Ants are so much like human beings as to be an embarrassment. They farm fungi, raise aphids as livestock, launch armies into war, use chemical sprays…[and] exchange information ceaselessly. They do everything but watch television.






 

LEWIS THOMAS (1913-93)

Ants

Ant Mills


'Ant mills' happen when a group of army ants get separated from the main foraging party, lose the track of pheromones and begin to follow one another, forming a continuously rotating circle. They keep going round and round until they die of exhaustion.  An ant mill discovered by William Beebe in 1921 was 1,200 feet in circumference; it took each ant two and a half hours to walk one revolution.  A similar thing has been seen with caterpillars and fish. Ant mills have been recreated in laboratories.

Army ants are not effective when they forage alone: they have to be in big groups. They form ‘swarm raids’ that go out to find prey, then bring it back to the nest in traffic lanes. Army ants are nomadic and make temporary nests in places where there is food.  The occasional but deadly formation of circular mills seems to be the evolutionary price that army ants pay to maintain such an ecologically successful and stable strategy of collective foraging.
 

Zombie Ants


In the rain forests of Cameroon lives a floor-dwelling ant known as Megaloponera foetens, the stink ant. It survives by foraging for food among fallen leaves and undergrowth. Occasionally it will inhale and become infected by the microscopic spore of a fungus from the genus height: inherit; font-family: inherit; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; vertical-align: top;">Tomentella, millions of which rain down upon the forest floor from somewhere in the canopy above. Once the ant inhales it, the spore lodges in the ant's brain and immediately begins to grow. This prompts bizarre behavioural changes in the ant host, which soon begins to climb up the forest canopy (something the ants do not normally do). Once it achieves a particular height, it impales the plant it is climbing with its mandibles and waits to die. The fungus continues to consume the ant's brain, the rest of its nervous system and, eventually any soft tissue that remains.

About two weeks later, a spike-shaped growth erupts out of what had once been the ant's head. It grows to about an inch and a half long, and has a bright orange tip laden with spores, which then begin to rain down onto the forest floor for other unsuspecting ants to inhale.


 

Brunei ants have guards who explode their own heads when threatened, leaving a sticky mess to slow down intruders.

BILL VAUGHAN (1915-77)

The whale is endangered, while the ant continues to do just fine.

Ant Rafts


Ginger ants are better known as red ants or fire ants. If there’s a flood in the jungle, they grab onto one another (using their claws, jaws and adhesive pads on their legs) to form a circular raft that floats. Surprisingly, even the ones on the bottom are fine. None of the ants become submerged because the rough surface of their exoskeleton is water-repellent and equipped with tiny hairs that trap air bubbles. This creates what is called a 'plastron layer' of air between their bodies and the water. (The word ‘plastron’ comes from piastrone, Italian for 'breastplate': a turtle’s underbelly is called a plastron, and so is a man’s stiff formal shirtfront.) Half a million fire ants can assemble themselves into rafts in less than 100 seconds. A big group of this kind creates such an effective plastron layer that the ants can float for days – even weeks – and migrate immense distances.
 
This all goes wrong if you introduce just a small amount of soap to the surface of the water; this lowers the surface tension and the raft will begin to immediately sink. The individual ants lose their plastron layer and can drown within seconds.

Farmers and Slavemakers


There are 230 species of ant that farm fungus. Leafcutter ants started this agricultural venture 50 million years ago. They actively cultivate and protect the fungus, bringing it vegetation to help it grow. In return they get to eat it. Some genera of ants are so dedicated that when they move colony the queen takes a nucleus of fungus in her mouth, in order to start a new crop elsewhere.
 
Other ants raise aphids as livestock, protecting them from predators and then eating the honeydew the aphids make. The ants patrol the area where the aphids are feeding, stinging or biting other insects until they leave. When the aphids have sucked a plant dry, the ants carry them to a new juicy stem where they can continue to feed. At night, the ants often carry the aphids to a safe place before bringing them back to ‘pasture’ in the morning. To get at the honeydew, the ants gently stroke the aphids' abdomens with their antennae.
 
Slavemaking ants oppress other ant species to sustain their colony. They take over colonies, either stealing eggs or starting a fight at a nest whilst their queen sneaks in and kills the resident queen. Some slavemaking ants breed their workers solely to conquer other nests, as they're unable to maintain their own nest. If Amazon slavemakers are separated from their slaves, they starve to death even if there’s food available. A typical colony of 3,000 slave-making ants may have more than 6,000 slaves. Slave ants gather food, feed their hosts, groom and feed the larvae and queen, and defend the colony against other insects. If the colony moves to a new location the slaves carry their masters, one by one.

HENRY DAVID THOREAU (1817-62)

It is not enough to stay busy. So, too, are the ants. The question is what you are busy about.

 

Honey Ants


A few genera of ants have developed a specialised caste of worker ants which store honey in their abnormally swollen abdomens. The ants, known as 'repletes', hang immobile from the roof of the underground nest, and returning forager ants empty their crop contents by feeding them. The abdomen of a 'replete' stretches until it's about 12mm across. If another worker ant wants to withdraw honey, she taps on the replete's abdomen with her feet, causing it to regurgitate the honey. These 'repletes' are also used to store water when colonies in arid regions run the risk of dehydration. In some countries they’re a delicacy – you can either eat the whole thing or just the little bubble of honey.
 

Ant, Human, Elephant


The Indonesian version of the 'rock, paper scissors' is 'ant, human, elephant'. The human tramples the ant, the elephant squashes the human, and the ant beats the elephant, because the elephant can't stand the ticklish sensation of having the ant in its ear.

Roasted leafcutter ant abdomens are sold in some cinemas in South America instead of popcorn.

There are about ten thousand trillion ants in the world.

SHUTTERSTOCK

The smallest ant could fit inside the brain-case of the largest.

In the jungles where most ants live, there are 800 of them per square yard.

Tribal Loyalty


The largest insect colony is a super-colony of Argentine ants spanning Europe, the USA, and Japan. Despite being from different continents, these ants recognize and will refuse to fight each other.

SAMUEL JOHNSON (1709-84)

Turn on the prudent ant thy heedful eyes,
Observe her labours, sluggard, and be wise.