# Acceptable levels of Varroa mite infestation



## beemandan (Dec 5, 2005)

Transparancy?


Barry said:


> We won't know unless they speak up and be transparent.


My apologies fafrd, from a different, related thread.


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## fafrd (Aug 22, 2009)

beemandan,

from your post, I can not tell if it was posted by accident or not.

I'm going to assume you meant to communicate something to me regarding my questions in this thread and see if we can engage in a constructive dialog. I've read through the entire thread you referred to and near as I can tell you are a small-cell naysayer.

I haven't read through all of your other posts on this board so I would appreciate your letting me know if you are a 'treatment-free' naysayer as well or if you believe treatment-free is possible but cell size has little or nothing to do with it.

If you treat your hives, then there is not really much we have to talk about on this thread, since I was specifically seeking input from beeks who do not treat and who have been successfully keeping hives without treatment for many years.

I probably fall into the category of 'starting beeks who jumped onto the small cell bandwagon and who failed' that you refer to in the other thread.

I am not giving up, I want to try again, but I also realize from the two hives that failed from PMS last year that it is not as simple a many of the small-cell / natural cell beeks make it sound.

I hope you will consider me very transparant, because I am more than happy to share details of my SC/NC failure, primarily because I am seeking input on what I can do differently this season to improve my chances of success.

If you are a beek who treats and the implied message you have for me is to "stop wasting my time trying to avoid treatments" then please stop wasting my time with non-constructive posts on my thread.

If you have something constructive to say to me about trying to manage Varroa without treatments (SC/NC or otherwise), then I am all ears and would value your input.

Varroa mites killed my treatment-free hives last season and I am looking for input from those beeks who are successfully managing hives without treatment to me to be more successful this season. I guess I assumed that that was the subject matter for the 'Biological Beekeeping' Forum.


-fafrd


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## beemandan (Dec 5, 2005)

I am not treatment free. Currently the only treatment I use is for varroa. I presently use thymol based products for those hives that need to be treated. I am certain that ‘treatment free’ is possible. I know a number of beekeepers who are. I don’t think it has anything to do with cell size. 
I ‘regressed’ thirty hives some years ago. I no longer have any small cell hives.
I am pleased that you aren’t giving up. My issue is that small cell is sometimes promoted to new beekeepers as a simple solution to varroa and other bee plagues. From what I’ve seen, all too many have experiences similar to yours and do give up. 
_ If you treat your hives, then there is not really much we have to talk about on this thread_
I’m sorry you feel that way.
Regards


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## fafrd (Aug 22, 2009)

beemandan,

thank you for this contructive post and my apologies if my response to your original post rubbed you the wrong way at all. I just found your original post somewhat cryptic and was at a bit of a loss to understand what you were trying to communicate to me.

I was typing a bit to quickly when I wrote what I wrote regarding treatment. What I should have typed was "_if you believe that treatment free does not work and is a waste of time then there is really not much we have to talk about on this thread_."

I was confusing the thread with the poll. The poll was specifically addressed to beeks that do not treat and I didn't create a place for beeks that _do_ treat to respond (which may be why the number of responses to the poll has been so low

The fact that you believe treatment free _is_ possible means there is much we can discuss on this thread. I am trying to understand how treatment-free is possible and what I can do to improve my chances of success without treatments.

As I've alread said, I 100% agree with you that small cell is promoted as an overly simple solution to combat Varroa - as a minimum it is certainly more complex than suggested and the liklehood of success is certainly far lower than suggested. I really don't care about cell size - what I care about is raising bees that are able to survive without medications (if that is even possible - after what I have experienced, I now have more doubts 

You say you know a number of beekeepers who are treatment free - I would be interested in any techniques you believe they may be employing to succeed. In particular, I am currenty trying to understand two things:

1/ what level of Varroa are managed/contained by the hives that survive with Varroa but never let them get out of control without treatments (the subject of the poll associated with this thread)

2/ I suspect that lots of drone comb and drones in my hives is what let to my Varroa problem getting out of hand and ultimately killing the hives with PMS, so I am interested to understand what other beekeepers who do not treat do as far as drone comb and drone brood management (the subject of another poll in my other thread).

If you have any idea from the treatment-free beekeepers that you know how they would answer either of these questions, I would appreciate your input.

And in general, if you have any ideas as to how I can be more successful in my second attemp at going treatment-free, I am all ears. My current plan is to monitor Varroa levels (which I did not do last year - I took the 'ignorance is bliss' approach which I know know is a mistake :no: ) and to intervene with drone comb management and possibly drone trapping if it looks like the Varroa levels are getting out of hand.

This may work, but it is certanly not 'biological' nor 'organic' beekeeping, because bees in the wild _do_ raise drones, so the other experiment I am considering is to leave drones unmanaged but to create an artificial swarm or induce a broodless period in the middle of swarm season, since the one things bees in the wild do which we as beekepers generally try to prevent is swarm, and in so doing they able to force all mites to be phoretic for a period of time.

Again, my apologis if my earlier post rubbed you at all the wrong way and I would value your inputs in a constructive dialog on these subjects.

-fafrd


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## sqkcrk (Dec 10, 2005)

Now apologize for quoting the previous post. When replying to the previous post it isn't necassary to quote it and certainly not the whole thing.

Have you had any results on your survey? None of the choices fit me, so I can't vote.


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## fafrd (Aug 22, 2009)

sqkck,

you are probably correct. I did edit down the original post (I did not quote the entire post) but I probably could have cut it down much more and still gotten my point across and I guess in general I still need to learn the _'do not quote if you are replying to the previous post' _rule:no:. Lesson for next time...

I think anyone can see the current result of the poll, right? At the moment there are 4 responses (which I guess is not a bad start, I mean it is friday, right )

When you say none of the choices fit you, I assume that means you are treating for mites, right?

-fafrd


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## Countryboy (Feb 15, 2009)

I have some small cell frames in my hives. I use them because it allows more cells per frame, and the bees can cover more brood in the same amount of space. If it has varroa control advantages, that's just icing on the cake. If it doesn't help with varroa, I still have more brood per frame.

I suspect that some bees are better than others at managing varroa. Some people suspect that some varroa are less virulent than other varroa mites.

If the hive is thriving and surviving without treatment, to me that is an acceptable level of varroa mites.

I believe it may depend on how tough your bees are, how weak the mites are, and a combination of other factors to determine what an acceptable level of varroa in your hives is.

One thing you will find is that what works for my bees here, may not work for your bees there. Beekeeping is very local. Trying to find a one-size-fits-all approach to beekeeping will just result in forever chasing your tail and always being a step behind the game.


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## Countryboy (Feb 15, 2009)

BTW, please define 'monitor' for mites. 

Are you talking about mite drops or alcohol washes? If I break drone brood and check to see if I can find mites, am I monitoring? If I look for DWV, am I monitoring? If I look to see if I can see very many phoretic mites, am I monitoring?


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## sqkcrk (Dec 10, 2005)

fafrd said:


> sqkcrk,
> 
> When you say none of the choices fit you, I assume that means you are treating for mites, right?
> 
> -fafrd


Right.
Interesting to me is that of the 4 who answered the poll, none of them sample to see if they have mites.

I'm also curious about the Thread Title. It's never addressed. Or is it assumed that if you don't treat then the level is acceptable?


