueish green scoli (branched, thickened spines protruding from the body) and black lateral scoli below the spiracles (Bhawane et al, 2011).

There are a few key differences in the larvae of A. atlas and the related species Attacus lorquinii and Attacus caesar . The dorsal, subdorsal, meso- and metathoracic scoli of A. atlas are flattened and greenish while that of A. lorquinii are rounded yellow knobs about 2mm long and that of A. caesar are flattened and yellowish (Peigler, 1983). The patch on the anal prolegs of mature A. atlas larvae is a light greenish blue surrounded by a bright orange ring (Peigler, 1983). In A. lorquinii the patch is solid brownish orange and in A. caesar it is solid brownish orange with a bright yellow edge (Peigler, 1983).

In the pupal stage, the pupa, comparable to the chrysalis of a butterfly, is surrounded by a cocoon, a papery outer covering of the pupa. It serves as camouflage as A. atlas pupates in the trees (Peigler, 1983). The cocoon coloring of A. atlas varies depending on the host plant from a blackish brown to a brownish yellow to whitish, though most commonly cocoons are light brown (Bhawane et al., 2011; Peigler, 1983). The cocoons may be spun with highly variable size shape, color and texture (Peigler, 1983). The pupa itself is dark brownish orange, smooth and shiny and is 35 to 55 mm long (Bhawane et al, 2011).

Basal metabolic rate is not known.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Development

The life cycle of Attacus atlas occurs in four main life stages typical of Lepidoptera, undergoing complete metamorphosis (Bhawane et al., 2011). These stages are the egg, larval, pupal and adult. The fertilized eggs are laid on a host plant by the female moth where they emerge a week or two later as first instar caterpillars (Bhawane et al., 2011). Instars are the distinct larval periods of growth that are separated by ecdysis (the shedding of the exoskeleton). Atlas moths have five larval instars (Bhawane et al., 2011; Peigler 1983; Sathe and Kavane, 2014), though a 6th has recently been recorded in rearing A. atlas on Citrus lemon (Nath et al., 2016). Following the final larval instar, the caterpillar spins silk around itself to form the cocoon where it pupates for about one to one and a half months (Bhawane et al., 2011; Sathe and Kavane, 2014). The pupa may go through diapause in the winter (Nath et al., 2016).

The adult moths emerge from the cocoon during the morning and remain there for 8 to 10 hours while their wings expand and harden (Sathe and Kavane, 2014). They are sexually mature at this stage and will seek mates to reproduce with (Bhawane et al., 2011).

The adult moths emerge from the cocoon during the morning and remain there for 8 to 10 hours while their wings expand and harden (Sathe and Kavane, 2014).

• Development - Life Cycle
• metamorphosis metamorphosis
• diapause diapause

Reproduction

Female moths attract males by releasing pheromones which are detected by the large feathery antennae of the males who follow the pheromones in order to find the female. They are active at dusk and couple for up to 24 hours during which time the male deposits sperm into the female to fertilize her eggs (Sathe and Kavane, 2014). Males may be able to mate multiple times depending on how long it takes to find a mate and couple with her, but females are monandrous (only mate with one male). The only documented case of polyandry in the moth family Saturniidae is with promethea moths (Morton 2009), therefore atlas moths do not likely exhibit polyandrous mating.

• Mating System
• monogamous monogamous
• polygynous polygynous

Female and male moths are sexually mature upon emergence from the pupal stage. The female atlas moths are oviparous, laying 134 to 169 eggs scattered on the leaves of host plants (Sathe and Kavane, 2014), which are identified in the “Food Habits” section and include cardamom, mango and tea plants. They are semelparous, mating once and laying eggs during a single week of their adult lives (Bhawane et al., 2011). The adults die once their fat stores, acquired in the larval stage, are used up as adults do not have functioning mouths (Britannica 2013). Eggs weigh 0.012 g and incubate for 10 days before hatching (Sathe and Kavane, 2014). The hatched larvae will emerge from the eggs and begin consuming leaves of the host plant.

• Key Reproductive Features
• semelparous semelparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Following mating (for males) and egg laying (for females) parent atlas moths are not involved in rearing their offspring.

