The Scientific Explanation For The Bible’s Great Plague Of Locusts

In Exodus, God summons Ten Plagues against the Egyptians to free the Jews. Although some people view this story as fiction, there are researchers who believe that a real event inspired the tale. Perhaps a swarm of locusts ravaged ancient Egypt at one point. But how did this happen? Read on to learn the scientific theories behind the Biblical locust plague.

Locusts Are One Of The Ten Plagues

In this 1480 illustration, God sends hail to the Egyptians as one of the Ten Plagues.
The Print Collector/Print Collector/Getty Images
The Print Collector/Print Collector/Getty Images

Those who have studied the Bible might be familiar with the Ten Plagues of Egypt. According to Exodus, God grew angry with the Egyptian Pharaoh for forcing the Jews into servitude. He instructed Moses to go to the Pharaoh and warn him about the plagues that were to come.

For the eighth plague, Moses warned the Pharaoh about a swarm of locusts. In Exodus 10:4-5, Moses says, “If you refuse to let [my people] go, I will bring locusts into your country tomorrow. They will cover the face of the ground so that it cannot be seen.”

Did The Ten Plagues Really Happen?

An oil painting depicts from 1800 the Fifth Plague from the Bible.
Fine Art Images/Heritage Images/Getty Images
Fine Art Images/Heritage Images/Getty Images

Whether or not the Bible’s events happened is up for debate. Some historians believe that certain stories were based on real-life events. For example, Moses might not have ordered a swarm of locusts, but a swarm of that scale might have occurred in Egypt.

According to Time, several historians have proposed theories for what could have happened that inspired the Ten Plagues. But in order to do that, they had to guess what might have caused the swarm.

The Bible’s Description Of Locusts Does Not Exaggerate

A man walks through a locust swarm in Kenya.
YASUYOSHI CHIBA/AFP via Getty Images
YASUYOSHI CHIBA/AFP via Getty Images

According to the Bible, the locusts were as devastating as Moses warned. Exodus 10:14-15 says, “Never before had there been such a plague of locusts, nor will there ever be again. They covered all the ground until it was black. They devoured all that was left…Nothing green remained on tree or plant in all the land of Egypt.”

Although this description sounds exaggerated, it is accurate. Locusts did–and still do–ravage everything in their path, driving some people to starvation.

Are Locusts Really That Dangerous?

Several locusts crawl on a man's hand.
ARIF ALI/AFP via Getty Images
ARIF ALI/AFP via Getty Images

Although locusts do not harm people directly, they can devour crops unbelievably quickly. According to National Geographic, a single locust swarm can span 460 square miles and consist of between 40 million and 80 million insects. They can also fly up to 11 miles per hour.

The Food and Agriculture Association claims that a small swarm–only half a square mile–can eat the same amount of food as 35,000 people in one day. That can devastate a country’s agriculture.

For The Ancients, Locusts Were The End Of The World

In this old photo, Israeli farmers try to ward off locusts with brushwood.
© Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images
© Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images

The ancients likely viewed locusts as apocalyptic, because they did not know how to stop the swarms. Even in the 19th century, farmers still struggled to save their crops. For instance, in 1874, one of the worst locust swarms in American history occurred.

Farmers resorted to lighting fires and gunpowder to get rid of the insects. Some even waved around wooden planks and farm gear. When one man made a trench fire, the locusts piled onto it and smothered the flames!

Where Did The Plagues Occur, Exactly?

Israelites And Their Taskmasters
The Print Collector/Heritage Images via Getty Images
The Print Collector/Heritage Images via Getty Images

Although Exodus explains that the Ten Plagues happened in Egypt, it does not specify where in Egypt. After all, the country used to be a much larger kingdom than it is today. According to The Standard, researchers believe that the plagues might have happened in Pi-Ramesses.

This city used to be the capital of Egypt during the reign of Pharaoh Ramses II, between 1279 and 1213 BC. For 3,000 years, Pi-Ramesses has been abandoned. Perhaps the plagues have something to do with it.

What Kind Of Locusts Were In The Bible?

Desert locusts eat from a maze field in Kenya.
YASUYOSHI CHIBA/AFP via Getty Images
YASUYOSHI CHIBA/AFP via Getty Images

There are several species of locusts, but only one type might have appeared in the Bible. Historians believe that they were desert locusts, or Schistocerca gregaria. These locusts are native to Africa, Arabia, and West Asia, although they can travel all the way up to Spain.

