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Heatwave experiment

So we’re having this heatwave here in Perth of four consecutive days above 40°C starting today.

My hives are in full sun, well insulated, painted white, and have roof vents. I see there are opposing views regarding ventilation so I decided to do a little experiment and see whether I notice any difference.

This experiment is in no way conclusive or scientific because my hives are still building up, and one is rather weak at this stage. But that’s what I have.

Both hive will have the corflute in the upper position, and are single brood boxes with no supers.

Hive 1.

This is the weakest of the hives. It will have the entrance reduced to around 10cm, and the crown board blocked, effectively having no top ventilation.

Hive 2.

This is a stronger hive, and will have a full entrance, and the hole in the crown board open, with a mesh.

If anyone thinks I’m putting the welfare of the bees in danger, let me know. I will report back with what I observe with bearding - though it would be hard to draw any meaningful conclusion due to the difference in hive strengths. This is unless a bushfire wipes my property off the map, which is a possibility.

What I really want to ask is - in such prolonged hot weather conditions, is there anything you can notice without opening the hives that the bees are in strife, apart from bearding?

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Wax and honey dripping out of the hive would be bad… :crazy_face:

Otherwise not much. You will likely hear a lot of fanning. Bees may go on water runs if you have a source for them about 20 feet away, they will likely use it.

Try to stay cool yourself. That is dangerous heat! :crossed_fingers: :thinking:


Thanks Dawn, yes, comb breakdown is a concern. I posted an article recently about that. If that happens, will the bees abscond or stay around?

I have a few water stations around but I keep it away from the hives themselves as I don’t want to attract the kangaroos, which will clumsily topple the hives.

It has never happened to me, but there was a chap on the forum here who had it happen in Arizona. You are not going to like this, but his bees didn’t survive it. He asked around local beekeepers, and if I recall correctly, more than 50% of the hives in his local area demised from the heat. I think it got up to around 45C though, and it was like that for a couple of days. They even stopped flights from the local major airport, because the heat made the density altitude change so much that the runway was not long enough for fully laden jets to depart.

Geez… I’m worried to be honest. I think in such temperatures shading is not enough and you have to think about actively cooling the hives, which is not an easy task.

I’m worried even more because I’m assuming that small hives like mine may be even more at risk with less bees fanning.

I had a water mister nozzle somewhere in the shed, and think I have to fish out and put in on a timer to mist the hives, hoping the mist evaporating will cool the hives. But then ‘wasting water’ like that in desert cities like Perth is questionable, verging on irresponsible.

For some reason i thought refrig and air con would be a good trade. Now, after hopping down from a black tile roof, I’m beginning to see some cracks in my reasoning. But then again my brain may be fried so this may be gibberish.
I’ll take a pic of my hives today when I get home, full sun and shade as a comparison.

Today it peaked 39.8°C here.

This afternoon I only noticed minimal bearding so far, a bit more in the weakest unventilated hive. I’ll keep on checking.

Bearding” seems to be the metric that everyone uses, and I’m not even sure it is an accurate indicator of hive stress.

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Gotta love the heat.


You will see a lot of fanning if it gets too hot but even hanging some shade cloth over the hive will help if they are in the direct sun. When comb melts in a hive it is sad news for any bees in the hive, It is very disheartening to see wax, bees and honey in a mess at the bottom of the brood box, only had it happen once and it was well over 40c. You could hang wet towels over the hives if you are concerned, that will work till the water evaporates.

Are they both with the same entrance size? 14% humidity, It was 78% here today and over 80% yesterday at 3pm so it felt really hot. Your pic doesn’t show bearding as much as a few bees just hanging about the entrance. Relax, have a cold one. Cheers

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Stefan, I think you should reduce the entrance to only 4" on each hive. You could put 2x2" entrances on the outsides. Or you could put the one entrance on the opposite side to the bees. That’s what I do in cold weather to keep the cold air away from the brood.

The idea of wet towels under shade cloth would be a big help, for sure.

Shade always trumps full sun. I start my sweet potato runners in shade as opposed to full sun which they normally perish in if the roots aren’t established beforehand.

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I checked the hives last night at 10pm when it still was 31°C and as expected they both had considerable beards. The ventilated hive had a bigger beard covering almost the whole brood box which reflects the number of bees in the hive.

