Inspections - "Wait until the day temperatures are over ___(insert a temperature)"

It is a bit quiet on the forum, so I thought I can provide a bit of entertainment for those who prefer to read :grinning:

Quite often we can see a piece of advice floating around about not opening the hive till the temperature reaches… I think 20°C is the most popular number. Otherwise, you will chill your brood. So, the question. Where this number did come from? Is it a fact or another beekeeping myth? Will you really chill the brood if you open hive at 15°C? Yes, I understand that opening a hive in low themperatures is going to upset the thermal regime of the colony inside but will brood really suffer? Lets have a look at some data :slightly_smiling_face:

If you read David Cushman’s site, you may find a careful statement there written by Roger Patterson: “I have heard it said that inspecting colonies on cold days causes chilling, but this is not my experience. If the weather is cold an inspection will need to be quick. There is residual heat in the combs and I have never had a problem.” Interesting, isn’t it?
But what happens if we will go beyond “residual heat in the combs”? There are few fellows who did it and did not mind sharing their data. The low temperature always has a negative impact on the brood, but it varies in different stages of development.

From a book by E.K. Eskov, Beehive microclimate, and its regulation, 1978

Embryonic Stage. (Normally, the first 72 hours of development.)
Based on N.M. Kulagin’s experiments, (quote in my clumsy translation):
“Even short-term chilling of eggs has a fatal effect. Death rate reaches 5% when exposed to 5-8°C during 1-3 hours.”
“Cooling down embryos at the early stage of development to 8-13°C during 72-135 minutes leads to the development of gynandromorphs.” I said “Wow!” here too :astonished:

Post-embryonic Stage.
N.M. Kulagin’s data:
Exposure of 4-days old larva to 3°C during 1-3 hours - death rate 4%.
Pupa exposed to 3°C during 2 hours - 100% death rate.
Bees ready to hatch, at the same conditions - 0% death rate.
B.M. Muzalevsky’s data:
Sealed brood, when cooled to 25°C, dies in 8 days.
At 27°C lives for 12 days and even reaches imago stage, but bees die soon after hatching.

So, as usual, while armed with some data, it is up to you to decide at what temperatures and for how long you can open your hive to have a look :slight_smile:


Wow, this is a very helpful and interesting read - thanks ABB for sharing! First springtime inspections are always tricky in my region because of the persistent wintry temps, with slightly or dramatically warmer days thrown in. Swarm prep begins in early March so I’m constantly monitoring the weather for the best day to split.


There’s Rusty Berlew’s common sense advice too. If you need to inspect or intervene to save your colony then it is (almost) never too cold.


Very interesting and helpful stuff, @ABB. As people are saying today, whenever possible, I like to “follow the science”. I know that many Aussies have the luxury of using the 20°C rule for inspections, but we certainly couldn’t do that in the UK. If you look at a climate chart of Oxford, UK, you will see that even the highs don’t reach 20°C (68°F) until June. We would never be able to do swarm prevention if we followed that rule! :blush:

So how did we manage it? As you say, firstly by having a plan before starting, and keeping the inspections short (15 minutes was usually plenty, often 5 or 10 minutes was enough). We only inspected on calm sunny days, when the bees were flying. Secondly, we had a flat lid on the ground next to the hive, with a spare crown board (inner cover) in it and an empty brood box on top. When we opened the hive, we put a heavy linen tea towel over the top of the hive to keep the heat in the frames that we weren’t inspecting. As we looked at each frame quickly, we transferred it into the empty box, and covered that with a tea towel too. This seemed to keep the brood warm enough to survive our inspection, and I can’t remember the last time that I saw chilled brood or chalkbrood, so I think it worked.

If you only have one brood box, you may not need to transfer every frame over to the empty box - after 2 or 3 frames, you will have enough space to just shuffle the frames over briefly. We did it because we alway ran brood and half, or double brood, and the boxes were too heavy for me to lift alone anyway. When the inspection is done, you just transfer the frames back in the same order that they came out. Very easy! :wink:


I love Rusty - her POV as a beek has been so valuable to me, including this very article!


