Unexpected emergence of 17-Year Cicadas — 4 years early

Daylife/AP Photo used by permission

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Periodical cicadas, insects best known for their 17-year long life cycle, are emerging four years early in several Atlantic states. The emergence was first noticed in Greensboro, NC, on Monday and has since been reported in Maryland.

“This appears to be a four-year acceleration of the periodical cicada Brood II,” said Dr. Gene Kritsky. Kritsky is an expert on these four-year early emergences being the first to predict an early appearance of the cicadas in 2000.

“It is thought that the timing of the emergence is determined during the first five years of the underground development of the juvenile cicadas.” Kritsky and his students monitor the cicada growth by digging up the insects each year. “We discovered that many cicadas were growing faster than expected, which led the prediction of their early emergence in 2000,” he said.

The emergence this year is the fifth 17-year cicada brood to appear early. Kritsky described the early appearance of Brood I in 1995 in eastern Ohio and predicted the early appearance of Brood X. Brood XIII appeared early in parts of Chicago in 2003 and Brood XIV accelerated in parts of Indiana and Ohio in 2004. This year’s acceleration is overlapping with the distribution of Brood II.

The cause of these early emergences is unknown, but Kritsky, in a paper to be published in the Proceedings of the Indiana Academy of Science, has found evidence suggesting that mild winters can affect the trees that young cicadas feed upon which in turn interferes with the cicadas’ timekeeping resulting in their emerging early. “This phenomenon might be another biological response to increasing temperatures,” Kritsky said.

People witnessing cicadas this year are encouraged to report their cicadas on mapping websites, at www.msj.edu/cicada.

Cicadas are one of those omnipresent bits of background life to summer in many climate zones and continents. On one hand, I kind of like their sound because it reminds me of early days in the hills near the Hudson River in upstate New York. On the other, I mostly miss the sound, nowadays, because of my tinnitus.

The relationship of climate change to periodicity is understandable. If you realize the essential premise of interrelatedness of events and processes that is ecology, side effects are never a surprise. Though, understanding all the links ain’t always so easy.