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female

Lifespan/Longevity

The lifespan of A. atlas varies slightly, depending on the host plant the larvae are reared on. Raised on Sapium insegne under lab conditions, a single generation of A. atlas lasted between 78 and 100 days, with a mean lifespan of 96 days and 99.8 days for males and females, respectively (Bhawane et al. 2011). Studies of lifespan were conducted under laboratory conditions, so actual lifespans may vary under natural conditions. The longevity of adults will vary depending on their activity levels since adults do not feed, instead they live off stored fat from the larval stage. Females typically live longer than males. The longest life stages are the larval and pupal stages. The 1st larval instar is the shortest and the 5th larval instar is the longest (lasting 2.8 and 15.6 days respectively), though this study did not demonstrate a sixth instar, so the longest instar when a 6th instar is present may be different (Bhawane et al., 2011).

Behavior

Atlas moths are sessile in the egg and pupal stages but can freely move as larvae and adults. Caterpillars have three pairs of true legs on the thorax and four pairs of prolegs on the abdomen that assist in the slinking, worm-like walking of caterpillars, as well as aid in grasping onto plant material. Once adults, the large wings of the moths allow them to fly in order to find mates and escape predators. While more than one moth may live in the same tree, these animals are solitary.

The larvae spend the majority of their time eating leaves in trees and only stop once fully grown and ready to pupate (Bhawane et al., 2011). The moths emerge as adults from their cocoons in the morning and remain there a few hours until their wings have expanded and dried (Bhawane et al., 2011). The adults are crepuscular, active at dusk and dawn, with the males flying to find a female to mate with in the evenings (Bhawane et al., 2011; Sathe and Kavane, 2014).

• Key Behaviors
• arboreal arboreal
• flies
• crepuscular crepuscular
• motile motile
• solitary solitary

Home Range

Given enough food supply, an atlas moth can spend the entirety of its life cycle on on a single tree or else move to neighboring trees if the tree it is on has been defoliated or if a nearby mate must be located (CAB International, 2020a).

Communication and Perception

Atlas moths perceive the environment primarily though chemoreception (the detection and interpretation of chemicals through taste and/or smell), and secondarily by mechanoreception (touch). Insects have large numbers of chemoreceptors on their antennae and legs for the detection of air-borne molecules (to find food), and in the case of adult male moths, the pheromones of females (Britannica 2013). Also located in the antennae are thermoreceptors and mechanoreceptors, as well as a specialized organ, called the Johnston's organ, for detecting windspeed and direction when flying.

Atlas moths primarily communicate through chemical cues, such as with the pheromones of female moths, and their visual appearance. Waxy larvae may resemble bird droppings or decaying caterpillars, thus discouraging predation (Peigler, 1983). Similarly, adult moths are patterned to resemble snakes, perhaps warding off predators, especially birds (Peigler, 1983). Interestingly, female atlas moths do not respond to the mating pheromones they or other females of their species produce (Maida and Ziesmann, 2001).

• Communication Channels
• visual visual
• chemical chemical

• Other Communication Modes
• mimicry mimicry
• pheromones pheromones

• Perception Channels
• tactile tactile
• chemical chemical

Food Habits

Atlas moths are folivores as larvae, consuming only the leaves of host plants rather than flowers, woody stems, roots, or any other plant parts (CAB International, 2020a). They prefer the mature leaves of small trees 2-5 meters in height and do not tend to consume developing leaves (CAB International, 2020a). Because the other life stages (egg, pupa, adult) do not consume food, the large growing larvae must consume large amounts of leaves to store enough energy to carry out future life processes (CAB International, 2020a).

Peigler (1983) identified over 80 species in over 40 genera of plants that are host plants of species in the genus Attacus . The following plants have been identified as the main hosts of Attacus atlas : Averrhoa carambola (carambola), Cinchona officinalis (Cinchona tree), Elettaria cardamomum (cardamom), Litchi chinensis (lichi), Mangifera indica (mango), Persea americana (avocado), Psidium guajava (guava), Swietenia macrophylla (big leaved mahogany), Syzygium samarangense (water apple). An additional 21 hosts have also been identified, including tea, cocoa, and pepper plants (CAB International, 2020a).

