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When they say powdered sugar for dusting, is that the kinda sugar they use for making icing on a cake, or it a special type?
 

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Pretty sure this has been determined to be a waste of time. Very little bang for the buck/effort
 

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Pretty sure this has been determined to be a waste of time. Very little bang for the buck/effort
I saw trials which pretty much stated this... but then again, given the methodology, it basically looked like that was their intent all along.

In my opinion, if sugar dusting is to have an effect, it would require repeated uses over a long enough period of time, combined with a screened bottom board with a sticky trap. None of the sugar dusting experiments I read had this protocol. Even that may not do much of a difference, though, but I don't believe it's been proved not to.
 

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'Sugar dusting' is an example of a mechanical control sometimes employed against varroa. The sugar doesn't kill the mites, but interferes with the mite's ability to maintain a grip on the host bee. As a mechanical control, you may have to sugar dust more frequently than if you were using some form of commercial/chemical control. Exactly how frequent is required for effective control is not clear - hence the comments above.

The dust doesn't necessarily have to be sugar - this publication from NC State University also mentions dusting with certain pollen substitutes as an alternative dust.

The Mechanical Control section starts on page 3:
http://www.cals.ncsu.edu/entomology/apiculture/pdfs/2.03 copy.pdf
 

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Here's an article about sugar dusting. It is mostly a reproduction of a post made by Jim Fischer back in '01 to BEE-L listserv regarding Dr. Fakhimzadeh's methods. He discusses the starch issue.

Nicely presented webpage of his post...
http://www.westsoundbees.org/beekeeping_articles_sugar.htm

The original, text only post...
http://community.lsoft.com/scripts/wa-LSOFTDONATIONS.exe?A2=ind0105D&L=bee-l&F=&S=&P=31808

There are people who swear by sugar dusting and those that swear at it...pick your poison. ;)

Ed
 

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The cornstarch in powdered sugar is of no concern in dusting. The bees are not consuming this sugar and work hard to remove it from the hive. Don't feed powdered sugar in syrup as that could cause digestive problems at a time the bees are confined.

I've been known to frequently "waste my time" with sugar dusting and the bees have not had a problem with powdered sugar containing cornstarch.

Wayne
 

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Regular powdered sugar works well, no need to powder granulated sugar because of worries about corn starch. I would recommend powdered sugar over the pollen substitutes because the bees clean up the sugar in less than 24 hours, cleaning up regular flower (which also drops the mites well) takes almost a full week. The only benefit to pollen subs would be in what they would store during clean up.

Sugar dusting works well on swarms and nucs when they are without sealed brood. When you have sealed brood the mites are protected and the sugar has no effect. Powdered sugar is not a method to use if you are commercial, but a hobby beekeeper has fewer colonies and more time to spend seeing after them. It slows the population growth and can keep varroa below the threshold numbers at which they start to damage the colony. A nuc or swarm dusted 3 to 5 times before it has sealed brood will have half the varroa population in late summer when compared to one that is not dusted.

The Dutch have a method that hobby beekeepers could use, it is labor intensive, but if you do not like chemicals, it would work. It is described in "Varroa Control in New Zealand." Do a Google search, it is well worth your time to read the information in that booklet.
 

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Rather than creating a problem with the bees digestive system, I thought the big problem noted with powdered sugar containing corn starch is that it can damage open brood. Supposedly it can desiccate the larvae and (for very young larvae) the puddle of royal jelly if enough of it enters the cells. Understandably, simply dusting between the frames isn't like dusting straight down into the cells, but still...cells are slanted upwards.

Ed
 

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Bottom line, do mite counts and find out if it is getting the job done. And, of course, one favorite way of counting mites is a powdered sugar roll. This method is probably not quite as accurate as an alcohol wash, but let's say the corn starch in powdered sugar might have some small deleterious effect on the bees. The alcohol is 100% fatal to the 300 or so bees in the alcohol wash.

If a powdered sugar dusting is not effective, I'd look at the dusting method. What I see recommend here is sifting a little powdered sugar over the tops of the frames and letting it work down thru the frames. How anyone can expect the bees to be well enough coated to cause them to dislodge a significant number of mites using this method is a mystery to me.

