Yogurt does work!
Normally, I harvest rogue swarm cells by carefully removing them from the frame, remove the queen pupae, and then pop the resealed queen cell in a bag and into the freezer until I'm ready to graft. That way, I have frozen fresh royal jelly at my disposal.
But, this year, I've had a problem with a lack of swarm cells. (What a problem, right?) My supply of royal jelly has dwindled and my dry grafting skills need some serious work. What to do?
Two options: Sacrificial larva in queen cups, placed in a starter nuc, and then harvest specifically for the royal jelly, which seems like a waste to me. Or, yogurt.
Per Dr. Larry Connor, plain yogurt, mixed 1:1 with water, provides a reasonable substitute for royal jelly for grafting purposes. Flavors will increase the chances of rejection, as will sugar-free variations. No comment was made about fat-free yogurts. A half a spoonful, mixed with room temperature water, will warm to room temperature quickly and prevent shock to the larva.
Is it "better" than royal jelly? Probably not. The nurse bees will eat all the royal jelly out of a queen cup and replace it with fresh, so by using yogurt, they'll be eating yogurt instead. By the way, lactose (milk sugar) has no nutritional value as a sugar for the bees, but the casin may provide "some" dietary protein.
Hope this helps!
DS