Weaver ants or Green ants (genus Oecophylla) are eusocial insects of the family Formicidae (order Hymenoptera). Weaver ants are obligately arboreal and are known for their unique nest building behaviour where workers construct nests by weaving together leaves using larval silk.^[1] Colonies can be extremely large consisting of more than a hundred nests spanning numerous trees and contain more than half a million workers. Like many other ant species, weaver ants prey on small insects and supplement their diet with carbohydrate-rich honeydew excreted by small insects (homoptera). Oecophylla workers exhibit a clear bimodal size distribution, with almost no overlap between the size of the minor and major workers.^[2] The major workers are approximately eight to ten millimeters in length and the minors approximately half the length of the majors. There is a division of labour associated with the size difference between workers. Major workers forage, defend, maintain and expand the colony whereas minor workers tend to stay within the nests where they care for the brood and 'milk' scale insects in or close to the nests. Oecophylla weaver ants vary in color from reddish to yellowish brown dependent on the species. Oecophylla smaragdina found in Australia often have bright green gasters. These ants are highly territorial and workers aggressively defend their territories against intruders. Because of their aggressive behaviour, weaver ants are sometime used by indigenous farmers, particularly in southeast Asia, as natural biocontrol agents against agricultural pests. Although Oecophylla weaver ants lack a functional sting they can inflict painful bites and oftentimes spray formic acid^[3][4] directly at the bite wound resulting in intense discomfort. For other uses, see Genus (disambiguation). ... Eusociality is the phenomenon of reproductive specialisation found in some species of animal, whereby a specialised caste carries out reproduction in a colony of non-reproductive animals. ... Orders Subclass Apterygota Symphypleona - globular springtails Subclass Archaeognatha (jumping bristletails) Subclass Dicondylia Monura - extinct Thysanura (common bristletails) Subclass Pterygota Diaphanopteroidea - extinct Palaeodictyoptera - extinct Megasecoptera - extinct Archodonata - extinct Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Blattodea (cockroaches) Mantodea (mantids) Isoptera (termites) Zoraptera Grylloblattodea Dermaptera (earwigs) Plecoptera (stoneflies) Orthoptera (grasshoppers, crickets... Subfamilies Formicomorph subfamilies Aneuretinae Dolichoderinae Formicinae - e. ... Suborders Apocrita Symphyta Hymenoptera is one of the larger orders of insects, comprising the sawflies, wasps, bees, and ants. ... The kinkajou is an arboreal mammal. ... For other uses of this word, see Silk (disambiguation). ... The term honeydew has more than one meaning. ... Suborders Heteroptera Homoptera Hemiptera is an order of insects, comprising some 67,500 known species in two suborders, Heteroptera and Homoptera. ... Bimodal can mean A bimodal distribution in statistics. ... Look up Brood in Wiktionary, the free dictionary. ... Families Aclerdidae Asterolecaniidae Beesoniidae Carayonemidae Cerococcidae Coccidae Conchaspididae Dactylopiidae Diaspididae Electrococcidae Eriococcidae Grimaldiellidae Halimococcidae Inkaidae Jersicoccidae Kermesidae Kerriidae Kukaspididae Labiococcidae Lecanodiaspididae Margarodidae Micrococcidae Ortheziidae Phenacoleachiidae Phoenicococcidae Pseudococcidae Putoidae Stictococcidae The scale insects are small insects of the order Homoptera, generally classified as the superfamily Coccoidea. ... Theodor Herzl Gaster (1906 - 1992) was an American Biblical scholar known for work on comparative religion, mythology and the history of religions. ... Formic acid (systematically called methanoic acid) is the simplest carboxylic acid. ...

Taxonomy

The weaver ants belong to the ant genus Oecophylla (subfamily Formicinae) which contains two closely related living species: O. longinoda found in Sub-Saharan Africa and O. smaragdina found in southern India, southeast Asia, and Australia.^[5][6] They are provisionally placed in a tribe of their own, Oecophyllini. The weaver ant genus Oecophylla is relatively old, and 11 fossil species have been found from the Oligocene and Miocene deposits.^[7] Polyrhachis and Dendromyrmex are two other genera of weaving ants that also use larval silk in nest construction, but the construction and architecture of their nests are simpler than those of Oecophylla.^[8] In Australia, Oecophylla smaragdina is found in the tropical coastal areas as far south as Rockhampton and across the coastal tropics of the Northern Territory down to Broome in West Australia. Satellite image of Africa, showing the ecological break that defines the sub-Saharan area African countries considered sub-Saharan Sub-Saharan Africa is a geographical term used to describe the area of the African continent which lies south of the Sahara, or those African countries which are fully or partially... For other uses, see Asia (disambiguation). ... In biology, a tribe is a taxonomic classification in between family and genus. ...

The common features of the genus include an elongated first funicular segment, presence of propodeal lobes, helcium at midheight of abdominal segment 3 and gaster capable of reflexion over the mesosoma. Males have vestigial pretarsal claws.^[9] A vestigial organ is an organ whose original function has been lost during evolution. ...

