Formic acid fumigator for controlling varroa mites in honey bee hives
ABSTRACT The 50% formic acid fumigator (FAF) for varroa mite control was developed as part of a SARE grant (1999 to 2001). The fumigator was evaluated for five years on 123 colonies in five bee yards in Connecticut, Maryland and West Virginia. Treatments eliminated all mites on adult bees and 90 to 95% of mites in sealed brood cells. Very few brood or new young adult bees were injured by the treatment. The fumigator is a simple design and the overall cost of treatment is about $1.00 per hive or less. The 50% FAF was less toxic to bees compared to other treatments using 65%. 80% or 90 % formic acid (FA). The fumigator was applied for 18-24 hours, when ambient temperatures were between 10-30° C. In the USA, one treatment in mid-August to mid-September was effective and usually all that was required each year. The 50% FAF used with other essential oil treatments including salt-grease patties with wintergreen, feeding 1:1 syrup with Honey-B-Healthy7 (spearmint and lemongrass essential oils), and use of screened bottom boards together provide a synergistic effect to keep mite numbers at a relatively low level, as part of an integrated pest management (IPM) system.
- SourceAvailable from: culturaapicola.com.arhttp://dx.doi.org/10.1051/apido:2003060. 01/2004;
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ABSTRACT: Varroa jacobsoni was first described as a natural ectoparasitic mite of the Eastern honeybee (Apis cerana) throughout Asia. It later switched host to the Western honeybee (A. mellifera) and has now become a serious pest of that bee worldwide. The studies reported here on genotypic, phenotypic and reproductive variation among V. jacobsoni infesting A. cerana throughout Asia demonstrate that V. jacobsoni is a complex of at least two different species. In a new classification V. jacobsoni is here redefined as encompassing nine haplotypes (mites with distinct mtDNA CO-I gene sequences) that infest A. cerana in the Malaysia Indonesia region. Included is a Java haplotype, specimens of which were used to first describe V. jacobsoni at the beginning of this century. A new name, V. destructor n. sp., is given to six haplotypes that infest A. cerana on mainland Asia. Adult females of V. destructor are significantly larger and less spherical in shape than females of V. jacobsoni and they are also reproductively isolated from females of V. jacobsoni. The taxonomic positions of a further three unique haplotypes that infest A. cerana in the Philippines is uncertain and requires further study. Other studies reported here also show that only two of the 18 different haplotypes concealed within the complex of mites infesting A. cerana have become pests of A. mellifera worldwide. Both belong to V. destructor, and they are not V. jacobsoni. The most common is a Korea haplotype, so-called because it was also found parasitizing A. cerana in South Korea. It was identified on A. mellifera in Europe, the Middle East, Africa, Asia, and the Americas. Less common is a Japan/Thailand haplotype, so-called because it was also found parasitizing A. cerana in Japan and Thailand. It was identified on A. mellifera in Japan, Thailand and the Americas. Our results imply that the findings of past research on V. jacobsoni are applicable mostly to V. destructor. Our results will also influence quarantine protocols for bee mites, and may present new strategies for mite control.Enperimental and Applied Acarology 04/2000; 24(3):165-89. · 1.85 Impact Factor
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ABSTRACT: Formic acid and oxalic acid field trials for control of Varroa destructor were carried out in autumn according to the Swiss prescriptions during three successive years in different apiaries in Switzerland. The following parameters were determined in honey that was harvested the year after treatment: formic acid, ox- alic acid and free acidity. The following range of values were found in honeys of untreated colonies: formic acid, from 17 to 284 mg/kg, n = 34; oxalic acid, from 11 to 119 mg/kg, n = 33. There was a small, but unproblematic increase in formic acid levels in comparison to the levels in the controls; average: 46 mg/kg, maximum: 139 mg/kg. No increase in formic acid was found with increasing number of treatment years. If emergency formic acid treatments were carried out in spring, the residue levels were much higher: average in- crease of 193 mg/kg, maximum 417 mg/kg. The oxalic acid content remained unchanged, even after two suc- cessive treatments during the same autumn. No rise of free acidity was encountered after a combined treatment with formic and oxalic acid during the three trial years. honey/residue/formic acid/oxalic acid/free acidity/Varroa destructorApidologie 01/2002; 33(4):399-409. · 2.16 Impact Factor
FORMIC ACID FUMIGATOR FOR CONTROLLING HONEY BEE MITES IN BEE HIVES
James W. Amrine Jr.1 and Robert Noel2
1. Division of Plant and Soil Sciences, G-168 Agricultural Sciences Buildinng, West Virginia University, P.O. Box
6108, Morgantown, WV 26506-6108. USA (email@example.com); 2. Fort Hill High School, 108 Blackiston Avenue.