Desert locusts only live for three to five months, but they repopulate quickly. They can lay as many as 1,000 eggs in a single yard of soil, according to The Economic Times. They also swarm and fly, as the Bible details.

Locusts Vs. Grasshoppers: What’s The Difference?

The shadow of a locust is seen eating against the setting sun.
Xinhua/Mohammed Mohammed via Getty Images
Xinhua/Mohammed Mohammed via Getty Images

Physiologically, locusts are grasshoppers. The desert locust is a type of short-horned grasshopper in the Acrididae family. But locusts have different “behavioral states,” according to the Australian Department of Agriculture.

For one, locusts swarm, while grasshoppers do not. Locusts also have different behaviors in fertility, mating, and survival. It can be difficult to distinguish grasshoppers from locusts, especially since some grasshoppers swarm in small groups. That said, desert locusts act very differently from grasshoppers and are easy to identify.

Climate Change Might Be Creating More Swarms

Swarms of locusts fly as the sun sets in Pakistan.
BANARAS KHAN/AFP via Getty Images
BANARAS KHAN/AFP via Getty Images

The United Nations Food and Agriculture Organization (FAO) believes that climate change is altering insect control and reproduction. Specifically, global warming might be causing more tropical storms across the Indian Ocean, which floods the land and weeds out locusts.

Since 2018, more cyclones have been appearing. More water increases the reproduction of locusts, resulting in more swarms, explains locust forecaster Keith Cressman. But this is not the only time that climate change has prompted swarms of locusts.

Climate Change Might Have Caused The Ten Plagues, Too

An illustration from the 16th century depicts locusts as described in the Old Testament.
PHAS/Universal Images Group via Getty Images
PHAS/Universal Images Group via Getty Images

Some researchers theorize that climate change might have caused the real-life Ten Plagues. Climate changes have occurred throughout history, albeit not on the same scale that we see today. In 2010, researchers found evidence of a dry spell from stalagmites, mineral deposits that form from calcium.

The researchers found that there might have been a long dry period during the reign of Pharaoh Ramses II. This theory directly ties into another theory about the Ten Plagues, about red algae.

Red Algae And The Ten Plagues

A boat man rows across a lake that has a red algae bloom.
Masrat Jan/NurPhoto via Getty Images
Masrat Jan/NurPhoto via Getty Images

In 1996, epidemiologist John S. Marr proposed an idea for what caused the Ten Plagues. He told The New York Times that an abundance of red algae might have caused the plagues. After all, the Bible describes the Nile turning to blood.

According to Marr, too much red algae might have sucked the oxygen out of water. His theory was backed in 2017, when researchers found evidence that this algae growth might have happened. So how does it tie into locusts?

This Algae Caused A Long List Of Consequences

A river on the Galapagos Islands is red because of red algae.
Wolfgang Kaehler/LightRocket via Getty Images
Wolfgang Kaehler/LightRocket via Getty Images

Biologist Stephan Pflugmacher suggests that the red algae would have caused many problems. For instance, as the algae made the Nile toxic, frogs might have left the river (the second plague). As the frogs died, lice and flies could have invaded the area (the third and fourth plagues.

With more insects surrounding rotten meat, diseases might have spread, causing the fifth and sixth plagues. The boils might have resulted from glanders, an airborne bacterial disease that spreads through flies. Livestock might have also gotten sick.

Then, The Locusts Came

Locusts swarm a field that a farmer stands in.
Fairfax Media via Getty Images via Getty Images
Fairfax Media via Getty Images via Getty Images

So how does the algae theory tie into locusts? According to the researchers, the locusts might have arrived for the same reasons as other insects. As food and water decreased, the locusts swarmed in search of food.

Before the algae formed, scientists found evidence that a large amount of rain hit Pi-Rameses. This extra water allowed locusts to breed rapidly. Then, when the water dried up, the locusts swarmed–similar to the 2020 occurrence in Africa.

Tying These Two Theories Together

An ancient relief shows farmers battling locusts.
Werner Forman/Universal Images Group/Getty Images
Werner Forman/Universal Images Group/Getty Images

The climate change theory and algae theory directly tie together. Paleoclimatologist Augusto Mangini suggested that the rise in temperature might have dried up the Nile and produced Oscillatoria rubescens, or Burgundy Blood algae.

