# Temperature effect on foraging bees



## Kcnc1 (Mar 31, 2017)

When the temperature is close to 50 can bees over exert themselves foraging and then die? I have a number of dead or dying bees outside my hive with pollen. The temperature here now is 51. I know that bees are not active below 50. 

A good number are active and returning ( seemingly healthy) with pollen. But there are at least 20 dead or dying below the hive, many that had been active enough to go forage pollen. 

I did an oav treatment 48 hours ago. 24 hour drop was minimal. I do not think this was responsible as these bees were healthy enough to leave go forage and return. They just aren’t making it all the way back. 
The ground is wet, so are they hitting wet leaves and getting to cold to get back into the hive?




















I helped some that were stilll alive but laying on the ground up to the entrance, but don’t know if they will survive. 

Any ideas on what is going on.?


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## Rader Sidetrack (Nov 30, 2011)

Bees can lose muscle control when they get too cold, but that doesn't mean they are dead. Try moving some of those bees to a warm place to see if warming them up revives them.

This study measures the temperature of the bee's bodies, and supports the idea that if the bee's thorax temperature falls below 9-11 degrees C (about 50 degrees F), bees lose muscle control, can no longer shiver to generate heat and will fall off the cluster.
http://jeb.biologists.org/content/206/2/353.full.pdf
Bees in a cluster take turns being on the outside of the cluster, and then rotate in towards the middle to warm up, but bees outside don't have that option.

Perhaps the bees on the ground are losing body heat fast enough that they are too cold to manage a takeoff.

.


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## ruthiesbees (Aug 27, 2013)

Those foragers are not dead, just cold. A little sunshine or heat lamp and they can make it back to the hive. Some days I feel sorry for mine and I put them in a jar and bring them inside to warm up and give them a drop of honey. Then the lucky ones get released outside to go back home (the unlucky ones get used for apitherapy)


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## Treehopper (Dec 9, 2012)

This week I found my bees hitting the "watering hole" at 41 degrees with the sun. I was curious at what temperature they would stop drinking?


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## jimbo3 (Jun 7, 2015)

Kcnc1 said:


> When the temperature is close to 50 can bees over exert themselves foraging and then die? I have a number of dead or dying bees outside my hive with pollen. The temperature here now is 51. I know that bees are not active below 50.


Maybe I have mutant bees, but it was around 35 this morning and had a few bees coming out. It got to no more than 45 this afternoon and there were a bunch of bees outside of both of my hives climbing around, and a bunch flying. Not sure where they were going.


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## Saltybee (Feb 9, 2012)

The only rule I know is I do not know. (Well the only dead bee is a warm dead bee is a rule I do know is true.) Ive had hives readily flying at upper 30's in the spring. lower 40's pretty common in the spring. Fall mid 40's if there is any sun.

Kind of conflicts with no syrup below 50, but that rule seems to work. Go figure.


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## Rader Sidetrack (Nov 30, 2011)

Keep in mind that "air" temperature measurements are always made in the shade, regardless of whether it is 'sunny' or not. But when it _is_ sunny, it makes one warmer in the sun. It sure works for _me_ that way, and one can find creatures like lizards and snakes taking advantage of the sun.

In this article ... http://articles.sun-sentinel.com/20...6_1_much-cooler-air-conditioning-temperatures
... a meterologist estimates that being in a 'sunny' spot makes a 10-15 degree temperature difference.


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## Saltybee (Feb 9, 2012)

A rising 40 is not a falling 40 to a bee. Not to me either.


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## baybee (Jan 10, 2016)

This happens quite often with our hives when it's clear and around 50°F. 

All five hundred bees or so here, except for very few, came back to life and started flying after having been warmed up.









Still not sure it was a good idea to dump them at the entrance as they could be sick from PMS and tracheal mites.


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## JWPalmer (May 1, 2017)

The cold bee playing dead phenomenon is really interesting. I find non moving bees clinging to the screen or a blade of grass almost every day now. Sometimes I'll hold them in my hand to warm them up, then set them on the landing board before they too active and decide they don't want to be held. Good opportuniry to check closely for varroa.


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## Saltybee (Feb 9, 2012)

While bees are not exactly cold blooded the ability to survive slowing down to the point of looking dead must be related to the ability outer cluster bees dropping in temp. 
Moths that freeze and live. Just a bugs, no sophistication in bugs.


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## mlanden (Jun 19, 2016)

ruthiesbees said:


> Those foragers are not dead, just cold. A little sunshine or heat lamp and they can make it back to the hive. Some days I feel sorry for mine and I put them in a jar and bring them inside to warm up and give them a drop of honey. Then the lucky ones get released outside to go back home (the unlucky ones get used for apitherapy)


Funny, how we can become humanitarian for 1 little ol' bee, but end up killing any # of them during an inspection.

One cold, wet night lately, I found a bee on my kitchen floor. Put her on a plate, covered her with a (meshed) colander, dropped a tiny bit of honey and a droplet of water on the mesh (which she took to fast), and the next a.m., out she went to her hive.