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## kwest (May 16, 2009)

i voted that i dont moniter and believe my hives are naturally mite free. well not really. i just have never treated and have never seen a mite. i do watch for them but i dont do anything more than that. i dont truley think my bees are naturally mite free but i dont think i have mite probeblems what so ever.


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## Merlyn Votaw (Jun 23, 2008)

I use grease pattys and have not had any mite problems yet.I have 15 hives and this is my 4th yr.I think my grease pattys are taking care of the mites better than chemicals.


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## sqkcrk (Dec 10, 2005)

To the previous two posts:
How often does one of your hives die and from what?


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## Michael Bush (Aug 2, 2002)

I always check the bottom boards for mites when I lose a hive. I montitored the live ones as well back when I had Varroa issues and would recommend it to those who are having issues. When you lose a hive to Varroa you have thousands of dead varroa on the bottom board.

When I did monitor I would say a natural drop of 50 mid summer was acceptable and a sugar roll with six or seven mites was acceptable. In the fall those numbers will go up and that is pretty normal. Still if I had natural drops in the hundreds per day that's a lot of mites. If you have a sugar roll with 15 or 20 mites in it, that's quite a few mites.

I gave up monitoring when I often couldn't find any.

You don't have a choice for "I used to monitor until things got stable..."


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## deknow (Jul 17, 2006)

beemandan said:


> My issue is that small cell is sometimes promoted to new beekeepers as a simple solution to varroa and other bee plagues.


funny, i think similarly about thymol treatments 

deknow


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## sqkcrk (Dec 10, 2005)

Michael,
Anyone tending your cols while you are where you are?


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## kwest (May 16, 2009)

i have lost four hives this fall but none to mites i dont think. this summer i was really busy with work and didn't have much time for the bees. i should have requeened two of the colonies as the queens just started having irregulare laying paterns, one was destroyed by mice, one was week and robbed out and the last was a swarm that i should have been feeding more. they just didn't build the #'s to survive our cold weather. i watch for mites and have never seen any, i watch bottom boards on lost colonies. most of the hives i have lost where probably my fault because of the lack of time.


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## honeyshack (Jan 6, 2008)

There is nothing for a monitor and treat vote. Oh well.
One person mentioned something about beekeeping being regional. And there is a mountain of truth to that. 
In the area where i live, winters are cold and harsh and for minimun 6 months of the year. Honey production is minimum 6 weeks max 8-10 weeks with 10 weeks pushing it. And those weeks are not spread out like in the southern states. Our honey production happens short fast and sweet. Our goal in our enviroment is 1. bee production to make through the summer honey flow and at the same time winter bee production so our colonies survive the long cold winter. Not monitoring and not treating for varroa is not an option. Yes varroa resistant queens aid in the fight, as does some sort of IPM aid in the fight. 
As for treatments we only have a few legal treatments. Formic, Apistan (like that works) check mite ( again...not working) and Apivar which is Amitraz (emergency use registration only). Powder sugar is also allowed, however from April to end of October is aprox 7 months, 28 weeks. At a cup of powder sugar per week that is 4 bags of sugar and at a price of $3.75 a bag with prices on the rise...gets expensive


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## Barry (Dec 28, 1999)

honeyshack said:


> There is nothing for a monitor and treat vote.


That's because this is a forum about not treating.


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## fafrd (Aug 22, 2009)

Michael Bush said:


> I montitored the hives back when I had Varroa issues and would recommend it to those who are having issues. ..."
> 
> You don't have a choice for "I used to monitor until things got stable..."


The poll was oriented towards what a beekeeper _'is doing' _(ie: today) and I should have made the options related to what a beekeeper _'has done' _(ie: including past practice) since I agree - once you know the bees are taking care of the mites on their own why waste the effort tracking mite infestation levels except when a problem surfaces?



Michael Bush said:


> When I did monitor I would say a natural drop of 50 mid summer was acceptable and a sugar roll with six or seven mites was acceptable. In the fall those numbers will go up and that is pretty normal. Still if I had natural drops in the hundreds per day that's a lot of mites. If you have a sugar roll with 15 or 20 mites in it, that's quite a few mites.


Thank you - this is exactly the kind of information I was looking for when I created the thread. From my simple model of mite numbers, I would translate a natural 24h mite fall of 50 mites into a phoretic mite count of roughly 250-350 mites (5-7 day phoretic period), meaning that for a 60,000 strong hive, an infestation level of about 0.5%. This is based on worker brood (where the mites falling are about 50% of the mites exiting), for drone brood the corresponding number of phoretic mites would be at least 2-3 times greater (1% - 1.5%).

And assuming the sugar roll is a standard sampling of about 300 bees, 6 mites would correspond to an infestation level of 2%.

You say that in the fall those number will increase and I interpret the other numbers you have provided to indicate the fall 'danger zone', right (not mid-summer)? Usng my same simple model, 200 mites dropping in 24h would correspond to an infestation level of about 1.5% - 2.5% (worker brood) or 5%-8% (drone brood). And 15-20 mites in a 300-bee sugar roll would correspond to an infestation level of 5%-7%.

So please correct me if you think I have understood the data you have provided incorrectly, but I am going to interpret your numbers to indicate that you believe your bees are able to deal with mite infestations that peak in the 1-2% range in mid summer and increase in the fall, but never as high as 5-7%.

If you were starting out with a new strain of bees and wanted to evaluate thier ability to contain mite infestation within your treatment-free beekeeping system (SC or whatever), would you have an opinion as to what level of mite infestation in the early spring would be OK to allow them to start with? Would a 1% infestation in the late winter/early sping be too high of an infestation level or should a good strain of bees (and a good beekeeping system) be capable of containing and dealing with that level of early spring infestation?

-fafrd


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## fafrd (Aug 22, 2009)

Merlyn Votaw said:


> I use grease pattys and have not had any mite problems yet.I have 15 hives and this is my 4th yr.I think my grease pattys are taking care of the mites better than chemicals.


Merlyn,

I don't want to enter into a debate about whether the use of grease patties constitutes a 'treatment' or not (if it is just grease and no oils then I would probably lump it in with powdered sugar as a benign chemical-free treatment), but I am curious as to how you use gease patties, how you believe grease patties are effective in fighting varroa, and most importantly, whether you monitor varroa infestation levels (through natural fall or sampling) and if so what level of infestation you have in your hives in the early spring (following grease patty treatment) as well as any idea you may have of infestation levels in the summer and fall.

-fafrd


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## fafrd (Aug 22, 2009)

sqkcrk said:


> Interesting to me is that of the 4 who answered the poll, none of them sample to see if they have mites.


Interesting to me as well. When I set up the poll, I didn't consider the possibility that mite levels would be monitored only for a season or two until the system was proven and then would be abandoned because it wasn't worth the effort. Since this seems to be a pretty common pattern, what it probably means is that most of the 'treatment-free' beekeepers (or at least the ones that spend time on his board ) are established and that there is a relatively low percentage of aspiring treatment-free beekeepers like me trying to get their treatment-free beekeeping system established (and so asking all these questions and putting all ths effort into monitoring Varroa infestation levels...)



sqkcrk said:


> I'm also curious about the Thread Title. It's never addressed. Or is it assumed that if you don't treat then the level is acceptable?


Michael Bush provided some data on this. I would greatly value any other inputs from other 'treatment-free' beekeepers as to what leves of varroa infestation your hives are managing naturally. I am especially interested in the 'acceptable' (out of the danger-zone) levels of early-spring infestation.

