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Author Topic: Dr. Dewey Caron's paper on Powder Sugaring Bees – Does it work?  (Read 4823 times)

Offline 2rubes

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Hi, Dewey Caron gave me permission to put his latest paper on our website.
Oops, I'm not allowed to put up the webpage, so, I'm going to copy the whole paper.

When an article by Dr. Dewey Caron came out in Oregon’s September 2009 issue of ‘The Bee-Line’ on Powder Sugaring Bees, the news editor, Rosanna Matterly asked for response from beekeepers using powdered sugar.

Hi Rosanna & Dewey, I just read the article, Powder Sugaring Bees by Dewey Caron in the September 09 issue of The Bee Line. I wanted to respond to the editor’s request about beekeepers powdered sugaring bees on a regular basis. Since March of 2005, almost 5 years, we have used nothing but powdered sugar to reduce and control varroa mites in our hives. This year, we had 7 hives and by September, even though we dusted the hives in mid-July, the mite counts were over the threshold (50 mites in 24 hours) in several of the hives. We did 5 applications of powdered sugar in 4 weeks and now our high counts are cut in half and the other hives are very low. Although we do not dust every week, we have someone in our club who dusts weekly and has no varroa. We tend to dust our bees several times a year 3 times, one week apart, mostly March, May and July. In September, with the really high counts we could dust 4 to 6 times in 3 weeks. From November though February, we dust once a month. Here in California, we do get a week of nice weather each winter month and it is a great time to get rid of the phonetic mites. August and September, we always have had high mite counts, and with regular dustings, we have always been able to get them down. Yes, it’s intensive, but not hard on the bees or brood at all. One of the things I noticed is at first, the bees almost sounded angry when you dusted them. Now, almost a curious buzzing, they no longer seemed upset.
Thanks, Janet Brisson

Morris Ostofsky also wrote.  Dewey included our information plus response to a letter I wrote to Jerry Hayes of the American Bee Journal, soon to be published in Bee Craft America digital newsletter and gave me permission to post it.    

Powder Sugaring Bees – Does it work?
                Using powdered sugar (PS) for varroa mite control has been recommended as an IPM tool - to knock mites off workers captured in a jar to monitor mite levels as well as in entire colonies as a way to slow mite buildup in the colonies themselves.  Monitoring mite numbers with PS is an relatively easy and helpful tool (see tutorial on MAAREC web site) but a new study suggests adding powdered sugar to a colony to control mites (sometimes called the Dowda method) might not be providing the perceived benefit  -  a 12-month study of powder sugaring bees every other week was unable to document an overall mite reduction in bee colonies!

The new study conducted in Florida by Amanda & James Ellis (U FL) with Jerry Hayes of FL Dept of Apiary Inspection, compared mite numbers, adult bee numbers and brood area of colonies treated with PS for mite control to untreated controls. Colonies were dusted  every other week for 11 months with 120g of powdered sugar. The study found no differences in adult bee populations or amount of brood between treated and control colonies but although there was significant initial (24h) mite drop following dusting, no differences between numbers of mites, numbers of mites prorated to adult bee numbers and no differences in mite numbers per capped brood cells in treated vs untreated colonies.


Does this mean PS should not be used in whole colony dustings? In the October 09 in Amer. Bee Jour., Jerry Hayes, one of the authors of the FL study, in his monthly Q&A column answered a letter from Janet Brisson of CA on whether PS works or not as follows:
                    “Yes  research results showed that varroa was not significantly controlled by dusting with
                    PS. Within the parameters of their research, PS didn’t work great. But that does not mean
                    that if the research trial were re-structured to treat more often or in a different way that
                    results would not be different….research shows it doesn’t work long term. But, in real world
                    situations it does. What to do? I’d treat with PS until research catches up with reality.”
Many beekeepers (including Tom Dowda of FL) dusting whole colonies with PS however believe it is an effective control method. In 9 years of surveying backyard beekeepers in the mid-Atlantic states, I found a growing number  of beekeepers  using PS for mite control while; over 50% of beekeepers who indicated they were monitoring mite levels prefer to use the PS roll method to determine mite levels vs sticky boards or other methods. In a recent  survey of 100 Oregon backyarders (who filled out a survey form during April local association meetings),  65% of the beekeepers who had no over winter losses indicated they used powdered sugar as a control scheme in contrast to 38.5% of beekeeper who did have winter loss (57 of the 100 had a loss;  43 had no loss). Overall colony loss levels were similar for Oregon ( 25.8%) and Mid-Atlantic beekeepers (24 %).

