OK, here are the facts. On 3 July I moved a queen out of a double brood colony into a nuc where she is still to be found. I moved in some grafts on that day (into the middle of the top box) and will distribute the resulting queen cells to Apideas tomorrow, the day before they are due to hatch. On 10 July we grafted again into the four spaces in the bar, alongside 5 good mature Q cells.

Today, no Q cells being drawn from the four grafted 3 days ago (the cups are empty), no unsealed brood in the colony apart from a couple of drone cells and two of these:



One was on the frame adjacent to the grafts, one on the next frame along. On the bottom bars of the top box in this double brood colony.

What on earth?! Most likely explanation seems workers moving the grafted young larvae into queen cups elsewhere in the box. I'm almost tempted to graft from an Italian-looking stock to see if they do it again with a stock of different colour. Other explanations could be drone eggs laid by workers (they don't look like them but I'll grow them on to check), or thelytoky (Google it if you need). I can't imagine that a queen would visit just to lay a couple of eggs.