Bearding is a term for bees that assemble on the outside of the hive during hot weather. They may cling to the outside of the brood boxes, hang from the alighting board, or gather near the entrance.
The conditions that lead to bearding are high temperatures, high humidity, overcrowding, lack of ventilation, or some combination of those factors. The bees form beards in an effort to keep the brood nest from becoming overheated. If too many bee bodies are covering the brood on a hot day, fanning may not be sufficient to keep the brood cool. By hanging on the outside instead of the inside, they lessen the heat load, decrease congestion, and increase the ventilation space.
Bearding is sometimes confused with swarming, but there are many differences.
- Swarming usually occurs in mid to late spring while bearding usually occurs in mid to late summer.
- Swarming usually occurs from mid-morning to mid-afternoon, while bearding may occur late in the afternoon into the evening. Generally, bearding bees don’t do back inside until the temperature drops—which may be quite late in the day.
- Swarming bees make a loud roar while bearding bees are relatively quiet.
- Swarming bees may cover the hive but they also form a cloud in the air around the hive. Bearding bees generally crawl out of the hive without becoming airborne.
If your bees are bearding, make sure the hive has good ventilation and a nearby source of water. If possible, hives should have some shade in the late afternoon. Bees do better and are more productive if they have some respite from the direct sun, especially in hot climates. Cooling a hot hive requires lots of time and energy—resources that could be put to better use.
After you’ve corrected any problems with ventilation, don’t worry about the bees. Just like humans, they like to spend a hot summer afternoon sitting on the front porch complaining about the heat.