Certain groups of cicadas only rise to the surface to breed every 17 years. I remember a huge group several years ago, and here comes another. When the soil temperature begins to steady in the mid-60’s, “Brood II” magicicada nymphs will hatch underground and crawl to the surface by the billions.
While not every cicada species hatches in 17-year patterns, these particular “broods” may follow the pattern to avoid predators predicting their arrival or to keep from going extinct during long periods of cold weather. For many of you, this may be the first time in your life that this group has hatched.
Let Cicada Mania (yes, that’s a real website) tell you how to see this year’s “periodic cicadas”,
some theories of cicadas and prime numbers, and
Help WNYC and Radiolab track soil temperatures with home-made cicada thermometers, and follow the Swarmageddon in real-time.
via It's OK to be smart.