Colony ontogeny and social organization

Weaver ants collaborating to pull nest leaves together.

Similar to other highly social insects such as honey bees and termites, weaver ant colonies are usually founded by a single mated female (the queen). The queen lays her first clutch of eggs on a leaf and protects and feeds the larvae until they develop into mature workers. The workers then construct leaf nests and help rear new brood laid by the queen. As the number of workers increases, more nests are constructed and colony productivity and growth increase significantly. Workers perform tasks that are essential to colony survival, including foraging, nest construction, and colony defense. Because the tasks performed by workers are spatially and temporarily isolated, the integration and coordination of worker activities are important in colony organization. The emergence of an organized, complex social colony results from nonrandom repeated interactions between individuals that follow simple behavioral rules.^[10][11] The exchange of information and modulation of worker behaviour that occur during worker-worker interactions are facilitated by the use of chemical and tactile communication signals. These signals are used primarily in the contexts of foraging and colony defense. Successful foragers lay down pheromone trails that help recruit other workers to new food sources. Pheromone trails are also used by patrollers to recruit workers against territorial intruders. Along with chemical signals, workers also use tactile communication signals such as attenation and body shaking to stimulate activity in signal recipients. Multimodal communication in Oecophylla weaver ants importantly contribute to colony self-organization.^[12][13] The honeybee is a colonial insect that is often maintained, fed, and transported by farmers. ... Families Mastotermitidae Kalotermitidae Termopsidae Hodotermitidae Rhinotermitidae Serritermitidae Termitidae Reference: Earthlife as of 2002-07-26 A termite (also known as a white ant) is any member of the order Isoptera, a group of social insects that eat wood and other cellulose-rich vegetable matter. ... A queen is the only female insect in a hive that is fertile and egg laying; for example, a queen bee, wasp, hornet, ant, or termite. ... In most birds and reptiles, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. ... Self-organization refers to a process in which the internal organization of a system, normally an open system, increases automatically without being guided or managed by an outside source. ...

Nest building behavior

Oecophylla weaver ants are known for their remarkable cooperative behaviour used in nest construction. Possibly the first description of weaver ant's nest building behaviour was made by the English naturalist Joseph Banks, who took part in Captain James Cook's voyage to Australia in 1768. An exerpt from Joseph Banks' Journal (cited in Hölldobler and Wilson 1990) is included below: For clothing store, see JoS. A. Bank Clothiers. ... Captain James Cook may refer to: James Cook - British explorer, navigator, and map maker Captain James Cook (TV miniseries) - 1987 Australian television miniseries This is a disambiguation page, a list of pages that otherwise might share the same title. ...

The ants...one green as a leaf, and living upon trees, where it built a nest, in size between that of a man's head and his fist, by bending the leaves together, and glueing them with whitish paperish substances which held them firmly together. In doing this their management was most curious: they bend down four leaves broader than a man's hand, and place them in such a direction as they choose. This requires a much larger force than these animals seem capable of; many thousands indeed are employed in the joint work. I have seen as many as could stand by one another, holding down such a leaf, each drawing down with all his might, while others within were employed to fasten the glue. How they had bent it down I had not the opportunity of seeing, but it was held down by main strength, I easily proved by disturbing a part of them, on which the leaf bursting from the rest, returned to its natural situation, and I had an opportunity of trying with my finger the strenth of these little animals must have used to get it down.^[14]

The weaver ant's ability to build capacious nests from living leaves has undeniably contributed to their ecological success. The first phase in nest construction involves workers surveying potential nesting leaves by pulling on the edges with their mandibles. When a few ants have successfully bend a leaf onto itself or draw its edge toward another, other workers nearby join the effort. The probability of a worker joining the concerted effort is dependent on the size of the group, with workers showing a higher probability of joining when group size is large.^[15] When the span between two leaves is beyond the reach of a single ant, workers form chains with their bodies by grasping one another's petiole (waist). Multiple intricate chains working in unison are often used to ratchet together large leaves during nest construction. Once the edges of the leaves are drawn together, other workers retrieve larvae from existing nests using their mandibles. These workers hold and manipulate the larvae in such a way that causes them to excrete silk. The workers then maneuver between the leaves in a highly coordinated fashion to bind them together.^[16] Weaver ant's nests are usually elliptical in shape and range in size from a single small leaf folded and bound onto itself to large nests consisting of many leaves and measure over half a meter in length. The time required to construct a nest varies depending on leaf type and eventual size, but often a large nest can be built in signficantly less than 24 hours. Although weaver ant's nests are strong and impermeable to water, new nests are continually being built by workers in large colonies to replace old dying nests and those damaged by storms. Probability is the likelihood that something is the case or will happen. ... A petiole (also called a pedicel) is the first abdominal segment of members of the Apocrita. ... A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... For other uses of this word, see Silk (disambiguation). ... Elliptical may refer to: Ellipse: a shape and mathematical construct Elliptical trainer: an exercise machine This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Use as natural biocontrol agents

