I did a walk away to one of my TBH this on Saturday (see http://www.beesource.com/forums/show...-25-inspection) and on Sunday the inside of the inspection window was covered with Drones. The old TBH has lots of bees using the entrance, about the same as before since the field force is oriented on this hive. On Sunday they were buzzing in the hive and noisier than usual.

The new TBH was pretty quiet and the combs were still covered in bees. A few bees were flying in and out of the entrance.

Any thoughts on why the drones are covering the window?