As those who live among them will know, the 17-year insect, the cicada, emerges en masse this year after five larval stages, mates and dies. They are an ongoing puzzle:
In 1665, the first volume of Philosophical Transactions of the Royal Society included a report from New England concerning “swarms of strange insects, and the mischiefs done by them”. Charles Darwin also puzzled over them. Even now, entomologists are trying to understand how the insects’ peculiar life cycles evolved, how they count the years underground and how they synchronize their schedules. “They are one of the big ecological mysteries out there,” says Walt Koenig, a behavioural ecologist at the Cornell University Lab of Ornithology in Ithaca, New York.
… some researchers have proposed that the cicadas have evolved life cycles around prime numbers of years because that arrangement limits the chances that predators will synchronize with the cicadas.
Maybe, but it means that any mistakes they make will take 17 years to get fixed. Not like yer average fruit flies. Yet that hasn’t harmed the species much.
It does make them difficult to study. You’d be lucky to see three swarms in a typical career.