India is bracing itself for a growing assault on its western front, with droves of intruders flying in from Pakistan.
While the first reports of the current cycle of desert locusts came last month, swarms of these voracious insects have grown significantly in recent weeks, making inroads deep into the country and posing a threat to crops as well as vegetation used for animal fodder.
The fresh outbreak has been severe in Rajasthan, a state bordering Pakistan. Locusts have been spotted in more than 17 districts there, including some where they have never been reported before.
India's previous cycle of attacks by desert locusts lasted from May last year to this February, causing reported damage across 371,000ha, totalling 10 billion rupees (S$187.7 million), in Rajasthan alone.
Not only has the new cycle of attack come earlier than expected, the locusts have also spread wider in search of food given the lower availability of vegetation in summer months. Sightings have been reported in the states of Gujarat, Punjab, Haryana and Madhya Pradesh.
The resulting shortages in food and animal fodder risk exacerbating the impact of the Covid-19 outbreak on marginalised families in these areas.
The crisis comes amid the worst outbreak of desert locusts in eastern Africa in decades, which has seen favourable breeding weather since 2018 caused by high rainfall.
The Food and Agricultural Organisation (FAO) of the United Nations has said the locust outbreak is the worst to strike Ethiopia and Somalia for 25 years, and also the worst infestation that Kenya has experienced in 70 years.
There are worrying spillover consequences for South-west Asia.
Mr Keith Cressman, the FAO's senior locust forecaster, told The Straits Times in an e-mail last Thursday that recent rainfall is expected to produce a dramatic increase in locust numbers in East Africa over the coming months.
"A portion of these second-generation swarms due in East Africa from mid-June onwards are expected to migrate from the Horn of Africa, across the Indian Ocean, to the desert areas along both sides of the Indo-Pakistan border," he said.
This anticipated migration from the Horn of Africa will be joined by swarms arriving from spring breeding areas in south-west Pakistan and southern Iran from this month to July. These locusts are slated to arrive in India during the monsoon season, allowing them to lay eggs for a further generation of breeding in the country.
If the locust problem persists in India until then, their presence could wreak havoc during a key cropping season when crops are grown with the onset of the monsoon and harvested between September and October.
"Depending on this year's monsoon and the success of control operations, new swarms could form at the time of harvest," Mr Cressman added.
The FAO estimates that the number of locusts could increase 20 times during the upcoming rainy season if anti-locust operations are not stepped up, prompting fears of damage far greater than that caused in the 2019-2020 cycle.
Various state governments, as well as the federal authorities and the Locust Warning Organisation, have already swung into action, spraying pesticides on these swarms.
The Press Trust of India reported last Thursday that New Delhi had proposed a trilateral approach to Pakistan and Iran to deal with the rapidly growing threat, besides offering pesticides. Last Thursday, the Indian government also permitted the use of drones to spray pesticides on swarms.
The desert locust is considered to be the most destructive migratory pest in the world. Locust swarms can vary in size from less than 1 sq km to several hundred sq km. There can be at least 40 million and sometimes as many as 80 million adult locusts in each sq km of the swarm.
Desert locusts devour massive quantities of vegetation - wild plants, shrubs, trees and grass, as well as food crops. A 1 sq km swarm of desert locusts can eat the same amount of food in one day as about 35,000 people, according to the FAO.
Dr Suwalal Jat, a Rajasthan state government officer in charge of anti-locust operations, said the season this time could last longer than the 2019-2020 cycle.
With the locusts coming earlier during the dry season, they are moving farther from the bare desert region near the border to interior areas with vegetation.
"The ones coming in are young adults capable of covering 200km to 250km a day, compared with the earlier ones that covered 150km to 200km per day," he told The Straits Times.
The Rajasthan government has already sanctioned the use of 600 power-operated sprays mounted on tractors, besides other vehicles for surveying and control operations currently underway.
"We used these spraying vehicles as late as December in the last cycle, but have already started using them now," Dr Jat added.
The federal government is reportedly also considering importing specialised equipment from Britain.