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves

Predation

As larvae, the green coloration of Attacus atlas offers camouflage against the green host leaves. The wax secreted by the caterpillars may also discourage predation by mimicking bird droppings or a dead larva infected with a white fungus, though this has not been tested (Peigler 1983). Caterpillars also spray irritating compounds, including vertebrate neurotransmitters, from small holes in their abdominal scoli when vigorously touched, likely as a defense against birds (Deml, 2000).

The hanging cocoons are hidden among the leaves of host plants and hang so that if pecked they swing back and forth and thus are more difficult for birds to pierce (Peigler 1983). The large size of A. atlas in its adult stage aids in defense against vertebrate predators, especially mammals and birds, by discouraging attack and perhaps frightening them (Peigler 1983). The wings of moths in the genus g. Attacus resemble snakes and if threatened may drop to the ground and thrash around like a snake uncoiling, or else feign death and attempt to blend in with the ground (Peigler 1983). Furthermore, since predators, especially birds, tend to attack the circular spots and the elongated sections of the wings, the moth can escape from an attack with its body intact and retain the ability to fly even with large amounts of wing damage (Peigler 1983). Because A. atlas occupies a large number of host plants, parasites and predators are less likely to learn to target only a few plants in search of hosts and prey (Peigler 1983).

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

Atlas moths act as tree defoliators as larvae and as hosts for over a dozen parasites in the egg, larval, and adult stages (CAB International, 2020a; CAB International, 2020b). They are also prey to birds, lizards, and possibly ants. Through defoliation, larvae may allow for more light to reach the forest floor thus allowing new plants to grow.

Economic Importance for Humans: Positive

The large cocoons of Attacus atlas have similar properties to those of the silk moth Bombyx mori and thus offer an alternative form of silk production (Reddy et al. 2013). The tan to brown silk of atlas moths has been used in east Asia to weave the naturally brown textile fagara silk (Seltzer and Peigler 2015). Atlas moths are popular in the pet trade due to their ease of care and docile activity levels; they also have been used in many zoos and museums as an example of insect diversity and adaptation.

• Positive Impacts
• pet trade pet trade
• body parts are source of valuable material
• research and education

Economic Importance for Humans: Negative

While atlas moths do not pose a direct danger to humans, they have been reported as pests of tea and quinine, as well as other host plants. Due to their voracious appetite and large size, even a few caterpillars presence may have a huge impact on the defoliation of trees, but in crops they are often kept from reaching pest status by the Lepidpteran-targeting pesticides already applied (CAB International, 2020a).

• Negative Impacts
• crop pest

Conservation Status

Attacus atlas is not listed.

Other Comments

Attacus atlas is most popularly called the "atlas moth" but is also called the "empire silkworm" after its large size or the "fagara silkmoth" after the fagara silk that is obtained from its cocoons (Peigler, 1983). "Atlas moth" is also used by some for any moth in the genus Attacus (Peigler, 1983). The scientific name Attacus atlas was given to the species by Carlus Linneaus, the father of taxonomy and binomial nomenclature, and has remained an accurate classification despite the repeated reclassifications of other species in the genus (Peigler, 1983).

Additional Links

Encyclopedia of Life

Contributors

Peyton Tajchman (author), Colorado State University, Nathan Dorff (editor), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Bhawane, G., A. Mamlayya, Y. Koli, Y. Phonde, S. Aland, S. Gaikwad. 2011. LIFE HISTORY OF ATTACUS ATLAS LINN. (SATURNIIDAE: LEPIDOPTERA) ON SAPIUM INSEGNE BENTH. FROM WESTERNGHATS, MAHARASHTRA.. Bioscan , 6 (3): 497-500.

Britannica, T. 2013. "Saturniid moth" (On-line). Encyclopaedia Britannica. Accessed May 04, 2020 at https://www.britannica.com/animal/saturniid-moth .

Deml, R., K. Dettner. 1994. Attacus atlas caterpillars (Lep., Saturniidae) spray an irritant secretion from defensive glands. Journal of Chemical Ecology , 20: 2127-2138.

Deml, R. 2000. Morphological aspects of the horn-shaped scoli of the larva of Attacus atlas (Linnaeus, 1758) (Lepidoptera: Saturniidae).. Nachrichten des Entomologischen Vereins Apollo , 21 (3): 177-180.

