This is a very common problem. A swarm of bees will attach themselves to a tree, bush, or random object. In most cases, the bees will fly away in a day or two. We recommend waiting for them to leave on their own. For your safety, DO NOT APPROACH THEM. DO NOT SPRAY THEM WITH WATER OR PESTICIDE. JUST LEAVE THEM ALONE THEY WILL LEAVE.
Don't be surprised if you notice bees flying in and out of your irrigation box. This is a perfect shelter for a bee hive. When you have bees in a irrigation box, you will need to have a removal done.
One of the most common areas for bees to enter a structure are vent holes in the eaves. In this situation, you will need professional bee removal. As you can see from these pictures, Bugs B Dead can access honeycomb without cutting through your roof.