Cumberland, MD 21502, USA (firstname.lastname@example.org).
ABSTRACT - The 50% formic acid fumigator (FAF) for varroa mite control was developed as
part of a SARE grant (1999 to 2001). The fumigator was evaluated for five years on 123 colonies
in five bee yards in Connecticut, Maryland and West Virginia. Treatments eliminated all mites
on adult bees and 90 to 95% of mites in sealed brood cells. Very few brood or new young adult
bees were injured by the treatment. The fumigator is a simple design and the overall cost of
treatment is about $1.00 per hive or less. The 50% FAF was less toxic to bees compared to other
treatments using 65%. 80% or 90 % formic acid (FA). The fumigator was applied for 18-24
hours, when ambient temperatures were between 10-30? C. In the USA, one treatment in mid-
August to mid-September was effective and usually all that was required each year. The 50%
FAF used with other essential oil treatments including salt-grease patties with wintergreen,
feeding 1:1 syrup with Honey-B-Healthy7 (spearmint and lemongrass essential oils), and use of
screened bottom boards together provide a synergistic effect to keep mite numbers at a relatively
low level, as part of an integrated pest management (IPM) system.
Key Words: Formic Acid Fumigator, Varroa destructor, Acarapis woodi, essential oils, salt
grease patties, screened bottom boards, Apis mellifera, Honey Bee, Honey-B-Healthy7, IPM.
The varroa mite, Varroa destructor (Anderson and Trueman, 2000)(Mesostigmata:
Varroidae) and the tracheal mite, Acarapis woodi (Rennie, 1921) (Prostigmata: Tarsonemidae),
are the most damaging pests of the western honey bee, Apis mellifera L. (Hymenoptera: Apidae)
in the world today. Since their introduction to North America in 1984 (tracheal mite) and 1987
(varroa mite), virtually all wild colonies have been eliminated, and many beekeepers, both
hobbyists and professionals, have abandoned the profession. Those who remain have the hard
responsibility for maintaining healthy bee colonies for pollination of crops and for the general
welfare of the environment.
Organic acids and essential oils now play a bigger roll in integrated pest management of
parasitic mites and pathogens of honey bees, because of development of resistant mites and
pathogens. The Varroa mite has become resistant to synthetic acaricides (Pettis 2004). We
developed our four-fold treatment protocol (Amrine et al. 1996; Noel and Amrine, 1996) of: (1)
screened bottom boards, (2) wintergreen/salt grease patties (Sammataro et al., 1996; Sanford,
1995), (3) feeding essential oil concentrate, Honey-B-Healthy7 (HBH) (Noel 2006), and (4) the
50% formic acid fumigator (Amrine & Noel 2001), to reduce and control honey bee mites using
essentially natural ingredients. Five years of using the improved version of the formic acid
fumigator showed that only one or two, 24 hr treatments in mid-August to mid-September
(middle Atlantic States Climate) controlled both Varroa destructor and the less destructive
tracheal mite, Acarapis woodi.
For a full description of the other three protocols, please see our websites:
http://rnoel.50megs.com/2000/index.htm and http://www.wvu.edu/~agexten/varroa.
