During the spring months bees are outgrowing their winter home.
In order to not be overcrowded in their hive they make a new queen. The old queen will leave the hive with half the colony (bees) in search of a new home. During this time they will stop to rest, making a big clump together, looking like a big ball of bees hanging from trees branches, fences, cars etc. This is the time to call a beekeeper so they can remove them safely and place them in a new hive. If they move into a wall, meter box, etc. then it means that they have identified that to be a good place for a new home for them but that may not hold true for you. This kind of removal can be difficult depending on the the place they decided to move into to.
If you're in the surrounding areas of Brentwood I will only ask for a donation.
If it's a hive removal, then my rates start at $300 and upwards depending on the difficulty level of the removal.