Last happened in 1803

USA expects invasion of one trillion cicadas

From the end of April, there is a veritable cicada invasion in parts of the USA.

(Bild: kameraOne (Screenshot))

They seem to come out of nowhere. Not just thousands and thousands, but countless numbers of cicadas will lead to a veritable invasion of the insects, which are often mistaken for grasshoppers, from the end of April. Experts estimate up to one trillion (1000 billion, note) animals. The last time such a natural spectacle occurred was 221 years ago.

The background: In the Midwest and Southeast of the United States, two populations known as "Brood XIII" (Roman 13) and "Brood XIX" (Roman 19) will hatch at virtually the same time in 16 to US states. Both populations lie dormant underground for most of their lives. "Brood XIII" only comes to the surface every 17 years, especially in the north of the USA, while "Brood XIX" comes to the surface every 13 years in the south and south-east of the states. The last time both occurrences appeared together was in 1803 - when Thomas Jefferson was US President.

"No one alive today is going to see this again," Floyd W. Shockley, entomologist and head of collections at the Smithsonian National Museum of Natural History, told the New York Times newspaper. According to the researcher, it will take another 221 years before the geographically neighboring cicada populations will appear together again.

The insects are hatching earlier and earlier due to climate change.

(Bild: kameraOne (Screenshot))

Animals chirp up to 110 decibels loudly
The cicadas will emerge from the end of April. They use their forelegs to burrow into the ground and use their red eyes to search for a place where they can finish maturing in peace. A few days after hatching and moulting, the males begin to buzz to find a mate - a slowly building crescendo that can be up to around 110 decibels loud in chorus - even louder than the engine of a jet plane.

The shimmering, metallic buzzing that fills the air for four to six weeks after hatching can become so loud that conversation on the terrace is impossible. The loud courting of the males therefore requires iron nerves in humans ...

Hatching earlier and earlier due to climate change
The cicadas hatch when the ground warms up to just under 18 degrees Celsius, which, according to scientists, is happening earlier and earlier due to climate change. The insects, which are confused with the voracious but unrelated grasshoppers, are more of a nuisance than causing biblical economic damage. However, they can damage young trees and some fruit crops, but this is not widespread and can be prevented, according to experts.

There are 15 different broods that occur every few years in 17 and 13-year cycles. These two broods can actually overlap - but probably not interbreed - in a small area near central Illinois, according to entomologist Paula Shrewsbury of the University of Maryland.

Expert: "Not dangerous for humans"
The cicadas are not dangerous to humans - quite the opposite. "Instead of throwing them in the trash or picking them up with the sweeper, people should basically consider them as free fertilizer for the plants in their gardens and natural areas," Shockley told the New York Times.