Weaver ants or green ants (genus Oecophylla) are eusocial insects of the family Formicidae (order Hymenoptera)
I first became familiar with weaver ants when wanting kill them with insecticide was told by Thai friends not to that as they were good to eat even though they were destroying my fence. They do have a sweet smell when crushed with the fingers.
My cat killed a small snake and the ants were carrying the snake and it small tail.
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. 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 (Hemiptera). Oecophylla 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. 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 often spray formic acid directly at the bite wound resulting in intense discomfort.
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 attention
Positive and negative interactions with crop plants
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 thisprotein 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. In several cases have the use of weaver ants 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 control. 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.
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
Weaver ants as food and medicine
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. It follows that weaver ants convert damaging pest insects into valuable weaver ant biomass that can be utilized as a food source. The ants may in this way provide double benefits to agriculture.
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.
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