Michael Nagle/The New York Times

Swarms of buzzing Brood X cicadas will take center stage this summer, for the first time in 17 years.

May 13, 2021

Brood X Cicadas to Emerge in the Billions, Creating Chorus of Clicking

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Billions of cicadas are set to emerge from the depths of the soil by next week, hitting about 18 states around the country. This year, the cicada emergence will have three epicenters in the Washington D.C. area, Indiana and Tennessee.

These insects remain underground for 17 years, counting freeze and thaw cycles of the seasons that serve as an internal clock, emerging only when the soil temperature is an ideal 64 to 65 degrees Fahrenheit. This evolutionary tactic helps cicadas avoid predators for most of their lives. Cicadas emerge at slightly different times depending on the region.  

This year’s emergence is known as Brood X and consists of 17-year cicadas, which last emerged in 2004. With tens of billions of cicadas burrowing out the soil, the emergence of Brood X marks one of the largest-ever broods of 17-year cicadas to date. Their loud buzzing will dominate the sounds of the summer as they try to mate and reproduce. After their short stint this summer, Brood X will emerge again in 2038.

Though New York was slated to see swarms of cicadas as well, Prof. Jody Gangloff-Kaufmann, entomology, said they would likely be rare sightings due to dwindling cicada habitats and lowered populations.

The cicada’s irregular pattern of emergence is a result of its periodical life cycle. Cicadas begin as rice-shaped eggs embedded in small tree branches, where they feed on the sap of   deciduous trees, those that shed their leaves annually. Cicadas can feed from the roots, twigs or branches. 

The cicadas then fall to the ground and burrow into the soil until they reach a root system they can feed on. They feed on the root system for the number of years they remain underground, and emerge as nymphs that turn into adult cicadas above ground. As adults, the cicadas set out to mate and lay eggs, and die out four to six weeks after emerging. 

“Your shrubs just end up with lots of emerging cicadas and they’ll sit for a while once they’ve emerged out of that full shell, to expand their wings,” Gangloff-Kaufmann said.

In more popular cicada hotspots, the critters’ mating and reproduction can benefit their habitats. According to Gangloff-Kaufmann, by laying their eggs, cicadas help the tree through a process known as flagging. Young branches with eggs in them will die and fall off the tree, stimulating growth in much the same way pruning does by trimming some branches. 

Though New York might miss the sight of cicadas this year, it has been home to its fair share of cicadas. Cicadas burrowed out of the soil in the Hudson Valley most recently in 2012, according to Gangloff-Kaufmann. 

Gangloff-Kaufmann explained that scientists also tried to locate a population of cicadas on Long Island in 2004, but found no evidence of cicada activity. It is possible this population is locally extinct, Gangloff-Kaufmann said. 

This local extinction might be a result of cicadas laying a particularly small number of eggs, leading to an insufficient population of larvae for the next generation. Landscaping also destroys trees, the cicada’s natural habitat, which could have further eliminated cicadas from Long Island as seen previously with Brood XI in 2016.

Despite their large size, cicadas are harmless and even edible, according to the Cornell Cooperative Extension. The only thing to watch for is their noise: “When they’re all singing at the same time, it can be extremely loud,” Gangloff-Kaufmann said.

The noise, described as a sort of buzzing, serves as both a mating call and a predator repellent — the sound is painful to bird ears and disrupts their communication, preventing group hunting. In groups, 17-year cicadas can reach sound levels of up to 90 decibels, comparable to a lawnmower or air conditioner.  

The insects produce sound through a special organ called a tymbal, which contains a series of ribs that are capable of producing a rapid clicking that produces a buzzing sound.

Cornellians who are crossing state lines might see cicadas, but it will be nearly impossible to find one in Ithaca this spring.