Förster, T., S. Hetz. 2010. Spiracle activity in moth pupae--the role of oxygen and carbon dioxide revisited.. Journal of insect physiology , 56 (5): 492-501.

Hampson, G. 1892. The Fauna Of British India Including Ceylon and Burma Moths-vol.-i . London: Taylor and Francis. Accessed February 23, 2021 at https://archive.org/details/dli.ernet.19264/page/15/mode/2up .

Hidayati, L., . Nuringtyas. 2017. Secondary Metabolite Profiling of Four Host Plants Leaves of Wild Silk Moth Attacus atlas L. Indonesian journal of biotechnology , 21 (2): 117-124.

Kavane, R. 2014. Studies on Natural Food Plants of Fagara Silkwrom Attacus Atlas from Western Ghats of Maharashtra. International Journal of Science and Research , vol 3, issue 10: 1165-1166. Accessed February 23, 2021 at https://www.researchgate.net/publication/281110245_Studies_on_Natural_Food_Plants_of_Fagara_Silkwrom_Attacus_Atlas_fromWestern_Ghats_of_Maharashtra .

Maida, R., J. Zeismann. 2001. Female Attacus atlas respond to pheromones of Antheraea polyphemus: a comparative electrophysiological and biochemical study. CHEMICAL SENSES , volume 26 (issue 1): 17-24.

Morton, E. 2009. The Function of Multiple Mating by Female Promethea Moths, Callosamia promethea (Drury) (Lepidoptera: Saturniidae). The American Midland Naturalist , 162(1): 7-18. Accessed March 23, 2021 at https://doi.org/10.1674/0003-0031-162.1.7 .

Nath, C., P. Bordoloi, B. Chutia, L. Gogoi, B. Goswami. 2016. A new record of six larval instars in Attacus atlas L. (Saturniidae) from North Eastern India. Journal of Entomology and Zoology Studies , 4 (3): 399-401.

Peigler, R. 1983. A Revision of the Indo-Australian Genus Attacus (Lepidoptera: Saturniidae) . Texas A&M University: ProQuest Dissertations Publishing.

Reddy, N., Y. Zhou, Y. Yang. 2013. Structure and Properties of Cocoons and Silk Fibers Produced by Attacus atlas. Journal of polymers and the environment , 21 (1): 16-23.

Sakar, B., B. Chutia, J. Ghose, A. Barah. 2010. Life history of Attacus atlas L. (Lepidoptera: Saturniidae) on Litsea monopetala Juss. in North-East India.. Journal of the Bombay Natural History Society , 107 (1): 42-44.

Sathe, T., R. Kavane. 2014. Biology of Attacus atlas (Lepidoptera : Saturniidae) A Wild Silk Worm of India. Indian Journal of Applied Research , vol 4, issue 2: 4-7. Accessed February 23, 2021 at https://www.researchgate.net/publication/266565320_Biology_of_Attacus_atlas_Lepidoptera_Saturniidae_A_Wild_Silk_Worm_of_India .

Seltzer, J., R. Peigler. 2015. "Attacus atlas (L.) | Fagara Silk" (On-line). Anthropological Entomology - Silk Textiles. Accessed March 16, 2021 at https://mississippientomologicalmuseum.org.msstate.edu/AnthroEnt/Textiles/Species/Attacus_Atlas_.html#.YFGBUZ1KiUk .

Singh, J., S. Tamil, S. Varadarasan. 1997. Biology of cardamom defoliator, Attacus atlas Linn. (Saturniidae).. Journal of Insect Science , 10 (2): 189-190.

CAB International. 2020. "Attacus atlas (atlas moth)" (On-line). CABI Invasive Species Compendium. Accessed February 19, 2021 at https://www.cabi.org/ISC/datasheet/7853 .

2002. Contribution on the morphology of the male antennae in Attacus atlas (Linnaeus, 1758) (Lepidoptera: Saturniidae).. Galathea Supplement , 12: 27-51.

CAB International. 2020. "Species Page | atlas moth | Attacus atlas" (On-line). Plantwise Knowledge Bank. Accessed February 19, 2021 at https://www.plantwise.org/knowledgebank/datasheet/7853 .