Conventional wisdom is that a 1% infestation level is a catastrophe-in-the-making. Michael has indicated that his bees regularly deal wth infestation levels higher than this (at least in the summer and fall).

Any opinions as to whether a 1% infestation level in the early spring will result in an untreated colony failing or not?

-fafrd


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## fafrd (Aug 22, 2009)

Countryboy said:


> BTW, please define 'monitor' for mites.
> 
> Are you talking about mite drops or alcohol washes? If I break drone brood and check to see if I can find mites, am I monitoring? If I look for DWV, am I monitoring? If I look to see if I can see very many phoretic mites, am I monitoring?


Sorry, you are right, I sould have clarified what I meant by 'monitor' at the outset:

By 'monitor' I _do_ mean any method that would allow you to provide some kind of estimate of infestation % (or at least a relative measure that can be compared over time). This would obviously include the classical alcohol washes and powdered sugar methods (sampling or dusting), as well as monitoring natural mite fall, and I would also include sampling of brood (drone or worker). (In fact, I am planning to use brood sampling this season to monitor the infestation level of my hives).

A more binary inspection method such as looking on the bees for the presence of ANY phoretic mites at all, signs of DWV, or signs of PMS (spotty brood pattern) to decide if you have a varroa infestation problem or not, I would would _not_ consider 'monitoring' since you have no way of anticipating ahead of time that you are headed towards the 'danger-zone'.

-fafrd


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## fafrd (Aug 22, 2009)

Countryboy said:


> If the hive is thriving and surviving without treatment, to me that is an acceptable level of varroa mites.


Yes, I agree. The purpose of this post and this poll was to get any idea of what infestation levels different treatment-free beekeepers believe are being successfully managed/contained by their hives (and hence 'acceptable' within their apiary, with their bees, and within their system of beekeeping). The literature indicates that a 1% infestation level is high and requires treatment. Do treatment-free beekeepers believe their hives enter the season in the late winter/early spring with infestation levels that are well below this conventional 'danger-zone' or are their hives starting the season with infestation levels of 1% (or more) and dealing with it just fine?



Countryboy said:


> One thing you will find is that what works for my bees here, may not work for your bees there. Beekeeping is very local. Trying to find a one-size-fits-all approach to beekeeping will just result in forever chasing your tail and always being a step behind the game.


I agree with you and I am not expecting a 'magic-recipe' from this exercise. That being said, data is enormously helpful for relative comparisons and that is why I am making the effort. Most of the available literature is based on commercial beekeeping operations and from beekeepers who use treatments, so the best way to learn more quickly and avoid mistakes as an aspiring treatment-free beekeeper (like me ) is to try to get direct data from other treatment-free beekeepers (which is what makes BeeSource such an outstanding resource!).

As an example of the point you have made regarding the importance of local environment, from what I have witnesses in two fall/winter seasons now in my apiary the Bay Area is that we do not have a broodless period. Since many of the treatment-free beekeepers such as Michael Bush live in colder climates where there is a broodless period, this will probably have a severe impact on varroa dynamics. If his bees are able to deal with Varroa infestation because they have good genetics for ridding themselves of phoretic mites, the broodless period will give them a good opportunity to greatly reduce the mite infestation levels before starting up the brood cycles for the next spring, meaning that it is very possible that they are able to start each spring with a relatively low infestation level (which is why I am making the effort to get this data).

Those bees with that Varroa-fighting approach would not work here in the Bay Area - there would be Varroa hiding out in brood all fall/winter long and even worse, that brood would be heavily infested with Varroa and would result in a greatly weakened crop of bees to get through the winter and enter the spring.

I will eventually start to ask specific questions aimed at treatment-free beekeepers in environments more like my own. For now I am just trying to get some first data from the treatment-free community on what they believe is a reasonable level of infestation to start the year with...

-fafrd


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## Countryboy (Feb 15, 2009)

_Conventional wisdom is that a 1% infestation level is a catastrophe-in-the-making._

That's news to me. It sticks in my mind that a catastrophe-in-the-making is significantly higher. 3% is moderate. 15% or 20% can quickly become a disaster.

_or signs of PMS (spotty brood pattern) to decide if you have a varroa infestation problem or not,_

Often in the fall, a queen's pattern will become spotty, and will not be the solid pattern of early spring. How do you determine if the spotty pattern is normal seasonal laying, or if it is related to varroa?

_and I would also include sampling of brood (drone or worker). (In fact, I am planning to use brood sampling this season to monitor the infestation level of my hives)._

This may tell you if you have mites, but will do little to tell you the level of mites. Varroa are not evenly distributed in a cluster, and you may find patches of drone brood with several mites on a pupa, and other patches of drone brood with no mites on similar aged pupae. 

_Any opinions as to whether a 1% infestation level in the early spring will result in an untreated colony failing or not?_

It will or it won't.

Most of the time you can expect a hive to go 18-24 months before collapsing from varroa. Splitting hives and catching swarms will likely be sufficient to sustain a hobbyist apiary.

_That being said, data is enormously helpful for relative comparisons and that is why I am making the effort. _

What relative comparisons are there? I have bees in 4 yards and none of them are the same. If my bees in yards within the same county aren't comparable, how do you feel that you can realistically make any relative comparisons?

_Do treatment-free beekeepers believe their hives enter the season in the late winter/early spring with infestation levels that are well below this conventional 'danger-zone' or are their hives starting the season with infestation levels of 1% (or more) and dealing with it just fine?_

I look at how strong the hive is.

_so the best way to learn more quickly and avoid mistakes as an aspiring treatment-free beekeeper (like me ) is to try to get direct data from other treatment-free beekeepers_

I disagree. Direct data will be of little benefit to you as a treatment free beekeeper. Conditions and techniques are too different. I would advise you to avoid trying to make mistakes - I learn more from mistakes than from things going perfectly.

_For now I am just trying to get some first data from the treatment-free community on what they believe is a reasonable level of infestation to start the year with..._

I can't speak for anyone else, but I don't care what varroa level I start with. That is of no importance to me. The ending varroa level may have more bearing, but there are many other factors affecting ending varroa levels.

Folks that treat for mites look at mite counts going into winter. Decide what mite level is acceptable to you going into winter. Look at the rate mites reproduce and double their population. Do some basic math to decide what level of mites you are comfortable with whenever your spring is. That may give you a decent starting point. (Then keep in mind that you will have mites coming in from other colonies, which will blow your model right out of the water.)

_I am not expecting a 'magic-recipe' from this exercise. _

You could have fooled me.

Expect losses. Have a way to replace those losses. Use that as your foundation to going treatment free. Plan everything around anticipating losses and how you will deal with those losses. This worked for me.


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## honeyshack (Jan 6, 2008)

1% at May 1 when the bees are entering the honey flow June 25th or so and ending Aug 15-30th is a disaster. The reason is the mites will double in numbers every three weeks without some form of control. So, by the end of June the hive will be near 4% which is visable where brood damage occurs. And a severe loss of honey production will happen.

Now for the winter bees before Sept 15, if memory serves, 5% will see a either loss of the winter hive or a small handfull (literally) of bees in the spring. This is because they are still rearing brood.

