The name 'Cicada' is a direct derivation of the Latin cicada, meaning "tree cricket". There is no word of proper English, or indeed Germanic, etymology for the insect.
The insect does not appear to have been chosen due to location as they exist on all continents except Antarctica.
Most of the North American species are in the genus Tibicen: the annual or jar fly or dog-day cicadas (so named because they emerge in late July and August).  The best-known North American genus is Magicicada, however. These periodical cicadas have an extremely long life cycle of 13 to 17 years and emerge in large numbers.  Another American species is the Apache cicada, Diceroprocta apache.
Male cicadas have loud noisemakers called "tymbals" on the sides of the abdominal base. Their "singing" is not the stridulation (where one structure is rubbed against another) of many other familiar sound-producing insects like crickets: the tymbals are regions of the exoskeleton that are modified to form a complex membrane with thin, membranous portions and thickened "ribs"
(Note. It is believed that the 'breath' sound at the beginning of the .mp3 file '761' is the sound of a large group of cicadas.)
Cicadas live underground as nymphs for most of their lives, at depths ranging from about 30 cm (1 ft) down to 2.5 m (about 8.5 ft). The nymphs feed on root juice and have strong front legs for digging.
In the final nymphal instar, they construct an exit tunnel to the surface and emerge. They then molt (shed their skins) on a nearby plant for the last time and emerge as adults. The abandoned exoskeleton remains, still clinging to the bark of trees.
A direct reference can be found to this in the parable clue (See 'What we know')
Some speculation has occured around this imagery and it's connection to the 'Übermensch' belief system, however this is purely speculation.
Connection To Primes
Many Cicadas have a life span of between 2 to five years, however larger cicadas have a much longer and more noted life cycle, emerging every 13 to 17 years. It is believed that cicadas are the only animal in nature besides humans able to count prime numbers, and it is believed that this life cycle is to avoid predators that may have even or shorter life spans. This however is disputed, as it begs the question why not other prime numbers such as 11 or 19? However some scientists believe 13 and 17 years to be important due to the larger gap between them
Quotes From IRC Channel
<lit_envoy> and this "Cicada"
<lit_envoy> why this bug?
<fasd> If memory serves cicadas only come out every 7 years or some other prime number
<scrounger> From wikipedia: "In the final nymphal instar, they construct an exit tunnel to the surface and emerge."
<Daffodilianv> Oh jesus
<scrounger> You mean to tell me that NOBODY who was "researching" this poem has fucking read the wikipediat entry?!
<scrounger> " They then molt (shed their skins) on a nearby plant for the last time and emerge as adults."
<scrounger> source: https://en.wikipedia.org/wiki/Cicada#Life_cycle
<Daomos> a lot of ancient beliefs about them
<scrounger> "The cicada is an ancient polyvalent symbol: resounding themes are resurrection, immortality, spiritual realization and spiritual ecstasy. "
<Daffodilianv> In China, the phrase 'to shed off the golden cicada skin'(????, pinyin: Jin Chán tuoké) is the poetic name of the tactic of using deception to escape danger, specifically of using decoys
<Daffodilianv> Golden cicada skin/golden mean/phi
<Lurker69> Safe periods for the emergence of cicada species on prime number cycles",
<scrounger> Hey, this is weird, and relates to the prime numbers again: "Magicicada is the genus of the 13-year and 17-year periodical cicadas of eastern North America. " https://en.wikipedia.org/wiki/Periodical_cicada
Socrates' Myth of the Cicadas
"Cicadas chirp and watch to see whether their music lulls humans to laziness or whether the humans can resist their sweet song. Cicadas were originally humans who, in ancient times, allowed the first Muses to enchant them into singing and dancing so long that they stopped eating and sleeping and actually died without noticing it. The Muses rewarded them with the gift of never needing food or sleep, but to sing from birth to death. The task of the Cicadas is to watch humans to report who honors the Muses and who does not." http://en.wikipedia.org/wiki/Cicada_(mythology)
A Few Links
This episode has some extra information about cicada's and prime numbers, which can help you understand it better.
The Code S01E01: "Numbers"
New link, old one deleted for licencing and all that (freedom of information)
Links broken, here's a working one:
https://www.youtube.com/watch?v=j7jfHM-mMC4 Cicada 17 - Numberphile
http://www.youtube.com/watch?v=M7kEpw1tn50 Encryption and HUGE numbers - Numberphile
Fell free to add more info
Check also this article: http://uncovering-cicada.wikia.com/wiki/Why_this_bug%3F_%28symbolism_of_CICADAS_and_INSTAR%29 (those two articles should be merged)