Explained: The Worst Locust Attack In 26 Years, What Makes The Insects So Dangerous And Why India Should Worry

Last week, union environment ministry warned in a statement that locust swarms have entered Rajasthan, Punjab, Haryana and Madhya Pradesh.

Reportedly, on Sunday, the swarms have moved deeper into UP, and at least three states— Rajasthan, MP and UP have sent out drones, tractors and cars to kill them with pesticides.

Apart from these states, the insects have also damaged crops in Gujarat and Maharashtra, and the union government has issued a warning to 12 states.

The locust swarms have reached UP’s Sonbhadhra district and Jhansi, and the adjacent states which share a border with the district — Bihar, Chhattisgarh, Jharkhand — have been put on high alert. Prayagraj in eastern UP is also preparing for a possible attack.

The farmers in Karanataka are also keeping a vigil as swarms may arrive via western Maharashtra. Andhra Pradesh and Tamil Nadu also witnessed some attacks.

Both Somalia and Pakistan had to declare national emergency over the locust attacks.

The current attack is said to be the worst desert locust attack in 26 years. United Nations (UN) has warned that armies of locusts swarming across continents pose a “severe risk” to India’s agriculture this year.

What are desert locusts and why are they bad?

The scientific name for desert locusts is Schistocerca gregaria. They belong to the family of grasshoppers. ‘Desert’ because they normally live and reproduce in in semi-arid or desert regions.

They lay eggs in damp soil in the bare ground, which is rarely found in areas with dense vegetation.

Locusts aren’t very dangerous when solitary or in small groups, but their behaviour changes when they transform from ‘solitary phase’ into ‘gregarious phase’, and start forming ‘swarms’. They change colours and develop muscles.

A swarm may contain 40 to 80 million adults in one square km, and these can fly at 16-19 km an hour, depending on the wind, and cover up to 150 km in a day.

Desert locusts have a lifespan of 3-5 months and lay as many as 1,000 eggs per square metre of soil. If unchecked, within one generation, a single swarm can increase 20 times of its original size, and then multiply exponentially in subsequent generations.

The hatchlings eat the vegetation around and then migrate in search of more food. Reportedly, one adult desert locust can eat roughly its own weight or about 2 gm of fresh food every day.

A one-km swarm with about 40 million locusts can consume what 35,000 people do in a day. A swarm the size of Paris eats as much food in a day as half the population of France.

This makes locusts deadly for agriculture. As they travel, they leave behind a trail of thousands of hectares of destroyed crops.

Why the deadly attack this year?

According to the Locust Warning Organization in Jodhpur, there were no major swarms or breeding reported from 2010 to 2018. But last year, Gujarat and Rajasthan reported a significant surge in locust infestations, most likely due to a unusually prolonged monsoon.

The desert locusts usually breed in the dry areas in the countries along the eastern coast of Africa in a region known as the Horn of Africa.

Ethiopia, Somalia, Eritrea, adjoining Asian regions in Yemen, Oman, southern Iran, and in Pakistan’s Balochistan and Khyber Pakhtunkhwa provinces constitute the breeding grounds of locusts.

A strong Indian Ocean Dipole brought torrential rainfalls in the above regions.

The cyclonic storms Mekunu and Luban that struck Oman and Yemen respectively transformed the empty desert tracts into large lakes providing damp soils where the locust swarms breed.

Locusts generally follow the wind, and are known to be passive flyers. The low-pressure area created by Cyclone Amphan in the Bay of Bengal strengthened the westerly winds which aided the movement of the locusts into South Asia.

The westerlies also brought with them several bouts of rainfall over north and western India which also helped the insects reproduce.

Normally, the locust season in India spans June-November coinciding with the kharif season. If left unchecked, the locust attacks may worsen as the monsoon arrives, destroying large areas of crops.

Early destruction is key. The governments should organise spraying of organophosphate chemicals by drones and planes to control the population and the spread.