Life is prolific, and time has caused life to evolve into a multitude of forms. Many groups have evolved and emerged victorious in this race of evolution, employing strategies which baffle even present-day thinkers and students. One such group which is the most prolific and dominant life-form across various landscapes is the tiny and inconspicuous ant. A vital part of our ecosystem, ants are found in all habitat types, except the coldest regions of our planet. Wherever they walk, they change their surroundings according to their needs, which has earned them the name “ecosystem engineers”. From being master architects to the first known farmers and livestock tenders, the female-based ant society has much to claim as its own.
Even though they are ubiquitous, very little is known about the life of ants in India. A recent review on India’s ants puts the number of species described from the country at 828. This number however appears to be an under-representation of the actual potential species from India, owing to the lack of systematic and well-documented studies on the ant fauna of the country. Let alone the estimate of total species, even know-how about the most common ant species is wanting primarily due to the “less glamorous” appeal of ants in comparison to butterflies, dragonflies or damselflies, who are relatively well-studied across the country.
Most times, the type of ants we know is limited to “black ants” and “red ants”, or “ants that don’t bite” and “ants that bite”, and hence it would come as a surprise to many, that an average urban Indian household can harbour no less than four species of ants and this can go up to 10 to 15 species in a suburban home with a small garden.
Karnataka has been lucky, with many students and researchers having explored the ant diversity of the state. 257 species of ants have been described from the state till date, including many which are new records to science. In this first of a two-part article, I focus on some of the most common ant species found in Karnataka.
Ants, like humans, like to conquer new lands and make them their own. Some species are so good at this that they overthrow anything that stands in their way, and establish themselves as the sole rulers of the land. Hence, it is no surprise that some of the most common ants we usually see around us are invasive species. Very few researchers, though, have looked into invasive species of ants which are silently expanding their dominion. All invasive life forms are successful because they can out-compete native species on their home ground; invasive ants too have many such strategies by which they out-compete native ant species. For starters, they will eat almost anything, from fallen sugar crystals on a table to dead rats on the roadside. They have very flexible nesting behaviour and can nest almost anywhere, ranging from small cracks in walls to underneath a flower pot. Many invasive ants are ‘polygynous’, meaning that a single ant colony has multiple (sometimes unrelated) queens living together with their daughters, all working in unison. Invasive ants are prolific and their colony size outnumbers that of any native species. They are very aggressive and defend their territories fiercely. They have very few natural enemies and can hence expand their territory unchecked.
Yellow Crazy Ant (Anoplolepis gracilepis)
This ant is so named because of its obvious yellow colouration and its peculiar behaviour to dance like a madman when provoked, by shaking its antenna and legs in all directions and running around in irregular patterns. The Yellow Crazy Ant is a very common species of our urban landscape. They are known to aggressively bite and spray formic acid when threatened. Surprisingly, no one knows its actual region of origin, with the best guess being western Africa.
Black Crazy Ant (Paratrechina longicornis)
This is a very common urban species that most of us associate with, which tickles us when they walk over our hands or legs. They too are called crazy ant because of the same behaviour as the Yellow Crazy Ant, when provoked. The origin of this species too is shrouded in mystery, with scientists speculating it to be in tropical Africa.
Ghost Ant (Tapinoma melanocephalum)
True to their name, Ghost Ants come as stealthily as they leave. These tiny ants are no longer than two millimetres, and are almost translucent, making them hard to detect. The kitchen is their favourite haunt and they are usually spotted milling around spilt milk or tea. Sugar is their favourite, and often a sugar jar which is not secured tightly will find it invaded by the Ghost Ant army. Ghost Ants also have a peculiar smell when crushed, which acts as a distress beacon to the other sisters of the colony. It is speculated that the Ghost Ant originated from the tropics of Asia or Africa.
Pharaoh Ant (Monomorium pharaonis)
An ant most of us will associate with painful bites, and often christened the “red ant”, the Pharaoh Ant is commonly found scurrying around in search of dead insects, which when found are dismembered and carried off to its nest. Interestingly, unlike other ants, colonies of this species do not compete and display aggression against each other, a phenomenon known as ‘unicoloniality’. Pharaoh ants expand their territory by a phenomenon called ‘nest budding’, where a few females with workers leave the main nest and establish a satellite nest, expanding from their colony autonomously. Like most species of invasive ants, it is not clear where Pharaoh Ants originate from.
The Native Generalists
The original rulers of our lands before the invaders arrived, these native species are still the most commonly found ants in places unknown to the invaders. They are generalists, having a wide diet spectrum. They will sometimes hunt small insects, but mostly scavenge for the dead. They tend to aphids and hoppers, maintaining a small herd of these insects which provide them with a continuous supply of honey-dew, a sugar rich food source, in exchange for the protection that the ants give them against their predators. Native ant species form an important link of the ecosystem, playing the vital role of scavenging the dead and moving tonnes of soil, thereby helping maintain soil fertility and nutrient cycling.
Black Carpenter Ant (Camponotus compressus)
This ant, commonly called the “big black ant”, is often seen scurrying around in loose groups. They are generally harmless, but can give a very painful bite if agitated. A typical colony of this species has a small-sized worker and a larger-sized soldier. Soldiers have huge heads and usually stand guard around the nest or with a foraging party.
Short-legged Hunchbacked Ant (Myrmicaria brunnea)
Another common native species, these have a black body and a reddish-brown abdomen which they keep tucked under their legs. They make huge, mound-shaped nests, usually at the base of trees, by excavating soil and depositing it around the tree’s trunk in a conical shape which is very conspicuous. Big nests can be raised to heights of one foot, which prevents water from flooding the nest chambers in the monsoon.
Golden-backed Ant (Camponotus sericeus)
Named so because of its striking golden coloured abdomen, which is due to fine, golden hair present on the abdomen, this species has two colour morphs – one morph has a red head while the other has a black head. It was previously speculated that the red morph is found south of Bangalore and the black morph is found north of Bangalore; however, it is now known that a single colony can have both colour morphs!
Long-necked Sugar Ant (Camponotus angusticollis)
Another common ant of the suburban landscape, these are big in size – about two centimetres in length – with long legs and antennae. It is interesting to note that this species was first reported to science from India.