Weaver ants or green ants (genus Oecophylla) are eusocial insects of
Formicidae (order Hymenoptera). Weaver ants live in trees
(they are obligately arboreal) and are known for their unique nest
building behaviour where workers construct nests by weaving together
leaves using larval silk. Colonies can be extremely large
consisting of more than a hundred nests spanning numerous trees and
containing 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 (Hemiptera).
Weaver ant workers exhibit a clear bimodal size distribution, with
almost no overlap between the size of the minor and major
workers. The major workers are approximately 8–10 mm
(0.31–0.39 in) in length and the minors approximately half the
length of the majors. 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
Weaver ants vary in color from reddish to yellowish brown dependent on
Oecophylla smaragdina found in
Australia often have
bright green gasters. Weaver ants are highly territorial and workers
aggressively defend their territories against intruders. Because they
prey on insects harmful to their host trees, weaver ants are sometime
used by indigenous farmers, particularly in southeast Asia, as natural
biocontrol agents against agricultural pests. Although weaver ants
lack a functional sting they can inflict painful bites and often spray
formic acid directly at the bite wound resulting in intense
3 Distribution and habitat
4 Colony ontogeny and social organization
5 Nest building behaviour
6 Relationship with humans
6.1 In agriculture
6.2 As food and medicine
7 See also
9 External links
Oecophylla longinoda (Latreille, 1802)
Oecophylla smaragdina (Fabricius, 1775)
†Oecophylla atavina Cockerell, 1915
†Oecophylla bartoniana Cockerell, 1920
†Oecophylla brischkei Mayr, 1868
†Oecophylla crassinoda Wheeler, 1922
†Oecophylla eckfeldiana Dlussky, Wappler & Wedmann, 2008
†Oecophylla grandimandibula Riou, 1999
†Oecophylla leakeyi Wilson & Taylor, 1964
†Oecophylla longiceps Dlussky, Wappler & Wedmann, 2008
†Oecophylla megarche Cockerell, 1915
†Oecophylla obesa (Heer, 1849)
†Oecophylla praeclara Förster, 1891
†Oecophylla sicula Emery, 1891
†Oecophylla superba Théobald, 1937
Liquid food exchange (trophallaxis) in O. smaragdina
The weaver ants belong to the ant genus Oecophylla (subfamily
Formicinae) which contains two closely related living species: O.
longinoda and O. smaragdina. They are provisionally placed in a
tribe of their own, Oecophyllini. The weaver ant genus Oecophylla is
relatively old, and 15 fossil species have been found from the Eocene
to Miocene deposits. Two other genera of weaving ants,
Camponotus and Dendromyrmex, also use larval silk in
nest construction, but the construction and architecture of their
nests are simpler than those of Oecophylla.
Two O. smaragdina transferring food to their colony
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.
Distribution and habitat
O. longinoda is distributed in the
Afrotropics and O. smaragdina from
Sri Lanka in southern Asia, through southeastern Asia to
Australia and Melanesia. In Australia, Oecophylla
smaragdina is found in the tropical coastal areas as far south as
Broome in Western
Australia and across the coastal tropics of the
Northern Territory down to
Yeppoon in Queensland.
Colony ontogeny and social organization
Weaver ants collaborating to pull nest leaves together
Weaver ant colonies are founded by one or more mated females
(queens). A 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. 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 contributes to
colony self-organization. Like many other ant species,
Oecophylla workers exhibit social carrying behavior as part of the
recruitment process, in which one worker will carry another worker in
its mandibles and transport it to a location requiring
Nest building behaviour
Weaver ant nest on a mango tree
Oecophylla weaver ants are known for their 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
1768. An excerpt from Joseph Banks' Journal (cited in Hölldobler and
Wilson 1990) is included below:
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 gluing 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 strength of these little animals must have used to get it down.
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 bent a leaf onto itself or drawn 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. 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. Upon reaching a seam to be joined, these workers tap
the head of the clutched larvae, which causes them to excrete silk.
They can only produce so much silk, so the larva will have to pupate
without a cocoon. The workers then maneuver between the leaves in a
highly coordinated fashion to bind them together. 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 significantly 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.
Relationship with humans
O. smaragdina tending scale insects
Large colonies of Oecophylla weaver ants consume significant amounts
of food, and workers continuously kill a variety of arthropods
(primarily other insects) close 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. They have traditionally
been used in biological control in Chinese and Southeast Asian citrus
orchards from at least 400 AD. Many studies have shown the
efficacy of using weaver ants as natural biocontrol agents against
agricultural pests. The use of weaver ants as biocontrol agents
has especially been effective for fruit agriculture, particularly in
Australia and southeast Asia. Fruit trees harboring weaver
ants produce higher quality fruits, show less leaf damage by
herbivores, and require fewer applications of synthetic
pesticides. They do on the other hand protect the scale
insects which they 'milk' for honeydew. In several cases the use of
weaver ants has nonetheless been shown to be more efficient than
applying chemical insecticides and at the same time cheaper, leaving
farmers with increased net incomes and more sustainable pest
Weaver ant husbandry is often practiced in Southeast Asia, where
farmers provide shelter, food and construct ropes between trees
populated with weaver ants in order to protect their colonies from
Oecophylla colonies may not be entirely beneficial to the host plants.
