Gargantuan swarms of desert locusts with a voracious appetite for staple crops like teff, wheat, and sorghum are sweeping over the Horn of Africa, the Middle East, and South Asia, leaving crops and rangeland destroyed.
A combined 42 million people in Eastern Africa and Yemen were already expected to face acute food insecurity this year, according to the United Nations Food and Agriculture Organization (FAO). The locusts, and now the novel coronavirus, could push more people to the brink of starvation.
For countries like Kenya, Somalia, and Ethiopia, the locusts this year have already been the worst in decades, with billions of insects forming swarms that spread over hundreds of thousands of acres.
Swarms have also swept into Yemen, Iran, Pakistan, and India, threatening harvests. India is also contending with evacuations for millions of people as Cyclone Amphan makes landfall. And now more ravenous insects are on their way.
The recent swarms have already devoured almost 100 percent of crops in some areas. At times, locust swarms have become so dense that they’ve even forced aircraft to divert. Officials in Iran reported that a layer of dead locusts piled up 6 inches high after they sprayed afflicted areas with pesticides.
“I have a lot of experience with locusts, but this is my first time to see such a size of a swarm,” said Mehari Tesfayohannes, chief information and forecasting officer for the Desert Locust Control Organization for Eastern Africa.
Locust swarms are an irregular phenomenon, with years passing without them. But weather and climate conditions over the past year converged to create the perfect conditions for a boom of these ravenous insects. They are landing at an especially tenuous moment for many countries dealing with longstanding conflicts, resource shortages, and now a pandemic. A humanitarian crisis could lie ahead.
Why locusts form swarms
“Locust” refers to several species of short-horned grasshoppers that can radically change how they look and behave under the right circumstances. Out of roughly 7,000 species of grasshoppers, about 20 are considered to be true locusts. They are found on every continent except Antarctica, though in many places they rarely gather enough numbers to swarm.
The species behind the recent swarms in Africa and Asia is the desert locust, Schistocerca gregaria. It’s normally an introvert, leading a solitary life. But every now and then, ideal environmental conditions cause a population explosion.
In prolonged close company, these introverts become what scientists call “gregarious.” They begin to move and act in sync rather than as haphazard individuals. And it’s not just their personalities that change; the desert locust changes color from a green or mottled brown to a vivid yellow. They change shape, too: Their body sizes are smaller and their brains are larger than in their solitary phase. The changes in behavior can occur in just a few hours, while the physical changes take longer.
After they transition into their gregarious phase, locusts form swarms with roughly 150 million individuals per square kilometer, or 600,000 per acre. Those 150 million locusts eat as much food as 35,000 people every day. This year has seen swarms spreading over as much as 2,400 square kilometers, nearly 600,000 acres, according to the FAO.
Once airborne, locust swarms can travel more than 100 miles in a day as they ride the wind, devouring almost all vegetation in their path.
Together, the scale, speed, and destruction of locust swarms make them an international danger to agriculture. “Locusts do not honor political boundaries and can easily invade other adjacent countries,” said Hojun Song, an entomologist at Texas A&M University, in an email.
Weather and climate conditions fueled the enormous locust swarms this year
Rainfall led to the recent population explosion in these insects, particularly in East Africa and the Middle East. That was due in part to the changes in the Indian Ocean Dipole, a pattern of changing temperature gradients in the Indian Ocean.
“The western side of the Indian Ocean was unusually warm as compared to the eastern side,” said Muhammad Azhar Ehsan, a researcher at the International Research Institute for Climate and Society (IRI) at Columbia University’s Earth Institute. “So when the western side was warm, we had a lot of evaporation happening over there, and that evaporation turned into a rainfall.”
In 2019, the Indian Ocean Dipole was at near-record strength with a temperature gradient not seen in decades. This led to torrential rainfall in East Africa, Yemen, and India, some of the heaviest in two decades. The rains caused floods and forced hundreds of thousands of people to leave their homes.
When the waters receded, however, there was a surge in lush greenery. The sudden bounty caused locusts to congregate and breed far more rapidly than they would when food is scarce, particularly in areas that are normally dry and bare.
