June 16, 2021

Cicadas Peak Before Disappearing Until 2038 

By Donald Gilpin

The millions of cicadas that have emerged in Princeton over the past few weeks have filled the trees, covered sidewalks and yards, and steadily increased the volume of their chant.  With few still emerging from the ground, however, their visit, the first in 17 years, will soon come to an end as the remaining adults die off and the larvae return to earth to begin the next cycle.

Commonly viewed as noise pollution, creators of a rancid odor, a threat to young trees, a mess of broken wings and exoskeletons, or a flying menace, the Brood X Magicicada is nothing short of a miraculous gift in some people’s estimation.

The emergence of the cicadas over the past month was described by Princeton High School (PHS) junior Mulin Huan as “an absolute wonder and the stunning result of natural choice.” A member of PHS science teacher Mark Eastburn’s cicada research team, Huan, who is co-leader of the school’s Insect-Eating Club, sees the cicadas as an ecological blessing, a badge of honor for Princeton, an unparalleled opportunity for research, and a nutritious, tasty treat for animals and humans.

“These cicadas invested all of their evolutionary points to increase their numbers to ensure the survival of their kind,” said Huan. “I am absolutely floored by the emergence of so many cicadas.”  Huan noted that in his former home in Beijing, the cicadas came out in large numbers and loud volume every summer, “but that is nothing compared to the huge emergence in Princeton in 2021.” 

Marveling that these insects are almost as old as he is, Huan pointed out, “With their emergence, they are bringing previously inaccessible nutrients from deep underground to the surface of the earth, which is great for the ecosystem all around. They feed animals and after they die, their bodies fertilize the ground.”

Whichever side you’re on, by July 1 this controversy is likely to go underground with the cicadas until their next emergence in 2038. “We’re probably right around the peak right now,” said Eastburn on Monday, June 14. “I’m not seeing many more emerging, and the adults live only about three weeks after emerging, so by the beginning of July, the newborns will have hatched and burrowed and they’ll be gone.”

He added, “They’re not going to be with us much longer. I’d like people to appreciate them while they can. We’re not going to hear them again for 17 years.”

Eastburn and his high school student researchers have so far collected thousands of cicadas, which they have stored in a seven-cubic-foot freezer that’s about two-thirds full.  They hope to fill it before the end of this emergence.

“We’re collecting as many as we can and we’re going to do the DNA test,” Eastburn said.  Because the opportunity for direct research comes only once every 17 years, a great deal is not known about cicadas, he noted.Eleventh grade PHS researcher Anna Schwartz is focusing on the cicadas’ songs and the kinds of trees that they prefer.  “We have frozen many cicadas so next year, even though the cicada emergence will have ended, we’ll be able to continue the research. In the future we hope to conduct genetic analysis of the cicadas and to study microbiomes of the cicadas.”

The research questions and possibilities are unlimited.  “There is so much data that we have the opportunity to collect,” said Eastburn, pointing out that there were at least two and possibly three different species of cicadas present in Princeton.

“The two species look similar, but they have very distinct songs,” he said. “Apparently they don’t inter-breed, but I’m not sure how closely related the species are. The research hasn’t been conducted on that, but I have students who are eager to make that exploration now.”

Eastburn noted the differences between the songs of the two different species. “One has a higher pitched kind of a whirring sound, and the other has a much raspier, hissing, rattling kind of sound,” he said.  He and his students will be making a day-long recording in one of the student’s backyards this Friday, which is supposed to be a warm day favorable for cicada singing.

“Originally the cicadas were calling kind of randomly, here and there,” he continued, “but now they’re synchronizing all their songs together so it sounds like continual waves, like waves crashing. It seems to start the day with random sounds then synchronizes as the day goes on. The males are competing with each other for females, and whoever has the loudest voice wins, but then at the same time they start to synchronize their sounds. Is that so they don’t drown each other out? Or do they have some other cooperative behavior that we never anticipated?  It’s going to be exciting to see.”

In seeking to promote the cicadas and help people appreciate them more, Eastburn and his students have held two cicada-eating events in the past few weeks, “as an opportunity to let people know about the environmental friendliness of these incredible animals and to promote the benefits of insect eating as well as the importance of preserving these cicadas so that they stick around in the long run,” said Huan.

Junior Matthew Livingston, co-leader of the PHS insect-eating club and host of the cicada-tasting events, embraced the “opportunity to make lots of different food to feed people so that they could be introduced to the idea of insect eating and then move on to eating more insects for both nutrition and sustainability reasons.”

Livingston and his fellow club members made cicada cookies and brownies with ground up cicada powders, as well as whole cicadas roasted, deep-fried, stir-fried, in a stew, in banana bread, in pumpkin bread, and covered with chocolate. 

The events attracted dozens of people and significant TV coverage, “which was a great way to inform the public about the benefits cicadas can bring, especially as a sustainable alternative protein source that provides tons of nutrition as it is packed with protein and some essential minerals as well,” said Livingston.

Livingston administered a survey and discovered that people preferred their cicadas with strong masking flavors — chocolate-covered, deep-fried, stir-fried or in cookies or brownies.

Huan added that people definitely preferred not seeing the actual bug when eating it, and he went on to point out, “While it might seem conflicting that I said I’m trying to promote the preservation of these cicadas while eating them, we are only eating a tiny, tiny fraction of the overall cicada population. There are 1.5 million emerging every acre and we are only taking a few hundred.” 

Eastburn emphasized the success of the two cicada-eating events. “I was amazed to see how many students came out,” he said. “Many came and tried insects for the first time, including my wife who is not a fan of insects or insect eating even though we’ve been married for 20 years. We had many people holding and touching cicadas for the first time.”

Another aspect of the cicadas investigated by the PHS research team is a particular fungus that Eastburn anticipates learning more about through future study. “We don’t have a lot of information on the process by which it infects the cicadas, gets into the abdomen, takes over the brain, and makes them try to mate with as many other cicadas as they can find. Becoming infected with the fungus, they spread it to as many other cicadas as they can.” 

Whether they were infected with the fungus underground, whether they attract the fungus after they emerged from the ground, and whether the eggs are infected with the fungus are all questions that Eastburn and his team will be able to investigate more deeply with their frozen cicadas.

“We still don’t exactly know how the cicadas are infected,” said PHS sophomore researcher Debolina Sen. “Only now do we really have the tools (genetic testing) to test whether this fungus resides within the cicada’s body for 17 years or if it infects as the nymphs climb to the surface through infected soil. This fungus grows and eventually is capable of splitting their abdomens open, but these cicadas still carry on with their regular life and spread the spores of this fungus everywhere they go.”

Eastburn urged local residents to “take the opportunity to appreciate something that’s really unique to Princeton. There are so many cicadas covering the community thanks to Princeton having a lot of old trees. The fact that Princeton has preserved its heritage and preserved its old trees means that cicadas have been able to continue living here. It’s a testament to Princeton’s heritage and environmental consciousness because we haven’t done anything to harm these cicadas or destroy their environment.”