Locust swarms threaten a “rolling emergency” that could endanger harvests and food security across parts of Africa and Asia for the rest of the year, experts warn.
An initial infestation of locusts in December was expected to die out during the current dry season. But unseasonal rains have allowed several generations of locust to breed, resulting in new swarms forming.
Huge swarms of locusts have been causing devastation across swathes of Africa, Asia and the Middle East. Erratic weather conditions and storms have aided their path. As a result, countries have been battling the pests for months to avoid a hunger crisis.
Q&AHow does a single locust become a swarm?
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In normal times, locusts are not usually a threat. Desert locusts are a type of grasshopper that feed off vegetation but are usually solitary.
But when conditions bring them together, their behaviour completely changes. As few as two locusts touching each other can create a connection that starts them forming into groups. This unlocks their destructive “gregarious” state that changes their behaviour and even colour.
Rains help the swarms to form. The moisture turns deserts into ideal habitats for breeding and the locusts feed off the growing vegetation. In two generations, the number of locusts can increase 400-fold.
They easily devour fields of crops and when the food dries up, they move on. “Bands” of wingless, gregarious locusts move in the same direction, while adult winged “swarms” migrate by air in search of greenery.
Dry weather usually kills them off naturally but when things change, plagues begin. A combination of ideal breeding conditions and a lack of control operations can allow unchecked breeding, which is what happened in Yemen in 2018. Two cyclones within months of each other created long breeding periods that allowed the numbers to grow 8,000-fold and the war in the region meant the locusts were not detected and destroyed.
Desert locusts, which live in areas between west Africa and India, cause the most devastation and like to breed in moist conditions. These locusts live for three months. Eggs hatch two weeks after they have been laid, and hoppers become adults after about six weeks.
Adult locusts can eat their body weight every day, and fly up to 150km a day in search of new supplies.
Kenya is experiencing its worst infestation for 70 years, with pastoralists complaining that the vegetation on which their livestock feeds is being wiped out. Ethiopia and Somalia have not seen an outbreak this bad for 25 years. Swarms have also been destroying crops in Uganda, India and Pakistan.
Fears that millions of people could be forced into hunger prompted mass control operations earlier in the year, which have had an impact in Kenya and southern Ethiopia. But experts fear rains and insecurity in Somalia and South Sudan could undermine efforts in the east and Horn of Africa.
Keith Cressman, locust forecasting expert for the UN’s Food and Agriculture Organization, said that over the coming months locusts are expected to move farther north into Ethiopia and South Sudan. High food prices in South Sudan could compound the threat of hunger.
“Ethiopia’s going to be the recipient of swarms from Kenya and then also probably from Yemen so it’s going to be busy for the whole year,” said Cressman.
Kenneth Kemucie Mwangi, from the Nairobi-based IGAD Climate Prediction and Applications Centre, which monitors 11 countries, said initial reports suggest 2,500 sq km of crop damage in Kenya, largely among marginalised communities.
“A lot of crop areas are in their planting stage and we’ve already had reports in Turkana [county] that the herbaceous vegetation planted by the community to supplement their diet [has been damaged]. We’ve had reports of locusts invading farms,” he said. “We really need a plan to [help] people because it can really shock the food security of agro-pastoralists who are in marginalised communities.”
Lark Walters, food security specialist for the Famine Early Warning Systems Network (Fews Net), said some regional bread basket areas had not yet been hit, but there was still reason for concern.
“Despite the successes of the control measures and the stroke of luck of where desert locusts have or have not entered due to environmental reasons, we do expect the impacts of desert locusts to contribute to the food-insecure population in parts of Ethiopia, parts of Somalia and parts of south-east South Sudan,” she said.
Fews Net predicted locusts could damage enough crops to feed 280,000 people for six months in Somalia.
The current locust outbreak originated in Yemen, where breeding conditions created by unseasonable rains combined with ongoing conflict had allowed an almost unchecked outbreak.
Cressman said Yemen had “become a reservoir” that could continue to stoke the crisis because it was still unable to monitor and control locusts. As well as the fighting, heavy rains that were once unusual have become an almost monthly occurrence.
Increasingly unpredictable weather will be crucial to how long the crisis goes on and which places will be affected, he said. Locusts are already moving to the India-Pakistan border.
He said the timing of rain in Sudan could determine whether there was an outbreak in west Africa.
“This is typical for desert locusts. It’s not a problem that starts in one place and ends in one place, it’s a rolling emergency.”
Mwangi said Kenya has been able to successfully limit the outbreak to areas near the border with Ethiopia, where operations have been focused.
He said the crisis had shown the importance of regional coordination in fighting the pests, highlighting how countries such as Kenya, which is not used to locust outbreaks, had to scramble for equipment and resources.
Security threats had also hampered cross-border activity. In one incident, a helicopter monitoring locusts almost sparked a standoff by accidentally crossing into South Sudan from Kenya.
Security threats have prevented Kenya from carrying out cross-border spraying with Somalia, and also prevented the Somali government from conducting some aerial operations.
“The minute a weak link is there, it means swarms are able to lay eggs in areas that cannot be covered and those swarms offer a new generation for a new invasion,” said Mwangi.