The insects gathered, ate, mated, and laid eggs. The rain also triggered dormant locust eggs to hatch, some that were laid years ago. These offspring were born into a world of abundance, with fields of fresh, juicy plants like grasses and shrubs to nourish them. This early stage in the locust life cycle, when they are known as “hoppers” or “nymphs,” also presents the most important opportunity for preventing them from forming swarms. Since they don’t yet have mature wings, they tend not to venture very far.
“The key is to detect the sign of population increase early on when locusts are aggregating as nymphs,” said Texas A&M’s Song. “When they are nymphs (immatures that have not yet developed wings), it is easier to control. Then they become adults and airborne, then it’s very difficult to control.”
These post-hopper, young adult locusts are often the most damaging because they are mobile and famished. “I like to say they’re like hungry teenagers,” said Keith Cressman, senior locust forecasting officer at the FAO. “They’re very active and they’re very voracious.”
Once the local cuisine, be it native vegetation or crops, is devoured, the locusts take flight and look for their next meal. About a month into this stage, the locusts are ready to lay eggs. Then exponentially more locusts hatch, up to a 20-fold increase each generation. The cycle continues, one that’s hard to break.
How governments are fighting back against locusts amid a pandemic
Locusts have been a threat to humanity for thousands of years, but anticipating them remains tricky. And with years, if not decades, passing between major swarm outbreaks, it’s easy for countries to lose sight of the threat.
The first signs of a pending locust swarm often arise in remote areas, so surveillance is a key part of a locust control strategy.
“There’s not people around watching, particularly in places that don’t typically have a lot of rainfall,” said John Furlow, deputy director for humanitarian and international development at IRI. “So you may get them breeding and multiplying in places and not be aware of it, and then once they reach a certain population, it’s too big to manage.”
Once a potential swarm is identified, the main response is pesticides, sprayed from ground vehicles or aircraft. The chemicals used are “ultra-low volume,” meaning a very small amount of pesticide is being used to do the job. But for it to work effectively, it has to actually come in contact with the locusts. Simply spraying crops or vegetation at a distance won’t work; it requires finding locusts and targeting them.
However, because decades have passed since the last major swarms landed in places like Kenya in East Africa, national and local governments don’t always have robust locust-control programs. That can leave countries without the tools or institutional knowledge to quickly respond. International organizations are trying to provide funding, equipment, technical support, but that takes time to scale up.
“It’s like a fire in a country that has no fire department,” Cressman said.
Some, but not all, of this has been complicated by the coronavirus pandemic. Cressman said teams had largely gotten the necessary equipment — things like pesticide and sprayers — on the ground by the time the pandemic really exploded, and countries began instituting lockdown measures. They’ve also tried to diversify sources for things like pesticides, to avoid pressures on the global supply chain, but some disruption is unavoidable.
“It went well with ground and aerial control operations” for locusts in East Africa, said Tesfayohannes of the Desert Locust Control Organization for Eastern Africa. “Even though there were some restrictions due to the virus.”
However, providing technical support and training is still tricky in the age of social distancing; it’s harder to help on the ground or hire people to help control the locusts or gather all the stakeholders (literally) in one room.
Teams trying to control these locust swarms have been deemed essential services in many of these countries, but they are still subject to quarantine curfews in some areas. In Kenya, for example, a 7 pm curfew can limit the extent of control operations in the afternoon, Cyril Ferrand, the resilience team leader in Eastern Africa for the UN Food and Agriculture Organization who’s on the ground in Nairobi, said.
Locusts are also active in wide swaths of East Africa and the Middle East, where fragile governments or outright conflict zones are complicating control efforts. The security situation in places like Yemen or Southern Somalia — both currently threatened by locust swarms — prevents local forecasters and control teams from operating on the ground. That can make it extraordinarily difficult to prevent swarms or to even know what’s going on. It also puts these already vulnerable areas are at greater risk for food insecurity or famine.
