DH Deciphers | What are locust attacks? Why should we worry about them?

Swarms of desert locusts have been hurtling towards Rajasthan, Punjab, Uttar Pradesh, Madhya Pradesh, Gujarat and Maharashtra for several weeks now, destroying crops and vegetation. This is the biggest locust attack in India since 1993, which means a majority of millennials and members of the generation Z have no idea what locust attacks are and how they disrupt human lives. Here's the lowdown on everything you need to know about these pesky pests:

What are locusts and their different types?

Locusts are grasshoppers with short horns and short antennas. They usually fly off together (=in swarms) in search of food and to start new colonies. The most common locust species

found in India are desert locust (schistocerca gregaria), migratory locust (locusta migratoria), Bombay locust (nomadacris succincta) and tree locust (Anacridium sp.). It is the desert locust that is found in large numbers in India. The UN's Food and Agriculture Organisation describes the desert locust as the most destructive migratory pest in the world.

Why are they dangerous?

Locusts are harmless during the solitary phase of their 90-day life cycle. But as they grow, the presence of a brain chemical called serotonin turns their reclusiveness into attraction, leading to the formation of gregarious swarms. It is this gregarious phase in their life cycle that is the most dangerous.
The immature swarms of locusts are ravenous eaters who target food crops, trees or anything green. A one square-kilometre swarm will have a staggering 80 million locusts that are capable of eating food consumed by 35,000 people in a single day.

Do locusts attack and harm humans?

Mostly no. Unlike mosquitoes or honeybees, locusts do not bite humans. They may just nibble on or pinch someone without breaking the skin. They may do this only to defend themselves.

Do locust attacks occur every year?

Desert locusts breed during the summer in India, primarily in western Rajasthan along the Pakistan border in June-July, coinciding with the arrival of the southwest monsoon. In Pakistan, locusts also breed during the spring season. However, unseasonal heavy rains in March-April this year in the breeding areas of eastern Africa, eastern Yemen, southern Iran and Balochistan aided the breeding process while the strong westerly winds coinciding with the Amphan cyclone brought these passive fliers to India. They usually ride the wind and travel 150 km in a day. So instead of arriving in India in May, the locusts arrived early, in April. The lockdown hampered the control operations, leading to their free run and making them far more dangerous.

Did big locust attacks occur earlier, too?

India witnessed multiple locust attacks over the past decades with the insects almost always flying into Rajasthan or Gujarat from Iran, Afghanistan or Pakistan, usually in the summer. The Centre’s Locust Warning Organisation (LWO) recorded 13 locust upsurges between 1964 and 1997, the biggest in 1993 when scientists documented 172 swarms, compared with 15 swarms in 1989, 26 in 1983 and 20 in 1978. The LWO also observed localised locust-breeding in 1998, 2002, 2005 and 2010, each of which had been controlled.

Why have locusts travelled beyond Rajasthan this time?

In most places in Rajasthan, the rabi crop had been harvested and the fields were empty, reducing the damage and forcing the locusts to move to greener areas. Aided by favourable winds, they travelled as far as Maharashtra and Uttar Pradesh.

Will there be a locust attack on Karnataka?

Authorities earlier feared the locusts could reach parts of North Karnataka from southern Maharashtra as the wind was blowing in the north-south direction. But Agriculture Minister B C Patil later said there was a "99.99%" chance the locusts will not move to Karnataka because the wind isn't blowing towards the state.

What is being done to stop locust attacks?

The ministry of agriculture carries out locust control operations by spraying pesticides such as Malathion in small concentrated doses using vehicle-mounted and aerial sprayers. Drones are also used for spraying pesticides over areas that are inaccessible by tractors and fire brigade vehicles. The spraying operations take place late afternoon/night or early morning when the locust swarms settle down to rest and munch on food.