Post September 15 if the mites are 10% or less, and there is very little brood production, the hive may be ok but if there are any other stress factors ie trachea or nosema, it might not make it.
http://www.capabees.com/main/files/pdf/varroathreshold.pdf
Page 6.
Please remember this is based on prairie winters, so adjust to fit your time line in your region


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## Michael Bush (Aug 2, 2002)

I've never calculated it as a percent of infestation, but the sugar roll is one cup of bees. Meaning you take the jar you will use, put one cup of water in it and mark the water level on the jar. Then when you use it you can fill with bees to the line.

My point of numbers is mid summer up to when brood rearing cuts back in the fall I hope to stay at or below about 50 natural 24 hour fall and 6 or 7 or so in the sugar shake. I expect those to double when brood rearing stops. More than that is probably going to crash.


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## kwest (May 16, 2009)

while you guys are worring about mite levels my bees are doing fine with absolutly no treatment whatsoever. i have decided since the begining not to treat and go foundationless. it is working well for me so why do i care about the percentage of mites? seems like a waste of time to me.


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## fafrd (Aug 22, 2009)

kwest,

you are lucky. Like you, I went to foundationless and treatment-free from my first days as a beekeeper, and like you I hoped that the 'out-of-sight-out-of-mind' and/or 'the-bees-ought-to-know-how-to-manage-the-varroa-by-themselves' strategies to Varroa management would work.

In your case it apparently did, and you should appreciate your luck. In my case it did not and I lost my hives to PMS.

I agree wih you that for a beekeeper who has established a successful system of treatment-free-beekeeping which is successful over multiple seasons, monitoring mite levels is a waste of time.

For an aspiring treatment-free beekeeper like me who is striving to understand how the local bees in the local environment deal with mites to contain them, having some idea of whether the situation is getting better or worse, how the mite infestation level varies through the course of the season, and whether the bees are containing the infestation or allowing it to grow out of control towards PMS would seem to be a critical investment in getting a successful treatment-free beekeeping system established.

Sounds like you have never lost a hive to PMS, and I congradulate you. I tried the 'quick-and-easy' path to treatment-free beekeeping last season and it did not work out very well for me. I am going to try a more methodical approach this season which involves more work including monitoring mite levels. If all works out well, I will hopefully end up where you are and may join you in cosidering continued monitoring of mite levels to be a waste of time

-fafrd


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## fafrd (Aug 22, 2009)

Michael Bush said:


> I've never calculated it as a percent of infestation, but the sugar roll is one cup of bees.


The value of estimating infestation percentage is to compare with different beekeepers and the literature on an apples-to-apples basis.

Most of the literature I have seen indicates that 300 bees is about 1/2 cup, which would make the full cup that you use about 600 bees. So in your case, #mites / 600 would provide the estimated infestation %.



Michael Bush said:


> Mid summer up to when brood rearing cuts back in the fall I hope to stay at or below about 50 natural 24 hour fall and 6 or 7 or so in the sugar shake.


6-7 mites in the mid-summer sugar roll of a full cup should correspond to 1-1.1% infestation.

In the mid-summer if we assume that the hive is full strength (60,000 bees) and that the infestation level is 1% (6 mites on 300 bees), this would mean that the total number of phoretic mites in the hive should be roughly 600 mites. And if we assume that the phoretic mites are the result of a 5-7 day phoretic period, 600 phoretic mites sould correspond to about 100 new phoretic mites a day emerging from infested capped brood.

On all worker brood, you would assume that for every new phoretic mite emerging and staying to reinfest a brood cell, there would be roughly one other mite that would fall naturally, so on worker brood only, this would correspond to a natural 24 mite fall of 100 (from about 100 infested cells emerging per day).

On all drone brood, the total number of new mites emerging per cell is at least double (4 mites total leaving every drone cell) so the total number of emerging drone cells per day would be closer to 25 than 100. If we assume that the natural mite fall is related to the number of cells emerging, then we would expect a 24 natural mitefall of about 25 from the 25 emerging infested drone cells (actually 33 drone cells emerging and 33 mites falling if you solve to end up with 100 new phoretic mites remaining on the bees every 24h).

All this to say that a simple model of Varroa emergence would predict a 24h natural mitefall of between 33 and 100 mites falling (between all drone brood and all worker brood), very consistent with your corresponding 50 mite 24h natural fall (since I believe you have drone brood in your hives and the mites are likely emerging from a mixture of both drone and worker brood).



Michael Bush said:


> I expect those numbers to double when brood rearing stops.


In the fall, when there is no longer any drone brood, the mites are infesting worker brood only. Assuming the same level of brood infestation of about 100 newly emerging phoretic mites per day, this would correspond to 100 infested worker cells emerging per day and resulting in a 24 natural mitefall of about 100, consitent with your observation that you would expect the 24h natural mitefall to double in the fall to about 100/day.

When the sugar roll increases to 12-14 per 600 bees in the fall, this would correspond to an infestation level of 2-2.2%. This increase could be caused either by the phoretic period increasing from 5-7 days as brood production starts to tail off or by the size of the colony starting to decrease from the peak population in the summer (or a bit of both).



Michael Bush said:


> More than that is probably going to crash.


Thanks for this data Michael. It is helpful to me in terms of defining indicators to know how my hives are doing through the year. I take your statment to mean that mite levels significantly higher than 100/day natural mitefall and/or a phoretic infestation level far beyond 2% indicate that hive is likely on its way towards collapse from PMS.

This data confirms my own observations from my infested hives. The hive I am struggling to save had a 24 hour natural mitefall of well beyond 100 mites/day. And when I first dusted it on October 26th, I had well over 500 mites on the bottom board 1 hour after dusting. If we assume that hive-dusting is 50% efficient, this would mean that there were over 1000 phoretic mites before I dusted. This was from dusting a partially-filled double-deep hive of probably about 30,000 bees, so the corresponding infestation level was probably in excess of 3%.

This hive was showing signs of advanced PMS including DWV and spotty brood pattern and would certainly have collapsed from PMS if I had not intervened with intensive powdered sugar dusting. I am still trying to save the hive and the mite infestation is now very low (average 24h natural mitefall of 1 mite/day), but the hive has dwindled and is now down to being a 5-frame nuc of no more than 10,000 bees and I am not yet certain they are going to survive.

This contrasts with another hive I had and treated with powdered sugar dusting at the same time. This other hive was a full single deep of about 30,000 bees and when I first dusted them on October 26th, the 1 hour post-dusting drop was about 250 mites. Assuming 50% dusting efficiency, this would correspond to about 500 mites pre/dusting or an infestation level of less than 2%.

This hive has been treated in parallel with the collapsing hive and has grown while the more severely hive hasdwindled. It is now up to a full deep and a medium, so probably close to 50,000 bees with a 24h natural mite drop in the range of 2 mites/day. I dusted this hive yesterday and had 13 mites, corresponding to an infestation of about 0.05% (assumind 50% dusting efficiency).

Of course, since I treated, I do not know if this less infested hive could have handled this 2% late-fall mite load without my helping them, but it is interesting that my observations support your view that a hive with a late fall infestation level well in excess of 2% is likely on its way to collapse, while a hive with an infestation level of 2% or less is probably OK (at least in the late fall).

-fafrd


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## fafrd (Aug 22, 2009)

honeyshack said:


> 1% at May 1 when the bees are entering the honey flow June 25th or so and ending Aug 15-30th is a disaster. The reason is the mites will double in numbers every three weeks without some form of control. So, by the end of June the hive will be near 4% which is visable where brood damage occurs. And a severe loss of honey production will happen.


Honeyshack,

Thanks for these inputs.

