Did a giant blob of bees just land in your yard? Maybe they're hanging on a branch in a tree or bush, looking like something out of a horror movie and you don't know what to do. This is known as a "swarm" of bees. Good, strong hives will reproduce in the spring by splitting. One portion of the bees will stay in the old location and raise a new queen. The other portion will take the old queen and fly off to find a new home-this is the bunch you will suddenly see clustered in your yard one nice spring day. They will probably only stay for a matter of hours, maybe a full day, and then fly off to their new, permanent home.
If you happen to see bees swarming on your property, please call a beekeeper right away and they will likely remove them immediately and for free if it's not in a difficult location. It will keep the bees from moving on to find that permanent home in your house or your neighbor's.
Or have you noticed a bee superhighway running directly into your house? All they need is a nice little hole as an entrance & exit and they'll make themselves a nice little home inside your walls, soffits, or attic.
This is an example of a rather inconvenient (for humans) permanent home. To remove these bees, beekeepers will do what is known as a "cut out". It usually involves some deconstructing of your home to get at the bees in order to fully remove them and their comb. The beekeeper may charge a fee for doing a cut out, as it is a much more involved process. It's a big, sticky mess and it can make for some cranky bees in the process.
In either of these scenarios, please do not spray them with insecticide in an attempt to kill them or "knock them back". Few beekeepers will want to remove bees that have been sprayed.