Weaver ant

Weaver ants, sometimes called green ants, are a type of eusocial insect in the ant family Formicidae, grouped in the tribe Oecophyllini. These ants live exclusively in trees and are famous for how they build their nests: workers pull leaves together and stitch them using silk from their own larvae. A single colony can be enormous, with more than a hundred nests spread across many trees and over half a million workers. Like many other ants, they hunt small insects and also get carbohydrates from honeydew, a sugary liquid excreted by scale insects (Hemiptera). The workers come in two distinct sizes, with almost no overlap between the smaller and larger ones. Major workers measure about 8–10 mm long, while minors are roughly half that size. Majors handle foraging, defending the colony, and maintaining and expanding the nest, while minors mostly stay inside the nests to care for the young and tend to scale insects nearby.

Depending on the species, weaver ants range in color from reddish to yellowish brown. In Australia, *Oecophylla smaragdina* often has a bright green abdomen. These ants are very territorial and aggressively defend their areas from intruders. Because they eat insects that damage trees, farmers in Southeast Asia sometimes use them as natural pest control. Though they lack a functional sting, they can deliver painful bites and often spray formic acid into the wound, causing intense discomfort. Researchers have found that weaver ants show remarkable teamwork, actually increasing their individual effort as the group gets larger—a pattern unlike human teams. They build complex leaf nests using a “force ratchet” system, where some ants pull while others anchor, boosting efficiency. This coordinated labor could inspire robotics, suggesting that copying ant strategies might improve multi-agent cooperation and autonomous systems. Their behavior challenges long-held ideas about group dynamics and productivity.

**Taxonomy** *Oecophylla* (subfamily Formicinae) is one group of weaver ants, with two closely related living species: *O. longinoda* and *O. smaragdina*. They are placed in their own tribe, Oecophyllini, along with the extinct genus *Eoecophylla*. The genus *Oecophylla* is quite old, with 15 fossil species described from Eocene to Miocene deposits.