UNION COUNTY, NJ — Don’t be alarmed if you start hearing piercing sounds and seeing the brown shells of insect bodies on the ground next month.

JD Stamler, a park naturalist at the Trailside Nature & Science Center in Mountainside, said some of the periodical cicadas in Brood X will emerge from the ground in Union County after 17 years in late May and early June.

“I fully expect to see some in the [Watchung] Reservation,” Stamler said, “but I don’t think you’ll be swatting them off your car.”

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Cicadas are red-eyed insects with black and orange bodies, Stamler said. “They spend 17 years underground just to live above ground for about a month.” 

Due to their naturally short lifespan, Stamler said the last cicadas should be gone by the middle of August.

Where will I find cicadas? Stamler said more cicadas will be seen in Somerset or Hunterdon than Union County. In addition to Watchung Reservation, he said it’s “absolutely possible” for the insects to emerge in trees in the yards of homes in the county. 

“A female cicada cuts little tiny slits into living branches or twigs to lay eggs,” he said. “Wherever you have trees you have the potential of cicada eggs.”

According to Stamler, cicadas only feed on deciduous trees, those which lose their leaves. They would not be found on pine or evergreen trees.

George Hamilton, the chair of Rutgers University’s entomology department, said Princeton, Morristown and Milford are likely to be cicada hotspots.

Weren’t there cicadas here less than 17 years ago? Periodical cicadas, like those in Brood X, hatch underground and feed on tree roots until they break through the soil after 17 years, but annual cicadas are also seen and heard in New Jersey every year. 

The state is home to three broods, or year classes, of cicadas, Stamler said. Brood II cicadas were seen in Westfield in 2013 and, according to the naturalist, Scotch Plains was swarmed with cicadas when Brood XIV emerged in 2008. 

What will cicadas leave behind? Adult cicadas that break through the ground when it is warm enough will leave behind the brown exoskeleton of their nymph stage, Stamler said. 

Once adult cicadas mate, they may live to mate again but will die within a few weeks, according to the naturalist. This means it’s possible for a yard with a tree line to have many dead cicadas that can be removed. If there are only a few dead cicadas on the ground, they will break down in a couple of months, he said.

Baby cicadas will drop hundreds of feet from the trees, and will then burrow underground to drink the sap of tree roots.

How do cicadas sound? Male cicadas will go into trees and sing to attract mates, according to Stamler. 

Hamilton, the entomology professor, said the sound is “deafening.” Stamler said the sound can be “as loud as a lawnmower or a motorcycle,” and added that the chorus of Brood X cicadas is sometimes thought to sound like a slow yell of the word “pharaoh.”

Will cicadas hurt me (or my pet)? Cicadas do not have a stinger and only feed on tree sap, Stamler said. “They are not known for biting people at all,” he explained. 

He said the insects can be consumed by any carnivore, from foxes to dogs to the occasional curious human, which is one reason they come out in large numbers.

“Dogs eat cicadas,” said Stamler. “I wouldn’t encourage them, but if it happens, it’s OK.”

How many cicadas should we expect? Both Hamilton and Stamler said it is difficult to predict the volume of cicadas that will emerge this year.

Hamilton said the insects were more evenly distributed throughout the state in the past, but “as we’ve developed, we’ve taken more of their habitat away. In certain places, they’ve gone locally extinct.”  

Stamler also said scientists suspect the cicada population may be declining and will be doing mapping to track the numbers this spring. 

“The best way to help is to limit your town’s footprint, preserving open space,” he said. “One strip mall could be removing thousands to millions of cicadas, depending on its size.”