If you live on the east coast of the United States, you've spent the last 17 years of your life walking, eating and sleeping above a dormant army of insects. These are the cicadas. Every 17 years, billions of them emerge from the ground to do three things: molt, mate and die. There are 15 different broods of cicadas out there, grouped by when they'll emerge from the ground. Some of these broods are on a 13-year cycle, others are on a 17-year clock. Either way, the cicadas live underground for most of their lives, feeding on the juices of plant roots. When it's time to emerge, the adults begin to burrow their way out of the ground and up to the surface, where they'll live for just a few weeks. During these weeks, though, everybody will know the cicadas have arrived. There will be billions of them. And they're loud. Male cicadas band together to call for female mates, and their collective chorus can reach up to 100 decibels -- as loud as a chain saw. In fact, if you happen to be using a chain saw or a lawn mower, male cicadas will flock to you, thinking that you're one of them. Now, like most things in nature, the cicadas don't arrive without a posse. There are all sort of awesome and gross predators and parasites that come along with the buzzing bugs. Take the fungus Massospora for example. This little white fungus buries itself in the cicada's abdomen and eats the bug alive, leaving behind its spores. When those spores rupture, they burst out of the still-alive cicada, turning the bug into a flying saltshaker of death, raining spores down upon its unsuspecting cicada neighbors. But while we know pretty precisely when the cicadas will arrive and fade away, we're still not totally certain of why. There are certain advantages to having your entire species emerge at once, of course. The sheer number of cicadas coming out of the ground is so overwhelming to predators, it is essentially guaranteed that a few bugs will survive and reproduce. And since cicadas emerge every 13 or 17 years, longer than the lifespan of many of their predators, the animals that eat them don't learn to depend on their availability. But why 13 and 17 years, instead of 16 or 18 or 12? Well, that part no one really knows. It's possible the number just happened by chance, or, perhaps, cicadas really love prime numbers. Eventually, the cicadas will mate and slowly die off, their call fading into the distance. The eggs they lay will begin the cycle again, their cicada babies burrowing into the earth, feeding on plant juice, and waiting for their turn to darken the skies and fill the air with their songs. In 17 years, they'll be ready. Will you?
Ako živite na istočnoj obali SAD-a, poslednjih 17 godina svog života proveli ste hodajući, jedući i spavajući iznad skrivene armije insekata. Ovo su cvrčci. Svakih 17 godina, milijarde njih izlazi iz zemlje da urade tri stvari: mitarenje, parenje i smrt. Postoji 15 različitih vrsta crvčaka, grupisanih na osnovu toga kada izlaze iz zemlje. Neke od njih su u ciklusu od 13 godina, neke od 17 godina. U svakom slučaju, cvrčci žive pod zemljom većinu svog života, hraneći se sokovima sa korenja biljaka. Kada je vreme da se pojave, odrasli će početi da kopaju nagore iz zemlje sve do površine, gde će živeti svega nekoliko nedelja. Ipak, tokom ovih nekoliko nedelja, svako će znati da su stigli cvrčci. Biće ih na milijarde i glasni su. Mužjaci se skupljaju da dozovu partnerke, i njihov zajednički zov može da dostigne i do 100 decibela, što je glasno kao motorna testera. Zapravo, ako koristite motornu testeru ili kosilicu za travu, mužjaci cvrčka će pohrliti ka vama misleći da ste jedan od njih. Poput većine stvari u prirodi, cvrčci ne dolaze sami. Postoje razne vrste sjajnih i odvratnih grabljivica i parazita koji dolaze sa zujanjem. Tu je na primer gljivica mazospora. Ova mala bela gljiviica se zakopava u stomak cvrčka i jede ga živoga, ostavljajući za sobom spore. Kada spore puknu, izlaze iz cvrčka koji je još živ i pretvaraju insekta u leteći slanik smrti koji ispušta spore na bezazlene komšije cvrčke. Ali iako prilično precizno znamo kada cvrčci dolaze i nestaju, još nismo sasvim sigurni zašto. Naravno, postoje određene prednosti kada se cela vaša vrsta pojavi odjednom. Sam broj cvrčaka koji izlaze iz tla je tako neverovatan za grabljivice da je u suštini zagarantovano da će nekoliko insekata preživeti i razmnožiti se. A pošto se cvrčci pojavljuju svakih 13 do 17 godina, što je duže od životnog veka većine njihovih grabljivica, životinje koje ih jedu se ne nauče da zavise od njihove dostupnosti. Ali zašto 13 i 17 godina umesto 16, 18, ili 12? To zapravo niko ne zna. Moguće je da je broj sasvim slučajan, ili cvrčci možda zaista vole proste brojeve. Na kraju, cvrčci će se razmnožavati i polako izumreti, kao i njihovo zujanje. Jaja koja polože će ponovo započeti ciklus, mladi cvrčci će se zakopati pod zemlju, hraniće se sokovima biljki i čekati na svoj red da zamrače nebo i ispune vazduh svojom pesmom. Za 17 godina, biće spremni. Da li ćete i vi biti spremni?