Did you know that those things are 17 years old when you finally see them? All that noise they make is part of the mating ritual, after which the fertilized eggs are buried in the wood at the tops of the trees. 17 years later, they hatch and start over again. You hear them every year, but that year's crop is 17 years old. Big rascals, too, although I might just be spoiled by the short growing season here in Michigan. Not many of our insects have a chance to get big like they do down south or in the tropics.