ADDITIONAL RESULTS OF RESEARCH
                         Varroa Mite Control, 1996
                    http://www.wvu.edu/~agexten/varroa2.htm
 
(September 17, 1996). We will update this web page about monthly as we learn more from
our
experiments and as we receive results from other beekeepers. This page is designed for
beekeepers.
(For those needing help with terminology, please see Graham, J. 1992. The Hive and the
Honey Bee,
Dadant & Sons, Hamilton IL, 1324 pp.)
 
Eradication possible? We believe that during the late fall and early winter the varroa
mite is very
susceptible to control by essential oils. By treating hives with the grease patties and
syrups containing
wintergreen, tea tree or patchouli oils, and making sure the treatments are near the
cluster, then the
varroa mites will have no place to hide and all can be killed. (No brood cells will be
available as
shelters.) Because most of the country has lost feral colonies, and only careful
beekeepers now have
bees, a concerted effort by all beekeepers at this time may achieve eradication of the
varroa mite. We
are not as sure about tracheal mite--(there are so few around this area that we can not
find a sufficient
infestation to test), but it, too, is probably susceptible to winter treatment with
grease patties
containing essential oils. This critical opportunity in beekeeping may not come around
again
for some time to come: our scenario is that with the feral colonies gone, many new
colonies will be
established in the next few years which will have light infestations of mites; swarms
will issue from
these and begin to reestablish a feral population--containing at first a few varroa
mites. In a few
seasons the mites will increase and another epidemic of fatal varroa mite + PMS will
occur. As the
new feral colonies increase, it will become impossible to find them and to eradicate
their varroa mites.
That is why now is such a special opportunity to attack this pest.
 
We learned recently that EPA exempted certain active ingredients from the requirements
of FIFRA
including some essential oils; this information can be found in the Federal Register,
Vol. 61, No.
45:8876-8879, Weds., Mar. 6, 1996 ("Exemption of certain pesticide substances");
materials listed
include cinnamon oil, citronella oil, lemongrass oil, mint and mint oil [eg., Patchouli
oil], peppermint
oil, etc. EPA further stated that the inert substances in Fed. Reg. Vol. 61, No. 45 can
be added to the
active ingredients listed in Fed. Reg. Vol. 59, No. 187:49400-49401, Weds., Sep 28, 1994
("Inert
ingredients in Pesticide Products"), including cloves, mineral oil, parafin wax,
wintergreen oil, etc. The
label for exempted products must list the name and percentage (by weight) of each active
ingredient
and the name of each inert ingredient, and must not contain any false or misleading
statements (40
CFR Art. 156.10, 1 July 1994). Many states require some form of state labeling such as
"Attention:
this product is a pesticide which is exempt from federal safety testing requirements.
State registration
does not imply safety of efficacy. User assumes full liability of use." Contact your
state pesticide office
for their requirements.
 
SUMMARY OF EXPERIMENTAL TREATMENTS (REVISED):
 
1). Syrup: 25 drops (1 cc) of wintergreen or spearmint added to two cups (about one
pound or 453.6
grams) of sugar in a quart jar (0.95 liter); hot water added to fill jar. Be sure to add
the oil to the
granulated sugar then add the very warm water (not too hot or else the oils will
evaporate). Feed the
bees as much syrup as they will take. We have had good results with wintergreen,
spearmint, and
peppermint oils.
 
2). Grease patties: are made with four cups of granulated sugar, two cups of shortening
and one of
the following: 21 cc of wintergreen oil or 21 cc of patchouli oil or 21 cc or tea tree
oil or 11.5 cc of
each of two oils (eg., wintergreen + patchouli). (This rate is 1/4 oz. of essential oils
per pound of sugar
and grease). The components are thoroughly mixed (wear gloves or use a large spoon, as
wintergreen
oil in such concentrations may be toxic; patchouli oil is not toxic). The mixture is
then made up into 4
ounce patties (like a small, 3.5" hamburger) which are divided and placed on top of each
brood box
(about one half pound or 8 ozs. of grease patties per hive; one batch treats 5.8 hives).
We plan to
make patties this fall that also contain terramycin (TM25) to determine whether
medications can be
combined for both mites and foul brood.
 
3). Tracking strips: are made by cutting sheets or pieces of 1/8 in. plexiglass into
strips 3" wide by
14" long (7.5 cm by 35.5 cm ), and used as a base for holding a treated slurry
containing essential oil.
The slurry is made as follows: 17.5 ozs. (2 and 1/5 cups) of canola oil are mixed with
6.5 ozs. (slightly
more than 4/5 cup) of melted beeswax, stirred and set on a hot plate. To this liquid add
24 cc's of
wintergreen oil (or 24 cc's of patchouli oil or 12 cc's of each ). Stir well and pour
into three 8 oz.
plastic cups. When cooled, the slurry has a shoe-polish or salve-like consistency. Then,
2 to 3
teaspoons of the slurry are applied to the tracking strip which is placed lengthwise
just inside the front
entrance of each colony. The bees must track through this slurry when they enter or exit
the hive; they
then clean off the slurry by eating it and feeding it to each other. Treatments are
repeated after 5 days:
the old slurry, dead mites and dead, deformed bees are scraped off and new slurry added.
Plexiglass
is used for tracking strips because it has a very smooth finish allowing an even
coverage and it is too
hard for the bees to chew up or remove; masonite or other similar material could be used
just as well.
 