As I asked before, I don’t know whether bearding itself is a stress indicator, and something that a beekeeper should make sure to keep under control. Or is it the kilos of honey harvested the ultimate metric by which hives are judged.

I read something about this Jeff - that is having the entrance reducer in the middle, with an entrance on each side, right? Once I build that slatted rack, I’ll incorporate one in it.

The wet towels are a good solution, but only if one is home to keep them wet. That’s why I’m considering a mister that goes on at intervals with a tap timer.

Jeff I have another question for you: you mentioned in another thread that it is good to keep the roof space accessible for the bees. Is there a reason for this? I was going to block the crown board hole so there is no top ventilation, instead of blocking the vents in the roof. That way there won’t be build up of heat in an enclosed roof cavity in full sun.

Jeff is advising a double entrance like this rather than a single entrance, there is many benefits in better air flow and protection of the brood cluster from cold drafts in winter. This was an experiment with the entrances right on the outside but it was no better than having them closer together, but much better than a single entrance. Follow the yellow brick road to the entrance.
I don’t see bearding as a stress indicator as much as an indicator of a strong hive in hot weather, When I have bearding the bees are calm. But better ventilation could make life more comfortable but don’t be shocked if some still stay out of the hive for the night. But I’m wondering why with your climate you are thinking of closing of the ventilation to the roof, you might find that works against your hives even in Winter.

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Peter, that’s why I’m approaching this topic with an open mind, not just doing what someone else says.

I have my own experience observing fully exposed wild honey bee hives in their native territory. I read books with diverging views, and then there are the experiences shared by real people here.

That’s the scope of this “experiment” I’m having in this 4-day heatwave. Unfortunately my two hives are young and not ideal - but they will still give me an indication I hope.

Jeff does have a very valid point - keeping a window open with air con on is inefficient. On the other hand, if there is heat build up in the hive you want to vent it out, and your solar fan worked a treat.

That is what I’m trying too find out - what is going to work best here, in high heat and low humidity and heaps of hot wind at night.

Hi Stefan, I don’t view bearding as an indicator of stressed bees. I see bearding as the bees strategy to keep the hive at the optimum temperature. You may also see a lot of washboarding during this period.

One thing to bare in mind is that bees collect water during the day which they use to help air condition their hive. During the night they can’t use water, therefore the only tool they have at their disposal is fanning. I reckon that a lot of bees hangout outside of the hive to allow room for the fanning bees to get the required airflow throughout the hive. Who knows, maybe they take turns at fanning.

The reason why I like my bees to have access into my lids is purely so I can monitor the population growth. That access into the roof is a type of population relief valve. It’s like us, if we hold wind back, it can cause problems. When I see bees starting to occupy the roof space, that is an indicator to me to think about swarm prevention measures.

PS, I wouldn’t wait to reduce the entrances. I would do it straight away. All it needs is a bit of sponge or a couple of bits of ply cut to fit snugly into the entrances.


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This shows that I practice what I preach. Each of these colonies are probably similar in size to yours. Or possibly not even as strong. The first three colonies I came to making new queens.

Only one has a short entrance on each side, however you get the picture.

I never saw them do that yet.

Great info Jeff thank you. I will take your advice and right away reduce the entrance of the strong hive too.

I’ll wedge a piece of irrigation pipe in the entrance because a $1000 hive doesn’t come with an entrance reducer haha…

I have a lifetime supply of entrance reducers. We have a latex mattress that lost it’s memory. I’ve been cutting that up.
This video is of the bees washboarding at my observation hive during hot weather.

It’s good to be able to see what goes on inside a hive as well as the outside during hot weather.

PS that was a couple of years ago. The bees were struggling to keep the hive cool because I only had that thin perspex plus thin ply covering that. I noticed after I properly insulated the sides that the bees didn’t struggle anywhere near as much in their effort to maintain the desired hive temp.


Thank you Jeff. That was you narrating, was it… with your observation hive! That was amazing! I didn’t know they washboard inside too… for whatever reason they do it.

You were saying it was a hot day at 30-32°C - here it is four days over 40°C mate. There are now forecasts for next week of days of 49-50°C in South Australia. Think about that…

I just been down to the hives and even painted white, they feel really hot on the outside, even the shaded side. I now got a piece of foil/foam insulation and am going to put it on the hives to help.

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