View full lesson: http://ed.ted.com/lessons/cicadas-the-dormant-army-beneath-your-feet-rose-eveleth

Every 13 or 17 years, billions of cicadas emerge from the ground to molt, mate and die. Adult cicadas only live a few weeks above ground, but you'd be hard pressed to ignore them -- they are extremely loud! Rose Eveleth explains everything you need to know about these noisy insects, admitting that there's still some things we just don't understand.

Lesson by Rose Eveleth, animation by Eli Enigenburg.