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Let’s Vent!

BEE CULTURE – May, 2010
(Joe Traynor)

I started in almond pollination in the 1960s when California almond acreage stood at 100,000 and bee-rental prices were $3/colony. California beekeepers, almost exclusively Central Valley beekeepers, provided all the required bee colonies. As almond acreage ratcheted up to 250,000 acres in the 1970s, higher pollination fees (around $10/colony) attracted a few beekeepers from Oregon and Washington and one or two from Montana and the Dakotas. This was the first opportunity I had to look at out-of-state bee hives and I wondered what those little holes in the upper hive body were for, as I had never seen them before. My curiosity overcame my fear of exposing my ignorance and when I asked a Dakota beekeeper “why the holes?” I was patiently told they were there to provide an upper entrance in case of snow but more importantly to provide ventilation. The snow explanation made sense but I had trouble with “ventilation” until it was explained that bees needed to rid their hives of excess moisture. If I had read (or retained) the information in the beekeeper bible The Hive and The Honey Bee, I would have known this since John Ambrose explained it in the 1992 edition, pp 645, 646 (and it was likely covered in the 1975 and 1963 editions which I can’t locate):

“Bees seem to have little trouble with cold temperatures, but cold temperatures in combination with moisture or high humidity, do present a problem. Therefore it is to the beekeeper’s advantage to provide adequate ventilation in the hive to reduce moisture buildup. This is particularly true in the winter when the bees cannot break their cluster to dry out the hive interior by fanning their wings… A strong colony that stays dry will be able to survive cold weather conditions and the beekeeper’s main concern is keeping the bees dry, not warm… ventilation flow can be augmented if the beekeeper maintains an auger hole in one of the upper hive bodies. This hole can be anywhere from ¾ of an inch to an inch in diameter and it should be on the front of the hive.”

Thinking back, I wondered why Central Valley beekeepers didn’t make ventilation holes since their hives winter in cold, foggy weather. I have since concluded that such holes were (and in some cases are) not necessary because colonies in our Central Valley shrink down to 4 frames or less in the winter unless significant supplemental feeding is done (few CV beekeepers provided supplemental feed in the 1960s). A 2-story colony holding only 4 frames of bees should have ample ventilation, even when beekeepers provide entrance reducers for cold protection. Today, some CV beekeepers with strong colonies (via supplemental feeding) refuse to apply entrance reducers because they feel they will impair ventilation. CV beekeepers with populous winter colonies should probably implement some form of ventilation for their hives if they continue to winter hives in the Central Valley. Some large southern California beekeepers that bring their bees to CV almonds in January (they must start early in order to get the last of their bees in before bloom) are concerned about ventilation for the 2 to 3 week period in the cold-foggy valley before almond bloom commences.

One thing that impressed me with Dakota bees in the ‘70s, was their tremendous populations when they brought them to California in November – 2 boxes crammed full of bees and even after a 10% drop in population during the winter, still 12+ frames for almond pollination – this was well before tracheal and varroa mites entered the picture. Populous hives generate considerable heat with consequent water condensation. You may have experienced the same phenomenon when you hop in your car on a cold day after a workout at the gym – your body heat causes the windows to fog up a bit. Pile 4 of your workout buddies into the same car and you’re talking major window-fogging. A populous bee hive will produce far more moisture during cold weather than a weak colony.

The importance of ventilation was brought home to me this past winter when a Colorado beekeeper who had always provided excellent almond bees suffered significant dwindling and nosema problems this past December-January. He had replaced many of his old, tattered, leaky supers with brand-new air-tight boxes. Great-looking equipment, not-so-great-looking bees. Fortunately, he wasn’t able to re-do his whole outfit and his cruddy-looking hives were fine. This beekeeper spent thousands of dollars on pollen patties and when he found mold and fungus growing on the patties in the air-tight boxes, he threw the patties away because he thought the foreign molds and fungi could be exuding toxins.

With beekeepers now attempting to provide hives with high bee populations for almond growers, the need for adequate hive ventilation becomes more important than ever. This is especially true in this era of CCD, believed to be caused by a virus or other pathogen, with nosema implicated in the malady. Just as the H1N1 flu virus can be rapidly spread when humans are confined in a small space (airplane, classroom) nasty bee bugs can be spread rapidly when high populations of bees are confined for prolonged periods in boxes lacking adequate ventilation. There has been a discussion for years among out-of-state beekeepers that winter their hives in California as to whether it is better to winter bees in the valley floor, where fog can confine the bees or in the foothill area to the east that is out of the fog belt. Those favoring the valley floor feel that the fog keeps the bees from making fruitless foraging flights that result in rapid aging of the bees. Those favoring the foothills feel that damp, foggy weather is detrimental to bees. All agree that best place to winter bees in California is in fog-free areas that have ample flower sources. These areas are on the coast or in Southern California but are very limited.

The spike in CCD instances this past winter could well be due to a combination of cold weather, populous colonies going into winter and poorly ventilated hives. The prolonged cold spells that hit the southern states this past winter were well covered on TV and also documented in the March issue of the American Bee Journal (p.237). These cold spells affected colonies in the major bee states, Texas and Florida. If these colonies had the bug, or bugs, that cause CCD during the summer-fall months, this bug (or bugs) could have spread rapidly during December-January confinement in cold weather, esp. in hives that lacked adequate ventilation.

The moral: if you winter bees in areas that are susceptible to prolonged cold snaps – even a once-in-twenty-year cold spell – and your equipment is “tight”, you would be wise to implement a slogan recently used in another context: Drill baby, drill.