Prime numbers aren’t just reserved to the ivory towers of pure mathematics – they are also the key to survival in the natural world.

In certain forests in America you can find special insects who depend on prime numbers for their survival. Called cicadas, these insects hide in the ground for years, then appear for six weeks: they eat, have sex, party, shrieking away so loud that the noise in the forest reaches volumes that make a disco sound like a library. Then after laying their eggs ready for the next generation of partying cicadas, they die.

The curious fact is that cicadas choose a prime number of year to stay hidden underground before they emerge for their six week party. Why primes?

It is believed there is a competitor – perhaps a poisonous fungus or parasite – that is deadly to the cicada. The competitor also emerges once every so many years. A prime life cycle for cicada guarantees that it will avoid the preditaor most often. In Nature we find the Magicicada septendecim (with a 17 year cycle) and the Magicicada tredecim (with a 13 year cycle).