At her recent Spring Management class, Sarah (BeeGirl) told us that when bees get too hot, they shut down production – the queen stops laying and it’s all hands on deck to bring water into the hive. The bees will spit the water inside the hive and fan it to create a swamp cooler effect. Many of the bees may collect on the front of the hive to help reduce the interior temperature in a process called ‘bearding’.

The Phenomenon of Bee Bearding contains a good explanation of bearding, and suggests several things that can be done to help the bees when the temperature is over 100 degrees. “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 (immature bees), 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.”

Keep Summer Bees Cool emphasizes the importance of providing ample water and ventilation for a hive: “When it’s hot in summertime a full size colony of bees will use a lot of water…a lot more than you think. At a minimum they’ll use a quart a day. Maximum, a gallon a day. For every colony you have. Think of how much that is for 10 colonies for a week of hot, hot weather. At the very least, that’s 10 quarts a day, for seven days…70 quarts…nearly 20 gallons of water, minimum if you allow for some of that water to evaporate naturally. When large colonies start collecting a gallon a day, you have 70 gallons you have to have available…that’s more than a 55 gallon honey drum plumb full in just a week.”

HoneyBeeSuite has several posts on how to Maximize Ventilation in the Hive and on Beekeeping in the Dog Days of Summer.

A short summary of approaches:

• Provide ample water.
• Use a screened bottom board, a slatted bottom board or slatted rack, a small upper entrance, and a Vivaldi inner cover or screened inner cover for optimal ventilation.
• Place the hives where they will receive some shade in the heat of the afternoon.
• Since super hot days coincide with the height of robbing season here in southern Oregon, leave the entrances reduced but provide a second or third entrance or ventilation hole in the upper boxes.
• Make sure there is ample space in the hive. 8 frame boxes have a good amount of extra space. You can remove a frame in a 10 frame box to increase air circulation.