The empty Zeidler Hive at Pertwood, lavishly encrusted with propolis. It even has a small stream running through it during wet weather.
The comb as always, in perfect condition - never mouldy due to characteristics of the tree hive.
After 3 years the Pertwood tree hive (video of construction) inside the old ash tree no longer has bees. It's hard to say that the colony died, because it split into four separate swarms that left the ash tree hive creating new colonies around the farm. The remaining bees in the tree hive were left with no queen, dwindled and eventually lost their food to stronger raiding colonies nearby - likely the daughter swarms.
In nature, new colonies reproduce by the swarming process. Weeks before a swarm, the bees start raising male bees called drones because the swarming impulse requires the mating of new virgin queens, and drones take a longer time to mature than queens. At the same time, the queen that would normally be laying ~1500 eggs a day, is put on a 'forced' diet to reduce her egg laying capacity, and thus her weight, this enables her to prepare for flying again; something she has not done since the first few weeks of her life when she mated with many drones in the air at special drone 'congregation' zones.
As the old queen is slimmed down, the bees also start selecting 'royal' eggs¹ to make new virgin queens. These virgin queens will emerge in just 16 days, but typically 7 days before they emerge the old queen, now able to fly again, leaves with half the colony to find a new home - this is called the prime swarm. When the new queens emerge, they often fight to the death to control the hive, but sometimes in strong hives you might get several secondary or cast swarms, each headed by their own unmated virgin queen, each taking half the colony with them, and this is what happened at the Pertwood tree hive.
In preparation for swarms we setup two log hives and two simple box hives in the trees. The prime swarm was lost, we do not know it's final destination, but one log hive and both simple box hives filled with smaller cast swarms.
Simple Bee Box - We have no large trees for more Zeidler hives cut inside trees so we have placed bees boxes and log hives around the farm for swarms.
Swarms, and especially smaller cast swarms, led by virgin queens have a difficult task to get ready for winter, approximately 77% of swarms² do not make it through winter, but we hope that the many flowering food sources at Pertwood will give them a better chance of survival. After the first year ~84% of established colonies² make it through winter and colonies have a mean lifespan of 5–6 years, typically changing the queen each year through the act of swarming.
While we are sad to lose the mother hive we now have 3 colonies in trees at Pertwood, and for the first time, had a chance to see inside the ash tree hive. Analysis of the comb by bee researchers has helped add weight to a leading theory as to why wild colonies survive without chemical treatment for the deadly varroa mite: When wild colonies have enough honey the bees turn their attention to hygienic behaviour which will include among other things destroying varroa mites. Looking at varroa mites in wild colonies, up to 70% are damaged by the bees, but if honey is removed from a hive this figure drops to 15%³. In addition when the hives fill with honey, the colony no longer needs more worker bees, the brood space for new bees is restricted by the honey, and the queen reduces egg laying.
Brood restriction - the brood area (marked in yellow) is restricted by ample pollen (filled cells) and honey stores (now missing due to raiding). In this case the hive can reduce the production of brood as there is ample food, and the hive can now turn attention to a more balanced existence of hive maintence and hygienic behaviour .
Without honey bee brood, the varroa mites cannot breed and become temporarily infertile. Wild colonies are able to fill hives much easier than commercial hives because they tend to select hives of ~40 ltrs volume - which can be 2-4x smaller than commercially farmed hives³. Selecting smaller hive hives allows bees to more easily control the development of the hive. This mechanism is clearly seen in the Pertwood ash tree comb.
We hope the Pertwood tree hive will fill with bees again in May 2020 and we wish our new swarms a safe passage through the winter as there are a lot of flowers to pollinate at Pertwood!
¹ Rare royal families in honeybees, Apis melliferaRobin F. A. Moritz·H. Michael G. Lattorff Peter Neumann F. Bernhard Kraus Sarah E. Radloff H. Randall Hepburn 2005.
² Life-history traits of wild honey bee colonies living in forests around Ithaca, NY, USA Thomas D. Seeley 2017
³ Torben Schiffer - Beekeeping (R)evolution – a Species Protection Program - Natural Bee Husbandry Issue 12.