Queens are typically 20–25 millimetres (0.8–1.0 in) long, and normally greenish-brown, giving the species its name smaragdina (Latin: emerald).

[3] Weaver ants of this species are important parts of the ecosystem in tree canopies in humid tropical regions.

In the Oecophylla smaragdina, the antennal lobe glomeruli is seen in clusters, this appears to be a common feature in many Hymenopterans such as ants and honeybees.

[4] The ants also attend aphids, scale insects and other homopterans to feed on the honeydew they produce, especially in tree canopies linked by lianas.

[5] Some species of jumping spiders, such as myrmecophilic associate Cosmophasis bitaeniata, prey on the green tree ants by mimicking them with deceptive chemical scents.

The larvae and pupae are collected and processed into bird food and fish bait in Indonesia,[10] are used in Chinese and Indian traditional medicine, and consumed as a delicacy in Thailand and other countries.

[11] In Java, Indonesia the larvae and pupae of these ants are known as kroto and are harvested commercially for use as captive songbird food and as fishing bait.

Songbirds are very popular in Java and the ant larvae provide a good balanced diet of proteins, minerals and vitamins.

[4] In some parts of India, the adult ants are used in traditional medicine as a remedy for rheumatism, and an oil made from them is used for stomach infections and as an aphrodisiac.