My understanding was that mites will double every 4 weeks if confined to worker brood (and can increase at 2-3 times that rate if allowed to infest drone brood). What is interesting is that whether it is an end-of June infestation of 4% or 3%, the infestation level at which you believe the hive will be severely impacted is 3-4x higher than Michael Bush's view of the expected/acceptable infestation level of 1% or less at midsummer.




honeyshack said:


> Now for the winter bees before Sept 15, if memory serves, 5% will see a either loss of the winter hive or a small handfull (literally) of bees in the spring. This is because they are still rearing brood.
> 
> Post September 15 if the mites are 10% or less, and there is very little brood production, the hive may be ok but if there are any other stress factors ie trachea or nosema, it might not make it.


In my case there is no broodless period and I believe I have seen that an October infestation rate of 3% or more will lead to hive collapse. In your prarie environment and with you broodless period, it sounds like the bees can survive a higher mite load (though in any case resulting in a significantly weakened hive that is unlikely to make it through winter without assistance).




honeyshack said:


> http://www.capabees.com/main/files/pdf/varroathreshold.pdf


This is a very interesting presentation that I had not seen before - thanks for providing the link. My first impression is that the numbers it is using support the levels that you, Michael and I have been discussing. I will read it through in more detail when I have time and let you know my thoughts...

-fafrd


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## KQ6AR (May 13, 2008)

a 300 bee sample is 100ml or .42 cups, according to Marla Spivak's article in the Dec ABJ. She said since bees are so small 1/2 cup could equal 400 bees. 1/3 cup about 200 bees.

Don't know if they where small cell bees?


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## fafrd (Aug 22, 2009)

Countryboy said:


> *Conventional wisdom is that a 1% infestation level is a catastrophe-in-the-making. (fafrd)*
> 
> That's news to me. It sticks in my mind that a catastrophe-in-the-making is significantly higher. 3% is moderate. 15% or 20% can quickly become a disaster.


As per other posts, it depends on _when_. 1% in the late summer is probably OK. 1% in the early spring is probably not OK. 3% in the late summer/early fall is probably heading for failure. By the time the phoretic infestation hits 15-20% it is all over, since virtually _all_ of the capped brood will be infested and there will be almost no healthy bees to overwinter.



Countryboy said:


> Often in the fall, a queen's pattern will become spotty, and will not be the solid pattern of early spring. How do you determine if the spotty pattern is normal seasonal laying, or if it is related to varroa?


A spotty brood pattern combined with other signs of PMS including DWV and a Vorroa infestation level of 3% or more are an indication of a varroa-related problem.

When I lost my first hive to PMS, the first thing I noticed was a spotty brood pattern and I assumed this was a sign of a failing queen and replaced her. Same spotty brood pattern with a new queen and by then the number of bees had started to dwindle significantly. I waited until far too long to notice that I had a severe varroa infestation and also to notice the other signs of PMS like DWV. By then the hive was doomed.




Countryboy said:


> Drone brood sampling may tell you if you have mites, but will do little to tell you the level of mites. Varroa are not evenly distributed in a cluster, and you may find patches of drone brood with several mites on a pupa, and other patches of drone brood with no mites on similar aged pupae.


While the first point is not correct, the second point is, which is why you need to sample _many_ capped drone cells to be able to assess the level of infestation. At least 100-200 up to an entire frames-worth if you want an accurate measure of the level of infestation. 

Also, to assess level of infestation through drone brood sampling, it is not the number of mites in drone brood you are attempting to estimate, it is the number of infested drone cells (all infested drone cells should have 3-4 mites depending on the timing of the sampling in terms of how close to emergence, but this is immaterial - any infested drone cell is counted as one foundress mite that entered the cell and infested it). One drone cell infested out of 100 capped drone cells sampled and that contains 4 mites within the single cell would represent a 1% infestation estimate of drone brood.



Countryboy said:


> *Any opinions as to whether a 1% infestation level in the early spring will result in an untreated colony failing or not? (fafrd)*
> 
> It will or it won't.


I will take your response to mean that you do not have an opinion on the matter.




Countryboy said:


> Most of the time you can expect a hive to go 18-24 months before collapsing from varroa. Splitting hives and catching swarms will likely be sufficient to sustain a hobbyist apiary.


I agree with these statements on all counts. I have sold nucs and queens to many local hobbiests whose bees 'suddenly dwindled and collapsed' and in almost all cases the culprit was PMS. Maybe this has moved me beyond the 'hobbiest' category, since my reasons for beekeeping are to identify, breed, and promote local feral bee stocks that have demonstrated a capability to survive without treatments for 3 years or more (in addition to wanting to harvest a bit of honey for my family and friends ).



Countryboy said:


> *That being said, data is enormously helpful for relative comparisons and that is why I am making the effort.  (fafrd)*
> 
> What relative comparisons are there? I have bees in 4 yards and none of them are the same. If my bees in yards within the same county aren't comparable, how do you feel that you can realistically make any relative comparisons?


This is a valid point and a reason to not get too carried away with absolutes, but I still believe that data from other teatment-free beekeepers will provide me a useful context to evaluate whether the strains of bees I am raising are especially weak or especially hardy against Varroa.

The view you are expressing would basically discount virtually all of the research done on bees and beekeeping as worthless (a view I strongly disagree with).



Countryboy said:


> *so the best way to learn more quickly and avoid mistakes as an aspiring treatment-free beekeeper (like me ) is to try to get direct data from other treatment-free beekeepers (fafrd)*
> 
> I disagree. Direct data will be of little benefit to you as a treatment free beekeeper. Conditions and techniques are too different. I would advise you to avoid trying to make mistakes - I learn more from mistakes than from things going perfectly.


I believe you intended to write _'I would advise you to *not* avoid trying to make mistakes,'_ but in any case while I also learn more from my mistakes than from doing things perfectly, we each have only a limited number of beekeeping seasons to learn everything we want to learn about bees and I believe that by learning as much as I can from the experience (and mistakes ) of others, I will accelerate my own learning and establish my system of treatment-free beekeeping more quickly.




Countryboy said:


> *For now I am just trying to get some first data from the treatment-free community on what they believe is a reasonable level of infestation to start the year with... (fafrd)*
> 
> I can't speak for anyone else, but I don't care what varroa level I start with. That is of no importance to me. The ending varroa level may have more bearing, but there are many other factors affecting ending varroa levels.


The primary factors determining ending Varroa levels are the starting infestation in the early spring and whether the Varroa are being allowed to reproduce within drone brood or worker brood only. If you care about ending Varroa levels, you should care about starting Varroa levels as this is the only way to assess the effectiveness of the bees in combatting varroa over the long haul.



Countryboy said:


> Folks that treat for mites look at mite counts going into winter. Decide what mite level is acceptable to you going into winter. Look at the rate mites reproduce and double their population. Do some basic math to decide what level of mites you are comfortable with whenever your spring is. That may give you a decent starting point. (Then keep in mind that you will have mites coming in from other colonies, which will blow your model right out of the water.)


For bees to sustain Varroa infestation over the long haul, they must succeed to reduce Varroa infestation levels when there is no drone brood - either through VSH behavior during the period of worker-brood only or through an ability to reduce the phoretic mite infestation level during a period of broodlessness in the late fall. 

And of course all of these assumption are in the absence of other factors such as significant drift of infested bees (which is a further reason to recognize the signs of PMS and save a hive before it collapses - I suspect the first hive I had that collapsed during the summer accelerated the infestation levels of all of my other hives).



