Billions of cicadas to emerge from underground in US in rare event last seen in 1803

Billions of cicadas from two different broods are set to emerge from underground in the US this year in an ultra-rare synchronised event that last occurred in 1803.

The two different broods – one emerging every 13 years and another with a 17-year cycle – will emerge from the soil to mate for the first time in 221 years, scientists said.

Cicadas occupy almost every continent across the world except Antarctica and there are over 3,000 different species of the insect.

Such a dual emergence of the black-bodied, red-eyed, winged cicadas is ultra-rare, and billions of these insects from two broods are anticipated to crawl out of the ground from around late May to June to reproduce and start their life-cycle afresh.

The Brood XIII cicadas with the 17-year cycle, which last emerged in 2007, will crawl out of the ground in parts of Indiana, Iowa, Wisconsin, and possibly Michigan, but mostly concentrated in Illinois, researchers say.

Brood XIX cicadas, which emerge every 13 years, are set to spring out in 15 states across the country, including Alabama, Arkansas, Georgia, Illinois, Indiana, Kentucky, Louisiana, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina and Virginia.

By emerging only once in 17 or 13 years, the cicadas have managed to avoid predators above the ground most often.

Mathematicians have also found that the emergence cycle of the two broods being prime numbers – 17 and 13 – has also ensured that they do not interbreed and merge as frequently.

The cicadas in Illinois – home to both the broods – may create some unique challenges for entomologists this year, researchers from the University of Connecticut say.

While these bugs are not harmful to humans and can be a valuable food source for birds, in such numbers, their calls and their carcasses littering the ground can be a nuisance.

This rare once-in-a-lifetime emergence of the two broods together may also result in “an extremely rare opportunity for genetic crossing between 13-year cicadas and 17-year cicadas that could lead to the emergence of a new brood,” entomologist Floyd Shockley from the National Museum of Natural History told NPR.

The greatest likelihood of contact between these broods is likely around Springfield in Illinois, researchers say.

There may even be trillions of cicadas emerging this year, according to some estimates.

In 2024, with cicadas expected to emerge from Maryland to Oklahoma, and Illinois to Alabama, “trillions of adult cicadas will be present,” according to scientists at the University of Connecticut, however not all are expected to be in the same place at the same time.