How do you tell the caste of a bee pupa?

You can't easily tell the caste by looking at the pupa itself, but you can tell by the cell it is in. Drone cells are larger than worker cells and when the cell is capped the capping is domed above the level of capped worker cells. A queen cell is completely different. It projects out from the comb and hangs down, and is much larger than either a worker or drone cell.