Abbreviations and acronyms used in this report: C - Centigrade, cm - centimeter, CT
- Connecticut, F - Fahrenheit, FA formic acid, FAF, formic acid fumigator, FA-HBH - formic
acid-Honey-B-Healthy7, FL - Florida, HBH - Honey-B-Healthy7, MD - Maryland, PMS -
parasitic mite syndrom, Qt - quart, WV - West Virginia, WVU - West Virginia University, “ -
MATERIALS AND METHODS
Screened bottom boards (using 1/8" (0.375 cm) hardware cloth) for varroa mite
control (Horn, 1987, Pettis & Shimanuki 1999) were used on all of our colonies. For our trials,
we made an opening in the back of the bottom board, below the screen, for inserting home-made
detector boards [12 1/4" x 16 7/8" (31.15x.9 cm) white demonstration board, coated with
petroleum jelly (Vaseline7)] which could be replaced with a sheet of masonite for fumigation.
Screened bottom boards take advantage of the natural, 10-20% mite fall that occurs throughout
the year. Without vaseline, the mites will crawl back up onto the bees.
The 50% formic acid fumigator, FAF, (Figs. 1-6) has two parts: an inner fumigator frame and an
outer supporting frame. The outer surface has the same dimensions as a Langstroth honey super
or 18" x 16 3" (45.72 x 41.275 cm). The inner fumigator frame (Fig 3) is 17 2@ long by 12 2@
wide (44.45 x 31.75 cm), made with :@ x 7/8@ (1.9 x 2.22 cm) wood molding (see details in
Figs. 4-5). The upper surface is covered with 1) standard aluminum or plastic window screen to
protect the absorbent pad from the bees on the underside, 2) an absorbent pad (non-woven
undergarment, Kendall7 7174 bed pads, available from hospital supply stores or drugstores) with
the absorbent surface down, and 3) a sheet of aluminum >flashing= (available from home
improvement stores) as a top cover, screwed into place with 4 screws, overlapping the two sides
of the fumigator frame by 2A (1.27 cm). This inner fumigator frame is nailed (from the ends)
into a 1 :@ x :@ (4.45 x 1.9 cm) outer supporting frame, with the same outer dimensions as a
Langstroth honey super (see above) forming two 3/8@ (0.9 cm) beeways on each side, with the
top, flashing surface of the inner fumigator recessed 3/8" (0.9 cm) below the top surface, and
with the bottom of the inner fumigator frame about 5/16@ (0.79 cm) above the bottom margin.
This construction provides an important air cavity, Athe activation cavity@ (Fig. 6), 1 3@ deep x
12 5/16@ x 17@ (3.175 x 31.27 x 43.18 cm), below the absorbent surface and just above the brood
frames. In American style hives, the tops of the brood frames are recessed about 3/16" (0.476
cm) below the super margin, and allowance for this additional space will have to be made in
British- or European-style hives.
Application - Before treatment, we taped over all holes, openings, etc., and we used a
solid bottom board, or sealed the bottom with an aluminum, plastic or masonite sheet. The
entrance was reduced to a small central opening 7/8" (.95cm) x 3.5" ( 8.9 cm) (Fig. 7).
At time of application (see below) we poured 2.9-3.4 ozs. (85-100 ml) of 50% formic
acid (depending on the size and number of the brood chamber(s)), mixed with 10-20% (0.5 to
0.67 ozs or 15 to 20 ml) of Honey-B-Healthy7 (mixed at time of application1) onto the pad and
placed the fumigator on top of the upper brood chamber, with the absorbent material down. The
amount of formic acid mix used depended on the number and depth of the brood chambers; eg.,
we used 2.9 ozs (85 ml) for a single deep chamber, 3.2 ozs (90 ml) for double Illinois chambers
or a deep + shallow, 3.21 ozs (95 ml), and for double deep chambers (3.38 ozs or 100 ml), etc.
Fumigation is done when the ambient temperature is between 17-31?C (60-85? F). The
fumigator is placed on the hive at about 12:00-18:00, and taken off at about 12 noon the next day
(18 -24 hrs. exposure). We kept detector boards on the hives for 13-14 days in order to sample
mite drop during one capped brood cycle (Fig. 8D, Fig. 9).
