Cicada Invasion of 2021

Every 17 years there is a massive invasion by the 17-Year Cicada, an insect that emerges from the ground after 17 years, massively invades the trees of the Eastern US, screeches loudly and endlessly for several weeks, mates, lays eggs in the tree tops and dies. After a few weeks a nymph emerges from the egg, drops to the ground, burries itself, and emerges 17 years later. There is also a brood of 13-Cicadas which emerge every 13 years. 13 & 17 are prime numbers, and the two broods only emerge to compete for resources once every 221 years. Prime numbers. Got to love it!