We all know how quickly bees react to smoke. I believe they will react just as quickly with a sudden drop in temperature. As long as a colony has more bees than is required to normally keep the brood warm, a sudden drop in temp will cause more bees to crowd around the brood to quickly restore the brood to the optimal temp.

The key is to understand bee culture & what temp kills brood. Don’t expose brood to cold air for any length of time, especially cold wind. Leave the bees on the brood if possible during brief inspections in cold weather. This is what I do.



Thank you, everyone. Glad you found this interesting :slight_smile:


Great info ABB …and great responses that followed.


Thank you ABB. I live in Flinders Victoria Australia and we are heading out of winter, so I have been looking for information on this on various sites. Very helpful information as are all the other comments and references below. Feel much more confident now. Kind regards and thanks to all. Regina

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You are very welcome, Regina :slight_smile:


This is such a great thread! Thank you, ABB. This has cleared up so much for me and it’s great to see that many others have experienced similar thought processes.

@Dawn_SD, you have such great points! Us privileged mild-winter Australians should be more mindful of other beekeeping conditions before we think to make any more complaints :grin:


You also have to take into account the microclimate of your apiary.
Ours is against a brick wall that faces north (where the sun is) and there is a block of flats behind us to the west and in a windless day where the forecast is for only 17 or 18c, the apiary can have temps in the low 20’s.


I realize this is an old thread, however the topic is so relevant to the warm to cold spring weather we are having in Solano County, California this year. It’s the beginning of May and today’s temperature is 59 degrees F (15C). The rest of the week looks like 64F - 68F (17C - 20C).

I installed a 5-frame nuc 3 days ago, Sat May 29th, and because it was getting cool I didn’t really get time to look over the frames. My concern was to get them settled in their new 10-frame hive as gently and quickly as I could and keep them warm. The bees were pretty agitated coming out of that nuc, so I didn’t want to prolong the transition. I’m really anxious to get in there and see what’s going on.
After reading the above article I’m concerned as to how am I able to do a proper inspection when the weather is so chilly (59F today and raining on and off)? Would 68F (20C) be warm enough for me to do a fairly quick inspection without harming the brood?

Given the info in that article and this unusually cool spring weather, does anyone have suggestions for when it would be safe to open the hive and do an inspection? With weather being so cool I’m also concerned about when I can get into the hive to evaluate for mites (nuc apiary did not treat for mites). Any advice re mite treatment this time of year, if it’s needed? I am familiar with the various treatments and I have OA.


What a great post @carol08 :blush:

This is very common for new beekeepers (and new parents, dog owners etc), but honestly, less is sometimes more. Most of the neurosurgeons that I have worked with follow this credo too… OK, not really relevant to beekeeping, but the point is, you have to balance the risks against the benefits.

You have a nucleus. That is a much stronger colony than a package. They have comb, food, brood and a laying queen. Woohoo - big head start. However, they have a lot of empty space in their new home, and they need to keep it warm and defend it. So it is important not to stress them with frequent inspections until they are stronger = 80% full rule.

I would definitely avoid inspections in the rain, unless you have a really vital reason to do so (low food stores, for example). I would avoid inspections on cold days, unless there is very little to no wind (less than 5mph), and even then, I would make them as fast as possible. No more than 15 minutes from lifting the inner cover, and only do it when there is a pressing need.

I wouldn’t worry about that for now. Let the colony build up for 4-6 weeks. You can do brief inspections every couple of weeks to make sure that they are not building crazy comb, but don’t try to find the queen if you can find eggs or uncapped brood. Once they have drawn most of the frames out, you can think about a mite count. That may be in June, or it could be earlier, it will depend on how the season goes in your area.

So for now, kudos to you for being a concerned bee parent, but sometimes you just have to wait and see.



