Cicada Science
- Sudeepto Roy | Klish Way
Summer on the east coast this year has a unique buzz about it. From Illinois to Georgia, fifteen states are experiencing the once-in-17-years emergence of a special species of large red-eyed bugs – the periodic cicadas, also known as Brood X (Ten). Scientists estimate that the hibernating cicadas emerge from the underground in their trillions. And at these numbers and penchant to procreate loudly, their din can exceed that of lawnmowers. They don’t sting, bite or bear poison.Yet, some people dread the emergence of the cicadas. They are strange-looking, noisy, smelly and show up in unfathomable numbers. Yet others have written cookbooks or dipped them in chocolate for protein-filled desserts.
Typically in May, when the soil temperature hits 64 Fahrenheit, adult nymphs emerge and head upwards, literally climbing anything in the way, from trees to walls, in a desperate attempt to avoid ground predators. They soon develop their wings, get to the treetops, waiting for the males to woo them. And woo, the males can, by flexing their drum-like abdomens, giving rise to their loud signature noise. Once impregnated, the females lay eggs in lower branches, which eventually hatch, dropping the nymphs to the ground, who quickly burrow, seeking safety of mother earth for the next 17 years.
Why 17? Let me give a hint. It is a number that is divisible only by itself and 1. This is nature’s way to beat the odds of predators that procreate in other periodic cycles (every 2, 3, etc, years). In other words, cicadas have found a way to use a prime number cycle to increase the odds of not being eaten. The other trick is to emerge in synchrony in trillions, further increasing the odds of perpetuation.
This awesome spectacle of nature lasts only six weeks. Six weeks every 17 years, like clockwork, reminding us of nature’s magical ability to harness both synchronicity and periodicity for species survival. However, given their ability to sense soil temperature, they are unwitting alarm clocks for climate change. Particularly in recent decades, they have begun emerging ahead of schedule. Cicadas were unheard of in April, but now they do appear earlier, since in some places the soil becomes warmer sooner, with shorter winters and earlier arrival of spring and summer. Disrupting the cycles of these important pollinators and nature’s once-in-17-year feast for birds and critters can have unpredictable consequences. These insects have been on our continent for millions of years, far longer than humans. As we marvel at their arrival this year, one can also hope that we will take a moment to reflect on our role as better custodians of the planet’s natural rhythms.