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Sugar Dusting for
Varroa Mite Control
Following is a posting that was made
by Jim Fischer to BEE-L
regarding the application of powdered sugar to honeybee
colonies to mitigate the infestation of varroa mites.
Jim is elaborating on the original concept as developed
by Dr.
Kamran Fakhimzadeh of the University of Helsinki,
Finland, and detailed by him in the June 2000 issue
of the American
Bee Journal.
1) What The
Heck IS "Sugar-Dusting", Anyway?
It is a technique that Dr. Fakhimzadeh proposed as a
part of his Doctoral work. He published it in the journals
listed above. I tried it. It works for me. Your mileage
may vary, but as a card-carrying scientist (sorry, physics,
not entomology), I can state that I have done my best
to "reproduce" his results, and I feel that
I can confirm and endorse his findings. (Heck, I'd nominate
him for an award if the beekeeping community had any
serious awards - the results are that good.)
The idea is simple. When varroa fall down below a varroa
screen, they don't crawl back up into the hive. Varroa
have little "suction-cup" feet. Sugar particles
that are around 5 microns in diameter clog up their
little suction cups, and they can't hang onto things.
They fall. They die. They don't live to reproduce. Therefore,
dusting the backs of the bees will knock off some significant
percentage of the mites, keeping the population "under
the economic threshold". (Beg, borrow, or Xerox
the ABJ article. Read the details for yourself.)
Given time, we may find that sugar dusting allows one
to stop using (or at least skip a year of using) Apistan
strips and other toxic stuff. I have nothing against
the makers of chemicals, but one wants to have more
than one weapon when one deals with a beastie like varroa,
and this is both a cheap and effective non-toxic treatment.
2) Which Powdered Sugar To
Use?
I do not think that 2% - 5% corn starch (found in Domino
10X and most other store brands) matters one bit. My
reasoning is that one does not sugar-dust a hive until
the warmer days, and there should be none of the problems
that one might have with impurities in winter feed (dysentery).
If the bees can fly, they can certainly avoid dysentery.
But, just in case, try to find the LOWEST percentage
of corn starch you can.
There are rumors of "pure" powdered sugar
with zero corn starch (added to keep it from clumping
up). I have yet to find any, but I have not looked further
than my wife's pantry. (Yes, yet ANOTHER opportunity
to drive your long suffering spouse completely insane,
this time by stealing her/his powdered sugar!)
3) How To Prep The Sugar?
If you read the articles, you find that VERY tiny sugar
particles are what clog up the "suction cups"
on the legs of the varroa mites. But how to insure that
you "dust" a minimal amount of useless larger
particles, when the optimal particle size is on the
order of 5 microns?
This is what I do. It is far from "perfect",
but it works, and requires no special equipment or skills:
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First, all sugar is
sifted with a good-quality baking flour sifter.
This removes the big lumps. One can simply dump
the lumpy stuff back into the supply of sugar to
be used in baking. |
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Sift the sugar AGAIN,
this time letting the sugar fall into a container
that you can seal tightly against moisture. |
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Do your sifting on
a dry day. How dry? The driest possible. Mid-winter
is a good time to do this, as heating systems tend
to dry out the inside air. A day when you can get
a shock from a doorknob is likely about the driest
you can have. |
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Add some rice to your
sugar container to absorb humidity, and keep the
sugar dry (Grandpa did it with his salt shaker...)
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SEAL the container
tightly (I use canning jars). |
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Note that you are likely
sifting sugar in a kitchen. Both the sifter and
the kitchen may be "community property"
under the law, but a wise beekeeper would do the
sifting over the sink, and be sure to clean up after
the sifting. I had one unfortunate accident involving
a sifter, a bowl of sugar on a coffee table, a large
dog, and an unexpected visit from the Fed-X delivery
man, so STAY in the kitchen. Listen to the game
on the radio. |
4) How To
Apply The Sugar To The Colony?
