Whoa there!!! Bees are "cute" and all, but a bee swarm can be alarming.
Have no fear!
Call a local beekeeper if you ever have a swarm.
Swarms are formed when the beehive splits in two. One half of the honeybee colony stays behind (with all the honey stores, and new queen about to hatch) and the other half 1) gorges on honey, then 2) takes off together---with the old queen---and looks for a new place to live.
Honeybee swarms are usually very docile. They have no honey or home to protect...they are simply looking for a new home.
Chinese man sets the Guinness world record for the number of swarming bees on one's body: 1.1 million!