At the Heart of the Swarm

A feast for opportunistic predators, this unique swarming phenomenon that termites display is an incredible moment to capture in nature’s landscape.

The turn of a new season is a bit like the changing of the guard. There’s massive anticipation, impatience, hope, people waiting for telltale signs. And this is more so with the impending arrival of the monsoon in India, with the humidity building to unbearable levels. Nature sends out subtle signals of the imminent relief from what has most likely been a very dry, hot summer. The most famous and definitive sign of the onset of the rains may be the arrival of the Pied Cuckoo from Africa but you are more likely to encounter another, more obvious sign as the pre-monsoon showers set in: the swarming behavior in termites and ants. These are the same termites that eat up furniture in your homes, but only 5 per cent of a colony of termites are fertile and form wings to breed. The other 95 per cent are sterile and are soldier ants at the colony.

We’ve all seen the pre-monsoon phenomenon. What initially starts out as a few winged individuals weakly fluttering around your night bulb, soon becomes a swarm of thousands of individuals fatally attracted to any sign of light around your home. Considering that more than 40 per cent of all households in the oriental region are infested with termites, there’s a good chance that you may have seen this all too often.

This swarming behavior in termites is a means for the colony to disperse its winged reproductive individuals – both, male and female – leading, ultimately to mating, and the establishment of new colonies in new territories.

The winged termites – also called as ‘alates’ are produced by relatively mature colonies (usually three to five years after their establishment). The swarm consists mostly of males; they outnumber females by around 5:1 but this ratio can vary widely with species.

Though termite swarming is seasonal, it peaks during certain seasons. Some species release alates several times a year and this is usually synchronized to local weather conditions. Swarming typically occurs at dusk and continues into the night, when thousands of winged males and females emerge from a single or multiple underground nests to mate. Swarming may last for several days but usually the emergence conditions for multiple species are different and they do not overlap.

The termites are much like ants and bees and live a social, stratified life with a king and a queen at the top of the order, and multitudes of workers and soldiers. Once the queen has laid her initial batch of eggs, tended to, and hatched it, the resulting workers take over the nest duties and take care of her. She then becomes an egg-laying machine, so to speak, and concentrates on increasing the colony numbers, producing thousands of eggs, every year for up to a decade.

When these eggs hatch, they give life, not just to sterile workers and soldiers, which help maintain the colony and defend the nest against enemies like ants, but also to fertile male and female termites, which are ready to fly away and start kingdoms of their own.

Several times a year, under conducive conditions: the right combination of humidity, temperature, light, barometric pressure and wind speed, males and females leave their home in a swarm, with thousands of aspiring Kings and queens taking flight. The females produce a fragrance, which attracts the males and the two perform a nuptial mating flight. The wings are sometimes lost within a few minutes of their first flight; wings that are not shed in flight are broken off by the individuals. After that, the pair then settles to the ground, digs a chamber in the soil or in moist wood and mates within it. Mating happens only after the pair is settled properly in this chamber and usually occurs one or two days later.

Clearly, the continued survival of the pair is required for a colony to flourish, but unfortunately only a handful succeed in their mission to reproduce out of the thousands of mating pairs. Typically, only 0.5 per cent of these alates go on to form a new colony and the rest – more than 99 per cent either fall prey to a variety of opportunistic predators both arthropod and vertebrate or die out. Most individuals get attracted to streetlights and other light sources and end up falling flat into a heap of dying termites. Others meet a watery end as their long wings are easily wet by water, trapping the individuals.

Though the entire phenomena may appear to cause a huge waste of life and bio matter, nature has its reasons. If you observe closely, it is not difficult to see that swarming in termites may be nature’s way of providing countless predators with a free meal and a supplement of protein. Such an abundance of food provided in a relatively short time frame is a rare event and calls for predators to respond swiftly to take advantage. This results in aberrant behavior in predators while they throw caution to the wind and concentrate on a feeding frenzy.

Ants appear to be the greatest benefactors among insects. If the wing-covered ground the morning after is a stark reminder of death, the constant movement of the dead termites being carried away by ants reminds us of the never-ending cycle of life being regenerated through death. Within a single night’s swarming, the ants can gain more food than they would otherwise accumulate in weeks.

Spiders are no less busy, both web spinners and stalking spiders have their hands (legs) full. Predatory insects like centipedes wander around, picking and choosing the individuals to feed on. The mass of struggling termites also attracts other predatory insects that are not usually seen in the area.

However, it is not the insects alone that benefit from this phenomenon. Birds stay up later than usual during swarming, feasting on the termites as they rise into the air. Drongos, swallows and Magpie Robins are known to stay up late into the dusk feeding off individuals as they rise from the nests. Other birds such as sunbirds, coucals and mynahs are also seen to pick the spoils from the ground the morning after. There have been reports of unusual assemblages of bird species that are never otherwise seen together feeding together on swarms. Bats and small insectivorous mammals feed on them by night. Lizards gorge themselves to the point of bursting.

These photographs show the calm after the swarm, so to speak… when the feeding frenzy is done, and the signs of a night of tremendous activity are scattered all over the floor.

Termites and ants as food

Animals that eat ants and termites can either be opportunistic myrmecophages like frogs, lizards, birds, mongooses, bears, other insects or obligate myrmecophages like pangolins, anteaters, ardwarks, tamanduas.

Ants and termites are most diverse in tropical latitudes. Rough estimates from the Amazon forest indicated that ants and termites comprised over 30 per cent of the total animal biomass and about 75 per cent of the total insect biomass. Calculations of termite biomass from Panamanian forests reveal that a single Genus: Nasutitermes had a biomass of 12.8 kg/ha. The biomass of all termites in the top five cm of soil in an Amazonian forest averaged 4.3 kg/ha whereas in the Brazilian cerrado four species of termites averaged 33.3kg/ha.

The concentration of lipid in termites and ants is relatively low and that of ash is actually high. What still makes them attractive and nutrient to predators is total nitrogen content and, moreover a higher biomass than any other animal group. Their concentrations are very high and localized and the winged individuals or the alates are rich in lipid content. All of this makes the swarming of termites and ants a feast for their predators.