Summary of Application:
1. Ambient Temperature should be 60 to 90? F (15.5-32.2? C).
2. Apply treatment between 13:00 & 18:00 (1-6 PM), ideally mid-August to mid-September.
3. Manage all brood frames in one or two brood chambers.
4. Thoroughly mix 85 ml (2.9 oz) of 50% FA solution with 15 ml (1/2 oz) HB; pour onto
absorbent pad in fumigator. Place above upper brood chamber.
5. Tape all openings shut; if using screened bottom board, use solid Bottom Board or cover the
screen with masonite, plastic or aluminum sheet.
6. Reduce entrance to 3@ x 3/8@ (7.5 x 1cm) at center.
7. Remove fumigator the next day between 12:00 & 18:00
(noon and 6 PM).
In most cases, only one treatment is needed per season. We often go two seasons between
treatments, depending on # of infested brood cells (and # of incoming mites from dying and/or
After applying the FAF, the bees quickly began to fan the air through the brood nest and
out of the small bottom entrance; you could easily feel the air and smell the formic acid coming
out of the central entrance. During the treatments, average temperatures were 93-94?F (33.9-
34.4? C) between the full brood frames, 92-93?F (33.3-33.9? C) just below the fumigator at the
center of the hive, and the air exiting the entrance was nearly always 90?F (32.2?C).
Temperatures were lower in the weaker colonies with just a few frames of brood. We had
excellent mite kill on most hives in all of our preliminary trials (Table 1), including mites inside
sealed brood cells. Because of the addition of HBH, we saw very little interruption of queen
performance, and no balled queens in the WVU trial. In August, 2000 we conducted similar
trials with formic acid only (no HBH), at the same concentration and amount, and lost queens in
6 out of 24 (25%) colonies (Connecticut). The Cumberland, MD, preliminary trial (41 colonies),
at the same time and same doses of FA, but with HBH, had two queen losses or 4.3% loss, which
may have been due to failing queens. The WVU trial of 82 colonies in September 2000, using
the same doses of FA, but with HBH, resulted in no loss of queens. In 2001, in Cumberland,
MD, three queens in 46 (5%) FA-HBH treated colonies were lost. Another trial in Cumberland at
the same time, of 31 colonies using synthetic acaricides (Apistan & CheckMite) showed a 6%
queen loss (no HBH). We have used our 50% formic acid fumigator at WVU and Cumberland,
MD, for the past five years with the same, consistent results. In addition to adding the HBH to
the formic acid mix, spraying the bees and brood area with 1:1 sugar syrup with 20 ml of
HBH/Qt (0.95 l) helps to prevent queen loss.
Queen losses were reduced from 25% to about 5% or less with some trials showing 0%
losses, while obtaining a 90-95% kill of Varroa on the bees and in the cells in treatments lasting
less than twenty-four hours.
Some open brood, and hatching young bee losses could not be totally eliminated. This
minimal loss of a few hundred bees at most had no detrimental effect on colony strength
(40,000-60,000). The treatments stopped varroasis in thousands of brood cells and allowed brood
to hatch as healthy adults, free of deformities and disease. Large numbers of clean, healthy brood
are needed for a colony to successfully overwinter. The potential loss of a handful of bees is
minimal when compared to the thousands of bees saved by the treatment.
Table 1. Results of 50% FAF-HBH treatment of bee hives at WVU Horticulture Farm, 18 Sep 2000;
numbers of dead VM on sticky cards. Hives were maintained on two Illinois-style brood chambers,
with 7 frames of brood in each hive. HFH: Hort Farm Homestead; bees purchased from Weaver
Apiaries, Navasota, TX, May 2000. RNH-1: Robert Noel hive treated at the same time. All had been
treated with 4 weeks exposure to “low acid” by wicks into brood chamber from reservoir below hive
containing 40% FA and 10% acetic acid (had no effect on VM). We estimated an 80% reduction in
Hive # 24 hrs+3d
HFH-2 691 2223
HFH-8 1184 3039
RNH-1 544 540
By using a lower concentration of formic acid, approximately 44% after HBH is added,
we have reduced the chance of injury to bees.
