Hi all
There is no question that the ability of a hb queen to maintain a productive colony decreases with her age:

> Embryo mortality is strongly affected by the age of the mother in the honey bee. In our study, the offspring of 2-yr-old queens show a 􏰆3 times higher mortality than the offspring of young queens. A negative correlation between maternal age and hatching rate of offspring has also been shown by Fox (1993), Hercus and Hoffmann (2000), and Kern et al. (2001).

> We have examined the inßuence of maternal age on embryo mortality and juvenile growth in offspring in 29 freshly mated (Y0), 29 1-yr-old (Y1), and 18 2-yr-old (Y2) queen honey bees, Apis mellifera L. (Hymenoptera: Apidae). Embryo mortality increased significant with maternal age (Y0 􏰀 9.1%, Y1 􏰀 12.5%, and Y2 􏰀 30.7%). Egg size declined signiÞcantly with queen age, did not affect embryo mortality

Al-Lawati, H., & Bienefeld, K. (2009). Maternal age effects on embryo mortality and juvenile development of offspring in the honey bee (Hymenoptera: Apidae). Annals of the Entomological Society of America, 102(5), 881-888.

The question remains: what cues initiate queen replacement, and why do some colonies fail to replace their queens in a timely manner. Christina Grozinger wrote in the most recent edition of "The Hive and the Honey Bee" --

> There has been dramatic progress in identifying and characterizing honey bee pheromones in the last ~20 years. However, this progress has led to many more questions. ... We have very little understanding of how these different pheromones interact to regulate worker behavior and colony demography. 

See Chapter 11 in: The Hive and the Honey Bee. Joe M. Graham. Dadant & Sons, 2015 

PLB

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