Pictures like these are the reason why at present a check of the broodcombs should take place every 7 days. A swarming colony creates masses of swarm cells in which young queens grow up. They are not always in such an exposed place and easy to find as in this picture.

The super-organism honeybee follows its reproduction instinct: as soon as one of the cells is covered, the queen's departure with half of all bees can no longer be prevented.

 

Birth control therefore means for the beekeeper to find and break every single swarm cell.