Why so precise? Aren’t they ever off by a year or two?
I’ve never understood this. As I said, we get them every year, but my understanding is that it’s different cicadas from year to year. I’ve always meant to find out more about them but never have.
http://georgiafaces.caes.uga.edu/storypage.cfm?storyid=2201
Link to a good story about the 17 year cicada that came out in 2004. Georgia FACES is a great place for information on plants and bugs and stuff.
I read somewhere that it may have to do with avoiding predators. If they emerged every year, predators would expect them and be ready to feast on them. If they were off by a year or two, it's likely they wouldn't find a mate and would die without reproducing.