Condensation
Winter condensation is a valuable resource for a healthy colony.
Wyoming winter day.
Upper entrances, for hive ventilation, are recommended by all the popular bee books. Yet, when swarms are given the choice, they reject a cavity with upper ventilation. When hives are given upper ventilation, the bees will reduce or eliminate it if possible. This behavior is so strong that premium grade propolis is harvested using it. Providing upper ventilation is a curious management strategy. The bees sure don't want it.
Plex Cover
I built an inner cover using plexiglass set in a wooden rim. I could look through this plex cover and observe the bees without disturbance. Winter bee behavior and winter condensation were easily monitored. Then, I placed a beehive, with the plex cover, next to my house.
Natural Water Sources
I live in a dry, thirsty land. Winters are long, windy and cold. Spring weather is unsettled. Summers are hot and short. Natural water sources are, at best, sporadic.
Beekeeping is possible only along natural drainages and in irrigated agricultural areas. Melting snow banks provide spring water. It's cold and many bees are lost when the weather rapidly deteriorates.
The irrigation ditches are filled by early summer providing water for the bees. Water sources are almost completely lacking once the irrigation ditches are turned off.
Minus 20 Degrees F. The water division board feeder is at the bottom of
these photos. This moisture is frozen.
Early Spring - In Hive Watering
Anytime hive temps climb and melt the frozen condensation on the plex, the bees lick up the water. It's gone in several hours. The bees drink even when their water source was frozen outside. So this wild and crazy bee wrangler, filled a division board feeder with water and put it on the hive's warm side.
Colony death by drowning, right? Not so. This hive quickly learned water was available. And they freely used it. Water levels would drop about 1" per day. By spring's end, this hive was as strong as any of my hives. It started brood rearing earlier. And bee population remained more stable throughout bad spring weather.
This hive consisted of three deep supers with 3/4" holes drilled in the upper corner of each super.
These observations were so different than I expected, that I maintained the plex hive and monitored them for four years. Here's what I saw:
Once internal hive temps got warm enough to keep water from freezing, the bees regularly consumed it. When outside temperatures were around 30 degrees, the bees, although clustered, would send an expedition to haul water back from the feeder. And they would consume condensation on the plex. The water stimulated them just like feeding thin sugar syrup does.
The greatest condensation occurs during the spring, when brood rearing is underway. Then, bees consume lots of honey while clustered. The cluster is an effective means of controlling both heat and humidity.
When the cluster breaks, abundant moisture is released. Large water drops condense across the plex's full extent. This additional moisture is quickly consumed in several hours. Top ventilation greatly reduced this condensation.
10 Degrees F. Moisture is frozen.
Bees completely ignore their outside water source when water was provided inside the hive. Bees continued to take water from the internal feeder when they normally don't have outside access such as during bad weather and at night.
The division board water is ignored during a moderate honey flow. And it would quickly become septic, especially with a few dead bees floating in it. This required dumping the feeders on occasion, a nasty task.
Only a small amount of condensation was seen during the summer. Small droplets would condense around the outer edges of the plex cover before sunrise. The bees would quickly consume this resource. Minor additional condensation occurred directly above the feeder.
At one point I removed the feeder. Within five minutes, bees were running on the frames looking for the water source. Within fifteen minutes the hive panicked. Most hive activities stopped. Bees ran throughout the hive and around the entrance.
They quickly found the neglected water source outside the hive. Within thirty minutes, hundreds of bees were hauling water into the hive. The activity was frenzied, much like a miniature version of honey robbing.
This frenzied activity continued for three hours after I replaced the feeder inside the hive. After that, activity at the outside source returned to a more normal level, with a half dozen bees taking water. But the bees never gave up working the outside source after that.
Water uptake paralleled the amount of brood reared. As brood rearing reached a minimum in October, little water was consumed. Fall condensation mirrored spring condensation, but the overall amounts were slightly less. Open vent holes almost completely eliminated what little moisture condensation occurred in the fall.
20 Degrees F. Moisture is frozen.
Winter
For winter, the 3/8" hive entrance was reduced to one third its length. A wind baffle was inserted to prevent Wyoming's howling winds from blowing directly into the hive. The hive was wrapped in a single brown plastic tarp which provided additional protection from the wind. All vents holes were plugged.
By late December, water levels would remain unchanged weeks. But when the weather warmed enough to melt ice in the feeder, the bees would rapidly and drastically drop the water level. Sometimes the level would drop four inches in a twenty-four-hour period. Initially, I thought I had a leaky feeder. But that wasn't the case. When the hive needed a drink, they came to the feeder and got one when it wasn't frozen.
Water, in the feeder, remained liquid when outside temperatures fluctuated at 20 degrees. When outside temps consistently dropped below 20 degrees, the water would freeze. Then the bees stopped working the feeder and plex cover for moisture.
Winter condensation was never a winter threat. It was a resource! It never dripped on the cluster. The area directly above the cluster remained free of condensation.
The bees are tightly clustered during the winter and tightly control water loss. Honey consumption is minimal. Brood rearing is almost nonexistent. And cluster temperatures are at their lowest. It's no surprise there's so little winter condensation.
