When summer kicks into high gear and both the days and nights become unpleasantly hot, bees begin to feel the heat too. One of the signs that summer has arrived is the sight of bees hanging out in front of their hive entrances, especially at nightfall.
Bees implement a sophisticated system of climate control inside the hive. They maintain their brood nest roughly between 80 and 95 degrees Fahrenheit, with about 93 degrees being the ideal. They also generally maintain at least 50% relative humidity within the beehive. Any lengthy fluctuation outside of these temperature and humidity zones is dangerous for the health of the brood and the overall well-being of the hive.
During summer, the challenge of the bees is to keep the hive from overheating. At this time of year they have two powerful factors working against them. First, obviously, is the relentless and potent summer sun that bears down and heats everything up. Bees overcome hot days by fanning water inside their hive, thus using water as sort of a honeybee swamp cooler. This is why it is critical to maintain a reliable water source for bees near the hive.
The second, and less obvious factor that can overheat a hive is that beehives’ populations are often at their peak during June, July and August, with upwards of 40,000 bees in a single hive! The sheer numbers of bees living so closely together can create heat of its own, further raising the temperature near the brood nest.
During the daytime, overcrowding is less of a factor because many of the forager bees and drones are outside of the colony. At nightfall, however, when all the bees have returned, the hive can become populous again, and overcrowding and overheating becomes possible.
The bees’ answer to this overcrowding is a good one. Why not sleep outside? In the summer months, most healthy hives have a good percentage of bees hanging out in front of their hive’s entrance, especially in the evening. These bees will spend most of the night outside, keeping themselves cool with a peaceful night’s rest under the soft moonlight. More importantly, this also keeps the brood nest from overheating by limiting the number of bees inside the colony. If the nighttime temperature chills, then the bees can head back inside to warm up. If not, then they spend the entire night outside, just hanging out and staying cool.