Why Do Honey Bees Swarm? 
Swarming is a term used when a portion of a hive - worker bees, a queen and possibly a few drones leave and look for a new home. The main reason for swarming is overcrowding in the hive.  In San Diego, swarms usually occur between February and August, but swarms can occur at other times of the year.  A swarm may contain from 2,000 to 30,000 bees. This instinctive process is nature's mechanism for colony reproduction. It's a good thing. 
 
What is the Difference Between a Swarm and a Hive? 
A swarm is a group of bees that recently left the "œmother colony" that has not yet found a new hive.  Swarming bees leave their hive, fly around briefly, and then cluster on a tree limb, shrub or other object. Swarms are usually football shaped. The queen is in the center of the cluster, protected by the other bees from both predators and the weather. Swarms usually remain in a cluster for an hour to a few days, depending on the weather and the time needed to find a new nest site by scouting bees. When a suitable location (such as a hollow tree) is found for the new colony, the swarm breaks up and flies to it. 
 
When a swarm finds a new home, the swarm moves in, starts building comb and becomes a hive.  Swarms are temporary. Hives are generally permanent (unless the bees are removed or die out). 
 
Are Swarms Dangerous? 
While swarms look very frightening, the bees in a swarm are usually very gentle and rarely sting unless directly provoked. For your safety, please keep your distance until a professional arrives.
 
Are Bee Hives Dangerous? 
Bees will defend their home, queen and young. Bees in a hive are more likely to sting than bees in a swarm. 
 
What Should I Do if I Find a Swarm or a Hive on my Property? 
If a swarm lands on your property, do not disturb it. If you do nothing, most likely the swarm will move to a new home in 1-3 days.  However, if you would like the swarm removed, contact a beekeeper for removal. 
 
If you find a permanent hive on your property, you may want to do nothing, allowing the hive to continue to exist if the bees are not creating a problem. However, if the bees are aggressive, or are located in an undesirable location, contact a beekeeper for removal. 
 
Can Swarms and Hives Be Removed Without Killing the Bees? 
Swarms can almost always be removed without killing the bees (the possible exception might be overly defensive bees). 
 
Many (but not all) hives can be removed without killing the bees.  Hive removal involves much more work than swarm removal. Whether or not a hive can be removed without killing the bees will depend on where the hive is located, and whether the bees are overly defensive.  
 
When a hive is removed, all bees, honey and comb should be removed.  Honey and combs must be removed to avoid rodents, insects and possible property damage.  Bees must also be prevented from re-colonizing the same area.
 
When Is a California Contractor's License Required? 
If you hire someone to perform contracting work (i.e., demolition or construction) valued at $500 or more (in labor and materials), California law requires that the person have a valid California Contractor's license.  If your project involves more than $500 in demolition and/or re-construction costs (the $500 threshold does not include the bee removal services), make sure that you contract with a licensed California contractor.  You can check for current licensure here.
 
When is a California Structural Pest Control Board License Required? 
Anyone performing live capture and removal of bees without the use of pesticides is not required to be registered with the Structural Pest Control Board.