A colony of wild bees gathering in large numbers, crawling over each other, like a living nest. These groups of bees are often found, hanging high-up in trees or from house roofs. They typically appear out of the blue and in no time form a living cluster of bees, as seen in the picture. After a while they depart, leaving behind a honey comb, i.e. a yellowish white, wax structure, which is produced by the bee's sweat and which has the same outline as that cluster of living bees had before.

Certain honeybees, such as Apis dorsata, are known to create waves on the surface of these living nests. This behaviour, known as defense waving or shimmering, is a defence against predators, such as wasps, and is created by bees in the outer layer that thrust their abdomens 90° in an upward direction and shake them in a synchronous way, often accompanied by stroking of the wings, thus creating a visible and audible ripple effect across the face of the comb that serves to confuse and repel wasps that get too close to the nest.