More than 1,000 billion of these insects burrowed into the ground, causing America to fall into the biggest 'disaster' in 221 years.

Since 1803, this will be the first time insects of these two generations have appeared in America at the same time .

Rare event in 221 years of America

The New York Times estimates that this will be a rare event occurring in the United States from the beginning to the end of this April. More than 1,000 billion cicadas belonging to two different generations of cicadas will appear at the same time in about 16 US states. Many people say that this event is America's biggest "disaster" in 221 years.

Dr. Jonathan Larson at the University of Kentucky (USA) said that they are periodical cicadas (Magicicada) and are among the insects with the longest life cycles in nature. They are divided into two main groups: Brood XIX, or Great Southern Brood - a cicada that appears every 13 years, and Brood Northern Illinois, or Brood

More than 1,000 billion cicadas belonging to two different generations of cicadas will appear at the same time in about 16 US states. (Photo: CNN)

These two species of cicadas spend most of their lives underground and grow by sucking sap from tree roots. After a period of 13 or 17 years, they will use their front legs to dig and come out from the ground. A few days after emerging and molting, males will begin making noises to find mating partners, lay eggs and die within a few weeks, so they can complete the maturation process.

Floyd W. Shockley - an entomologist shared with Smithsonian Magazine that because 13 and 17 are both prime numbers, these two types of cicadas can only appear at the same time every 221 years . The last time these two groups of cicadas appeared together was when Thomas Jefferson was president of the United States. And this event also has another name: double emergence, Americans will witness more than 1,000 billion cicadas appearing in many places.

What kind of insect are cicadas?

Cicadas, also known as golden cicadas, are a super family of insects with large heads and wings with many stripes. There are about 2,500 species of cicadas in the world, in both temperate and tropical regions. Cicadas are the most well-known insects because of their larger size, special shape with large heads and the ability to make loud, gurgling sounds throughout the summer. In the Appalachian Mountains, Americans call cicadas "dry flies" because their carcasses remain intact and dry after molting. Cicadas do not sting, do not bite and are harmless to humans.

When they reach the final transition stage to end the larval period, the tick larvae dig a tunnel to the ground and emerge. (Photo: CNN)

After mating, female ticks dig small grooves into the bark of tree branches and lay eggs there. The female tick can do this many times until she lays several hundred eggs. When the eggs hatch, the tick larvae fall and burrow deep into the soil. When they reach the final transition stage to end the larval period, the tick larvae dig a tunnel to the ground and emerge. They then molt for the final time on a nearby tree and become adult ticks. The tick's body is still there and attached to the bark of the tree.

A few days after emerging and molting, males will begin making noises to find mating partners, lay eggs, and die within a few weeks. (Photo: CNN)

Unlike other insects, such as crickets, that make sounds by rubbing their wings together, male cicadas make sounds by vibrating two "speakers" made of thin membranes, growing from the thorax, with ribs. inside. The ribs are stretched rapidly, vibrating the thin membrane, creating sound waves. The cicada's abdomen is hollow so it can amplify the sound of the cicada very loudly. The tick shakes its body and uses its wings to create an up and down beat for its "song". Each breed of cicada has a different voice, intensity, and pitch - to invite female cicadas of the same breed.

Some species of ticks are capable of making sounds up to 120 dB, the second loudest sound among insects.

4 harmful effects of cicadas appearing in large numbers in the US

However, the presence of large numbers of cicadas in the US could cause serious harm to this country.

• Firstly , their noise is too loud, even louder than the sound of an airplane and can create terrible destruction.
• Second , these cicadas only live about 4 to 6 weeks and they die on sidewalks and streets, where they can be crushed by people or cars, making everything dirty and slippery. slip.

However, the presence of large numbers of cicadas in the US could cause serious harm to this country. (Photo: CNN)

• Third , these cicadas will suck tree sap, punch holes everywhere to lay eggs, which can cause heavy damage to trees and land, up to millions of dollars.
• Fourth , birds that normally rely on leaf-eating caterpillars for food will switch to hunting cicadas. However, this causes the number of caterpillars to increase, they will also eat the young leaves of the tree and cause great damage.

Do cicadas really only cause harm and no benefit?

According to entomology professor May Berenbaum from the University of Illinois, USA, in fact, people are afraid of the wrong insect species. The rise of cicadas is not as scary as we think. Apart from noise, cicadas do not bite, do not sting and do not carry any diseases. On the contrary, the holes they dig help the soil breathe and rainwater can easily seep into the ground to help nourish tree roots.

The holes they dig in the tree will cause the branches to break, but this is like a natural pruning method that helps the branches and fruits grow back bigger than before.

In fact, the presence of cicadas also brings some benefits. (Photo: CNN).

In addition, instead of cleaning up cicada corpses, people can use them as natural fertilizer to provide nutrients for plants.

That's why the Environmental Protection Agency (EPA) and some scientists have urged Americans not to try to kill cicadas in extreme ways. Instead, accept it as a magical event of nature that only appears temporarily.