After an early attempt to sift sugar onto frames while inspecting achieved spotty coverage and a single mite drop, and a discussion of dusting methods here, I've picked up an insecticide duster. Next time in for inspection, my wife and I are going to use that duster during our next inspection. First we'll do a sugar roll and get a count, then inspect the hive and dust all well-covered frames, avoiding getting heavy deposits into open brood (the only known downside to the method). Then we'll get a mite drop count and see if it looks reasonable against the sugar roll result.

I found a paper on the effects of sugar dusting, and the only downside the researchers found is that if you nearly filled the cells of brood that would cap within something like 2 days, there was measurable mortality. My hope is a nice even coating from a proper duster will avoid the clumpy application from a sifter, and be harmless to brood.

And honestly, knowing mite load and checking drop rates during treatment ought to be SOP. Heck, there are several mite treatments out there that they'll tell you flat out the mites are getting resistant to.

One of the reasons I bought an observation hive is that I intend to sugar dust for mites and video the resulting cleaning activity.
 

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Formic acid is my treatment of choice. Works awesome for ridding swarms of varroa for a fresh and healthy start. I also use it in a "flash" treatment which penetrates the brood and kills the male mite thats inside the brood so he can't fertilize his sisters.
Just my preferred method. Dust away if that is your preferred method-whatever works. just kill the mites.
 

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Rather than creating a problem with the bees digestive system, I thought the big problem noted with powdered sugar containing corn starch is that it can damage open brood. Supposedly it can desiccate the larvae and (for very young larvae) the puddle of royal jelly if enough of it enters the cells. Understandably, simply dusting between the frames isn't like dusting straight down into the cells, but still...cells are slanted upwards.

Ed
I saw a study stating this as well.

And frankly, once again, I found myself saying "what the heck did they expect!?". The only study I read that stated that sugar dusting resulted in larval mortality applied powdered sugar... directly on the brood. I've never heard of people applying it that way, as far as I know, people apply it on the top of the hive, thus between the frames, and not on the comb.

As Phoebee stated, I don't think a normal use of powdered sugar dusting will have any significant effect on brood.

AR, did you mean this document: http://www.biosecurity.govt.nz/files/pests/varroa/control-of-varroa-guide.pdf

It doesn't really say much at all. The results described there, and which I've come across elsewhere, suggest an increase of varroa mite drop, but none go so far as affirming that this effect is sufficient to curb varroasis. Anyone using this method should therefore keep in mind that he may very well be wasting his time and his money.
 

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Randy Oliver has written quite a bit on this subject. He thought the idea was ludicrous as well until he figured out how to use it correctly. I have used it too with surprisingly good results, but it has to be done with the appropriate methods. Humidity also plays a big factor, so be sure to consider this aspect.
http://scientificbeekeeping.com/ipm-7-the-arsenal-natural-treatments-part-2/
 

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Yes Dominic, that is the booklet I was thinking of. I did not mean it for just information on PS dusting, but for overall information on varroa and their control. The Dutch method described was for the use of drone brood removal, but by combining drone brood removal and powdered sugar dusting, the process is shortened.

As for a waste of time and money, I can treat 10 to 15 nucs with a two pound sack of PS, or 4 to 6 double deeps. I have more nucs than full colonies and with nucs choices are limited when it comes to varroa control. If I am just treating a double deep takes about 5 minutes of my time. As I said, for a hobbyist this is nothing, but I can see where a commercial beekeeper would not want to use PS. PS will not control varroa alone but if used with other methods will reduce the varroa population growth and will reduce the number of chemical treatments needed.

Phoebee, sifting the sugar with a top screen will put sufficient sugar on the bees. Coverage is better if each box is dusted, dusting the top of doubles doesn't give the drop you get if you separate the boxes and then dust.

I am not saying dump all other methods and just PS dust, but I think rejecting PS without giving it a try limits a beekeeper's options.
 

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Dusting broodless swarms or winter clusters is a great way to zero out the mite population. Dusting summer nucs repeatedly leads to brood problems and lack of growth, and a single application does no particular good. Dusting full hives causes mite drops, and the hive can recover from the larvae problem, it is really disruptive and time-consuming however.

Perhaps the most useful part of dusting is its role in the education of young beeks. These folks typically tell me "I'm treatment-free and I don't have varroa, but my hive is not growing and I'm seeing crawling bees". Okay, I tell them, "lets dust the hive and see what drops". Most go along with this because sugar doesn't seem like a evil "treatment". Withing 30 minutes of dusting the bottom board will be red with little crawling chips moving through a sugar snow. You can see scales drop from the young beeks eyes.
 
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