Bearding
Verhalten der Bienen
On hot summer days part of the colony hangs as a cluster outside the entrance.
On hot summer days part of the colony hangs as a cluster outside the entrance. The Swiss Bee Health Service regards this as harmless in summer: temperatures are very warm, so part of the colony sits outside the hive, and no action is needed.
The Bavarian beekeeping advisory service names a second possible cause for the same observation. In its guide to entrance observation, lack of space and hot weather are listed side by side as causes of bee clusters in front of the entrance, and when it comes to adding space, bearding is explicitly counted as a sign of lack of room, together with densely occupied combs, a cluster of bees below the frames and brace comb built in empty spaces.
So do not decide on the beard alone, look inside. If the combs are densely occupied, if the bees build wherever there is no room, or if the brood chamber is becoming honey-bound, the colony lacks space and more room is added. If only the heat is behind it, shade and a sufficiently wide entrance are enough. In early summer, bearding is also a reason not to skip the swarm check, because crowding is one of the triggers of swarming mood.