Great advice and calms my frazzled nerves too, lol. Thank you! I won’t feel so neglectful now continuing to wait to inspect things. I am worried about them drawing wonky comb though. We’ll see.

If you don’t mind, one more question relating to the cool weather…I put the Flow entrance reducer on the front entrance of the hive and I closed the vent in the back (the board with the level and vents on it), so the bees don’t have to work so hard to keep the temperature regulated inside. My concern is that reducer has a pretty small opening so I’m worried whether or not they are getting enough air into the hive through it. I think I need to get a 4-inch reducer. I see a lot of people using those.

So, is that ok to have that reducer on there while its still cool out, or should I take it off ? And is it ok to have that back vent closed, or should I turn that around and open it back up? They have a top feeder of 1:1 sugar water under the roof (empty flow super covering it) on the plug hole in the internal lid (for drawing comb), so there’s no additional ventilation coming in from up there.

Thank you so much for your kind help!! These are the things that have been keeping me awake at night lately because I didn’t have anyone to ask. I appreciate you and this incredible forum very much!


Hey Carol, congrats on your new bundle of joy :smile::honeybee:

It’s been SO chilly & rainy here for the past week too! One thing that I find comforting is to press my ear up to the back wall and listen to all the busy buzzing and chewing sounds every so often while I wait until there’s a good time to look in.

About your excellent ventilation & entrance reducer questions, the way you have it now makes perfect sense and is fine while it’s cold. You can switch it to one with a larger opening later when it warms up and you’re able to do an inspection. Incidentally, ever since I learned about how the bees fan to control their airflow and temps I now have my entrances closed off in the center so it leaves two small openings on either side. They will use this setup to create convection - amazing!

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@Eva thanks…they’re stressing me out more than a new born :smile:
I’m going to try that! So long as my guard bees don’t catch me in the act, it should be fun listening in on them! Mind if I ask where you got your reducer with with the two small openings on either side? I’d like to check that out. And thank you for clarifying the ventilation questions I had. Your help is much appreciated!!. Now I think I’ll sleep good tonight and not worry whether or not I am providing them with enough ventilation.

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I agree with everything that @Eva wrote. Leave it on, but I would add that if you see a massive traffic jam on the landing board, they need a bigger entrance. I also agree with the dual entrance concept, or at least having an entrance about 6" wide in total. This provides the 15 sq cm entrance that research has shown is preferred by bees when they have a choice.

You can make an entrance reducer very easily by gluing a stack of paint stirrers, craft sticks or comb guides together to fit into the entrance. Make sure it is a tight fit, because bored bees love to push them out. I am not kidding! They are amazingly strong when they set their mind to it. :laughing:

Leave the ventilation they way you have it right now, and don’t fret about the top feeder. :wink:

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Thanks for chiming in on that Dawn! You guys are so amazing and helping me feel more comfortable each day.
About the Rapid Round Top Bee Feeder, I keep reading that bees will drink like a gallon a day when building comb. I see some bees crawling around in the feeder, but after 2 full days the 1:1 sugar water is mostly all still there. They had a full heavy frame of honey when I transferred them from the nuc. Is that why they aren’t slurping down the sugar water? Also how many days is sugar water good till I need to change it?


You probably have a good nectar flow then. Bees prefer natural nectar to our sugar syrup concoctions! They are sensible, because nectar has vitamins and the right pH for them, syrup usually doesn’t.

It depends… I make mine with ascorbic acid powder (vitamin C from health food suppliers). Nectar has vitamin C in it, which is why i use it - healthy and more like nature for the bees. If you acidify it with vitamin C to about pH 4 using pH paper strips from Amazon, it will last about a month to six weeks. If you don’t do that, you will probably get mold or bacterial growth in it within 2 weeks. Once you see black (most common), white or pink strings or scum in it, you should throw it out. Clean the container thoroughly with 10% household chlorine bleach in water, rinse well and start again

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