Tales of a deadly army
LIVING in colonies of 600,000 or so, tales of South American army ants are legendary, but many of them are true. These tiny creatures are formidable predators, but only if they work together. Normally, great columns of these nomadic ants march and bivouac through lowland tropical rainforests from Peru to Mexico. They are capable of killing every living thing in their path.
Any animal, big or small, unable to flee, or even an injured person is attacked and within few hours stripped to the bone. There was an incident in Central Brazil in which a column of these insects, measuring about I mile by half-a-mile, was seen moving towards the town. Immediately, the police and the townsfolk became active and tried to stop the ants, but they failed until flame-throwers were used. In the struggle, the police chief and few of the townsfolk lost their lives to these insects.
The success of army
ants lies in their ability to work as one gigantic super-organism.
Foraging parties follow scent trails left by scouting soldier ants (a
group within the colony that protects large raiding parties of worker
ants of the same colony). These powerful scents also act as territory
markers, and are recognised and avoided by other colonies of army
ants. While on a food-finding expedition, successful scouts head back
down the trail and encourage any ants they find en route to continue
onwards by pummelling their antennae and offering them a blob of
When the eggs hatch and a new army of mouths must be fed, the colony returns once more to a nomadic lifestyle. At dawn, columns of workers, guarded at intervals by large-jawed soldiers, set out from the daily bivouac and go hunting. Maintaining a constant compass heading, they travel at about 15 yards per hour over a distance of 200 yards per day. Scuttling to and from the bivouac, where the queen and her entourage spend the day, there can be over 200,000 ants in a column. Side streams split off from the main column and spread out to form a raiding front up to 20 yards wide. Streams are not a barrier. Workers simply interlock legs and form a living bridge over which the colony can pass. If caught in floods, the colony rolls into a large ball and floats to safety.
In the evening, the queen’s bivouac unravels like a ball of wool and follows the route of the day’s raiding column. They travel under the cover of darkness for about 8 hours to the next bivouac site, about 90 yards along the trail, setting up temporary camp before dawn breaks.
In some parts of the world army and driver
ants, another species with almost same habits, are not feared, but welcomed. If
columns of ants are heading for human habitation, local village folk will just
leave until the ants have passed through. The ants strip the houses of vermin,
snakes, scorpions and other insects.