>> But it is clearly a problem of "modern times", as my 
>> average and outlier useful queen lifespans have gone 
>> down as compared to even the late 1980s and early 1990s. 

> What evidence do you have of this? None, I would guess.

As I mentioned, I do not just had evidence, I have graphed my bell curves of
queen "useful lifespan".
Anyone who keeps adequate records certainly has sufficient evidence about
their own requeening.
What do your own records tell you, if you keep any?
Call me narrow-minded, but I think that anyone who can't afford a spiral
notebook, a #2 pencil, and the time to take notes can't really call himself
a beekeeper.

Dr. Jeff Pettis also has data, and was very candid in his talks in 2013 and
2014 about this specific issue.
He has not seen a 4-year old queen with his own eyes in a decade.
He has seen lots of drone layers who were well-mated but had dead sperm in
their spermethicas. 

It would appear that Dave Tarpy, who was just quoted, also agrees with me:

"Thus, we do not currently have evidence as to why the perception among
beekeepers is that overall queen quality has diminished in recent years.
Therefore, it is likely that if queen quality is an important factor in
honey bee management, then testing the numerous environmental factors that
can influence queen productivity after mating should take priority."

So, I find shorter queen productive lifespans, Jeff Pettis finds
"well-mated" queens with dead sperm, and Dave Tarpy wants to look at
post-mating factors to try to figure out what is happening with queens.
Sounds like my concerns are shared by others.

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