And since locusts can move, the inability to control swarms in one place means that an entire region remains under threat. Yemen, according to Ferrand, is particularly concerning right now, where the locusts are currently in their “hopper” stage, and where the ongoing conflict has complicated control efforts. “And this is really worrisome because our control capacity there is limited — but we need to control there. If we don’t control now, these hopper bands will turn to swarm, and this swarm, at some point will come to our region,” he said, referring to East Africa.
In this way, the locusts are a bit like the coronavirus: A rapid and effective response in one place can be undermined by failures elsewhere. But beyond spraying pesticides, there are few options for limiting their spread. “There is no lockdown for desert locusts,” Ferrand said.
Then there’s Mother Nature. The same climate shifts and weather patterns that supercharged this locust need to lessen. That might mean a break from the rains, or cooler temperatures, or winds that send the locusts to a location that’s much less favorable to their survival. None of that is really happening right now.
“For the last two years we have not seen any single break in the weather for desert locusts,” Cressman said. “It’s just been phenomenally favorable to them.”
Locust swarms and the coronavirus are threatening to cause a humanitarian crisis
The disaster caused by locusts is both impossibly quick and lasting. A dark cloud descends on a farm, and a swarm can devour an entire season’s crop in an afternoon. But their reproductive cycles, and their ability to take their destructive appetites on the road, means that crisis can repeat itself over and over again.
Countries in East Africa — parts of Somalia, Kenya, and Ethiopia — are bracing for the next wave of this crisis now through June, when the new swarms will start to form. If conditions remain favorable, and if control operations falter, another wave could devastate the region from September through December this year.
And over the long term, climate change is increasing the likelihood of extreme Indian Ocean Dipole events, meaning that the downpours that helped drive the recent swarms could become more frequent. So giant locust swarms could also arise more often in the years ahead.
For now, famine and food insecurity remain the biggest threat: More than 20 million people in the East African region already faced severe food insecurity in 10 countries, according to the FAO. Climate shocks and other natural disasters, conflict, and displacement have created those conditions, though that predates the coronavirus crisis. The World Food Program has said the pandemic could cause famine worldwide, pushing an additional 130 million people close to starvation, on top of the 135 million already on the brink.
Locusts will make this worse in places like East Africa and Yemen, where each bug can eat its weight in a day. If control operations can spare farmers’ crops, or the grass that herders depend on, that will prevent the most acute crises. If the locusts return later in the year, the crisis can repeat itself. But if those crops and vegetation can’t all be saved, people will exhaust their food supplies, pushing another 2.5 million to the brink of hunger in East Africa.
Countries like Yemen already have about 17 million people on the brink of famine due to conflict and drought. Locusts are now eroding its already faltering agriculture system. The locusts themselves have become a food source.
So far, the FAO says it has saved about 720,000 tonnes of cereal across 10 affected countries, which amounts to food for about 5 million people. The UN agency is still seeking additional funds, primarily for livelihood support for farmers and herders who’ve lost their crops or food source. The organization will launch a new international appeal, starting Thursday.
Food and resource scarcity are also increasing tensions and violence in some of these regions. Some seeking to graze their herds of cattle, for example, may be displaced to other pastures, igniting potential conflict over diminishing natural resources.
“There will be an increase in resource-based conflict … people will be moving towards areas where there will be grass. We need to prepare for conflict,” Josephine Ekiru, a Turkana pastoralist and peace-builder for the Northern Rangelands Trust in Kenya, told the Guardian this week.
The coronavirus pandemic could also make the humanitarian crisis more fraught. Many who see their crops destroyed or fields torn up might seek work elsewhere, likely in big cities. Quarantine, curfews, and travel restrictions in some of these countries may make that extraordinarily difficult. The economic pressures of lockdowns, which are affecting countries rich and poor, may also make labor opportunities scarce. Some governments are focusing their limited resources within their own borders to control the spread of the virus.
However, controlling locusts will require countries to work together, and it will take a sustained effort to fight this ancient plague, even among modern conflicts and a global pandemic. “Our gains have been significant,” said Qu Dongyu, director general of the FAO, in a statement. “But the battle is long and is not yet over.”