Green Ants: Combat Engineers of the Rainforest

Skyrail Nature Diary: December 2014

Guests travelling on Skyrail often ask, “What are those leafy ball things in the trees?” Those marvelously constructed “leafy balls” resembling scaly bladders are satellite colonies of the rainforest’s combat engineers – green ants.

Green ants nests are most likely to be noticed in the tops of trees as visitors to Skyrail peer below into the rainforest canopy. Note that most nests are intentionally made from large leaves so as to hasten construction time. Nests made of dried leaves are likely to have been abandoned. Green ants, also known as weaver ants, regularly change their homes to ensure optimum defence against the elements and to uphold their finicky hygiene standards. Nests are also vacated as satellite colonies grow and need to expand outwards.

Individual satellite nests are part of a colony that consists of up to two thirds of a million ants who occupy more than 100 nests spread over numerous trees.

To construct their homes, a joint effort is necessary. After determining a suitable spot, numerous workers seize the edge of a leaf with their mandibles and fold it onto another leaf. In the meantime, other workers arrive with larval silk from existing nests and bind the leaves together. This process continues until some 16-24 hours later a home that may be up to 18 inches in length, has been completed.  As a measure of their determination, in order to bridge a large space between leaves required for building, green ant workers may grip one another with their mandibles and form chains of workers spanning the two leaves. A successful construction engineering outcome is inevitable!

If you look along surfaces advantageous for rapid movement, such as tree trunks, buttress roots and fallen trees, you will observe interaction and communication between individuals within a colony. Along these runways, like an orderly public transport system, two lanes of green ant traffic will be moving: one towards and another away from the colony. Sometimes oncoming individuals will interact with one another by briefly pausing and interlocking their elbowed antennae. These antennae are sensitive chemical receptors that enable green ants to communicate subtle signals.

First and foremost, this is an identification ritual to ensure that the colony remains free from infiltration by rival colonies. Successful foraging parties may also emit trails of pheromones to fellow proletariat ants in order to lead them to new supplies of food. Patrolling green ants may likewise lay pheromone trails to direct reinforcements to areas vulnerable to territorial incursions from hostile colonies.

Higher-ranking workers will sometimes appear to ride roughshod over minor workers by forcibly redirecting their direction of travel and even dragging them in the desired direction, to areas of critical importance such as those containing an ephemeral source of food or to a territorial border flashpoint.

Please be wary of handling green ants and of standing too close to their nests – the latter action will be construed as a threat and ants will swarm out and over your body and you are likely to feel a good number of smarting green ant bites!

However, green ants do not always bite humans with impunity; some times the tables are turned. Rich in protein and fatty acids, green ants (especially their larvae) are prized by humans in some parts of the world as a food source. When chewed, their abdomen delivers a knock out citrus taste. Gin and tonic, anybody?

Did you know: One species of spider, Amyciaea albomaculata (it does not have a common name) lives around green ants and mimics them with such deadly accuracy that they form the spider’s staple diet.

By Paul, Skyrail Ranger