Perfect storm for plague of locusts in Africa

Ravenous: In one day, a single locust eats its own weight in food. © EPA

Is climate change to blame for the swarms of locusts? The UN warns of famine in east Africa as wet weather and civil war contribute to the largest infestation of locusts in decades.

It is a Kenyan farmer’s worst nightmare.

A dark cloud on the horizon. One billion locusts; a flying grasshopper from the Arabian deserts, swarming over your fields.

Covering an area the size of a city and eating every green thing in their path, within hours they’re gone. And so is your way of life. Without help, you will starve.

The UN warns millions will face this fate if the desert locusts are not stopped.

The worst plague since the 1980s has now reached Uganda and Tanzania, after devastating Kenya, Somalia and Ethiopia. Keith Cressman at the UN says there is only a “small window” of time to prevent catastrophe.

They have plagued farmers for thousands of years and are mentioned in the Bible, but it is only recently that scientists have begun to understand the strange behaviour of locusts.

Most of the time, the insect avoids its own species. But very occasionally, something triggers a dramatic change in its behaviour. Heavy rain in the desert brings them together to feed on fresh green shoots. They reproduce, change colour, and begin to migrate in enormous numbers.

The last two years have seen an above-average number of cyclones in the Indian Ocean. These storms have brought heavy rain and the perfect conditions for locust swarms.

With further rain predicted, the UN warns that the population of locusts could skyrocket to 400 times its current size in the next few months. At its peak, it could cover 10% of the total land surface of the world and affect 20% of humanity.

The fear is that the climate crisis will make these outbreaks more likely. As sea temperatures rise, storms will become more frequent. “If we see this continued increase in the frequency of cyclones,” says Keith Cressman, “I think we can assume there will be more locust outbreaks.”

But there are many other factors at play. Civil wars in Yemen and Somalia have made it difficult to spray pesticides in those countries, allowing the swarms to grow out of control.

The many years since the last plague has also not helped. In a region with limited resources and plenty of problems, the money for preparation and prevention dried up when the locusts didn’t return. But now they’re back.

So, is the climate crisis to blame for the locust swarms?

Global swarming

The evidence is clear, say some. Instead of one cyclone every few years flooding deserts where locusts breed, we are seeing multiple storms in each season. This doesn’t just mean more frequent swarms, but bigger swarms lasting for longer. Instead of dying out, the year-on-year wet conditions are helping this plague grow further. Global warming is creating a perfect habitat for a permanent plague.

Not every natural disaster is the result of the climate crisis, say others. Major locust swarms are rare events that happen once in a generation, and there are billions of people alive today who will not remember the last one. This makes it appear new and strange, but it is as old as human civilisation. There were six major locust plagues in the last century, and swarming insects have been damaging crops as long as people have been farming.

You Decide

  1. Are the locust swarms caused by the climate crisis?
  2. Do some disasters get more news coverage than others?


  1. Design a poster to raise money to help farmers affected by the locusts in Africa.
  2. In groups of three, use the expert links to design an action plan to prevent future locust swarms.

Some People Say...

“They covered the surface of the soil until the ground was black with them. They devoured all the greenstuff in the land and all the fruit of the trees.”

The Bible, Book of Exodus 10:14-15

What do you think?

Q & A

What do we know?
In May and October 2018, storms created lakes in the Arabian desert and a population explosion of locusts. Over the summer last year, the swarms crossed the Red Sea into Africa. Further wet weather in the autumn helped the plague to spread across the continent. The locusts bred over winter, and the population will rise dramatically as the juveniles take flight in search of food.
What do we not know?
The process by which locusts change from being solitary to swarm insects is not fully understood. External factors speed up, slow down, and reverse the transformation between the two versions of the species. Given that climate science is also very complex, the relationship between this process and climate change still requires further research.

Word Watch

Kenya in east Africa has seen the worst swarms in 70 years.
Desert locusts
A species of grasshopper and the most devastating migratory pest in the world.
Keith Cressman
Senior locust forecasting officer at the United Nations.
Dramatic change
They grow larger brains and smaller legs, and turn yellow to ward off predators. They also become cannibals, feeding off each other.
Chemicals used to control insects. Excessive use can damage the environment and get into the food chain.


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