I hear the record is around 14.
Generally speaking, they take a couple / few years to reach maturity, and "average" lifespan is given at around eight years. So, if you get a WC adult from a petstore, don't count on getting more than five years out of it (my first emps made it one and two years, each).
Warmer conditions + more food = faster growth and shorter lifespan; cooler + not powerfeeding = slower growth and longer lifespan. Either extreme is not good.
