I don't know but I attempt to breed them every year. I have noticed that my oldest girls will often skip a year or two, I suspect that they eventually just stop laying. I recently lost a very old female that I suspect was either in her late 30's early 40's (I had her for about 13-14 years and I know the person who gave her to me had her for over 15 years and the snake was an adult when she got her) She didn't lay any eggs for the past 4 years despite breeding her every year.