Studies indicate that the presence of Oecophylla colonies may also
have negative effects on the performance of host plants by reducing
fruit removal by mammals and birds and therefore reducing seed
dispersal and by lowering the flower-visiting rate of flying insects
including pollinators. Weaver ants also have an adverse effect
on tree productivity by protecting sap feeding insects such as scale
insects and leafhoppers from which they collect honeydew. By
protecting these insects from predators they increase their population
and increase the damage they cause to trees.
As food and medicine
Leaf packets of larvae in
Isaan typically sell for about 20 Thai Baht
each (about 0.65 USD)
Weaver ants are one of the most valued types of insects eaten by
humans (entomophagy). In addition to being used as a biological
control agent to increase plant production, weaver ants can be
utilized directly as a protein and food source since the ants
(especially the ant larvae) are edible for humans and high in protein
and fatty acids. In some countries the weaver ant is a highly
prized delicacy harvested in vast amounts and in this way contributing
to local socioeconomics. In Northeastern Thailand the price of
weaver ant larvae is twice the price of good quality beef and in a
single Thai province ant larvae worth 620.000 USD are harvested every
year. It has furthermore been shown that the harvest of weaver
ants can be maintained while at the same time using the ants for
biocontrol of pest insects in tropical plantations, since the queen
larvae and pupae that are the primary target of harvest, are not vital
for colony survival.
The larvae of weaver ants are also collected commercially as an
expensive feed for insect eating birds in Indonesia and the worker
ants are used in traditional medicine in e.g.
India and China.
Polyrhachis, other ants that weave nests (though less complex)
Where the Green
Ants Dream, a 1984 film directed by Werner Herzog
Myrmarachne plataleoides, a spider that mimics the weaver ant
List of animals that produce silk
List of Thai ingredients
Nanfang Caomu Zhuang, earliest Chinese record of O. smaragdina "citrus
ants" protecting orange crops
^ a b Bolton, B. (2015). "Oecophylla". AntCat. Retrieved 30 January
^ a b Dlussky, G.M.; Wappler, T.; Wedmann, S. (2008). "New middle
Eocene formicid species from Germany and the evolution of weaver
ants". Acta Palaeontologica Polonica. 53 (4): 615–626.
^ a b c d Hölldober, B. & Wilson, E.O. 1990. The ants. Cambridge,
Massachusetts: Harvard University Press.
^ Weber, NA (1946). "Dimorphism in the African Oecophylla worker and
an anomaly (Hym.: Formicidae)" (PDF). Annals of the Entomological
Society of America. 39: 7–10.
^ Wilson, Edward O. & Robert W. Taylor (1964). "A fossil ant
colony: new evidence of social antiquity" (PDF). Psyche. 71 (2):
^ J. W. S. Bradshaw, R. Baker, P. E. Howse (1979) Chemical composition
of the poison apparatus secretions of the African weaver ant,
Oecophylla longinoda, and their role in behaviour. Physiological
Entomology 4(1), 39–46 doi:10.1111/j.1365-3032.1979.tb00175.x
^ N. Peerzada, T. Pakkiyaretnam and S. Renaud. Volatile constituents
of the green ant Oecophylla smaragdina. Agric. Biol. Chem., 54 (12),
3335-3336, 1990 
^ Azuma, N., Kikuchi, T., Ogata, K. & Higashi, S. 2002. Molecular
phylogeny among local populations of weaver ant Oecophylla smaragdina.
Zoological Science 19:1321-1328.
^ Rebecca N. Johnson, Paul-Michael Agapow & Ross H. Crozier
(2003). "A tree island approach to inferring phylogeny in the ant
subfamily Formicinae, with especial reference to the evolution of
weaving" (PDF). Molecular Phylogenetics and Evolution. 29 (2):
317–330. doi:10.1016/S1055-7903(03)00114-3. PMID 13678687.
Archived from the original (PDF) on 2012-04-06.
^ Bolton, B. 2003. Synopsis and Classification of Formicidae. 370 pp.
Memoirs of the American Entomological Institute, Vol. 71. Gainesville,
^ Crozier, R.H.; Newey, P.S.; E.A., Schlüns; Robson, S.K.A. (2010).
"A masterpiece of evolution – Oecophylla weaver ants (Hymenoptera:
Formicidae)". Myrmecological News. 13: 57–71.
^ Lokkers, C (1986). "The Distribution of the Weaver Ant, Oecophylla
smaragdina (Fabricius) (Hymenoptera, Formicidae) in Northern
Australia". Australian Journal of Zoology. 34 (5): 683–687.
doi:10.1071/ZO9860683. ISSN 0004-959X.
^ RK Peng, K Christian, K Gibb (1998) How many queens are there in
mature colonies of the green ant,
Oecophylla smaragdina (Fabricius)?
Australian Journal of Entomology 37 (3), 249–253
^ Hölldobler, B. 1999. Multimodal signals in ant communication. J
Comp Physiol A 184:129-141.
