Locusts – How Can Such Small, Winged Insects Become a Disaster?

In June 2019, swarms of locusts began to gather in eastern Ethiopia and northern Somalia, but due to their relatively small scale, they did not receive much attention from the country and international levels.

However, no one could have imagined that just three months later, these locusts would turn into a disaster.

In December 2019, the locusts had grown beyond the scope of East Africa, they crossed the Red Sea and swept across the entire Arabian Peninsula. They also entered Iran through the Persian Gulf.

In January 2020, the locust plague area had already expanded to India, and wherever the locusts went, there was no grass.

On the 31st, Pakistan declared a state of emergency. In February 2020, due to the continuous expansion of the locust plague, it seriously affected the crop yields in the affected areas, especially the locusts had entered the grain production areas of India and Pakistan. If the scale continued to expand, it would lead to famine for several hundred million people. To attract high attention, the United Nations declared a global emergency on February 13, 2020, and a major global crisis was about to come.

And all this started from the small bugs in our backyard grass – locusts.

As for locusts, we are all familiar with them, but we also know little about them. We know they can be found everywhere, but most people only know that they are called 'grasshoppers' and they eat grass and jump. We don't know much about them.

Let's introduce them first:

Locusts belong to the Animal Kingdom, Mouth Animal Group, Jointed Animal Phylum, Insect Class, Hemiptera Order, Locusts Suborder, and Locusts Class. Below there are many families and subfamilies. For example, the common 'bucket hook', there are actually two types of locusts, the short and fat ones are called short-horned locusts, belonging to the Cone-head family, the Locust genus; the long ones are called Chinese Swordhorn Locusts, belonging to the Locust family, the Swordhorn genus.

As a member of the Hemiptera Order, the Locusts Class members can be considered the 'underdogs' of the four major families in the Hemiptera Order, they mainly eat plants and have no maxillae like grasshoppers and crickets, and they don't have specialized digging feet like mole crickets. When encountering danger, they mainly fly and jump. However, they are not the same as adults, they can open their small wings and say 'come and bite me'.

But being able to eat and grow quickly is not enough, because the bottom-level creatures can't escape the fate of being eaten. To avoid being eaten, you must be able to reproduce, so you don't have to be afraid of being eaten by predators. Locusts are very prolific, a female locust usually produces 4-5 egg cases, and up to 12, and the total number of eggs produced in one lifetime averages 300-400.

In addition, locust eggs have a special property – drought resistance. Desert locusts produce a large number of eggs when the weather is dry, and when the rainy season comes, the locust eggs hatch collectively.

This is one of the reasons for the appearance of a large number of locusts in East Africa.

So, what's the question? Generally, East Africa belongs to the tropical grassland climate, and in September, it will enter the dry season. Then, the locust population should be very small, how could it suddenly become a disaster?

The reason is the appearance of an abnormal rainy season – the El Niño phenomenon.

As for the El Niño phenomenon, it involves two knowledge points: ocean currents and trade winds.

Ocean currents are simply the alternating flow of cold and warm water in the sea. Generally, the tropical sea area is warm current, the cold area is cold current, influenced by the Earth's rotation and counter-currents, and ring currents. As for trade winds, they are the airflow caused by the difference in atmospheric pressure due to the influence of cold and hot air, and influenced by the Earth's rotation, they form trade winds with deflection direction.

Knowing about trade winds and ocean currents, the story behind them will be easy to tell.

First, it's affected by the speed of Earth's rotation. Every 4-5 years, the southeast trade wind will weaken, leading to a rise in temperature in the eastern Pacific Ocean, and the rainfall in the equatorial region will be concentrated in the Americas, while the rainfall in East Africa and the Arabian Peninsula will decrease significantly.

Just now, from 2017 to 2018, the world experienced relatively severe El Niño, which caused two years of severe drought in East Africa. The locusts also began to lay eggs during this period.

Now, the global warming trend is becoming more and more serious, and the carbon dioxide content in the atmosphere is increasing, leading to a continuous rise in the Earth's temperature and the rise of sea temperatures. However, the East Indian Ocean still receives cold seawater from the Tsushima Islands, so there is a significant temperature difference between the East Indian Ocean and the West Indian Ocean, so the cold air from the Indian Ocean began to blow to the West Indian Ocean. Considering the original equatorial region is a low-pressure belt, a large amount of humid and hot air converged in East Africa, and the rain fell more heavily in East Africa.

Unlike the cold air from Siberia, the cold air blown from the Indian Ocean also carries a lot of water, after arriving in the West Indian Ocean, it makes the rainfall in East Africa more heavy.

This rain led to the growth of vegetation, the grassland increased, and the locusts also increased, and the humans were harmonious.

This is the starting point of the large-scale locust plague. However, at that time, the vegetation was still very lush, and the rain was very abundant, so the locusts were safe and sound, and humans did not interfere with each other.

But the Earth is an integrated whole, and often when one place has a lot of rain, another place has less rain.

Because the Indian Ocean's El Niño phenomenon caused the Indian Ocean to become very dry, directly affecting the rainfall in Australia.

Originally, in the tropics, the temperature around Australia was already low. Coupled with the dry weather, the locusts thrived.

In addition, you can increase vegetation coverage to reduce the number of locusts. You can also spray highly, low-toxicity, low-residue locust-specific insecticides to minimize harm to the environment.

You can also protect and introduce local locust predators to carry out ecological prevention and control.

Finally, I hope everyone can safely get through 2020, and strive for a better future.

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