 Morris Ostofsky of Eugene OR is one backyard beekeeper who feels PS is effective. He shared with me his success using PS:

                    “I have successfully used PS to control mites. To give you an example
        of the efficacy of the PS treatment here are the results of my
        treatment of one of my hives, # 9 - 6, this year. This hive has two
        full depth brood boxes.
               Date: 8/27 200 mites 24 hr drop using sticky board
               8/28 PS dusted
               8/31 144 mites on 24 hr on sticky board
               9/3 & 9/7 PS dusted
               9/10 48 mites on 24 hr sticky board
                9/11 & 9/15 PS dusted
               9/20 4 mites on 24 hr sticky board
        Please note that I would NOT normally treat this often; however,
        it was late in the season and I wanted to get the mite count down
        before fall. I know this was awfully invasive; however, I felt that
        the alternatives were worse.   I have used this strategy to reduce
        mite loads in other problems hives this year and in previous years.
        The fact that I did not lose any hives last   winter and had used
        powdered sugar to reduce mite counts in fall is an indication that
        dusting is effective.
Whether targeted, short time use of PS in spring or fall or using a different method of applying the powdered sugar, such as the newly available powder sugar duster (a converted pesticide applicator from China),  modifies the conditions sufficiently to improve overall mite control is unknown. The initial report of mite control using powder sugar (by Nick Aliano in his PhD studies with Marion Ellis at U Neb) utilized the labor-intensive method of shaking adult bees off their comb and powdering them in a shaker box. Up to 35% of mites fall off the adults when the shaking  heats the adult bees in the shaker box (and in monitoring a sample mite numbers of 300 adults in a glass jar, it is important that the bees heat up the jar interior to get an accurate mite estimate).

 Certainly an initial count of 200 mites in 24 hr drop (as Morris found) should  trigger a decision to "do something" (50 or more mites is the widely accepted threshold number from Us and European studies). Morris and other beekeepers have demonstrated that PS can, at least in some instances, reduce the number of mites on adults to a more "reasonable" load. It would seem reasonable that beekeepers using PS should continue to do so – and continue to document and report PS effectiveness.
Read  results and parameters of FL study in 2009 Jour Apic. Res & Bee World: Vol 48(#1), page 72-76 .

U Nebraska study is available in: Jour. Apic. Res.  Vol 44(#2): 54-57

Randy Oliver is going to do some testing to see if he can duplicate those numbers and see how more intensive dusting reduces mite loads. He talks about it on his website.

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Janet Brisson

Offline Robo

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Re: Dr. Dewey Caron's paper on Powder Sugaring Bees – Does it work?
« Reply #1 on: October 19, 2009, 07:05:02 PM »
Has anyone studied the effect of the stress put on the colony when the hive is continually (2 weeks or whatever the cycle) bombarded with sugar dust?   We know that the pH of sugar doesn't align well with the pH of the hive, but I suspect there are other stresses as well.

Just curious, and no one seems to be able to answer the question.
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Offline annette

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Re: Dr. Dewey Caron's paper on Powder Sugaring Bees – Does it work?
« Reply #2 on: October 19, 2009, 11:01:16 PM »
Has anyone studied the effect of the stress put on the colony when the hive is continually (2 weeks or whatever the cycle) bombarded with sugar dust?   We know that the pH of sugar doesn't align well with the pH of the hive, but I suspect there are other stresses as well.

Just curious, and no one seems to be able to answer the question.

I have to be honest here and tell a story. I had been powder sugar dusting since I started beekeeping (2006). I used to take the entire hive apart and dust each super separately and yes, it worked. Got the mite population down.

