Insects called cicadas spend most of their lives underground.?

Question

Many come above ground every 13 years or 17 years. In North America, many people call these cicadas 13 year locusts and 17 year locusts.Why are there no 12 year, 14 year or 16 year locusts?

Answer 1

i've heard of 7-year cicadas. maybe they like odd-numbered years because they are odd insects.

Answer 2

13 and 17 are prime numbers. Hence a cicada cycle enables the cicadas to emerge in mass, without concern that other cyclical predators will be around.
In other words if they arose every 6 years, then they would fall prey to predators that arose every 2 years or every 3 years (2 x 3 = 6) or if they arose in 12 years they would fall prey to predators that were on 2, 3,4, or 6 year cycles. by wiating 13 years, only prey that are on a 13 year cycle can emerge and devour them. (and there arent any)

Answer 3

Magicicadas emerge in what's known as Broods -- which you can think of as families or tribes. Each Brood emerges in 17 (or 13) year cycles. There can be more than one Brood in a state or even the same area, which is why you have emergences happening every 4 years or less in certain areas. Broods never get a chance to interbreed, so they're usually genetically different than other broods, and are often comprised of different species (Magicicada is a Genus name not a species).

Everything you could ever want to know is at this website:
http://www.cicadamania.com/faq.html

Happy Reading!

Answer 4

Perhaps cicadas count only in prime numbers.

Answer 5

Yet, predators on a 1 year cycle just have all the fun they want :)