Locusts Now Extend To Northern India:

Locusts ravage north India: The chilling science behind the insect plague

Shiv Nalapat

• Previous invasions across East Africa have already raised grave concerns about food shortages, as armies of these pests not only lay waste to crops in the field, but those in storage too

• Desert locusts need to lay eggs in moist soil for them to hatch, but when heavy rains arrive, locusts are able to breed at incredible rates

Three of India's northern states, Rajasthan, Madhya Pradesh and Uttar Pradesh, have been overrun by an army of locusts in the last few days that, by some accounts, have spanned a 2.5 to 3km track. Swarms were previously reported in multiple districts in Rajasthan and Madhya Pradesh and had reached Uttar Pradesh by the weekend. There have also been earlier reports from April where locust swarms had made their way into Rajasthan from Pakistan. 

The desert locust, widely regarded as the most destructive migratory pest in the world, is the scourge of the farmer. Some estimate that a swarm that covers just a single square kilometer could include upwards of 80 million locusts, with the higher end of the range reaching as much as 150 million. 

Last week, representatives from the United Nation's Food and Agriculture Organisation warned that further swarms could be on their way from East Africa to India, via Pakistan, in the coming month. As of now, it is the African nations of Ethiopia, Kenya and Somalia, along with parts of southern Iran that are facing the largest invasions. 

In small numbers, locusts pose little threat, but when allowed to reproduce, they do so exponentially, leading to swarms of biblical proportions, capable of laying waste to large tracts of crops within hours. In fact, a swarm of locusts spanning one square kilometer is, reportedly, able to consume as much food in a single day as 35,000 humans. Previous invasions across East Africa have already raised grave concerns about food shortages, as armies of these pests not only lay waste to crops in the field, but those in storage too. 

About 20 species of the grasshopper are able to transform into what is known as a gregarious phenotype. These creatures are unique in that, when they come into contact with larger swarms, they are able to quickly morph their bodies, gaining muscle mass, and changing colour, as they roll across the terrain and devastate crops. Scientists believe that these kind of locusts take on this “gregarious”characteristic as a conseuquence of the environments that they thrive in. 

Desert locusts need to lay eggs in moist soil for them to hatch, but when heavy rains arrive, locusts are able to breed at incredible rates, ultimately leading to large, crowded swarms, known even to block out the sun. Locusts usually eat as much as their own body weight in a single day and, as such, end up migrating as far as 90 miles per day, in search of food.

According to some reports, the cyclone that struck East Africa in May released enough water to allow vegetation in the desert to grow for six months - enough for two generations of locusts to spawn. Each successive locust generation translates to an exponential increase of 20-fold. As the frequency of cyclones increase, this provides more breeding time for further locust generations to form. This is particularly worrying because the ability to deal with a locust threat is directly proportional to their numbers. Locust swarms that are not identified and destroyed at their early generations, could grow beyond the control of humans, causing widespread devastation to vegetation. 

Locust migration patterns are also unpredictable making it very difficult to devise a plan to stop them, especially when they travel through remote areas. Pesticides can be sprayed, but such a strategy will need to be pre-emptive in nature. A failiure to tackle the problem early could have devastating consequences.