Why do swarming honeybees usually sting less often?

Honeybees in a swarm rarely sting because they have departed their hive with a full stomach of honey.1

When a colony becomes crowded, the queen and a portion of the worker bees—typically numbering between 5,000 and 25,000—suddenly leave the hive to propagate a new colony. Because these bees are focused on this natural method of reproduction and are carrying significant food stores, they are generally less defensive than they would be when protecting an established nest.2314

While honeybees—including Africanized honeybees—will sting if they perceive a threat to their colony, they typically do not sting while swarming or while foraging for nectar and pollen.4