Cicadas and Prime Numbers

The cicadas are coming. The map shown has Washington on the edge of the "Brood X" area. I was around during the Brood X's last visit in 1987 and remember that they were everywhere. If Washington is on the edge, I can only imagine what the heart of the area will be like.

The Economist has a science article about the current brood which discusses with a model that suggests

that prime-numbered lifecycles could help cicadas avoid damaging “resonances” with the two- and three-year population fluctuations of their predators... over a 200-year period, average predator populations during hypothetical outbreaks of 14- and 15-year cicadas would be up to 2% higher than during outbreaks of 13- and 17-year cicadas. That may not sound like much, but it is enough to drive natural selection towards a prime-numbered life-cycle.