This would explain the Nile turning red in the Bible. It also suggests that the Nile dried up, which would have lead to devastation in both crops and livestock. Although this sounds plausible, there is another theory about how the Ten Plagues might have occurred.

The Volcano Eruption Theory

A volcano erupts on Rakata Island.
FERDI AWED/AFP via Getty Images
FERDI AWED/AFP via Getty Images

Researchers have proposed a different possible cause for the Biblical locusts. In The Plagues of Egypt: Archaeology, History and Science Look at the Bible, microbiologist Siro Trevisanato proposed that a volcano eruption might have spawned some of the plagues.

Trevisanato argued that ancient Egyptian medical texts alluded to a volcano eruption. Scientists have also suggested that the volcano Thera, which sits on Santorini, might have exploded 3,500 years ago. Scientists have found pumice, or cooled volcanic lava, in Egypt from that time.

But How Does A Volcano Spawn Locusts?

Locusts are seen flying through the sky.
YASUYOSHI CHIBA/AFP via Getty Images
YASUYOSHI CHIBA/AFP via Getty Images

In his book, Trevisanato proposed, “The ash fallout [from the volcano] caused weather anomalies, which translates into higher precipitations, higher humidity. And that’s exactly what fosters the presence of the locusts.”

Climatologists have provided some evidence for this theory. At the beginning of Ramses II’s reign, Egypt had a warm, wet climate. These rains might have produced more locusts. During the later dry spell, the insects could have searched for more food, resulting in the swarm.

The Volcano Prompted Other Plagues, Too

A volcano erupts and launches a lot of smoke into the sky.
LINUS ESCANDOR II/AFP via Getty Images
LINUS ESCANDOR II/AFP via Getty Images

According to the volcano theory, the eruption of Mount Thera might have caused the ninth and tenth plagues. The ash might have caused the three days of darkness. Or perhaps a sandstorm shrouded Egypt in darkness.

As for the death of firstborns, a fungus might have infected the grain supplies. As diseases spread, newborns became the most vulnerable. This is why some people believe that the climate change, algae, and volcano theories are all true.

However, We Will Never Know Whether The Plagues Were Real

A Bible with a cross on it lies on a table.
Kiwihug/Unsplash
Kiwihug/Unsplash

Although these explanations make sense, they are not confirmed. They are simply hypotheses for what might have happened. We may never know whether the Ten Plagues had a historical basis or if they were fiction.

For Hebrew scriptures professor Robert Miller, explaining the Ten Plagues loses the entire point. “The whole point was that you didn’t come out of Egypt by natural causes; you came out by the hand of God,” he told The Standard. Perhaps the story does not need a theory.

But These Hypotheses Can Help Us

A single desert locust eats wheat on the ground.
Asim Hafeez/Bloomberg via Getty Images
Asim Hafeez/Bloomberg via Getty Images

Although the Ten Plagues theories are not confirmed, these explanations can lend us some information for modern times. For instance, the climate change theory is similar to how the 2020 locust swarms began. Perhaps these hypotheses can help scientists predict locust swarms in the future.

Whether you believe in the Bible or not, locust swarms are still a real issue that plague people today. The more we understand about locusts, the more crops–and lives–we can save.

Locusts Can Terrorize The Entire World

In this black and white illustration, locusts swarm a farm in northern India.
Universal History Archive/Universal Images Group via Getty Images
Universal History Archive/Universal Images Group via Getty Images

Although desert locusts are mainly found in Africa, they can fly through as many as 30 countries, according to National Geographic. And this is during a quiet period. Locusts can swarm through as much as 1/5 of the world’s surface.

That said, Bible authors had a limited perception of the world. To them, swarming Egypt would have been like swarming the entire earth. Seeing a locust swarm on a “Biblical scale” is possible, and it has happened throughout history.

Locusts Invaded As Recently As 2020

A Palestinian farm shows a locust on his hand as other farmers aim to get rid of them.
SAID KHATIB/AFP via Getty Images
SAID KHATIB/AFP via Getty Images

In 2020, one of the world’s worst locust swarms occurred. According to the UN, this swarm affected at least 23 countries. It was the worst swarm in 70 years in Kenya, 26 years in India, and 25 years in Somalia and Ethiopia.

This swarm was larger than usual. In Kenya, it reached up to 930 square miles. For reference, the state of New York is only 23 square miles. Over 25 million people suffered from food shortages because of this swarm.

