If you do find actual cicadas, generally what you'll find is corpses. Apparently, sitting in the ground is the main thing that keeps them alive for 17 years. Once they're out of the ground, they find it much easier to die than to do anything else. Their body structure isn't really strong enough to support its own weight -- and neither is the structure that holds their wings on their body. So the cicadas climb up out of the ground, onto the nearest structure (be it tree, mailbox, or random wall), spread their wings to take off -- and then plummet to the ground where they go squish.
Or at least, the ones that haven't been eaten by the time they take off plummet to the ground and go squish.
There are several clusters of cicada bodies around the building here at work; and while it's kinda creepy to see cast-off shells and several fat black red-eyed grasshoppers clinging to the walls, it's also strangely sad to have to watch where you walk to avoid stomping on the pathetic remains of these one-hit wonders of nature -- the whole time still watching where you're going so you can duck when one of them randomly comes buzzing towards you at roughly 2 m.p.h. ... then smacks into a tree or just gives up and collapses to the ground.
It's hard to imagine that this bizarre species manages to survive long enough to reproduce; I can only guess that the survivors must produce a ton of offspring to make up from the DOA nature of their emergence.
Life is mysterious. :)