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Why are locusts so destructive?

January 31, 2020

The worst locust outbreak in decades has devastated crops in East Africa and shows no signs of stopping. What are these ravenous insects, and what's being done to stop them?

Migratory locusts feeding and resting in grass
The locusts have already destroyed hundreds of square kilometers of vegetationImage: Imago Images/Nature Picture Library

What are locusts?

The billions of voracious insects darkening the skies of East Africa are desert locusts, a large herbivore that resembles a grasshopper. About the length of a finger — on average 6-8 centimeters (2-3 inches) — one locust can consume its own weight in food each day, a massive threat to crops and pastures. 

They often travel in dense, crackling swarms which can contain as many as 80 million locusts per square kilometer, according to the UN's Food and Agriculture Organization (FAO). Swarms can vary from less than 1 square kilometer in size to several hundred square kilometers.

Desert locusts can live for up to five months, depending on the weather and local conditions. According to the FAO, eggs can hatch in about two weeks, with locusts maturing to adulthood in two to four months on average. If nothing is done to stop them, their numbers could grow 500 times by June.

Read more: How to stop an insect apocalypse

A farmer looks back as she walks through swarms of desert locusts feeding on her crops
Image: picture-alliance/AP Photo/B. Curtis
Global Ideas Kenia Heuschreckenplage
Image: picture-alliance/AP Images/B. Curtis

How bad is it?

Locusts aren't picky eaters; as the 2017 BBC documentary Planet Earth made clear, the insects will "consume every edible thing that lies in their path." In one day, the average swarm can destroy around 192 million kilograms of vegetation, according to National Geographic — the food supply for thousands of people.

The swarms now plaguing Kenya, Ethiopia and Somalia are "so thick [that people] can barely see through them," said Ian Vale, regional director for aid organization Save the Children, in a recent statement. Swarms move with the wind, covering anywhere from 5 to 130 kilometers (3-80 miles) in a day.

The locusts have already destroyed hundreds of square kilometers of vegetation and may yet spread to Uganda and South Sudan, bringing further instability to one of the world's poorest regions. Recent data from the Food Security and Nutrition Working Group shows that more than 19 million people are already suffering from acute hunger in East Africa. 

Locust plagues

In a region still recovering from a devastating drought and deadly floods in 2019​​​​​​​, this latest blow could lead to "a major food security problem," Guleid Artan of the Climate Prediction and Applications Center told a press conference in Nairobi earlier this month. Artan stressed that if the threat wasn't brought under control by the next planting and rainy season, which starts as early as March, newly planted crops could be wiped out before they have the chance to grow.

Read more: World hunger continues to rise due to conflict, climate change, says UN report

Pakistani children try to avoid locusts swarming in Rahimyar Khan, Pakistan
Swarms of locusts also descended in multiple areas in Pakistan in NovemberImage: picture-alliance/AP Photo/S. Baluch

What triggered this invasion?

Years of drought in the region, followed by heavy rains and warmer temperatures in 2019, created "exceptional" breeding conditions for the locusts, Nairobi-based climate scientist Abubakr Salih Babiker told The Associated Press.

The wet, warm weather has created the ideal circumstances for vegetation to grow — and more vegetation means more food for the locusts.

Has the region ever experienced such a devastating outbreak?

Locusts are native to Africa, the Middle East and parts of Asia, and they've been menacing farmers for millennia. They even made it into the Bible, mentioned as one of the 10 plagues inflicted on Egypt.

But this is East Africa's worst infestation in decades. According to the FAO, it's been 25 years since Ethiopia and Somalia experienced an invasion of this size, while Kenya hasn't seen this many locusts in 70 years.

Neighboring countries are also worried. "Uganda has not had to deal with a locust infestation since the '60s so there is concern about the ability for experts on the ground to be able to deal with it without external support," said Rosanne Marchesich, the FAO's head of emergency response.

According to the FAO, a major locust invasion between 2003 and 2005 across 20 countries in northern Africa caused more than $2.5 billion (€2.2 billion) in harvest losses.

Locusts in a tree
A swam can strip plants of their foliage in a short space of timeImage: Getty Images/AFP/T. Karumba
Global Ideas Kenia Heuschreckenplage
Image: picture-alliance/AP Photo/B. Curtis

Read more: Are insects the food of the future?

What's being done to stop them?

Some locals have tried using loud noises to shoo the insects away — firing off gunshots, banging cans and honking horns — but that hasn't done much to deter the swarms, and can help them to spread further. Other local agencies have suggested eating the locusts, which are considered a delicacy in some parts of the world. But even a massive feast would do little to dent their numbers.

Aerial pesticide spraying is "the only effective way to combat them," according to the United Nations, which has already allocated $10 million to the effort. It has warned that about $70 million will be needed to intensify the campaign.

The Desert Locust Control Organization for Eastern Africa says Kenya has deployed five aircraft to spray the pesticides, which it says do not pose a threat to humans. In Ethiopia, four planes are taking on the swarms. Similar operations have also begun in Somalia, though the al-Qaida-linked militant group al-Shabab is making things difficult in some areas, according to the FAO.

With files from AP, AFP

Martin Kuebler Senior editor and reporter living in Brussels, with a focus on environmental issues