This new, improved 50% Formic Acid Fumigator has inreased the efficiency of formic
acid in the following ways:
1) A recessed air space is provided just above the upper brood chamber within the fumigator.
Heated air from the brood rises into this enclosed space which has a controlled 92? F (33.3? C)
temperature. We call this space the Aactivation cavity.@
2) The upper surface of this space has an absorbent material saturated with a 44.1% FA-HBH
mix, overlying the entire brood area. The FA is much heavier than air (specific gravity of 1.11)
sinks to the bottom board and does not rise. This is probably why so many investigators had
variable results when placing small pads of FA on the bottom board, in the back corner of
colonies, in modified frames placed between brood cells, or in small pads on top of the brood
supers, but with no controlled heated or evaporation space and with a fully open entrance.
Placement of the FA-HBH mix about 1.25" (3.175 cm) above the upper brood frames is critical
for the performance of this fumigator.
3) By reducing the entrance to 3/8" x 3.5" (0.95cm x 8.9 cm)(Fig. 7), and by having only two
3/8" (0.9 cm)bee ways on the sides of the fumigator (Fig. 3), allows the FA-HBH mix to saturate
the hive atmosphere which then penetrates all capped brood cells, killing 90-95%+ of the mites
in most colonies in less than 24 hours. Dead mites can be found in brood cells during the next
13-14 days, and these accumulate in dense bands on the detector board during this time. (Fig.
4) The upper aluminum sheet prevents the warm air from being lost to upper supers (boxes of
frames for honey storage above brood chambers) (Fig. 2).
Thus, warm air rises from the brood and activates the FA-HBH in the absorbent pad
causing evaporation. The pad can hold 150 ml of solution without dripping. The bees respond
with a roar of fanning, and the FA-HBH saturated air circulates throughout the brood space and
eventually exits the small entrance opening. The circulating air is warm (90?F, 32.2? C) when it
exits; the FA penetrates capped cells, killing mites inside, but not the brood. Within 24 hrs,
virtually all of the FA has evaporated and the fumigator can be removed.
The more brood frames, the better the performance of the fumigator. We feed HBH to the
bees in August to stimulate brood production prior to fumigation with the FA.
The detector board should be left on for 13 days (14 days for drones) to get an estimate of
the mite population and mortality. This period corresponds to the number of days required for
one cycle of capped brood to complete development and exit cells. As bees exit the cells, dead
mites and debris fall between the frames, through the screened bottom, and onto the detector
board below. Some colonies produced counts exceeding 3,000 mites on a single detector board
in 13 days. We have 426 boards (Fig. 8B-E) taken from as many treatments, and it is very
satisfying to see the 1000's of dead mites in the petrolatum.
For most hives, one treatment usually places the colonies far below injury level for
several months (fewer than 5 of 100 examined drone cells infested). Occasionally, a second
treatment may be needed about two weeks after the first.
Honey-B-Healthy7 and Queen Preservation - Honey-B-Healthy7 is a mixture of
spearmint and lemongrass essential oils with water, lecithin and a trace of sodium laurel sulfate
to stabilize the product. It has a shelf-life of several years. It is formulated so that one teaspoon
(5 ml) of HBH delivers 0.5 ml of spearmint oil and 0.5 ml of lemongrass oil to the target
solution, which is usually a quart of 1:1 sugar: water syrup. We compared many essential oils in
treatments of colonies with parasitic mite syndrome (PMS) in 1995 and 1996; we found that
wintergreen and spearmint were excellent at reducing the PMS and allowing colonies to produce
normal healthy bees. Spearmint always gave superior results. However, honey bees are not
attracted to spearmint oil syrup; they may take a week to consume the spearmint syrup. Bob
Noel experimented with many additives to try to get the bees to feed on spearmint-syrup; he met
with success with lemongrass oil. The combination was excellent and the bees took it rapidly;