April is swarm season. Honey bee reproduction does not take place at the ‘lay an egg, hatch a new bee’ level. It takes place when the colony as a whole decides that it is time to swarm. That decision is made by the entire colony – a superorgamism.
In the spring, when the colony broods up and has so many bees that they cannot physically co-exisit in a single hive the decision to swarm is made. First the nurse bees start nourishing a few newly hatched larvae with an exclusive diet of royal jelly. That rich diet triggers epigenetic differences in the larva resulting in the birth of a queen. The same larva on a different diet would become a worker bee. Same initial genetics + different diet = queen instead of worker.
Meanwhile the worker bees start harassing the existing queen. They chase her around the hive. They cut back on the amount of food that she gets. In effect, they put her on a diet and fitness regime. This allows her to drop weight and strengthen her flying muscles. When the time comes she will abandon the original colony, taking about half of the bees with her. This is a swarm. Off they go to form a new colony!
The swarming event is triggered by the capping of the first queen cell in the original colony. At that point the original colony is feeling pretty confident that a new queen is on the way. Out with the old queen and in with the new.
No one like to travel on an empty stomach
Before the swarm departs all of the departing bees fill up their stomachs with honey. They will need these resources to establish a new colony.
The swarm departs with a roar. Imagine the hum of 20,000+ bees taking flight. They pour out of the hive in a stream. They swirl around loudly in the air, and eventually coalesce into a bee comet that heads off toward a preselected bivouac site. If you’ve experienced it, you’ll never forget it. It is amazing!
At the bivouac site, they settle – forming a tight cluster. While clustered their brains reset. They forget the location of their original hive. They start to formulate a “what’s next” plan. What’s next is finding a new home.