Since application of the sugar is the only "technique"
one must master, I have messed with several different
"varroa pistols", ranging from a bagpipe-like
contraption to a foot-pump-driven monstrosity.
The lowest-cost (and perhaps overall best) approach
would be to use a well-washed and dried baby-powder
container, one with a cap that twists to reveal tiny
holes. You open the twist-cap so that the holes are
partly open, squeeze the plastic bottle sharply, and
the result (with a little practice) should be a satisfying
cloud of fine sugar particles.
With a little practice, you can perfect your "range"
accuracy, and dust the bees without getting too much
on the comb or frames.
If the tiny holes get plugged up, give the bottle a
sharp thump to dislodge the clogs.
Now, you can remove frames, one at a time, give each
side a few "poofs" of sugar, and replace them
in the super or hive body. One hand holds the frame,
and the other holds the baby-power container. Need two
hands to pull that frame? Wear a carpenter's tool belt,
and you have a "holster" for your varroa pistol
and your hive tool.
There are some who have mentioned simply dusting the
top bars rather than removing the frames, but the idea
here is to do one's best to knock down all the adult
varroa in the hive, so I have dusted every side of every
frame (except those with open cells, on the grounds
that the queen looks for "clean" cells [watch
a queen sometime, she "inspects" every single
cell before laying], and those cells that contain unsealed
brood.)
Dr. Fakhimzadeh says that one need not be so careful,
and that sugar DOES NOT have a negative effect on open
brood or eggs. (Allen Dick recently pointed out that
OTC dusted with sugar was claimed to be fatal to brood,
and Dr. Fakhimzadeh stated that it is the OTC itself
that can kill the brood, not the sugar.)
Regardless, I'd still try to avoid open cells ready
for laying, since one does not want to slow down one's
queen.
5) I'm A Klutz - I'll Drop
A Frame, Or Crush Bees!
Don't sweat it. Several of the bee suppliers sell a
handy gizmo called a "frame hanger". It has
two brackets that slide over the edge of a hive, and
two arms that support several frames at a time , hanging
them out where you can dust them. You can buy one, and
use two hands to handle the frames at all times.
If you are a klutz, this will be a good way to get in
the habit of developing skill, style, and panache in
tearing down a hive, looking at comb, finding the queen,
and other skills basic to "working with bees".
Keep at it. You'll get better.
6) OK, I've Dusted My Hives
- Now What?
I going to assume that you have a varroa screen, a slatted
bottom board, or at least a sticky-board insert with
a mesh cover. (If you don't, get one! Sugar dusting
will not help if the mites can crawl onto another bee
after their fall. Better yet, even when you are NOT
sugar-dusting, quite a few mites will fall through a
varroa screen.)
I use plain old "shelf paper", cut to the
correct size, with the backing paper removed at the
hive, and the shelf paper slid into the rear opening
below the varroa screen STICKY SIDE UP. I'll say it
again - STICKY SIDE UP!!!
If you slide a fresh sheet in just before you do your
dusting, you can get the most accurate "body count".
There are many methods to count, and I am sure that
some statistics expert will tear my head off, but I
don't care how you count ("pick a few square inches",
count all the varroa in a stripe across the sticky paper,
whatever). But pick a method and STICK with it, so your
data is all based on the same "sampling technique".
When you sugar-dust, you should get more varroa on your
sticky paper than you have EVER seen before. More than
you would see after 48 hours with varroa strips, more
than with any chemical. From what I have seen, the only
thing that would knock down more varroa would be a direct
nuclear strike on the hive. :)
Remove that paper after a day or two, and replace it
with a fresh sheet to count "falling survivors".
You should see few on the second sheet, even after a
week or two.
Why sticky paper at all? Well, if you are doing sugar
rolls as a varroa detection method, you may choose to
NOT use sticky paper, but I LIKE seeing the actual results
of the sugar dusting. Call me vindictive, but I laugh
a maniacal laugh when I see a sticky sheet with lots
of varroa. I laugh even more as I set the sticky paper
on fire and drop it in a burn bucket. If you listen
carefully, you can hear the little vampires scream.
