Aaron wrote - thinking no matter what is written, no matter how carefully, somebody's going to challenge it.
 
Well, Aaron, I won't let you down.
 
If I, as a commerial queen bee breeder, grafted larvae that was 48 hours old, I would be in big trouble.  My aim is less than 24 hours old.  How do I do this?  By putting in combs and taking them out after 4 days.  Yes, someone may quote research to say that eggs can hatch is less than 3 days but the general rule is 3 days.
 
There is work by Prof. Woyke from Poland that shows as the age of the larve increases, when you are rearing queens, the number of ovarioles decreases.  This then in turn means that the queen will not be able to lay the same number eggs in a day.  This then means less bees and therefore less honey gathered.
 
So, the younger the better.  Things like the Jenter system will deliver this but as a commerial breeder, the Jenter stystem does not allow me to produce the number of cells I require.  Also, it is too time consuming and, as others have posted, is not real reliable so it is not good for a commercial operation.
 
Of course, there are many other factors that will affect the quality of the queen produced but I can start by selecting the youngest larvae possible and therefore getting more ovarioles per queen.
 
By the way, was there ever a proceedings or papers published from the ABF seminar?
 
Trevor Weatherhead
AUSTRALIA