4). Paper inserts at top of hive: For control of varroa mite on displaced nurse bees
(see below). Use
2 cups of canola oil containing 11 cc's of wintergreen; put some in a honey bear (as a
squeeze bottle)
and apply 6 lines of wintergreen oil in both directions on a paper towel so that the
towel is saturated.
The bees chew it up and remove it in a week or so. You should replace it as needed to
treat the varroa
mites trying to avoid the other treatments.
 
Varroa Mite Assessment: You can place a sticky board on the bottom of the hive in
combination with
both patties and a tracking strip to obtain a good count of varroa mites within 24 to 48
hours: in our
tests the essential oils killed more mites than Apistan.
 
We use the essential oils throughout the year, either feeding syrup (when nectar is not
coming in),
using patties (pretty much year around, but bees do not use the patties as much during
honey flows),
and using the tracking strips, which are especially useful during the honey flows. The
best results
came from a combination of all three treatments.
 
We have found in recent months:
 
In colonies treated with tracking strips at the entrance and grease patties over the
brood chambers, we
found that varroa mites were able to escape treatment: displaced nurse bees, which
gather under the
inner cover were used as a hiding place by the mites. We treated this group of bees and
mites by
putting a piece of paper towel treated with canola oil and wintergreen (8 cc wintergreen
in one cup of
canola) just under the inner cover. We placed the oil treatment in a honey bear (used as
a squeeze
bottle) and applied 6 lines of wintergreen oil in both directions on a paper towel so
that the towel was
saturated. The bees chewed it up and removed it within a week or so. Very few mites were
found on
these bees after treatment.
 
The tracking strips and grease patties are lethal to exposed mites, but the mites also
escape the
treatment by going into brood cells being capped. There were very few mites on adults in
treated
colonies (thus, the ether roll would have come up with 0-4 mites), but the mites were
reproducing at
normal levels in worker brood cells and drone cells. The few remaining drone cells had
lots of mites in
them (13 Sep 96). We conclude that the essential oils in tracking strips and grease
patties do not
enter the food chain sufficiently to impair mite development.
 
The colonies that were fed syrup with essential oils, in addition to using tracking
strips and
grease patties, were virtualy free of varroa mites, without using Apistan.
 
Large colonies: we also found that colonies with many supers and thus lots of space made
mite
control more difficult: the treatments were too diluted by the volume of space and
number of bees.
Therefore, we recommend getting honey supers off as soon as possible and reducing
colonies to 1 or
2 brood chambers at most.
 
In some of our colonies, grease patties containing spearmint oil were propolized; but
not those
patties made with wintergreen, tea tree or patchouli oils.
 
Queens: A potential problem may be that queens on mating flights may have their
pheromone masked
or may become somewhat disoriented by essential oils. We recommend that the essential
oil
treatments be removed from the hives when queen rearing and mating is taking place.
 
Drones: We found that large numbers of drone cells provide protection to the varroa
mites and are
definitely the source of most breeding varroa mites. Consequently, we recommend that the
amount of
available drone cells be kept to a mininmum; be sure to remove and replace old comb
containing lots
of irregular drone cells. (See the literature for techniques using periodic drone
removal to reduce varroa
mites).
 
Note about tracheal mites: We checked Bob's colonies for tracheal mites by collecting
older
foragers: those that have frayed wings and a bald thorax. We removed their heads and
first pair
of legs and examined the tracheal trunks that are visible inside the cavity where the
legs were (peel off
the "collar" with forceps); infested tracheae could be seen with a hand lens and were
dark spotted or
uniformly dark. Results: in some control colonies (no treatments) 30% had tracheal
mites; in treated
colonies, 10% or less had tracheal mites. Since bees are able to drift considerable
distances, we
suspect that some of those in our treated colonies may have come in from other,
declining feral
colonies in the neighborhood (a few feral colonies still remain near Cumberland, but
these should be
gone soon). The older bees give a more reliable test for the presence and extent of
infestation by
tracheal mite. We learned that British beekeepers, up until about 1950, used a bottle of
wintergreen oil
(with a wick through the top) in the bottom of their hives to control acarine disease
(tracheal mites).
So, apparently, wintergreen (methyl salicylate) was use to control these mites. We also
learned that
Dr. Rennie, around 1920-1925, recommended wintergreen over the original Frow treatment
of
safrol-nitrobenzene-petrol as a treatment for Isle of Wight Disease (acarine disease or
tracheal mites)
(courtesy of Mr. Joe Hemmens, UK).
 
Questions or comments please contact:
James W. Amrine, Jr.
Division of Plant and Soil Sciences,
P. O. Box 6108, West Virginia University
Morgantown, WV 26505-6108 USA
Telephone: 304-293-6023
E-mail: [log in to unmask]
 
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