NATURE
Fascinating life of tree ants
Lt-Gen Baljit Singh (retd)

I first chanced upon tree ants when I noticed a globular, brown object, the size of a football attached to the tip of a branch of a ficus tree. On viewing through the binoculars, it was evident that a whole lot of leaves of the same branch had been bunched and held together by an adhesive. Their stems were still attached to the host branch. Most of the leaves had dried and become brown.

A contingent of forager workers compressed the leaves of this ficus infectoria into shape. Workers inside simultaneously secreted a saliva, which was used as an adhesive to bind the leaves
A contingent of forager workers compressed the leaves of this ficus infectoria into shape. Workers inside simultaneously secreted a saliva, which was used as an adhesive to bind the leaves

Forager workers on the globular leaf nest on a ficus gulermereta tree
Forager workers on the globular leaf nest on a ficus gulermereta tree
Photos by the writer

To have closer look, I parked my car beneath the tree, climbed atop the car roof and looked at the leafy globe. Since there was no opening to the structure, therefore, it was not a birdís nest. A while later I felt as though the branch was "pulsating". Persevering some more, it appeared that a whole lot of fuzzy, tiny mites were on the move all over the branch and its nearby leaves.

A few days later, I found the object of my curiosity face-to-face. They were the tree ants, also called red ants (oecophylla samaragdina), which have been around for 30 million years. They were now clearly visible but so tiny (about 3mm to 4mm along their longest axis) that but for a micro-lens attachment it appeared hopeless to capture their images on camera.

I learnt of the identity and basic behaviour of the arboreal ants from Dr Vibhu Prakash of the Vulture Breeding Project at Pinjore. He informed me that in India we have three species but this is only one of its kind in the world, which live in leaf-nests.

But what prompted me to enquire even further was that oft-quoted advice of Soloman: "Go to the ant and consider her ways." Perhaps what the wise king hinted at was that the salvation of mankind lay in emulating the societal pattern of the tree ants by settling for one queen as the sole supreme leader and everyone else simply as "workers". No elections, no scams, no wars, no climate change worries. And just one dwelling for one queen and her entire progeny for their allotted life cycle of eight to 10 weeks.

The queen spends her entire time laying eggs, as many as 25,000 at one time. The workers, almost all females, genetically divide themselves into three task forces.

The youngest attend to the queen and mind the interior of the nest, including repairs to the living chambers. Those in the middle age take on foraging for food for all, from sunrise to sunset. Apparently, they all settle down to a community eating session. Those past middle age are allotted the task of defending the nest against intruders. The soldier ants can attack in strength through stings on the most sensitive, exposed body parts, inducing an instant agonising pain that can last for better part of the day.

The queen has a genetic alarm to alert her of approaching old age. That is the time when she produces a few males of the species. The males are short lived. As soon as they develop wings and fly, they mate and die immediately. The fertilised queen busies with the procreation of generations to come in a new nest.

Some ant colonies on a single tree have as many as 100 nests. The site of the nest is essentially centred around a branch bearing ripe berries. The tree ants are not frugivorous but such berries are home to their primary source of nourishment, that is, the plant lice or aphids, which thrive on the berries. These mites that can be spotted through a powerful microscope only, possess and secrete a sticky substance, which the ants call "honey-dew" or "milk". These aphids are called "cows". They are tended in specially constructed cowsheds within the nest and just as human beings stroke a cow to induce here into the milking process, the tree ants likewise stroke their domesticated, cows with their elbowed antennae, for much the same purpose.

Now coming to the construction of the nest per se. A large contingent of the forager workers assembles over the cluster of leaves on the chosen branch. Using their mandibles and elbowed antennae as hands, they collectively draw the leaves together. Simultaneously, the workers attending on the queen gather the freshly formed larvae which when squeezed between their outer pair of jaws secrete sticky whitish-brown saliva. This, in turn, is applied as the adhesive at the junctions of leaves over-lapped by the foraging workers from the outside. And some of the saliva is stretched to form silky thread to stitch the leaves together into shape or repair tears to the nest and create chambers and partitions inside their home.

The entire effort is performed to such perfection that rain and breeze can never enter the inside. Great care is taken to ensure that the stems of the leaves remain attached to the host branch so that the nest remains firmly anchored. Some foragers, in the meanwhile, supplement the milk diet by collecting insects (dead or killed) from the leaf litter on the ground, directly beneath the nest.

Considering the immense productivity of a single queen ant, mankind could well have been swarmed over by the tree ants by now. But bird species such as the shrikes (in America they are even called anti-birds) and ant-eating mammals such as the ardvak habitually follow the ant-columns to feed upon them and, hence, keep their population in manageable proportions. When you next marvel at the computer chip, spare a thought for the incredible intuitive skills packaged inside this tiny life form.





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