After
living 17 years in the ground, a swarm of cicadas ominously called "Brood
II" is set to come topside. And if you live on the Eastern seaboard,
you're in for a treat, as billions (that's right) of Magicicada
will swarm and mate, and, of course, "sing" loudly at night.
Buy some earplugs
so you don't have to say goodbye to a good night's sleep, then read on
for some neat
17 year cicada facts, from Dan Mozgai's very cool Cicada
Mania website:
They’ll attack land on you if you’re
using a power tool or lawn mower. Cicadas think the sounds
made by power tools and lawn maintenance equipment are made by cicadas.
They get confused and will land on the people using the equipment!
Cicadas have five eyes: Cicadas have two, obvious,
large, compound eyes, and three ocelli. Ocelli are three jewel-like
eyes situated between the two main, compound eyes of a cicada. We believe
ocelli are used to detect light and darkness. Ocelli means little eyes
in Latin.

Cicadas pee: Yes cicadas pee, so wear a hat when walking
under trees if that sort of thing bothers you. Cicadas drink tree fluids,
and then expell the excess fluid they do now need. People call it “honey
dew” or “cicada rain”.
There are billions of them: there are literally billions
of 17 year cicadas. Why? One theory suggests that the large number of
cicadas overwhelms predators, so predators are never able to eat them
all and cicadas, and many always survive to mate. This is a survival
strategy called “predator satiation”.
Stragglers: Periodical cicadas that emerge in years
before they are supposed to emerge are called stragglers.

17 and 13 are prime numbers. Scientist speculate that
one reason why these cicadas emerge in 17 or 13 year cycles is because
those are prime numbers. The fact that 13 & 17 are relatively large*
prime numbers makes it difficult for predators to synchronize with them.
(*Relative to the average lifespan of an animal.) Annual cicadas (cicadas
that arrive every year) often have wasps specialized to prey on them;
periodical cicadas have no such wasp because no wasp could evolve to
synch with it.
17 year and 13 year broods co-emerge every 221 years.
Cicada Broods usually don’t overlap geographically, and it is
very rare when they emerge in the same year. The next time Brood II
(the brood emerging in 2013) will co-emerge with another brood will
be in 2115 when it co-emerges with Brood XIX. You might need a time
machine to see that happen.
Read more over at Dan's website: Link