</font><font color="blue" class="small">( I think at this point, they lay eggs in the ground, which stay there for 17 years )</font>
They will lay eggs after mating and then after the eggs hatch, the nymphs will crawl down the tree and burrow in the ground. They will "live" underground living off the roots of the trees. In 17 years, they will come back up and do their last deeds before death. Not that short of a life -- slightly longer than the average dog's life.