Weaver ants or green ants are eusocial insects of the Hymenoptera family Formicidae belonging to the tribe Oecophyllini. Weaver ants live in trees 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 the nests.
Image: Red Weaver Ant, Oecophylla smaragdina
Image: Red Weaver Ant, Oecophylla longinoda
Dead weaver ant queen carried by a worker ant
Liquid food exchange (trophallaxis) in O. smaragdina
Eusociality is the highest level of organization of sociality. It is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform behaviors characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.
Co-operative brood rearing, seen here in honeybees, is a condition of eusociality.
Suzanne Batra introduced the term "eusocial" after studying nesting in Halictid bees including Halictus latisignatus, pictured.
Weaver ants, here collaborating to pull nest leaves together, can be considered eusocial, as they have a permanent division of labor.
Swarming Iridomyrmex purpureus ants. The young queens are black, winged, and much larger than the wingless workers.