Countryboy said:


> *I am not expecting a 'magic-recipe' from this exercise.  (fafrd)*
> 
> You could have fooled me.


You seem to confuse the curiosity for data and experiences of other treatment-free beeeepers with assuming that I think this is going to provide me with _answers and solutions._ Wrong. Data and advice are going to provide me guidance in defining the experiments I am going to try this season (and the specific mistakes I am going to make when I look back a year from now on what I have learned from those experiments).




Countryboy said:


> Expect losses. Have a way to replace those losses. Use that as your foundation to going treatment free. Plan everything around anticipating losses and how you will deal with those losses. This worked for me.


This is good advice and advice I would like to think I have already given to myself and planned for. I have lost essentially 100% of my two large hives to PMS in my first season as a beekeeper. This winter, I have overwintered three mating nucs as well as a nuc resulting from trying to save one of the larger hives severely impacted by PMS. I have been breeding queens using a Nicot Cage and plan to breed more queens in March from the most successful of my overwintered nucs. I caught about 10 swarms last year and plan to catch more this year.

The only point on which you and I seem to fundamentally disagree is that I believe that there is nothing to be gained or learned by letting a hive fully collapse from PMS. Once the signs are there (5% infestation level, 10% infestation level, or whatever), the queen and her genetics may be suspected and perhaps should be replaced, but the bees themselves teach you nothing by following the path towards destructon to its end.

As I have with the first hive I have attempted to salvage from advanced PMS, I believe that more can be learned by saving the bees and using them as the basis to start a new colony (in my case overwintereing a weakened and dwindling colony to see if they can successfully make it through winter once the mites are pretty much dusted out of their hive).

-fafrd


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## fafrd (Aug 22, 2009)

KQ6AR said:


> a 300 bee sample is 100ml or .42 cups, according to Marla Spivak's article in the Dec ABJ. She said since bees are so small 1/2 cup could equal 400 bees. 1/3 cup about 200 bees.


Interesting. The capabees presentation pointed to by Honeyshack indicated that 300 bees was about 1/3 of a cup (section III). So I've seen references to 600 bees per cup (300 bees per 1/2 cup - the most common figure, from what I have seen), the capabees reference to 900 bees per cup (300 bees per 1/3 cup) and now the Spivak reference you have sighted indicating 800 bees per cup (400 bees per 1/2 cup).

Of course it will never be precise, but it seems like the range from 600 to 900 bees per cup is more variation than makes sense and it should be possible to get consensus on a more accurate range...




KQ6AR said:


> Don't know if they where small cell bees?


Good point - small cell bees should have a higher density than large or standard cell bees (there should be more small cell bees in a cup than standard sized bees in a cup). While I believe that Michael Bush has all small cell bees (as do I), it is unlikely that the capabees article based on Candian bees (which indicated the highest density at 900 bees per cup) would be small cell.

Obviously if Michael's small cell bees have a density of 900 bees per cup or more, all of the numbes I estimated in my recent response to his post need to be adjusted accordingly.

For a dicussion such as this, nailing down an ageed upon number-of-bees-per-cup or half-cup would seem to be a pretty fundamental factor for comparing apples to apples.

-fafrd


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## fafrd (Aug 22, 2009)

I found this presentation surfing the web which is relevant to this discussion:

http://www.mannlakeltd.com/publications/PSsampling.pdf

It indicates the following seasonal-dependant infestation thresholds to trigger treatment:

spring: 1%
summer: 5%
fall: 6%

-fafrd

p.s. I found this as one of the sources indicating a density level of 600 bees/cup (300 bees per half-cup).


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## Countryboy (Feb 15, 2009)

One frequent and recurring word in your posts is "assume", or some derivation of that.

Avoid assumptions. They'll get you in a pile of trouble.


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## honeyshack (Jan 6, 2008)

fafrd said:


> t indicates the following seasonal-dependant infestation thresholds to trigger treatment:
> 
> spring: 1%
> summer: 5%
> ...


Need to add:

Spring at 1% means loss of honey production in the summer due to rising mite infestations if no means of control is given

Summer at 5% means brood damage starting to show. If hives are expected to survive the winter then some form of contol needs to start soon. And in three weeks infestation will be 10% if no form of control is given Depending on when the 5% was determined, can mean either loss of the winter bees (late August) or loss of honey production (late June early July). If 5% is found in June July, colony will fail before the end of the year if no control is given, and if the number is found end of August, control is needed immediately for winter survival.

Fall at 6% is right around the time which brood production shuts down for the winter. However, if no treatment is given early spring those numbers will outpace bee production.

Please note, these % will go down if there is other stressors. For example, if nosema is found at a moderate level, that 1% number in spring should be dropped to say 1/2%.
The numbers you mention are dependant on all other stressors at a minimum. 

Mite % double every three weeks, timed with the brood cycles. 1% in April 1 means 4% by mid May, 8% by the end of the first week in June, July 1 16% and July 22 32% if no control is given. 
Control can be anything you want. Sugar, IPM, EO's or chemicals.


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## honeyshack (Jan 6, 2008)

Countryboy said:


> Avoid assumptions. They'll get you in a pile of trouble.


Especially if you rely only on these mite numbers but forget that any other stressor added will toss those mite thresholds right out the window.
Add in nosema or viruses or weather stressors and those mite numbers might as well take a hike cause all bets are off

fafrd, You are in the right direction in understanding mites and what to do about them, but now add in other stressors and know what to look for. Then the picture as a whole will make even more sense. It will open the understanding..."but my mites were low and they still died!"... Other stressors will impact the levels of threshold mite infestations and drop those levels significantly and increase recovery time, if that is even possible


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## Delta Bay (Dec 4, 2009)

My understanding is that your hives collapsed in their second fall/winter because of varroa infestation. This should tell you what you have to work with. If the bees you have can not get past this barrier without treatments you will need to build a management system that takes this into account if you want to go treatment free. To start you will need to look at your bees as a biannual creature rather than a half hardy perennial with the goal to move toward the latter. If you feel the need to count mites you can retrieve data on mite levels as you go and see what levels are acceptable to your bees. In the last year and a half your bees have given you some very important information that you can work with.

I would work with what you know and build from there.


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## fafrd (Aug 22, 2009)

Delta Bay,

the suggestions you have made are exactly my plan for this season. The only thing I would clarify in terms of your understanding is that most of my hives were started last year (2009). Here is a recap:

*First hive *- started with a swarm captured in July 2009, requeened in September 2009, wintered as a nuc, grew to a double-deep hive by spring,yielded about a supers-worth of honey by mid-summer, developed spotty brood pattern in late summer and requeened, queen dead and bees dwindled to one or two frames by the end of the summer - this hive died from PMS (though I did not know it at the time).

*Second hive *- feral hive cut out from a bird-feeder in March 2010 (so number of overwinters unknown). Used as a hive for queen-rearing and a source of bees for mating nucs early summer 2010. Double-deep hive but never yielded any honey (probably due to breeding manipulations). Began to collapse like first hive in September and noticed signs like spotty brood patter, DWV, and 100's of mites falling in 24h. This is the hive I have treated with intensive powdered sugar dusting and which I am still hoping to save which has now dwindled down to nuc-size but is mite-free.

