# Winter cluster generating heat



## Moon (May 7, 2011)

I've read in a bunch of books that during winter while the bees are clustering they can 'unhook' or 'unhinge' their wings from the muscles used for flight and vibrate those muscles to generate heat rather than for flying. Could someone point me towards a resource or give me a scientific explanation of what is actually occuring physiologicaly when the bees do this?


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## Rader Sidetrack (Nov 30, 2011)

Here is some info:



> The ability to fly far and fast has greatly contributed to the success of bees. They can forage up to three miles from their hives, and reach speeds of 15 miles per hour. Bees have four wings, but a row of small hooks, called *hamuli*, on the leading edge of the hindwing fits securely into a groove on the trailing edge of the forewing, allowing the bee to couple the wings together into a single flight surface. When at rest, the bee can unhook its wings and fold them back.
> 
> More at
> http://www.aragriculture.org/insects/bees/anatomy_honeybee.htm


And a remarkable photo of the hamuli (hooks):










Photo linked from this site: (there's an enlargement there also)
http://www.photomacrography.net/forum/viewtopic.php?t=1599


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## G'ville beek (Jul 2, 2012)

That is so dang cool, and I think those hooks are made of gold... hummm I have to guard my girls , or the dang greedies will get the hooks. These amazingly blessed creatures sure cease to amaze me.


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## Moon (May 7, 2011)

I think you meant never cease to amaze you G`ville beek  . That's a phenomenal picture thanks Rader. So it's not that the wing itself detatches from a muscle or muscle group it's that the wings detatch from one another. Does the forewing move while generating heat then? If I'm understanding this correctly the muscles would be the actual energy output, the forewing is on the receiving end of the muscles output and by "hooking" the hindwing to the forewing the bee is able to create a large wing used for flight. At rest it can fold it's hind wings back by unhooking from the forewing (obviously usefull for crawling around the hive) but the forewing is still connected to the muscle it doesn't ever disconnect from the energy source that generates heat.


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## Vance G (Jan 6, 2011)

I don't think that is correct either but I may be wrong. The internal muscle flexing I believe is what causes the heat. Even one unhooked wing beating in a cluster would seem to me to cause outward airflows that would be damaging. That is just what makes sense to me from what I have read. The outer layer of bees on a winter cluster that I have actually observed don't seem to be doing much.


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## Rader Sidetrack (Nov 30, 2011)

When a human, or other mammal, gets cold and starts shivering, the shivering action is a series of small contractions of muscles, and generates heat. Even though your arm muscles may be moving in a shivering action, your arms themselves are not moving significantly. 

I haven't found a reference that says whether bees have a way of disconnecting both sets of wings or just one set, but either way I suspect that bees can engage in a shivering type action that exercises their wing muscles ( and generates heat) without making their wings move back and forth appreciably.


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## solstice (Oct 18, 2012)

I was unaware of this fact---very interesting and thanks for sharing!


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## PAHunter62 (Jan 26, 2011)

Last winter was my first winter with bees. I have them located directly behind a shed in my back yard. I was curious to monitor the temperature inside the hive at the top of the top box. The temp in both hives was between 90 and 94 degrees pretty much anytime I looked. Even at 6am on mornings where it was 10 degrees outside, it was still 93 at the top of the hives. Pretty amazing.


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## beemandan (Dec 5, 2005)

I’ve read this as well but for the life of me cannot remember where. My recollection is that several sets of muscles are involved in bee flight. The wings must be able to move in various directions to control travel direction, hovering and then folding against the body when not in use. One set of muscles essentially fibrillates and is connected to the wings for appropriate movement by a secondary mechanism. During winter clustering these fibrillating muscles remain unconnected to the wings thereby generating heat. My recollection of it.
If I get a chance later, I'll see if I can dig up a citation.


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## beemandan (Dec 5, 2005)

Hardly a scientific citation but from First Lessons in Beekeeping by Keith Delaplane, 2007, page 22.
_‘In the center of the cluster are the queen and a cadre of workers that are actively generating heat by consuming honey and shivering their thoracic flight muscles.’ _


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## JRG13 (May 11, 2012)

It's a shiver not a flapping movement as beeman posted.


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## sqkcrk (Dec 10, 2005)

Calesthenics. Muscle flexing.


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## Jeanette (Jul 7, 2012)

@ Radar - that's a remarkable photo, thanks for posting it!

@ Moon - this might be what you are looking for; a scientific paper on 'Neural Control of Fibrillar Muscles in Bees during Shivering and Flight' (1991) http://jeb.biologists.org/content/159/1/419.full.pdf


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## Daniel Y (Sep 12, 2011)

The unhooking of the wings is not unhooking form each other although the above is correct they can be unhooked form each other. it is that the wings can also be disconnected from the muscle that moves them. This way the muscle can still be used as if the bees is flying without the wing moving.

When you work hard you get hot. This is because muscle is producing energy. Some of the energy is goign into the lifting.t he moving of your arms etc. but no energy transfer is perfect. and the most common way unused energy is passed off is by heat. energy of your muscles that is not used to lift or move. is converted to heat and your body is able to get rid of it.

Bees have muscle that are intended to power their wings. but they are able to disconnect that work from the muscle and use them as if they are flying. much more energy goes into heat than woudl otherwise. also using flight muscles is very efficient. in comparison flight muscles are the larges muscles of any physical body. Think of the breast of a chicken. that is their flight muscles. They are simply huge in comparison to every other muscle in the chicken. they have to. they have to be strong enough to lift the chickens entire body from the ground. Larger muscles produce more heat. So the bees are using the largest muscle they have to make almsot pure excess energy that is transferred into heat. IT works so well that not every bee in the cluster has to produce heat at all times. but it is actually just a few bees doing the job.


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## sqkcrk (Dec 10, 2005)

Otherwise known as flexing of muscles, right Daniel?


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