2020’s Swarm Was On “A Biblical Scale”

Swarms of locusts fly over trees.
BANARAS KHAN/AFP via Getty Images
BANARAS KHAN/AFP via Getty Images

Considering how disastrous the 2020 swarm was, it is no surprise that people compared it to the Bible. The BBC titled its article “The Biblical Locust Plagues of 2020.” In India and many other countries, people claimed that the Bible “warned us” about this swarm.

Oddly enough, the 2020 swarm might give us some clues as to how the Biblical swarm occurred. If we look at the cause of the 2020 swarm, we uncover find some answers.

What Caused The 2020 Swarm?

A man stands in a field while locusts swarm around him.
YASUYOSHI CHIBA/AFP via Getty Images
YASUYOSHI CHIBA/AFP via Getty Images

Experts believe that the 2020 swarm might have resulted from extreme weather events. Keith Cressman, the U.N.’s senior locust forecasting officer, told NPR that powerful cyclones have occurred since 2018.

These cyclones battered Oman, Yemen, and the Horn of Africa with water. The excess water provided the ideal breeding grounds for locusts. As more locusts were born, they quickly ran out of food. They eventually resorted to swarming to get more food for their unusually large population.

But Locust Swarms Are Impossible To Predict

A man holds a glass jar with a locust inside of it.
SAMUEL ARANDA/AFP via Getty Images
SAMUEL ARANDA/AFP via Getty Images

While scientists can hypothesize why locust swarms might have occurred, they still do not know what causes them. Researchers have yet to find a pattern in history’s locust swarms. Some of the largest occurred between 1926 and 1934, 1940 and 1948, and 1967 and 1969.

And that is only the 20th century. Locust swarms seem to pop up randomly, and they can continue for years. Even the 2020 “Biblical” swarm began in 2019 and continued for over a year.

Eating Locusts Does Not Work, Either

Locust Lunch In Nepal
Narayan Maharjan/NurPhoto via Getty Images
Narayan Maharjan/NurPhoto via Getty Images

Throughout history, locust swarms have rapidly depleted food stocks. Because of this, many people resorted to eating the insects. It makes sense; the locusts offer protein and can replace some of the lost crops.

There are two problems with this method: people cannot eat the bugs quickly enough, and some are covered with poison. Farmers use insecticides and pesticides to combat the swarms, and eating them might be “extremely toxic,” according to The Conversation. It seems that no method can fully defeat locusts.

Only Recently Did People Find A Semi-Effective Method

Two men catch locusts with a net.
TONY KARUMBA/AFP via Getty Images
TONY KARUMBA/AFP via Getty Images

Farmers did not find an effective method against locusts until the early 20th century. In 1937, at the height of the Great Depression, a locust swarm consumed Colorado. These locusts could not even fly, but they ate so much food that Governor Teller Ammons called in the National Guard.

The National Guard tried using flamethrowers and dynamites. None of it worked. “They kept right on flying – just bounced a little and went on,” wrote Brigadier General Alphonse J. Ardourel.

Using Locust’s Food Against Them

A volunteer sprays pesticides to deter locusts.
TONY KARUMBA/AFP via Getty Images
TONY KARUMBA/AFP via Getty Images

During the 1937 locust swarm, the National Guard discovered an effective method against the swarms. They used their own food against them through poison. When the locusts ate poisoned food, they died in rapid numbers.

To this day, poison and pesticides are common tactics against swarms, says Chris Adriaansen, the director of the Australian Plague Locust Commission. Pesticides and fipronil harm the insect’s nervous system. When used effectively, this method can kill up to 80% of locusts.

Even So, This Does Not Solve The 2020 Swarm

A desert locust crawls on a leaf.
YASUYOSHI CHIBA/AFP via Getty Images
YASUYOSHI CHIBA/AFP via Getty Images

Although poison and pesticides sound like an easy solution, they are not. When locust swarms begin, it can be difficult to catch up to them. The Kenyan government rapidly employed people to spray pesticides, trying to predict which fields the locusts would eat next with varying success.

Throughout Africa, farmers have resorted to more drastic methods. Some have burnt tires, banged drums, or simply shouted at the insects. These methods have been ineffective, and the swarm has become nearly apocalyptic even in modern times. We may never know the truth behind the Bible, but we can certainly strive to understand the world around us better.