Bee Bearding

In extremely hot weather, when the hive's internal temperatures can rise to excessive levels and the hive population is so great, bees make their way out and cluster outside the hive in a huge numbers, here they can try to escape from the heat and remain cool. honeybees do this mostly to keep the inside of the hive from overheating and killing the brood and to help regulate the brood nest temperature. Brood and too many busy bees in the hive increase heat output. It is a simple way to regulate the internal hive temperature.
Often bees beard because the temperture outside is high, lack of ventilation and overcrowding. During lack of honey flow in summer the field bees don't have any work to do, therefore if the hive is hot, they will crowd together out on the front of the hive out of the way of the busy house bees.
On hot and humid evenings, many bees will loiter through the night and even during the day outside the hive clinging to the front of the hive or on the landing board doing nothing. Looks like my bees above are hot, and doing some bee bearding.