Well then I finally heard from beeks on this forum that I did not have to dust each and every super. I could just dust the top super and so I continued doing this last year. It worked and the mite population went down.

Well last fall the mite population got away from me on one hive and I tried to dust them in the late fall. This was a very strong hive with a beautiful queen. I dusted them on the top super and something happened. Immediately a huge cluster of bees left the hive and was hanging from the top entrance. They seemed to be balling something. I even tried to separate the cluster so I could see what they were doing.  I had a very bad feeling about this and wondered if the queen was in that cluster. They stayed there for hours until finally they went back into the hive. I wondered if I lost the queen in that hive. They never made it through the winter.

I have been afraid to do the powder sugar dusting since this happened. I have always felt that it was hard on them, but I felt I needed to do this, since I do not use any other treatments.  This year I did not treat at all, the mite counts are ok, and I will just see how they get through the winter.

Offline 2rubes

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Re: Dr. Dewey Caron's paper on Powder Sugaring Bees – Does it work?
« Reply #3 on: October 20, 2009, 03:42:01 PM »
Hi Annette, I am so sorry to hear about your hive.  I’ve never heard of that happening while dusting bees.  I’m wondering if they were just ready to swarm.  We had a swarm in September, we noticed it when we were pulling off our honey.  We examined all of our hives then dusted them.  One hive, that was one of our strongest had obviously less bees and when we went through it,  we saw remnants of queen cells.  I would have called them supersedure because they were in the middle of the frame, but with so few bees left, it must of swarmed.  I couldn’t believe it that bees would swarm so late.  And now this hive is in trouble, I was hoping it would recover, but it’s not.  I will probably combine it this week, maybe try and put it in a nuc. 
   We’ve been dusting very intensively lately  and just got our mite population down and now we will dust once a month through the winter.  We have a club member who dusts his hives every week and he said his bees are doing great.  Dr.s Amanda and James Ellis did monitor brood and saw no evidence of the powdered sugar doing any harm.
    We go so busy with this business this fall, after listening to Randy’s August talk about different mite controls,  I actually bought some Apiguard this fall from him.  When we picked it up, Randy told us how hard it is on the bees and the different applications to use based on the strength of the hive.  He told us all of the products available, including Oxalic and Formic are very hard on bees, but they do recover nicely. Also, he would be treating again with one of the acids in December when his hives were broodless.   On the way home, my husband and I started to talk about Randy's conversation and we decided we just couldn't do it.  Yes, it was one application and then nothing to do until December, where we would be dusting this fall at least 3 times in 3 weeks and maybe more if we had high mite counts, which we did on 3 hives and those got dusted 2 times a week during the 3 weeks.  And then, once a month until spring.   We ended up returning the Apiguard and just made up our minds, we would make time for our girls. 

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Janet Brisson

Offline Bee-Bop

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Re: Dr. Dewey Caron's paper on Powder Sugaring Bees – Does it work?
« Reply #4 on: October 29, 2009, 12:12:10 PM »
If I may;
In reading the above report;

Like so many reports, I think things are missing, 1 being,

How big were the hives, 1 full, 2 full, any supers ? Being in Flordia I would think that in a years time the number of hive boxs would grow and shrink according to bee population and honey production.

The report states 120 gm were used per hive per treatment thru out the year, altho I would think the bee population would variey  greatly.

120 gm of powdered sugar equal just a tad over 1/2 cup.
Would this be a sufficient amount to cover the bee population of a 2 or 3 full size box hive ?

I guess the few times I have sugar dusted I over did it, using about a 1/2 cup per each hive box !
[ however I did have a large mite drop ] But I still have mites, some hives more than others.

I would agree with Robo,that a dusting every 2 weeks for a year would be hectic for the bees, but thats research.

Oh Yes, as a researcher you never want to find a cure, that would stop the Free Grant Money, Dr.Sulk proved that !

" If Your not part of the genetic solution of breeding mite-free bees, then You're part of the problem "