Summer ventilation increases honey yield
Whenever I think of summer ventilation, I think of the White House beehive. Beekeeper Charlie Brandt uses a large eke with a hole cut in each side. The eke is mounted above the stack of honey supers, just below the telescoping cover. The holes are large—I estimate about three inches in diameter—and are screened on the inside. On the outside, the holes are protected from lawn sprinklers by clear plastic splash guards. The splash guards are mounted several inches from each opening to minimize interference with the air flow.
My preference for top ventilation in summer is a screened inner cover with shims on each end. The shims keep the telescoping cover elevated so the air flow is not blocked. The screened inner covers keep even my busiest hives dry during the summer and they keep out insect predators as well. Since the bees have an easier time dehydrating their nectar, a well-ventilated colony can cure more honey faster.
I don’t have enough screens for all my hives, but a reader gave me the idea of turning a moisture quilt upside down and using it in place of an inner cover. My moisture quilts have holes on only two sides, but this system works fairly well. It’s not quite as good as the screened inner cover, but it is certainly better than nothing.
Before I had either screens or quilt boxes, I shimmed the outer covers on the front side of the hive with two pieces of wood about a half-inch high–another technique that keeps the hive well-ventilated. In addition, the bees use it as an upper entrance which lowers congestion at the main entrance. The downside of shims is that both robbers and yellow jackets can also use the opening. So while shims work fine during a nectar flow, they must be removed during a dearth when robbers and wasps are more of a problem.
An enormous amount of bee energy is wasted when bees fan moist air that can’t go anywhere. If the hive is closed at the top, moisture from the nectar condenses under the cover and the relative humidity in the hive stays so high that further drying of nectar is almost impossible. You can help your bees cure more honey by providing adequate through-the-hive ventilation.