^ Hölldobler, B. 1983. Territorial behavior in the green tree ant
(Oecophylla smaragdina). Biotropica 15:241-250.
^ Deneubourg, J.L., Lioni, A. & Detrain, C. 2002. Dynamics of
aggregation and emergence of cooperation. Biological Bulletin
^ Offenberg J. 2014. The use of artificial nests by weaver ants: A
preliminary field observation. Asian Myrmecology 6: 119-128 
^ Offenberg, J.; Havanon, S.; Aksornkoae, S.; Macintosh, D.J.;
Nielsen, M.G. (2004). "Observations on the Ecology of Weaver Ants
Oecophylla smaragdina Fabricius) in a Thai Mangrove Ecosystem and
Their Effect on
Herbivory of Rhizophora mucronata Lam". Biotropica. 36
(3): 344–351. doi:10.1111/j.1744-7429.2004.tb00326.x.
^ Chen, S. (1991). "The oldest practice of biological control: The
cultural and efficacy of
Oecophylla smaragdina Fabr in orange
orchards". Acta Entomologica Sinica. 11: 401–407.
^ Barzman, M.S.; Mills, N.J.; Thu Cuc, N.G. (1996). "Traditional
knowledge and rationale for weaver ant husbandry in the Mekong delta
of Vietnam". Agriculture and Human Values. 13 (4): 2–9.
^ Van Mele, P. (2008). "A historical review of research on the weaver
ant Oecophylla in biological control". Agricultural and Forest
Entomology. 10 (1): 13–22.
^ Van Mele, P.; Cuc, N. T. T.; VanHuis, A. (2002). "Direct and
indirect influences of the weaver ant
Oecophylla smaragdina on citrus
farmers' pest perceptions and management practices in the Mekong
Delta, Vietnam". International Journal of Pest Management. 48 (3):
^ a b Peng, R.; Christian, K. (2007). "The effect of the weaver ant,
(Hymenoptera: Formicidae), on the mango seed weevil, (Coleoptera:
Curculionidae), in mango orchards in the Northern Territory of
Australia". International Journal of Pest Management. 53 (1): 15–24.
^ Peng, R. K.; Christian, K. (2008). "The dimpling bug, Campylomma
austrina Malipatil (Hemiptera: Miridae): the damage and its
relationship with ants in mango orchards in the Northern Territory of
Australia". International Journal of Pest Management. 54 (2):
^ Offenberg, J.; Firn, J. (2015). "
Ants as tools in sustainable
agriculture". Journal of Applied Ecology. 52 (5): 1197–1205.
^ Van Mele, P.; Vayssières, J.F. (2007). "Weaver ants help farmers to
capture organic markets".
Pesticides News. 75 (6): 9–11.
^ Thomas, Donald W. (1988). "The influence of aggressive ants on fruit
removal in the tropical tree, Ficus capensis (Moraceae)". Biotropica.
20 (1): 49–53. doi:10.2307/2388425. JSTOR 2388425.
^ a b Tsuji, Kazuki; Ahsol Hasyim, Harlion and Koji Nakamura (2004).
"Asian weaver ants, Oecophylla smaragdina, and their repelling of
pollinators". Ecological Research. 19: 669–673.
doi:10.1111/j.1440-1703.2004.00682.x. CS1 maint: Uses authors
^ Weber, Neal A. (1949). "The functional significance of dimorphism in
the African ant, Oecophylla". Ecology. 30 (3): 397–400.
^ Blüthgen, N. Fiedler, K., 2002 Interactions between weaver ants
Oecophylla smaragdina, homopterans, trees and lianas in an Australian
rain forest canopy. Journal of
Animal Ecology, 71:5
^ Raksakantong P, Meeso N, Kubola J and Siriamornpun S, 2010. Fatty
acids and proximate composition of eight Thai edible terricolous
insects. Food Research International 43(1): 350-355
^ van Huis, Arnold et al. (2013). Edible insects: future prospects for
food and feed security (PDF). FAO Forestry Paper 171. FAO.
ISBN 978-92-5-107596-8. CS1 maint: Uses authors parameter
^ Sribandit W, Wiwatwitaya D, Suksard S and Offenberg J, 2008. The
importance of weaver ant (
Oecophylla smaragdina Fabricius) harvest to
a local community in Northeastern Thailand. Asian Myrmecology 2:
^ Offenberg J, 2011.
Oecophylla smaragdina food conversion efficiency:
prospects for ant farming. Journal of Applied Entomology 135(8):
^ Offenberg J and Wiwatwitaya D, 2010. Sustainable weaver ant
(Oecophylla smaragdina) farming: harvest yields and effects on worker
ant density. Asian Myrmecology 3: 55-62.
^ Césard N, 2004. Harvesting and commercialisation of kroto
(Oecophylla smaragdina) in the Malingpeng area, West Java, Indonesia.
In: Forest products, livelihoods and conservation. Case studies of
non-timber product systems (Kusters K, Belcher B, eds), Center for
International Forestry Research, Bogor, 61-77
^ Rastogi N, 2011. Provisioning services from ants: food and
pharmaceuticals. Asian Myrmecology 4: 103-120.
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