Bees that look like a huge mass, typically a football size or even a beach ball; are in the “swarming” phase.  Swarms are masses of bees that have split from another existing hive that still exists but now the swarm has a new queen.  The new queen takes flight to find a new place to live with about 1,000-10,000 bees flying around just like in the cartoons.  The bee swarm, unlike cartoon depictions, are actually in their most docile state.  The reason for the unusual friendliness is the fact that they are simply full of honey, not defending anything, and they are moving usually in a nice time of year.  So essentially they are fat and happy and really in most cases not able to bend their little abdomen around to sting a person.  They can still sting and can be very dangerous, but they are simply less dangerous than their normal.  That being said check out… to find out more about what to do what you are near a “Swarm” of bees.  Also swarms are a lot different than hives, check out… for more information on hives.  The main  characteristic to look for is white honey comb beneath them, and also take note of the time they formed.  Every day from the time they land in a tree is time to start building a hive. I have removed 2 foot x 3 foot hive out a of tree in  a Tempe home.  I have also removed Swarms in Scottsdale that started to build comb within 1 day!