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> With their long cycles mainly underground, they are certainly weird:
> 
> https://www.smithsonianmag.com/science-nature/what-are-cicadas-180975009/?utm_source=smithsoniandaily&utm_medium=email&utm_campaign=20200603-daily-responsive&spMailingID=42652082&spUserID=ODg3NDcwNDQ2NDA1S0&spJobID=1780277901&spReportId=MTc4MDI3NzkwMQS2
> 
> "Cicadas spend the majority of their lives underground. They spend years developing into adults before they can emerge to sing, mate and lay eggs. For a majority of the nearly 3,400 cicada species, that emergence happens every two to five years and can vary from cycle to cycle. The strange periodical cicadas, on the other hand, are very different.
> 
> ***
> 
> "Periodical cicadas like Magicicicada spend 13 or 17 years underground, and millions of them surface together. To make sense of it all, biologists classify the periodicals into one of 15 existing “broods” based on their species, location, and—importantly—which years they emerge. This year, for example, Brood IX is emerging in North Carolina, West Virginia and Virginia for the first time since 2003.
> 
> ***
> 
> "But why do cicadas emerge in 13- and 17-year cycles, anyway? One hypothesis with much buzz among mathematicians is that it’s because both numbers are prime; the theory goes that the cycles prevent specialized predators from springing up. Cicadas are easy prey. They’re not hard to catch, Cooley says, and “anything that can catch ‘em will eat ‘em.” But predators, such as foxes or owls, whose populations cycle up and down every one to ten years can’t sync up with such irregular prey."
> 
> Comment: Totally unexplained as an instinctual behavior. The bugs did not teach themselves to do this.