When a bee colony becomes too crowded the workers start raising a new queen, as the new queen hatches out the old queen will leave with about half the workers in the colony. these bees are generally harmless as they have no brood to protect and have gorged on honey before leaving the hive. almost none of those bees will be males, the drones (males) are unproductive to the hive other than mating with a queen, this hive will need wax and honey production right away thus mostly workers. the hive will send out a scout to find a suitable location for a hive and go to that location, but only fly as far as the queen can go between brakes. You can catch swarms with lemon grass oil soaked into a rag in a box attached to a tree, the scent will attract the scout. the queen also helps keep the hive mellow by her pheromones, my hives that lose a queen get very aggressive.
