Here is a picture of a swarm that has landed in a tree. When they are in the air, they look like a small dark cloud with a large hum. When landing they may clump up on several branches and there will be quite a few flying around in circles for a while. As it the swarm settles they will form a clump like the picture, or they will take on the shape of the object they are covering such as a mailbox or a post. Relax, call a beekeeper, watch the entertainment as they are gently coaxed into a container.