Here in the United States, we’re suffering through a cicada plague. The insects lie dormant for 17 years, then dig themselves out of their little holes, mature, mate, lay eggs, and die. The little ones lie dormant for 17 years before repeating the process.
When I read about the 17-year cycle, I thought to myself, “Hmmm… 17 is a prime number. I wonder if there’s any significance to that?” It turns out that it’s very significant. By coming out on a prime year, the cicadas avoid predators that arrive in two-, four- and eight-year cycles. Read more about it here.