17-year-old cicadas are coming – NASA and meteorology could tell us when


I remember living in Maryland as a scientist at NASA’s Goddard Space Flight Center. In 2004, there were warnings about the emergence of cicadas. It really happened, and it was so cool to experience it. Within days to weeks, the 17-year-old cicadas known as Brood X will reappear. This particular set of cicadas is called a periodic species. According to Penn State University Extension Website, “Periodic cicadas are native to eastern North America and emerge en masse in huge nests” and are often confused with annual cicadas. Although relatively harmless, emerging insects can certainly be a nuisance. What fascinates me is that two things dear to my heart can help predict their emergence: NASA and meteorology. Let me explain.

Seven species of North American periodic cicadas are known. They include 13- and 17-year-old cycle species associated with the genus Magicicada. According to NBC News writer Sebastian Echeverri, “The emergence of this year is a group containing the three species of 17 years.” When they emerge, it’s a dense and noisy affair. 1.5 million cicadas can occupy an area as small as 1 acre according to scientists at Virginia Tech.

What factors determine their emergence at the end of the 17-year cycle? University studies suggest that the critical tipping point for the emergence of periodic cicadas is when the temperature of the soil 8 inches below the ground reaches 64 degrees F. Scientists have also linked warm rain to their emergence. According to Cicadamania.com website.

This is where NASA comes in. David Mocko and Eric Kemp recently described a modeling system that provides soil moisture, soil temperature, snowpack, and other types of land information. . Posted on a NASA website, their blog notes, “Phase 2 of the North American Land Data Assimilation System (NLDAS-2) is handled daily by NOAA’s NCEP central operations … (and) generates these fields by running multiple models. Surface Land Survey (LSM) which are forced with high quality surface observations including rain gauge analysis. The above graph, although not published academically by NASA, shows ground temperatures 10 to 40 cm (3.94 to 15.75 inches) below ground level from NLDAS-2. Although below the 64 degrees F point, this data from April 22 suggests that emergence may only be a few days to a few weeks. The graph below compares the ground temperature near NASA’s Goddard Space Flight Center to or near emergence points in 1987, 2004, and 2021.

The NOAA Climate Prediction Center predicts above normal temperatures for the next few days in the eastern United States. This backdrop and a rainy day will they be the stimulus for the cicadas. Only time will tell. We have a freezing point, a boiling point and a dew point. It is clear to me that we also have a “cicada point”. I wonder if the little bugs are humming, “I’m Coming Out,” by Diana Ross. It’s a great song, and it fits the moment.


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