As Mr. Bush and others have correctly claimed, the age of larva destined to become a queen is critical for a prime vibrant healthy queen. My problem is larva hours old are translucent, clear and invisible in the semi opaque liquid. When I see the jelly in the bottom of a cell, if I can?t see the larva with the naked eye, the larva are the best age. If I can see the C shaped white larva with the naked eye, the larva is to old for my use.
The stereo microscope easily detects the youngest larva for grafting. The scope readily makes visible the extremely tiny breathing tubes of the larva. I believe some beeks grafting larva are actually picking larva that I would deem to old to make the superior queens. If the larva is a white letter C, I consider to old. Translucent, clear larva are a guarantee to be under 24 hours. In other words: Clear larva is crown for the queen, white larva withers a queen before her time.
Some very successful queen rearing friends of mine, graft with a jewelers head band, the ones that have several magnified lens. These work great and are a fraction the cost of a stereo microscope. Some beeks use the large lighted magnifying glass, also a winner.
Point is: the better the view of the larva, the better the queen to be.
Van