The 13-and 17-year broods are maximizing their survival chances by using prime number intervals -- really! I have described the mathematics the evolutionary process is using in this article: https://frederic-38110.medium.com/prime-number-cicadas-really-96cdeca5c15d I also describe what a trillion one-inch cicadas would look like if they were lined up. They would reach reach to the moon and back – 33 times!