The Oxfordshire group invited members from the neighbouring Hampshire and Wye Valley natural beekeeping groups to join us for a joint meeting at Gareth’s apiary – 34 people from 7 counties converged for the session. These annual co-events allow for wider networking than one group can provide.
The meeting lasted all afternoon and was in 3 sections: an informal opportunity to chat over a bring-and-share meal, a lecture by Gareth presenting the latest findings on insulation and cavity size, and an apiary visit focusing on the Einraumbeutes (Golden Hives) which Gareth has been experimenting with for the last 2 years.
The initial unstructured meet-and-eat is one of the most fun aspects of our meetings, an opportunity to find other enthusiasts who can answer specific questions for you. We try to introduce newcomers to others who will be useful to them, like near neighbours and potential ‘bee buddies’.
For example there were about 5 people trying out cork insulation on a variety of hives here, who could compare notes.
Several OxNatBees people were very excited to finally meet John Haverson from Hampshire, a very respected teacher specialising in Warré and log hives.
The group was then treated to a lecture Gareth had prepared on the latest research on bee nests.
Insulation and bee behaviours
The key finding here is that scientists are beginning to uncover why well insulated hives are so beneficial. Basically, hollow trees are so warm that the bees in them only need to gather one tenth the fuel to keep the colony going, compared to a conventional framed hive. And it turns out, to everyone’s surprise, that they don’t just use the free time to gather more honey for a rainy day. Instead, they turn to cleaning the hive, propolising (sterilising) the walls, grooming mites off each other, and inspecting brood for signs of disease.
In other words, bees have a hierarchy of behaviours. The priority is gathering enough food to survive. If you keep them in cold hives, and keep taking their honey away, you suppress the others… the ones which keep them healthy.
You may want to pause and think about how unmanaged colonies thrive despite the lack of human help.
The initial research here was by Derek Mitchell in the UK, which we covered in this previous article. In summary, Mitchell, an instrumentation scientist, got thinking about his wife’s hives and modelled hive heat flows on computer, and backed up his predictions with heaters in hives. He realised the immense impact insulation and absence of draughts had – every kilo of honey needs several kilos of nectar fetched to make it, so small differences in insulation and draught proofing make a big difference to the stress on a colony.
Torben Schiffer, in Germany, has backed up Mitchell’s theory with measurements on actual tree / hive nests and confirms that a well insulated tree colony may only have to gather one tenth as much nectar as one in a framed hive – i.e. 50kg instead of 500kg (half a ton!) a year. TBHs and Warrés are better than conventional framed hives, but still need considerably more nectar to run than a tree cavity. All hives and colonies benefit from extra insulation.
Not only has Torben Schiffer confirmed these results, but by observing bees in such nests he has discovered the behavioural hierarchy described above. He’s also found that above 10C, propolis volatilises, suppressing mould growth and mites – another reason cold hives are unhealthy.
Torben is also researching how bees control humidity in hives. Warm air holds much more water vapour than cold: when ripening honey, bees warm the honey processing combs to 40C. If they can only warm them to 35C, the air will carry away 30% less moisture which means they need to work harder (fan more air) to remove water from nectar to make honey.
The other main point Gareth and Torben have been thinking about is that when swarms move into a cavity, they seem to build comb and breed at a rate to suit that cavity. The bees must use comb to optimise ventilation to suit the size and shape of the cavity, and position of entrance. It follows, then, that removing top boxes full of dense, warm honey and adding a new empty box above or below is going to disrupt things. Even changing the volume of a hive is going to change internal conditions – after all, the hive is the skin of the colony. Gareth’s advice here is, once you’ve hived them, leave them alone.
Gareth showed us two Golden Hives (Einraumbeutes). The first was a recent deadout which allowed him to show us the internal arrangement and comb. He has made these himself; the only UK supplier is Matt Somerville at Bee Kind Hives.
The idea behind an Einraumbeute is to combine the good thermal design of vertical hives, with the ease of use of a horizontal hive. So the combs can be pulled out individually – much less back strain than lifting an entire box – but they are deep enough that the bees can use airflow in the way they have evolved for. Remember bees are adapted for deep tree cavities – which is why they sometimes go into chimneys – and they make use of the fact that warm air circulates vertically, and fan air around to maintain temperature and humidity at optimum levels for honey processing and brood rearing. A shallow horizontal hive is not deep enough to optimise this airflow control technique.
Gareth’s initial Golden Hives were pine with an internal cork lining for extra insulation. However, although the bees seemed to love the cork in their first year, and covered it in propolis, this second year has been a “chewing rather than gluing” one and they have chewed the 30mm thick cork right away in large patches! Particularly round the entrances. This has created large amounts of (probably harmless) cork dust on the floors and contaminating their honey. He’s now considering a double walled design or possibly external cork cladding.
The top cloth is impregnated with wax (melted with a heat gun) to stop the bees chewing through to the insulating quilt box. A flour paste wasn’t tough enough to deter the determined chewers.
John Haverson commented that the Hampshire group is experimenting with just using cork cladding along the 2 sides of hives which have the highest heat loss, i.e. the sides against the ends of the combs.
Gareth has added shallow supers to the Einraumbeutes, and these fill with perfect honeycomb. I wondered how he did this without a queen excluder, so he explained: just place the super in position when there is sealed honey at the top of the brood frames. This will be the case once the brood area has expanded downwards and incoming nectar exceeds usage, which is much more easily achieved in well insulated hives.
Gareth has made two sizes of Einraumbeute: 8 frame and 12/13 frame. He finds his bees fill a 12/13 frame one with comb in one season. Interestingly the prime swarm that colonised the 8 frame Golden Hive we saw came from a tiny hive, which demonstrates how a colony will adapt to the volume of its cavity, i.e. the claims that some breeds of bee require larger hives than others may not always be true. Gareth finds that a 12/13 frame hive is less disturbed by supering than an 8 frame hive. There is also a huge 22 frame variety but you need exceptional forage for the bees to fill those, and there are indications that those get cold in winter if honey is removed, which is counter to Gareth’s direction of travel.
The frames are precision crafted. They use a sharp edge under the top bar to encourage straight comb. There is no reinforcing wire. They’re made from constructional pine from the builder’s merchants (“best” quality if there is a choice). Gareth cuts his from 3 x 2 to ensure the wood is straight rather than buying planks, which generally are already warped when you get them. Warping is reduced by having rebated joints and assembling the frame on a flat workbench.
We were shown an occupied Golden Hive, but it was not opened as it was a rainy, windy day. This colony is a year old and has completely filled the hive. The bees seem to use the upper entrance for coming and going, and the lower one to expel air – where humans would use the upper one to expel air as heat rises. But what do we know?!
Vast thanks to Gareth and Lynne for allowing such a crowd to mill around their house and garden, the lecture and wisdom!
Next meeting: 14th September, 2 to 4:30PM, at Ron Hoskins’ apiary near Swindon