Opening or closing the vent holes had no effect on the plex's winter condensation. The feeder's presence made no difference in the amount of winter condensation on the plex cover.
During the winter, outside temperature was the determining factor for condensation on the plex cover as it controlled how tight the bees cluster.
30 Degrees F. Moisture is liquid. Notice the few wandering bees.
Discolored Top Bar Ends
Maximum moisture occurs when the cluster is actively rearing brood and disperses during the day, in the early spring.
Air rises above the cluster to the hive's top. It cools. Then flows downward along the exterior portions of the hive. Eventually, condensation occurs. If the temperature is low enough, the moisture forms ice. In my climate, ice formed only against the exterior hive's portions and never directly above the cluster.
In the spring, black mildew was found on the top bar ends. This indicated that moisture sat in the frame rest area. That's the coldest part of the hive with only 3/8" thick wood or less. It's possible that only a thin layer of propolis separates the hive interior from the outside when the supers were worn.
I had always used this discoloration as an indication of excessive winter moisture. It's a poor indicator. A thirsty hive gets discolored top bar ends.
Maximum condensation when it's cold, the bees are rearing brood
and the cluster breaks.
Water - Ventilation Management
I changed my water management practices and provided internal water from December through May. All upper ventilation was eliminated during winter without adverse effects. Any normal sized, healthy cluster didn't develop problems with winter moisture.
Very small clusters, in a cold location, can get wet. I over wintered five frame nucs in a stack. One nuc, with a very small cluster, got too wet. It was located on the north side at the bottom of the pile and mold grew on the cover. The nuc survived but was clearly damaged by excessive moisture.
Hives that dwindle due to disease, parasites or poor nutrition can suffer from excessive moisture during early spring. But the excessive moisture is symptomatic of other problems and not the cause.
I've over wintered hives outdoors in Alaska where temperatures didn't climb above 0 degrees F for months. And extreme temperatures approached 65 degrees F below zero for weeks. Clear rim ice would form inches away from the cluster. Hoar frost would fill up the rest of the box. Yet, these hives didn't succumb to excessive moisture if they were healthy and had extra food.
Bees working the water shown above.
Natural Comb Sized Bees Are Different
My natural comb bees consume water like my large cell bees do in the spring through fall. But their consumption is different during the winter. They consume the condensation but pay little attention to the feeders. They haven't taken that big drink like my large cell bees. It seems they get all the moisture they need from the condensation.
Maybe natural comb bees need less water during the winter. And that could one factor why they over wintered so well for me.
Musings
Bees, in a natural cavity, wouldn't have much top ventilation. If the bees were in a tree, Most insulation is above and below the cluster. If the entrance were at the cavity's bottom, airflow would rise above the cluster and descend along the nest's outer margins. Most condensation would occur in those outer margins. It wouldn't drip on the cluster but would provide a ready source of scarce, winter water.
Water might be absorbed by the wood in the nest cavity. It could act like a sponge and work like the feeder in my hive.
A water source inside the hive would moderate the need to forage under marginal conditions. Broodnest humidity could be more easily maintained. And granulated honey could be utilized before outside water sources are available.
Two hours later, no condensation. It's a resource, not a problem!
As outside conditions improve, the natural moisture flow is down the sides and out. That would follow the natural airflow direction enhancing cavity drying.
A lack of moisture often becomes a problem with bees wintering indoors. When inlet air temperatures are low and airflow rates are reduced, they become very dry. Rather than generating excessive moisture, the bees run short during the winter. When this happens, the bees die. Piles of crispy, shrunken bees are found outside the hives. If the bee's stores are granulated, a massive bee loses occurs.
The bees don't generate a water surplus during winter in my climate. Some water source is a necessity during the winter
Climate and Situation are Everything - Maybe
My hives are located in a dry, windy climate. Their entrances aren't blocked by snow for more than a few weeks at a time. Our skies are mostly clear and sunny during the winter. The bees break cluster about once every three weeks or so. They need a canteen during the winter.
In a climate, where hives are covered with ice and the skies are cloudy all day, the water situation could be different. Yet, as far as I know, the bees seal the upper hive areas. Maybe bees in a situation like this need an umbrella rather than a canteen.
40 Degrees F. A few bees are working water in the feeder.
Unfortunately, to find out what your bees need requires monitoring them for yourself. A plex cover is an excellent way to do that. A cover made from lexan could be considerably cheaper than plexiglass but wouldn't be as durable.
If you monitor your bees, let others know what you see. Post your results on one of the bee lists. With enough observations, hive water and ventilation will become better understood. I suspect that a winter water deficit occurs in most situations.
England
Dave Cushman, a beekeeper in England, sent me an email. He wrote:
I used glass tops and a few plastic ones, what was seen was a dry circle in the middle and spherical drops right out to the corners.
The size of the central circle varied, the centre of the circle moved about a bit (our colonies do not fill even our smaller boxes). The size of the droplets got smaller towards the actual corners.....
Best Regards & 73s, Dave Cushman... G8MZY
