How many ants are there on Earth? When we were children we often asked such riddles and answered with ridiculous numbers. But today we have a scientific answer. According to a recent study published in the journal Science, there are 20,000,000,000,000,000 (20 thousand million million or 20 quadrillions) individual ants on earth. They weigh more than the combined biomass of all wild birds and mammals and are equal to 20% of all human beings weighed together.

Ants are ubiquitous and part of our day-to-day life – they create a nuisance by encroaching on every nook and corner of our homes, raiding food, and occasionally delivering irritating bites or painful stings. But, how much do we really know about ants? Why are they always seen marching together like a disciplined army regiment? Where do they live and what do they eat? ‘Familiarity breeds contempt’ is true about ants too. We ignore them and hate them because of the little nuisances they cause and forget the great services they provide to nature, making our life comfortable on Earth.

Ants are tiny insects found everywhere, except in the coldest parts of the world. They live in small to large colonies with a few hundred to several thousand individuals. The queen is the ‘matriarch’ of the colony and only she can lay eggs. The colony has several workers, a few males, and a single queen. All workers are females in the ant colony, but they are not capable of laying eggs or producing young ones. Workers are mainly of two castes – the soldiers or major workers and minor workers. There is a clear division of labour among the workers. Minor workers take care of pupae and young ones and collect food for the colony while the soldiers protect the colony and help carry the heaviest loads of supplies to the nest.

A queen ant – Oecophylla smaragdina

When resources are sufficient, the colony produces several fertile females and males – the winged reproductive forms. Just when the conditions are favourable, the females and males from most colonies in a locality swarm out, giving them a chance to meet, find a partner from other colonies and mate. They mate in the air and after the nuptial flight (mating flight), male ants die. The new queen finds a suitable place and starts building a new nest and lays the first set of eggs. The queen does all the errands until the worker ants from the newly hatched eggs emerge to help complete the nest and take care of the queen. From there on the queens only lay the eggs.

Ants live and nest in soil, plants, leaf litter, concrete constructions, fallen tree logs, under stones, and tree barks depending on the genus/species. They are well-known architects as well as ecosystem engineers. Some ants even build complex nest entrances to ward off enemies. Anochetus daedalus, reported recently from Sirsi, Karnataka, by our team, is one such ant, which makes labyrinthine nest entrances with mud. It is named after Daedalus, the master craftsman and architect of the ‘labyrinth’ in Greek mythology.

Head view of the Anochetus daedalus

The nest of the Anochetus daedalus, with a labyrinthine entrance

Ants are eusocial and live in colonies, with hundreds to thousands of ants in a single colony. All are well-organised and successful in teamwork; it is tough to point out one worker who is working and the other worker taking advantage of it. Their discipline, teamwork and planning are models for humans in solving many of their day-to-day issues. Statistical models of how ants find the shortest route to transport food to their nest were used to identify the shortest possible route to solve the ‘travelling salesman issue’. Marco Dorigo, a computational intelligence expert at the Free University of Brussels, Belgium, created a probabilistic technique for solving computational problems based on his observations on how ants seek a path between their colony and a source of food. Today this is known as the Ant Colony Optimization Algorithm, a subject in computer science.

We use sight, sound and touch for communication. But ants use chemicals called pheromones as the primary mode of communication. They can also communicate by touching and tapping the antennae. Once a worker ant finds a source of food, she guides all comrades by sending pheromone signals, and the other ants follow the pheromone to reach the source and back to the nest.

Polyrhachis bihamata is often known as the ‘fish-hook ant’ due to the hook-like spines on its back, used for defence. Ants hook their spines together to form a chain to ward off approaching enemies. Even though they are native to Karnataka, they are rarely noticed, as they seldom descend to the ground from their treetop dwellings.

The spine of the Polyrhachis bihamata, resembling a fish hook.

To date, 14,241 species of ants are known from all over the world. Each species is distinct from the others. There are 861 species in India, with 257 ant species in Karnataka. More than 120 species of ants are known from Biligiri Ranganatha Swamy Temple (BRT) Tiger Reserve and a few remain to be named. Nagarahole National Park has more than 130 species and the Soppinabetta forests of Sringeri are home to around 100 species. In Kannada, we commonly refer to ants based on their colour as kari iruve (black ant), kempu iruve (red ant) etc. But some ants have specific names in vernacular depending on their behaviour and appearance. Oduga (lit. Runner, Anoplolepis gracilipes), Kari Oduga (lit. Black Runner, Paratrechina longicornis), Kempu Godda (lit. Red Big Ant, Camponotus irritans), Vibhuti Iruve (lit. Ash Ant, Camponotus sericeus), Kari Godda (lit. Big Ant, Camponotus compressus), Kenjiga (lit. Red Ant, Oecophylla smaragdina), Cheliruve (Crematogaster subnuda), Goorala (lit. Hairy Ant, Meranoplus bicolor), Hottiruve (lit. Harvester Ant, Monomorium pharaonis), Gooniruve (lit. Hunchback Ant, Myrmicaria brunnea), Kempiruve (lit. Fire/Red Ant, Solenopsis geminata), Boodi Goorala (lit. Ash Hairy Ant, Tetramorium walshi), Saaliruve (lit. Procession Ant, Leptogenys processionalis) etc. are a few common ants found here.

Camponotus sericeus – Vibhuti Iruve, or the Ashy Ant

The first memory of pain for many of us may be an ant bite or mosquito bite. Just because of that, we were all trained from childhood to be cautious about insects. So, we humans hate all insects, especially ants, even though most ants are beneficial. They disperse seeds, help in pollination, act as natural predators to help regulate the populations of herbivorous insects and save our crop plants from pest attacks. They till the soil and aerate, scavenging the dead and decaying matter to keep the premises clean.

Crematogaster sp. feeding on a dead reptile

The Red Ant or Weaver Ant (Oecophylla smaragdina), which makes box-like nests by stitching the leaves together, is widely used as food. Odisha is trying to register a Geographical Indicator (GI) tag for the Red Ant chutney that the people there relish. They are also used as a remedy for colds, cough, and fever. Some communities in the Northeast use ants to treat wounds. Some, even today, use ants to stitch wounds, a practice that dates back to 13th century China. They make the ants bite and hold the separated skin with long mandible or trap jaws and then sever the ant body leaving the head behind.

Oecophylla smaragdina workers weave leaves together to build a nest. Their larvae produce a silk-like thread and the workers hold the larvae between the mandibles to stitch the leaves together, while other workers hold the leaves together.

Ants are ubiquitous and play a vital role in the ecosystem as they act as seed dispersers, pollinators, predators, soil aerators etc. However, certain ants can become pests and a few species like the Yellow Crazy Ants (Anoplolepis gracilipes) are infamous invasives that spread across the world, causing damage to ecosystems and troubles for people.

Harpegnathos saltator is also known as the Indian Jumping Ant. Ants usually walk or run, but Indian Jumping Ants move with swift jumps and spring on the prey with a swift leap. Not so rare in Karnataka, they are found in less disturbed areas with more trees. They have big eyes and distinctive long mandibles that are almost twice as long as the head.

The head view showing the large eyes and scythe-like mandibles of Harpegnathos saltator.

Although ants have been comparatively well explored when compared to other insect groups, there are still many ants in the world yet to be discovered. Overall, ants are intriguing and important creatures, and despite their tiny size, they significantly influence the natural world around them.