Honeybees swarm to make new colonies: when the mother hive gets too crowded, they raise a new queen, and then the old queen and about half of the worker bees leave to find a place to establish a new hive. Because the swarming bees don't have a home to protect, they are very docile in a swarm state: keep a respectful distance, but they are not aggressive.
A honeybee swarm will look like a ball or clump of bees, like this:
Photo credits: Josh Calo and Erik Darm of the Northern Virginia Beekeepers Association. Photos solicited with the assistance of the DC Beekeepers Alliance.
If you encounter a swarm, do not spray or disturb it— it won't hurt you or your pets, and it is extremely good for the environment because foraging bees help plants reproduce! Clear the area, and call a local beekeeper's organization to come and remove it (they'll take it away and put it in a prepared hive box).
The Richmond Beekeepers Association maintains a list of beekeepers who will collect swarms, and their contact information, here. They cover Richmond City, Charles City, Chesterfield, Goochland, Hanover, Henrico, Hopewell, Louisa, Midlothian, New Kent, Petersburg, and Powhatan.
If you don't live in Richmond, there are 40 local beekeeping associations around the state, and the Virginia State Beekeepers Association maintains a list here. Contact your local organization to find out who to call about a swarm.
For help figuring out if that buzzing thing in your yard actually is a bee, check out this article about all the different bee and bee-like pollinators, from pollinator.com.