:)
Seriously, once a varroa falls down below the varroa
screen, it will NOT crawl back up into the hive and
onto a bee. They just are not that smart. The varroa
will simply lie there and starve to death, waiting for
a bee to come close enough to climb upon. One does not
need the sticky paper. Several articles have addressed
the effectiveness of varroa screens.
7) WHEN Do I Dust My Hives?
When you see "high enough" varroa counts as
a result of a sugar roll or on a sticky paper placed
under your varroa screen. (For instructions on how to
do the sugar roll test, see this web-page,
pointed out to the list by Mr. Aaron Morris).
But what's "high enough"? Well, you have to
keep track, keep records, and develop a judgement about
such things. I can't simply give you a number, since
there is no single number that would work for all hives,
and no two beekeepers are going to even "sugar
shake" their bees the same way.
There is a trade-off here. One could sugar-dust a hive
every week, but think of the impact on the productivity
of the bees. Doing a complete tear-down of a hive is
VERY disruptive. Better to tolerate a low varroa population
for a while than to disrupt the hive so often. I would
not dust more than once a month. (But one can do a sugar
roll, or if you must, an ether roll as often as you
wish.)
One is likely never going to see zero varroa during
the summer, so if you see zero varroa, question your
test methodology.
From what I have read, the varroa population, if left
unchecked, starts to get out of hand in June, July,
August, and September. Of course, if one sugar-dusts
early, one could argue that one could stop the population
growth before it starts. A military strategist would
argue that one must do a second sugar-dusting just in
time to get any mites that were sealed in brood cells
when you did the first dusting. I dunno, I am just happy
that I have an all-natural way to kill the majority
of the mites that does not require removing the hive
from the season's honey production.
8) I Want Photos! I Want Video!
I Want More Instructions!
Oh grow up. I don't have the time to stage a photo shoot,
and I am about as photogenic as a wart hog. If I have
been unclear in some area, post a question. I read Bee-L
every week or so. I'll answer, or better yet, someone
smarter will answer.
9) I Have An Insecticide Duster
- Can I Use It To Dust My Bees?
You can use the same type of device, but I would buy
a new one and mark it "Sugar Only", for obvious
reasons
10) I'm A Commercial Beekeeper,
And Don't Have Time For This Nonsense Of Tearing Down
Every Hive...
OK, send me an e-mail,
and I'll be happy to build and sell you the ultimate
sugar dusting rig. I've got a Pratt and Whitney turbine
engine from a Navy F-16 out in the barn that shows promise
as a high capacity "whole hive" sugar duster.
You could also use it to clean pollen if you had a football-field
sized room in which to clean pollen... :)
11) Where Do We Pool Our Data?
Good point. We should. Mites and diseases are forcing
beekeeping to become much more of a "science"
than an "art". "Science" means accurate
records, archived in a central repository, and made
available to all. I am open to suggestions on how we
might standardize our "mite counts" to make
such a data-collection effort worthwhile.
12) Where Do The Varroa Come
From? How Do They Get In My Hives?
I wish I knew. I wish I knew someone who knew. If you
can find out where varroa come from, call me, so we
can go napalm the place some Saturday night.
Jim Fischer
Farmageddon
May 25, 2001
Jim adds this post script on October
11, 2002
If Bob Stevens (of Betterbee) and his team had gotten
the quirks out of the "Formic Acid Gel Pack",
I would have been using it rather than enduring all
the extra work to use powdered sugar.
Given that the problems with the Formic Acid Gel Pack
will not be solved this year or next, my eyes are now
on Brushy Mountain Bee Farm, who will be offering a
USA version of "Api-Life VAR". Alternating
Api-Life with Apistan in alternate years should do the
trick, and not result in "resistance".
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