*Third hive *- started from a mating nuc summer 2010. Combined with a swarm caught in July. Up to 7 deep frames by September when I disovered an infestation level about half-as bad as the second hive. Was treated with intensive powdered sugar dusting along side second hive. Is now my largest hive and is thriving - up to a full deep and a full medium - mites down to a 24h natural fall of only 1 mite.

I was not concerned about mite levels last year and introduced bees from many different sources into my apiary without monitoring or knowing their level of mite infestation. I plan to be much more careful this season about:

1/ getting my current hives to establish a baseline of infestation and monitoring the infestation level as the season evolves.

2/ checking the mite infestation levels of any new swarms or cut-outs that I bring into my apiary this spring and if the infestation level is higher than the other hives in my apiary, treating them BEFORE the new bees are introduced into the apiary.

I got a bit too enamoured with the philosophy of 'survival of the fittest' as I started into beekeeping, and as a result I was baically ignorant about mite levels last season and sloppy in the way I brought bees into my apiary. This lesson has been learned but it makes 2010 a bad year for establishing any kind of 'baseline'. Hopefully I am entering 2011 in better shape from that point of view and a year from now will have a much better idea of what mite levels are 'acceptable to my bees.'

Thanks again for your constructive advice,

-fafrd


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## fafrd (Aug 22, 2009)

Honeyshack,

thanks for clarifying the details on my oversimplified summary of the University of Delaware presentation.




honeyshack said:


> Especially if you rely only on these mite numbers but forget that any other stressor added will toss those mite thresholds right out the window.
> Add in nosema or viruses or weather stressors and those mite numbers might as well take a hike cause all bets are off
> 
> fafrd, You are in the right direction in understanding mites and what to do about them, but now add in other stressors and know what to look for. It will open the understanding..."but my mites were low and they still died!"... Other stressors will impact the levels of threshold mite infestations and drop those levels significantly and increase recovery time


You are absolutely correct that the numbers bandied about are best-case from the point of view of assuming no other stresses.

Still, I think that makes them valuable for establishing best-case thresholds. The idea is not so much to wonder why your bees may not have survived at infestation levels below these thresholds, but rather to know when it is clear that the bees have failed to contain the mites to the point that they are on their way towards collapse and you should intervene.

My goal is not to save _all_ hives. I expect to lose hives and hopefully lose primarily hives with weak genetics. In the specific case of weak genetics for combatting Varroa, I believe it should be possible to identify when a hive is heading towards failure early enough to treat it, introduce new genetics through a new queen, an give it a chance to restart as a new hive.
Among other things, I think it will be better to try to recover the bees in a failing hive in this way rather than allowing them to completely collapse because of the impact a hive collapsing from PMS can have on neighboring hives in the apiary.

-fafrd


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## fafrd (Aug 22, 2009)

Countryboy said:


> One frequent and recurring word in your posts is "assume", or some derivation of that.


I use the word 'assume' to identify things I do not know from direct experience. I am not a bee researcher. I do not know for a _fact_ that powdered sugar dusting is 50% efficient as is claimed in the literature. I do not know for a _fact_ that Varroa mites double their population every month when limited to worker brood as also clamed in the literature.



Countryboy said:


> Avoid assumptions. They'll get you in a pile of trouble.


I don't agree. It is not _making_ assumptions that can get you into trouble, it is _not knowing_ when you have made assumptions that can get you into trouble.

Anytime you are trying to figure out what went wrong, it is usually not the problems (and assumptions) that are in front of you (and that you are aware of) that can trip you up, it is almost always the problems that are behind you (the assumptions that you are not aware you made and the incorrect 'facts' that you took for granted without knowing it) that can get you into a 'pile of trouble'.

I think that making assumptions and being clear about what assumptions you have made is important when communcating the approach you are taking to any complex problem...

-fafrd


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## fafrd (Aug 22, 2009)

honeyshack said:


> Mite % double every three weeks, timed with the brood cycles.


Honeyshack,

you have mentioned this 'mites doubling every three weeks' a few times now, and I would be interested to know the source of that statement.

All of the literature I have seen indicates that mite population will double about every month (~4 weeks) when reproduction is limited to worker brood. When drone brood is available, the literature I have seen has indicated growth rates of 'at least 2x up to 3x' the rate of growth in worker brood (which would mean doubling about every two weeks or less).

While the bee worker brood has a three-week brood cycle from egg being laid to emergence, the mite breeding cycle is only 13 days (in worker brood) because they enter the brood cell on day 8 just before it is capped and emerge with the new nurse bee 13 days later.

When you make this 'doubling every three weeks' statement, are you referring to worker bood or drone brood? Clarification appreciated.

-fafrd


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## Michael Bush (Aug 2, 2002)

If you have either a tray under a SBB or a solid bottom board it's not hard to tell if you lost the bees to Varroa. There will be thousands of them dead on the bottom. I always try to figure out why a hive died. I always consider Varroa as a prime suspect. There are a lot of things to consider, but if there are thousands of dead Varroa on the bottom board, I'd consider Varroa the most likely cause. If not, then I'd consider other things. Are your bees acclimatized to your location or are they a Southern package. If they starved. Were they clustered or scattered (scattered being a sign of Tracheal mites). Etc.


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## fafrd (Aug 22, 2009)

Michael,

I do not know if there were many mites on the bottom board of the hive that failed because I did not think to inspect it at the time. I thought I had a failing queen because of a spotty brood pattern, replaced her and checked several times for successful introduction (she seemed to be laying well) and when I came back several weeks later there was still a very spotty brood pattern, the new queen was dead on the bottom board and there were only about 1-2 frames of bees left.

Only when a second hive started to fail and I noticed DWV in addition to the same spotty brood pattern did it occur to me to check the bottom board of the second hive for mite levels.

My bees are all from local swarms or cutouts, and the hive that completely died, died in the late summer and was full of stores, so it did not starve. It just suddenly dwindled to nothing seemingly due to lack of brood over a sustained 6-week period.

I am pretty sure that the second hive (that I am still trying to save) was on its way towards collapse from PMS. It had the same spotty brood pattern, bees with DWF around the entrance and on the combs, and I did check Varroa on the bottm board and was getting 100's in 24h natural drop. I've treated that hive and am hoping to save it, but I am pretty sure it was in the same state as the failed hive when I first noticed the spotty brood pattern (about 4-5 weeks prior to collapse).

I did not suspect for Varroa at the time that first hive collapsed and did not think to inspect the bottom boards at the time - it is the spotty brood pattern that was common to the second hive where I did confirm a severe Varroa iinfestation that has me conviinced the first hive probably collapsed from Varroa as well...

-fafrd


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## honeyshack (Jan 6, 2008)

fafrd,
I do not have any "sources" it is what i have been taught, and read in a few places.
As well, worker brood is 21 days = three weeks. So if mites are infested in the worker brood...three weeks. Drones are 24days that is three weeks + 3 days. That is what is says in my bee book


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## fafrd (Aug 22, 2009)

Honeyshack,

if you don't recall where you have read about 'doubling every tree weeks' that is fine. I only point it out because it is different than everything I have read on the subject (and it sounds like neither one of us has any direct experience measuring Varroa population growth rates that we can point to ).

Everything I have read has said that Varroa double their population every month (4 weeks) in worker brood. In fact in worker brood, they apparently have an average of 1.1 daughters plus the mother foundress mite exiting the cells with the emerging nurse bee, but then enough of the new daughters and older foundress mites fall or die off to result in a growth rate of only 'doubling every month'.

