ONBG meeting, March 2023 – new year, new lessons

Twenty people convened at Gilliane’s to share thoughts on bees, and rather a lot of food. A recurring theme was winter mortality and factors affecting this: weather, hive design and climate change.

Greeting and eating

Food is a marvellous social lubricant, and we’re all pretty local so conversation was irrepressible. In between talk about Oxford colleges, Covid, and changes in when plants are flowering, we managed to squeeze in a few bee things.

Chris has returned to beekeeping after a gap and has been struck by how climate change has really messed up the bees’ calendar – he’s seen them foraging on Christmas day and the seasons are less distinct; winter brood break no longer seems so well defined. The lack of predictability erodes their resilience.

News and projects

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It was near freezing so no hives were opened, but Gilliane mainly monitors hers using wireless temperature sensors placed above the brood nests. Her graphs show one large, established colony is now consistently 15-20C above ambient, but a smaller colony from a cast last year is struggling, and no longer maintaining warmth, so she assumes it is failing. There is no point opening it to confirm this – she wouldn’t be achieve anything except stressing it more.

Several people are building or modifying hives, I made a beelining box over winter (Chris has been pondering making one too) and I brought along a modified top bar to clarify constructional details with David, who’s building his first hive. Helen has made a special insulated floor, to eliminate mould and help hygienic bees eject debris in cold weather.

6 of those present are going to the Learning from the Bees conference next month, and at least 2 more OxNatBees members not present are going. Very exciting having an international conference on your own subject on your doorstep! Gareth will be speaking there. He treated us to a mini-talk:

Hive Design, Humidity and Health

Gareth hasn’t had any winter losses for some years, but this winter he’s lost 4 of 20 colonies (looks like it will be 5). Why?

To illustrate some points he had taken along the contents of two hives – both super-insulated. One was a double walled golden ratio one he built himself, whose colony had lasted 2 years, the other a Freedom Hive from Matt Somerville which had died in its 6th winter. Both had loads of accessible stores, starvation was not a factor.

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It’s been a very hard winter for bees, he explained, because although we don’t live in an extreme climate, we’re in an extremely changeable one and there have been very few flying days since December due to so many cold, rainy, and windy days. Normally the weather would be a bit more stable over winter. That’s reduced bees’ options.

Also, ivy kept flowering late in the season and bees kept gathering its nectar, but when temperatures drop below about 12C they can no longer evaporate it into honey. Both colonies had combs full of open nectar – generating humidity in the hive.

The older colony just seems to have dwindled from queen failure; 6 years is a good age for a colony allowed to supersede, but eventually you get a queen who runs out of sperm in Autumn and the colony dwindles into winter. That colony shows evidence of drone laying. As numbers dropped, there were insufficient bees to cover brood resulting in chilled brood.

The younger colony has succumbed to a combination of stressors, no one of which was lethal on its own. There was evidence of varroa (irregularly torn open brood cappings, see photo) but as a colony dwindles any varroa converge on the last few brood, so it always  appears there were a lot. No adults in the remnant cluster showed deformed wings. The major stressor seems to have been too few bees to run everything, keep warm and remove humidity.

A big stress has been high humidity. Think about all that open ivy nectar, and the bees eating a box of honey. That box will burn to create about twice its volume of water, breathed out by the bees, which they get rid of by fanning it out the entrance. In fact most of the energy bees use ventilating their hive is to pump humidity out: if they were just doing it for oxygen they would not need to fan nearly as much. Cold, damp weather makes it harder to remove condensation from a hive because cold air holds so much less water than hot.

There’s always a debate about mesh floors versus solid floors. Open mesh floors let humidity out with a tradeoff of increased fuel use to keep warm. Will doesn’t use an open mesh floor, the bottom of his hives are sealed shut; but he argued strongly for a mesh floor above an inspection tray: almost all his inspections now are purely by examining floor debris. If the mesh was not there the bees would clean away evidence.

Ivy honey, beginning to ferment. The raised caps in the centre of the left hand image are a sign of capped honey fermenting. Click to enlarge

When honey crystallises, excess water is expelled from the crystals into the fluid between them. As this fluid rises above 21% water, yeasts activate and ferment it, causing bubbles and pushing plugs of honey out of the cells.

Arcane lore

An interesting point about these hives is both feature very long  combs, and have pollen under the brood. Gareth explained this is often seen in deep hives.

We discussed brood patterns, and how these can mislead people into assuming there’s a problem. As Roger Patterson (a well known BIBBA beekeeper) says, a glitch in laying like a supersedure can cause ripples in laying patterns which propagate all season.

Louanne asked how one can distinguish between primes and cast swarms. Gareth explained primes tend to be large, cohesive and cluster lower, and when hiving, a virgin queen (in a cast) will be hyperactive and darting all over the place, where a mature queen marches straight into a hive.

This led to an explanation of how casts sometimes act as outstations for mother colonies: sometimes the cast has no queen at all (because the queen does not mate) and just builds comb and gathers honey, then the bees return, with the honey, to the mother colony. This leaves honeycomb in a prepared cavity, and as it is not brood comb it is not eaten by wax moth over winter. Next Spring… this is where the prime swarm goes. (Gareth observes his colonies very closely and doesn’t assume anything – he’s seen this several times.)

Entrance effects

Liz wanted to know how Gareth gets consistently straight foundationless comb? Dowsing to position hives, he replied, and maybe entrance arrangements. He doesn’t just use bottom entrances. He came up with his 2-entrance system after noticing bees enlarging a hole in a damaged hive. With much hard chewing, they created a second entrance. He finds bees pull air in at the top, which is counterintutive to us; they fly mainly from the top entrance and store honey all the way down.

Edge effects

I shared my thoughts on ecological edge effects. Natural beekeepers tend to look more at what’s going on outside the brood nest. In other biological systems, ecologists say the most important drivers occur at habitat boundaries like woodland edges – in hive terms the less patrolled areas of comb, floor and below the entrance are where the pests and predators hang out. We infer colony health from these clues without opening the nest.

Tea and cake, because this is Britain

After all that listening we all charged downstairs for yet more sustenance, and at this point we remembered Liz had taken some comb from a deadout along for me to demonstrate some analysis techniques.

Comb dissection

A lot of the time people look at weird things on a comb and jump to conclusions, or post a photo to a forum and ask for opinions. You can do more!

Using tweezers, sharp dissection scissors and a powerful magnifying glass, we pulled apart the more interesting cells. (I probably shouldn’t have done this next to the human food!) What we saw was that the dodgy looking mould was always above bee bread, it wasn’t anything sinister like chalk brood fungus on mummies. We could also see how the cell walls on these old combs were wafer thin layers of propolis-tinted silk with essentially no wax left.

The right hand picture shows several features: the layered structure of a bee bread cell (topped by mould), with different colours of pollen; honey beginning to granulate; thin silk walls forming sharp cornered, hexagonal cells.

In retrospect, we missed a trick – we could have dissected some of Gareth’s combs to look for varroa and “mite frass”, guanine deposits (white spots of excrement) inside brood cells, which are characteristic of varroa.

Heartfelt thanks to Gilliane for opening her home to a crowd of excitable chatterers, and Gareth for the amazing lecture!

Next meeting: probably early April shortly after the LfB conference, to review and share what we learned.

This entry was posted in Ecology, Experimentation, Hives, Meetings, ONBG, TBH, Warré and tagged , , , . Bookmark the permalink.

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