[3] Colonies can be extremely large consisting of more than a hundred nests spanning numerous trees and containing more than half a million workers.
Because they prey on insects harmful to their host trees, weaver ants are sometimes used by indigenous farmers, particularly in southeast Asia, as natural biocontrol agents against agricultural pests.
Oecophylla (subfamily Formicinae) is one group of weaver ants containing two closely related living species: O. longinoda and O.
[2][8] The oldest members of both Oecophyllini and Oecophylla are fossils described from the mid-Ypresian Eocene Okanagan Highlands of Northwestern North America.
[17] A queen lays her first clutch of eggs on a leaf and protects and feeds the larvae until they develop into mature workers.
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.
Possibly the first description of weaver ants' 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 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.
[12] The weaver ants' ability to build capacious nests from living leaves has undeniably contributed to their ecological success.
When a few ants have successfully bent a leaf onto itself or drawn its edge toward another, other workers nearby join the effort.
[20] 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).
Upon reaching a seam to be joined, these workers tap the head of the clutched larvae, which causes them to excrete silk.
[21] 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.
[25] The use of weaver ants as biocontrol agents has especially been effective for fruit agriculture, particularly in Australia and southeast Asia.
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 control.
[35] In some countries the weaver ant is a highly prized delicacy harvested in vast amounts and in this way contribute to local socio-economics.