In drone brood, the growth rate is apparently much worse because the foudress mite has an additional couple of days to breed another couple of daughters - I believe I have read that the varroa growth rate in drone brood is '2 to 3 times faster than in worker brood', which would mean doubling every two weeks or less. Much of my information has come from Randy Oliver's website: www.scientificbeekeeping.com which unfortunately appears to be down as I type this.

Anyway, my point is that if the reality is that Varroa can doudle their population in as little as two weeks or less in drone brood and only in 4 weeks when confined to worker brood, the actual situation could be significantly better or worse than 'doubling every three weeks' as you have stated (depending on whether the hive has drone brood or not).

I think part of the confusion could be that on the question of the Varroa breeding cycle, I believe that you were right and I was wrong. The mites do enter the cell on day 8 just before it is capped and they do spend only 13 days breeding in worker cells (not 21) until the nurse bee emerges on day 21 (13 days after day 8), but I forgot about the phoretic period.

A newly-emerged daughter mite will spend about 7 days riding on the bees as a phoretic mite before re-enterig an 8-day-old brood cell to begin another breeding cycle. So the full Varroa first-time-foundress mite breeding cycle (on worker brood) is: 7 days as a phoretic mite + 13 days breeding in a brood cell = 20 days (or 'about three weeks' as you said).

The total Varroa breeding cycle of 20 days in worker brood happens to be very close in duration to the bee development cycle of 21 days from egg to emerging nurse bee, but they are not at all the same cycle and are only indirectly related (for example, the older foundress mites that succeed to breed a second time have a phoretic period of only 5 days and an overall breeding cycle of 18 days...).

Breeding on drone larvae, you are correct that the the Varroa breedng cycle would be longer, but because drone cells are capped only a day later than worker cells even though they emerge three days later than the equivalent worker cell (day 24 versus day 21), the varoa breeding period in a drone cell is only two days longer than in a worker cell (15 days breeding in the capped cell), so the overall breeding cycle is 7 + 15 = 22 days (again, 'about three weeks').

If your bee book is only referring to the standard worker development cycle of 21 days and the drone development cycle of 24 days, I don't think there we have any disagreement about that. If your bee book is referring to the Varroa breeding cycles and also possibly to the Varroa population 'doudling every three weeks', I would apprecate it if you could provide me the title and author.

-fafrd


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## beemandan (Dec 5, 2005)

You might find this interesting. He discusses theoretical growth of varroa populations.
http://www.langleybeeclub.org/files/info/Outbreeding Mites and Overwintering Nucs.pdf


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## fafrd (Aug 22, 2009)

beemandan,

thank you for the pointer to tihs very interesting article.

The feral colonies around here that other beekeepers claim have existed for more than 5 years are apparetly deaing with Varroa on thier own. I bred queens from this stock (donor queen cming from swarms recovered from these feral hives) and in my managed hives, this stock has not performed nearly as well against the growth of Varroa infestation as I had hoped.

I had been thinking that the feral hives ability to swarm could be one of the behaviours that help these feral bees survive in the wild and had been considering using periods of broodlessness and/or splits to simulate swarms as a varroa-fighting strategy. I had that idea just because when others described these feral hives, they were described as putting out multple swarms every season, always at last 5 and sometimes as many as 8. Aside from the break in the varroa breeding cycle, I didn't have any clear idea why swarming might help the feral bees survive.

This article provides a clear and compelling argument for how swarming helps the bees - it splits the mite population at the same tiime that it stimulates the bee breeding rate.

I am trying to overwinter three mating nucs this winter and I can attest to some of the claims made in this article - as long as I have been assuring that they have enough feed, these nucs have been increasing throughout the late-fall / early winter - probably doubing in size over the last two months (with alot more capped brood about to emerge soon).

Thanks again for this reference - it's really given me food for thought...

-fafrd


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## beemandan (Dec 5, 2005)

You may want to do a search on this board for posts by Michael Palmer. He utilizes a similar method of creating a controlled broodless period along with overwintering nucs to successfully suppress his varroa populations without using miticides.


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## fafrd (Aug 22, 2009)

Will do. Michael Palmer is very active on the board and makes alot of posts, so unless you have an idea for a thread title or a keyword or two to search, I may send him a private message asking for some pointers. This is very interesting....

The article you sent makes reference to the broodless period being especially effective because after a broodless period with no 'stimulation' (open brood), the mites all rush in to the first few hundred cells of open worker brood once the new queen has started laying and many/most kill themselves from overcrowding.

I had not seen or heard this before and if true, it is good, but I am wondering if anyone else has heard of this 'post-broodless-period-overcrowding' effect?

If it is true, it should also be true after a natural seasonal broodless period, so this effect ought to be a reason that mite population initially declines once brood-rearing begins again in the late winter...

-fafrd

p.s. do you practice any of these techniques beemandan?


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## beemandan (Dec 5, 2005)

I used to overwinter nucs and unintentionally created a broodless interval. I didn’t really understand what I was doing at the time. The problem now is that we have a high population of SHB by late season. Weakening hives by doing splits or allowing queenlessness, even for a day, can be ‘the kiss of death’. I’m scheming up some strategies that I plan to try, on a limited scale, this season and see if I can implement a system of this sort without creating SHB disasters in my wake. 
I expect that the overwintering broodless period is less likely followed by an overcrowding event and more likely the fact that age/winter attrition has taken a toll on much of the mite population. 
Regardless, it is interesting stuff. And, as I’ve said, Michael Palmer manages to be treatment free.


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## fafrd (Aug 22, 2009)

Thanks. Any idea on how I could find some of the threads where Michael Palmer discusses his techniques? Are there any good search words you can think of? (I think the search facility is one of the best features of the BeeSource Forums )

-fafrd


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## Barry (Dec 28, 1999)

And we even have two different ones. The search function on the home page is the most exhaustive, but the forum search has the ability to narrow the search, like all posts by Michael Palmer.


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## fafrd (Aug 22, 2009)

Thanks for the heads-up about the more advanced search options. I think that by going to someone's profile I have also seen another way to find all of their posts as well.

Finding all of Michael Palmer's posts one way or another had been my back-up plan to try to find some information on his broodless techniques for varroa management, but given how prolific Michael is on the Forums, I was hoping someone could provide me some good keywords or other ways no narrow the search down a bit...

-fafrd


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## Countryboy (Feb 15, 2009)

_the mites all rush in to the first few hundred cells of open worker brood once the new queen has started laying and many/most kill themselves from overcrowding._

That works in theory, but this does not coincide with actual observations folks have made. It seems the mites are smart enough or patient enough to make sure they aren't overwhelming the first few brood.


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## fafrd (Aug 22, 2009)

Thanks, Countryboy.

I thought this might be the case, but was just interested in the opinions of others with more experience on the subject.

This 'theory' was not mine, but was one of the essential points expressed in the 'langleybeeclub' article that beemandee pointed me to.

I am very interested in any opinions or references on the reasons swarming and/or periods of broodlessness may help the bees to combat varroa, as this is one of the bees response mechanisms that we as beekeepers generally take away from the bees in our managed hives...

-fafrd


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## Delta Bay (Dec 4, 2009)

On average the mite lives about 1.5 to 3 reproduction cycles during the bee’s active brood season. Some live longer some shorter. My belief is that the mites that are close to the end of their final cycle during the brood break lose/miss their opportunity to reproduce and parish during this time.


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