Large colonies of Oecophylla weaver ants consume significant amounts of food, and workers continuously kill and retrieve all kinds of arthropods (primarily insects) to their nests. Insects are not only consumed by workers, but this protein source is necessary for brood development. Because weaver ant workers hunt and kill insects that are potentially harmful plant pests, trees harboring weaver ants benefit from having decreased levels of herbivory. Many studies have shown the efficacy of using weaver ants as natural biocontrol agents against agricultural pests.^[17] The use of weaver ants as biocontrol agents has especially been effective for fruit agriculture, particularly in Australia and southeast Asia.^[18][19] Fruit trees harboring weaver ants produce higher quality fruits, show less leaf damage from herbivores, and require fewer applications of synthetic pesticides.^[20][21] Farmers in southeast Asia often build rope bridges between trees and orchards to actively recruit ants to unoccupied trees. Established colonies are often supplemented with food to promote faster growth and to deter emigration. Subphyla and Classes Subphylum Trilobitomorpha Trilobita - Trilobites (extinct) Subphylum Chelicerata Arachnida - Spiders, Scorpions, etc. ... Orders Subclass Apterygota Symphypleona - globular springtails Subclass Archaeognatha (jumping bristletails) Subclass Dicondylia Monura - extinct Thysanura (common bristletails) Subclass Pterygota Diaphanopteroidea - extinct Palaeodictyoptera - extinct Megasecoptera - extinct Archodonata - extinct Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Blattodea (cockroaches) Mantodea (mantids) Isoptera (termites) Zoraptera Grylloblattodea Dermaptera (earwigs) Plecoptera (stoneflies) Orthoptera (grasshoppers, crickets... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... A deer and two fawns feeding on some foliage Herbivory is a form of predation in which an organism known as an herbivore, consumes principally autotrophs[1] such as plants, algae and photosynthesizing bacteria. ... Biological control of pests and diseases Overview A key belief of the organic gardener is that diversity furthers health. ... Location of Southeast Asia Southeast Asia is a subregion of Asia. ... Popular Japanese fashion magazine throughout the 1990s; the photography of which has recently been reissued in two collections from Phaidon press. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... the plane is spreading pesticide. ... Location of Southeast Asia Southeast Asia is a subregion of Asia. ... An orchard is an intentional planting of trees maintained for food production. ...

Weaver ants (Oecophylla longinoda) collaborating in attacking a larger insect Image File history File linksMetadata Download high-resolution version (2746x2058, 2154 KB) Oecophylla sp. ...	Weaver ants nest Weaver ants File links The following pages link to this file: Ant Wikipedia:Recent additions Weaver ant ...	Weaver ants nest on a Mango tree	Weaver ants (Oecophylla smaragdina) foraging on lime sap, Rayong, Thailand Binomial name Oecophylla smaragdina Fabricius, 1775 Oecophylla smaragdina (common names include weaver ant, green tree ant and orange gaster) is a species of arboreal ant found in Asia and Australasia. ...
Green Tree Ant (Oecophylla smaragdina), North Queensland, Australia Binomial name Oecophylla smaragdina Fabricius, 1775 Oecophylla smaragdina (common names include weaver ant, green tree ant and orange gaster) is a species of arboreal ant found in Asia and Australasia. ...

References

Selected bibliography

• C. Ronald Kube and Hong Zhang.(1993) Collective Robotics: From Social Insects to Robots, Adaptive Behavior, 2(2):189-219.
• Huang, H. T. and Pei Yang. (1987). Ancient Cultured Citrus Ant Used as Biological Control Agent BioScience 37(9):665-671.
• Bonabeau, E, Dorigo, M & Theraulaz, G. "Swarm Intelligence: From Natural to Artificial Systems" NY, Oxford: Oxford University Press, 1999.

See also

• Ant
• Social insects
• Self-organization
• EO Wilson
• Bert Hölldobler
• Emergence
• Boids
• Cellular Automata
• Symbolic communication

For other uses, see Ant (disambiguation). ... Eusociality is the phenomenon of reproductive specialisation found in some species of animal, whereby a specialised caste carries out reproduction in a colony of non-reproductive animals. ... Self-organization refers to a process in which the internal organization of a system, normally an open system, increases automatically without being guided or managed by an outside source. ... Bert Hölldobler (born 1936) is a German myrmecologist who is a co-winner of the Pulitzer Prize for his work on The Ants (1991) with Edward O. Wilson. ... A termite cathedral mound produced by a termite colony: a classic example of emergence in nature. ... Boids, developed by Craig Reynolds in 1986, is an artificial life program, simulating the flocking behaviour of birds. ... A cellular automaton (plural: cellular automata) is a discrete model studied in computability theory and mathematics. ... Symbolic communication is exchange of messages that change a priori expectation of events. ...

External links

Wikimedia Commons has media related to:

Oecophylla

• Colonised for Life! - A peek into a colony of Weaver Ants
• myrmecos.net - Oecophylla (weaver ants, tree ants)
• [4]
• Green Tree Ants, Australian State of Environment Report, retrieved 9/15/2006 [5]
• Insects in the Wet Tropics - Green Ants, retrieved 9/15/2006 [6]