j -- emergences, are once in a lifetime. >> a million and a half could appear per acre, a trillion in all, rising when the soil temperature reaches 64 degrees. are they dangerous? no. although they can damage some small trees where they lay their eggs. are they edible? yes. >> that's the sound you want to hear. >> there are videos online offering recipes, like this one from the tennessee farm bureau. if you can stomach it. >> do i eat the eyes, too? a little crunchy, got a leg stuck between my teeth here. >> if you spice them right, they taste a lot like shrimp. >> why are there so many, because everything eats them. cicada stay alive because there are too many to be devoured entirely. will they be around long? no just a few weeks. >> they are only out as adults for that one thing, mate, lay eggs and die. >> will they bug some people? absolutely. there's even a new film this