Working hard

I was driving again today and found this interesting sight. I never knew bees were kept in old metal drums. There were hives near by, but most activity was going on around the green metal drum. I did not dare to come closer, so I put on my 2x extender with my 100-400mm lens. It's too bad I have to manually focus with it, but it gets me close to the action. So anyone know why the bees are kept in the old metal drums?

Bee hive?
Canon 5D, ISO 640, 1/500 sec, f/11, 800mm