> You commented that you "see virtually
> no moisture under the cover once it got
> cold". What do you think happen?
Cold air is dry air, it does not hold as much moisture as warm air does. The water you see earlier while it is warmer is evaporated in the dry cold air.
Several studies coupled with my own experience caused me question the need for upper ventilation in my location.
Rodger Morse, the late Cornell University professor, surveyed feral bee colonies and set up swarm traps around Albany, NY. Swarms generally rejected any cavaties with light entering near the top. Also the bees quickly seal any cracks near the upper part of the hive. It's the first thing they do around a plexiglass inner conver when its installed. The bottom of the hive is not propolized as screen bottom boards left open remain open.
If the bees wanted ventilation at the top they could easily make a few holes like they do when a pollen trap is installed.
A series of studies published in the American Bee Journal, July, 1998, entitled "Rethinking Our Ideas About the Winter Cluster" investigated cluster size, hive insulation, etc on overwintering. The most critical factor for successful overwintering when the cluster was big enough to keep warm was water balance. Super insulated colonies and super sized colonies did poorly.
I observed the same type of behavior when overwintering hives indoors in Alaska and again in Wyoming.
Finally, my own observations with the plex cover on a hive wintered outdoors convinced me otherwise, at least in my location.
So how do the bees get the necessary water in the wild? I speculate that very little condenses at the top of the cavity, in a tree that's where most of the insulation would be. Rather the water would condense on the vertical sides where it might be absorbed somewhat by the tree, maybe as a water source when needed.
Does it happen that way in our hives? I think so. Most of the water damage occures in hives with smaller cluster and typically affects the ends of the top bars with the central portions unaffected.
I have posted some additional pictures of my plex shots at different temperatures.
Barry, feel free to post these shots on beesource if you think they might bee of value.
I had some additional thoughts on moisture problems.
Several factors could affect the results. I overwintered five frame nucs stacked in a block on top of each other. The nucs consisted of a single deep with a divider down the middle and a standard migratory top and bottom board.
Those nucs that were on the bottom, on the shady side of the stack and that had weak clusters had mold on the covers and the typical black mildew on the ends of the top bars when unpacked in the early spring.
Moisture had condensed and remained for some time on the covers. No difference was noted in the amount of dead bees in the bottoms of the nucs were seen. The clusters were just too small.
I did notice that they attempted to dry the nucs out by fanning much like they do when drying nectare during the summer. This activity would occure on good flying days early in the spring.
I wonder if hives with other problems develop problems with moisture during the winter?
In a tree cavity, feral bees are protected by approx 1" of bark and 2 or 3" (maybe more) of sap wood. Thats a lot of insulation! Wood (per-inch-of-thickness) is the best insulator known. Maybe, feral hives dont sweat.
How much condensation is collecting in the frame notch? Thats the thinnest, least insulated, part of the hive. Dont old suppers rot at the notch? Having the brood clustered over the "central portion" of the bars may warm the bars. That heat is then conducted towards the ends of the bars, and meets the cold, damp air from the notch and increases the damage problem.
Maybe there is a balance between interior warmth, and necessary insulation to prevent condensation. Is that balance constantly changing with outside temperature? Maybe the easiest way, is to provide ventilation.
I believe there are three sources of excess mositure inside a hive. Condensation, when the bees are evaporating nectar, and humidity. Will ventilation work for all three?
I'll bet the very first hive cover didnt have a hole in it, and moisture was a problem. Although, I remember my granddad's 'gums', and I dont know if they had moisture inside. Maybe there is a simple solution. Hope you can help!
I have a DE ventilation unit on all of my hives. This provides some winter ventilation.
The standard inner cover provides for some of that warm moist air to go up into the space between the cover and the inner cover. I have noticed condensation there when using that arrangement.
I've never used them, but there are references to cloth inner covers in several very old books and some discussion of it on this board. I was a bit confused as to the purpose, but I think helping with condensation must be the purpose. A feral hive has a lot of rough wood inside to absorb moisture also.
I have not seen the same behavior with my small cell bees that I had seen with the larger bees concerning water usage. The small cell bees have not come up and drastically dropped the level of the water in the feeder at one time. They collect the water off the cover. A few bees drink out of the feeder but no big drink by the colony itself.
This is the second year I have observed this difference. Last year my small cell colonies were dinks and I thought that their size was a factor. This year the winter cluster are very large and still no big drink.
In previous years, all of my large cell colonies would take a big drink about every 10 days.
Just an update
Are you providing plain water OR sugar water?
How are you offering the liquid? Top feeder, Division Board?
Does it freeze?
When did you start?
When do you stop?
I'm not sure what bwrangler does, but I often have water in boardman feeder for a new nuc in the summer. I just figure they spend a lot of time hauling water. When starting a small nuc I think it helps free up some field bees to more important work.
I think bwrangler is using it for winter water. The need for this probably depends a lot of the climate and the length of the winter. If you have a fairly moist climate there's likely to be too much moisture condensing in the hive anyway. If you have a very dry climate (like Casper, Wyoming) and a long winter (like Casper, Wyoming) it becomes more critical that the bees have enough water to get through the winter.
I am curious also what bwrangler does.
I use a boardman type feeder in the top box, on the sunny side of the hive. I fill the feeders in January with plain water. It does freeze at times.
I start in January and stop when the bees can freely gather water for themselves without getting chilled by a sudden squal and lost while getting moisture from a snow bank. That's a very common experience in Wyoming.
Greetings . . .
BARRY: Please update all of us on your Plexi-glass Inner cover.
an old timer told me to put an empty super above your inner cover and fill it with wadded newspaper,this is supposed to take care of excess winter moisture.
Update on my Plexi-glass Inner cover hive.
Thumbs up! Still not much moisture on the under side. Some frost at times when it gets down in the 20's, but the bees look fine. They are now up in the top super with bees spread across 3-4 top bars showing the top of the cluster. Have not seen any mites on the bees for over a month now.
For me here, I will not give top openings for venting. All the lids I cut notches in the bees seal up anyway. Can't wait to get bees in my TBH!