I have my bees in National hives with a standard brood box, and have never thought it necessary to insulate them. However, since working with bees in trees and comparing the two environments, I can now see the vast difference in the thermal properties of a tree trunk and a National hive which is made with the minimum amount of wood.
As is usual in the world of beekeeping, there is no consensus so having researched superficially I came away none the wiser. Our winters here in the south east of England are mild, wet and windy, and unlike many places in the world where folk keep bees, we rarely have snow or even much of a frost most years. I had noticed that the bees from the oak tree were quite slow in building up and I wondered if this was because they were expending so much energy in keeping warm after their propolised and established cavity in the oak. I have another fairly small colony, and a large but very late swarm as well as the rebel bees from the Crutches Farm Cottage wall who are merrily building a bee-metropolis among the wild comb in their brood box. All these colonies could probably use some help so I would like to see if it makes a difference. Please note: I have never lost a colony to starvation or cold so this is probably the least rigorous trial in the history of science but I am interested to see what the bees do.
I have used WBCs in the past and these have a double wall structure so preserving the heat and also keeping any wet and weather off the boxes that the bees actually inhabit. I would love to go over to these again and as my Nationals disintegrate, I will replace them with WBCs. Warré hives work on the principle that the small boxes mean they are easier to keep the heat, and don’t get cold spots as the cluster reduces in size for winter. They also have a quilt of sawdust above a cloth cover and this absorbs moisture and also helps with heat retention. Sadly I have not had a viable colony in my Warré, but the bees at the Marsh certainly did very well last year.
I’ve looked at top insulation – so putting in a layer of wool, straw or other insulation under the roof but I’m not sure if I’d need some sort of cover so the bees didn’t go up in to it through the holes in the crownboard. I know a number of people who put lifts from a WBC over their National boxes and as I have a lot of lifts not currently in use, I thought I would start with this, on the Oak Tree bees who were looking extremely bonny, but they have only built out about half of the box, illustrated perfectly here by the inspection board:
WBCs have an integral stand and floor so I had to prop the lift up a bit so the bees could get in and out of their entrance as the lifts are a bit of a squeeze around the bigger boxes of a National. Thankfully I had bits of frame to hand so improvised with them:
The bees soon found their way in:
Abdomens aloft, Nasanov gland exposed and releasing a marker pheromone to guide in their fellow foragers.
The difficulty with this is that the lid isn’t properly on the hive as it’s resting on the top lift. I wondered about replacing the National roof with the WBC one but as the whole of the base is technically accessible, I didn’t like the idea of things being able to get in at the bottom and infiltrate the hive through the holes in the crownboard. The question of ventilation is addressed here in a post from the excellent Oxfordshire Natural Beekeeping Group: Warm Hives. So, ventilation is not the main issue, meaning one less thing to have to try and factor in, and explains why bees spend their time propolising over the vents we helpfully provide for them in the roof…
So, I reduced the lifts to one and blocked up the holes with more frame bars. I realise this is not retaining any heat at all but we have thunderstorms forecast for tomorrow and it will at least prevent the rain from soaking in to the wood. I don’t really want to be trying to insulate my hives when they are wet and soggy.
I will use some wool insulation under covers in the smaller hives. I probably should have combined them but I want to keep the oak bees separate. I could combine the swarm with the smaller colony but as the swarm is an untested queen I’m loath to combine them so late in the season in case she gets superseded and there’s no alternative.
Here’s the inspection board from the small colony, clearly showing the space they were occupying as well as a lesser wax moth:
There are a few mites so I’ve scraped the boards clean on all the hives and will do a mite calculation in a week’s time. I don’t treat my bees but it’s important to monitor the levels to learn the tolerance level of the host-parasite relationship.