To rear queens on demand, beekeepers graft very young worker larvae from a donor comb into artificial cell cups mounted on a cell bar, then place the bar into a queenless, well-fed "starter/finisher" colony. Nurse bees, fooled into thinking they have lost their queen, flood the grafted larvae with royal jelly and draw the cups out into long, peanut-shaped queen cells. This scene models that grafting bar in 3D — from the moment of grafting through acceptance, feeding, capping and emergence.
Because all female larvae are genetically capable of becoming queens, the only difference is diet: a diet of royal jelly throughout larval life triggers full ovary development, while worker larvae are switched to pollen and honey after a few days.
A 3D cell-bar of grafted queen cups sits inside a starter-finisher colony: watch larvae get accepted or rejected, fed with royal jelly, capped with wax, and finally emerge as virgin queens.
Grafting success depends on larva age and nurse-bee strength. Accepted cups swell into peanut-shaped queen cells, get capped around day 3, and release a queen around day 10–11 of the compressed cycle shown here.
Set how many cups are grafted, the larva age at grafting, and the nurse colony's strength. Toggle royal jelly visibility and watch the acceptance rate, day counter and emerged-queen count update live.
Any fertilised worker egg or very young larva can become a queen — diet alone determines caste. A larva fed royal jelly exclusively develops functional ovaries; one switched to worker jelly and pollen does not.