Thursday, June 11, 2009

Cooling the Bee Hive

The honey bee colony regulates the temperature in its nest to protect the developing brood. Whenever the bees are producing young, they maintain a temperature of 95 degrees inside the hive. In cool weather, the bees cluster together and generate heat by consuming their high energy food, honey, and vibrating their flight muscles. In warm weather, like we are experiencing now, the bees must cool the hive. They do this by first expanding the distance between bees in the nest to allow for air circulation. If there are too many bees in the hive, some merely move outside and cling to the outside of the hive or festoon down from the landing board. The bees inside the hive actively cool the nest by bringing in water from outside sources and fanning their wings across a droplet of water. The evaporating water cools the hive. A hot, humid afternoon found the bees actively cooling the hives. Click on the picture to see the bees aligned in an orderly arrangement to carry the air out the entrance, which is at the bottom. Other bees are aligned head-down to carry heat away from the entrance.

The honey bee colony is effective in regulating the temperature of its nest. During the dead of winter, when the queen is not producing brood, the bees don’t waste energy heating the hive to 95 degrees; they only warm the cluster of bees to about 70 degrees. They also conserve energy by not trying to warm the entire hive cavity, just the cluster of bees. For cooling the hive, the bees devote a number of workers to fanning tasks. When the summer temperatures rise into the high 90s, the bees stop their normal activities and begin foraging for water. Bees foraging for pollen and nectar will redirect their efforts to bringing water back to the hive. With the major nectar flows in the Arkansas Delta approaching, the bee hives are full of bees.


  1. Dear Mr. Underhill,

    I do so appreciate your explanation of how bees cool the hive in the heat of summer.

    Having been a beekeeper for just 33 days, I was a bit alarmed by the large clusters of bees loitering at the hive entrance and up the face of the brood box these past few days. Although this behaviour seemed to coincide with the onset of the hot and humid days and nights, my greatest fear was of losing my new bees to swarming (since much was made of swarming in my beekeeping course). No mention was ever made in my beekeeping course about how bees manage to survive the Oklahoma summers (not to mention Brazil, or Africa, etc etc!)and none of my reference books mentioned it, either.

    So, thank you, again, for sharing your thoughts and beekeeping wisdom with everyone, especially us new-bees. I love my bees and want to do right by them.

    Best wishes and happy beekeeping,

    Tulsa, Oklahoma

  2. I was also stunned by the number of bees on the outside of our hive. We've only had them since May, and their numbers have grown a lot. In Savannah, it's so hot and humid that we placed our bees under the light shade of a Japanese Magnolia. Still, there has been a bee beard on the entrance for the past couple weeks.

  3. Wondering if my bees are clustering outside because of heat or because I made the entrance too small. It's about 75 on my San Francisco rooftop today and the bees are clustering on front and in between the top bars and the lid and some along the side of my top bar hive. Would they do this in 75-76 degrees to stay cool, or is it beacause they don't have a big enough entrance? If it's the ladder, I'm not sure what I can do to fix it now. The hive had about 20+ frames built. Maybe I need to harvest some honey to make more space? Don't want them hungry before winter. Any suggestions?

  4. My problem is my Bees started Bearding three days ago when the temperature was in the high eighties but the weather changed and it is now 53 degrees and raining and I still have bees bearding. I just checked and they are not dead but it looks like they have the entrance plugged by their sheer numberd. Any insight would be much appreciated by this amateur beekeeper of 37 days.

  5. Gene,
    While bearding at the hive entrance is normal bee behavior in hot weather, you need to make sure that the bees have enough hive capacity to make sure that the queen has cells available for egg laying. Add another brood nest box if it is needed. You also want to make sure that the hive is configured so that there is adequate ventilation. A screened bottom board is helpful; and, if you are using telescoping covers, you want to make sure that the vent port is open.