It Only Happens Every 221 Years: Mysterious Phenomenon Begins – "No One Alive Will Experience This Again"

Experts claim that this once in a lifetime phenomenon which happens every 221 years has just begun.

This is a unique phenomenon that only happens every 221 years. It is currently captivating scientists and millions of people in the USA and looks like it will so for the next few months.

We are talking about the large swathes of cicadas that are currently sweeping the nation. These insects are quite loud and will swarm through forests and suburban gardens in the USA for about a month. Countless cicadas are emerging from the ground, where they have lived as nymphs for years. Interestingly, for the first time since 1803, two events will coincide this year: cicadas that emerge every 17 years, and those that emerge every 13 years. These two groups of cicada will appear simultaneously. 

Around the world there are more than 3000 species of cicadas. These small insects spend most of their lives as nymph underground, and it is only when they are fully grown do they come to the surface to mate. For some cicada species, this happens annually, but for other species, this happens every 13 or 17 years. This year is special as these two cycles will overlap. 

One thing that has puzzled scientists is why cicadas appear at prime number intervals. Dr. Zoe Getman-Pickering, an ecologist and program coordinator for the Energy Transition Institute at UMass Amherst, discusses the mystery in an interview with Spiegel and explains some scientific theories. "One theory suggests that cicadas developed during the ice ages when the surviving plants grew very slowly. Therefore, cicadas also developed this very slow lifestyle," she says. "Another theory is based on their sheer numbers. If a billion cicadas suck the sap from trees, it can damage the trees. If the tree dies, so do the cicadas. They must take enough sap to grow but not kill the tree, hence the slow growth."

The spectacle is accompanied by the deafening noise of many ready to mate, chirping male cicadas. Recently, the Newberry Sheriff's Office in South Carolina reported on Facebook: "There have been several calls about a noise in the air that sounds like a siren or a wail or a roar." It does get really loud! "In areas with high concentrations, when all the males chirp simultaneously, it can reach up to 110 decibels, which is close to the noise level of a jet engine," explains entomologist Floyd Shockley of the Smithsonian National Museum of Natural History. Experts compare the chirping of a single male cicada to the noise of a lawnmower or motorcycle.