Another anecdote: I found a mass of bees clumped in a "moat" I created for my outdoor bee-feeder (to keep ants out); they'd fallen into the moat after filling up with syrup. I dumped the wet mass of 'em onto grass, covered 'em with a plate, and placed a pan of really warm water atop the plate. Next a.m.: all the bugs were gone. I'm hoping they thawed /dried enough to fly home -- 30 feet away......


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## JWPalmer (May 1, 2017)

As we go slightly off-topic, thought I would share. This past summer I took all my cappings and damaged comb from extracting and placed them in a shallow pan for the bees to clean up. Several hours later we had a summer shower that rained buckets for about 10 min. I ran out to the pan and was horrified to find hundreds of apparently drowned bees. Well, I carefully drained the honey water out of the pan and set the pan on my covered back porch. Then proceeded to lift bees out of the sticky mess and set them on pieces of comb. The next day there were only about 30 dead bees in the pan. All the rest had dried out and flown back to the hives.

Back on topic. Bees started flying today around 45° in bright sun, although it was just a few brave girls. By the afternoon it has warmed to about 60° and the nuc was very active.


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## beepro (Dec 31, 2012)

I'm not sure how long is your hive's landing board. I find it that when the 
landing board is extending longer from the hive entrance the bees will not likely to
miss their entrance. A reduced hive entrance will sometime overcrowd the foragers that 
they don't have a place to land when coming home. Some will be forced to land on anything
nearby before gathering strength again to fly back into the hive. This is not good on cold weather
because the longer they stay outside their body temp can drop too. So they just stay outside to
die slowly with a full load of pollen and nectar. On my hive entrance design I
will extend the landing platform at least 2 inches further from the entrance to accommodate the incoming foragers. This 
way they can just land on the board and then crawl inside. No need to wait. Wonder what kind of a landing board do you use?


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## JWPalmer (May 1, 2017)

Beepro, please consider sloping the extended landing board downwards slightly. To put it in pilot terms, the bees are landing short, not because the runway isn't long enough, but because they misjudge the sink rate when they are heavily loaded. A sloped board will help with that.


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## Mike Gillmore (Feb 25, 2006)

Kcnc1,
Something else to consider if it's not temperature related. I've noticed at this time of year that most of the bees I find on the ground outside the hive with pollen, as yours, are older bees. There is very little hair left on the back of their thorax and the wings sometimes appear to be a little worn. It could be that some of these are older bees making their final flight, and not quite able to make it back to the hive.


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## beepro (Dec 31, 2012)

Correct, these are the older bees from 2 months ago. I still have some that 
are gradually dying by the days coming home. And new big fat winter bees are replacing them now with the recent new bees emergence. This is a normal dying until the new foragers can replace them all.


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## Kcnc1 (Mar 31, 2017)

I have virtually no landing board. I have a robber screen on and a small entrance. So which is worse, potential robbing or some bees not bringing in the forage? Attached are some pics. 

Thanks for all of the info.


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## sqkcrk (Dec 10, 2005)

I have never heard of bees over exerting themselves. I have heard of them working themselves to death. But that is natural, not extra stress, I believe.


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## beepro (Dec 31, 2012)

The idea is that extending the landing board will have fewer bees that will
missed their landing ended up on the ground. A bee on the extended landing board 
will have more time to go inside. The landing board will hold them until that time. This was what
I learned in my second season of beekeeping designing my hive boxes for mating nucs.

With your existing hive stand, you can put a piece of plywood or solid wood over it, extending
2 feet not 2" out of the hive entrance under the hive box. If you worry about stability then put 2 vertical
4x4 post under the board. Or you can shorten the extension to 1 foot out. Let's see if the returning
foragers can land better than before. On the ground it is colder than on the landing board!

Another option is to reduce the hive entrance to one bee space and take out the robber screen.
Only a strong hive you can do this. My rather weak nuc hive with 2 frames of bees is a bit risky.
Maybe you can move this hive away from the other strong hives to avoid robbing..



Reduced hive entrance:


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## 1102009 (Jul 31, 2015)

I had some bad experience with big dark landing boards.
The dark color heats up the entrance and simulates warmer weather. The bees start to fly and are chilling outside.
The returning bees are landing under the boards and have no strength to go around and up.
This will not happen if the landing board meets the ground, but then mice will try to go in and damage the mice excluder.
Snow will accumulate on the boards and close the entrance.
So now I don´t use landing boards anymore. Robber screens I have taken away this time of year and now use mice excluder mesh. We are in winter modus, frosty, snowy.
The bees if they do cleansing flights, are landing on the box walls and walk in.


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## beepro (Dec 31, 2012)

I use the brown landing boards also out of rigid cardboard coated with a layer of
epoxy paint. The cardboard is first treated with melt wax before painting. Brown color the 
bees have no issue with the warm heat.


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## 1102009 (Jul 31, 2015)

Mine:


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## Mike Gillmore (Feb 25, 2006)

I have nothing against anyone using landing boards, but I think they are highly overrated. For me it's just another unnecessary piece of equipment. 
I have yet to find a landing board on a feral bee tree. They seem to do just fine without them.


https://drive.google.com/file/d/1Ji15QfHkQnKGrhfivZJACqbzJ3YPbS7P/view


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