# Oxalic Acid - Old, Old post



## snl (Nov 20, 2009)

This is a very old post by member Dave W ? from 2006 (no longer posting). 
Anyways a lot of good and some outdated material with many bad links. 
What struck me was the use of paper towels to distribute OA many moons ago..........




OXALIC ACID - CAS # 6153-56-6 Dehydrate (144-62-7 Anhydrous) 

Chemical Class - Organic acid

Description - Oxalic Acid dehydrate (OA), is a white (colorless) crystal, granule or powder. It is used in solutions for a wide range of industrial processes. ItÂ’s slightly soluble in water. Corrosive to metals. Poison. OA reacts explosively w/ strong oxidizing materials and some silver compounds. Incompatible w/ alkalis, chlorites, hypochlorities, furfuryl alcohol, steel, moisture. Avoid contact w/ metals. Carbon dioxide and carbon monoxide form when heated to decomposition. Also forms formic acid [http://www.jbaker.com/msds/englishhtml/o6044.htm] (1% - 10mg/1g of vaporized OA) [http://www.mellifera.de/Engli2.pdf - Accessed 7/13/04].

When heating, about half (46%) of OA decomposes into harmless carbon dioxide and water. Other half (54%) vaporizes and forms fine drops and dusts of OA that precipitates everywhere in hive. Because of this even distribution of fine particles, high and consistent efficacy against Varroa mites is possible [http://www.mellifera.de/Engli2.pdf - Accessed 7/13/04].

OA is a naturally occurring component of our nourishment. It can be found in almost every plant we eat and is a natural component of honey (0.02 to 2 g/kg). Rhubarb becomes sour because of 2.6 to 6.2 grams of OA that is contained in each kilogram of fresh plant [http://www.mellifera.de/Engli2.pdf].

CHEMICAL NAME - Ethanedioic Acid MELTING POINT - 219.2oF - 222.8oF
SYNONYMS - Ethandionic Acid, Aktisal, Aquisal BOILING POINT - 300 - 320F 

Health Effects - Pure OA is an unhealthy, toxic and corrosive substance [http://www.mellifera.de/Engli2.pdf - Accessed 7/13/04]. Can cause severe irritation and burns of nose, throat, and respiratory tract, causing coughing, wheezing and/or shortness of breath. Exposure can cause headache, vomiting, stomach pain, weakness, seizures, coma and death. May cause nausea, severe gastroenteritis and vomiting, shock, and convulsions. May cause renal damage, as evidenced by bloody urine.

Human Fatal dose (estimated) - 5 to 15 grams [Source???] 15 to 30 grams 
[http://www.cdc.gov/niosh/idlh/144627.html]. May be absorbed through skin. Can cause severe irritation, possible skin burns. OA is an eye irritant, may produce corrosive effects. Very destructive of mucous membranes. May cause congenital malformation in fetus. May damage kidneys and cause kidney stones. May affect nervous system.

Lethal Dose to kill 50% (LD50) - Rats: 375mg/kg (oral). 

Beekeeper Exposure - Special safety precautions for the beekeeper are necessary, as w/ other products for Varroa control. When preparing solution for spraying, trickling or vaporizing OA crystals do NOT inhale dust. Use protective mask (FFP 3 S/L), gloves and protective glasses. Mask should be worn during treatment [http://www.mellifera.de/Engli2.pdf - Accessed 7/13/04]. Colonies in a beehouse must be treated from outside, and beehouse must be well ventilated during and after treatment [http://www.mellifera.de/engl2.htm-Accessed 2/3/05].

A study at the Institute of Occupational and Social Medicine, University of Tubingen, Germany has determined (while spraying or evaporating OA) that beekeeper exposure is below existing exposure limits for OA in the air at work place. There is no risk to the health of apiarist
[www.apis.admin.ch/en/krankheiten/docs/saeuren/os_anwendersicherheit_e.pdf]. 

When cutting rhubarb, exposure to OA is 25 times higher than beekeepersÂ’ exposure to residues on frames after vaporizing OA [http://www.mellifera.de/Engli2.pdf - Accessed 7/13/04].

Regulation by OSHA (cited by ACGIH, DOT, NIOSH and NFPA) requires OA to be on the Hazardous Substance List. 

Registration Â– The American Bee Federation (ABF) directors have decided to pursue the registration of oxalic acid for treatment of V-mites [ABJ, 10/05, p782]. (Canadian approval announced in ABJ, 11/05, p864. See http://www.honeycouncil.ca/users/fol...=876&nID=512.) Oxalic acid is NOT approved for use in the US [ABJ, 7/04, p475]. 

Testing of OA in dry vs. humid climates, and colder climates by Diana Sammataro, Carl Hayden HB Research Center, Tucson, has been funded (Spring 05 - Spring 06) by the National Honey Board [ABJ, 4/05, p271].

Austria was first (Oct 2001[http://www.mellifera.de/Engli2.pdf-Accessed 7/31/04]) to officially approve OA evaporation method [http://www.mellifera.de/engl2.htm-Accessed 2/05]. Oxalic acid is in widespread use in Europe because of its ease of application, high efficiency and low cost. A substantial amount of data exists on OA as a mite control substance. Unlikely that a chemical manufacturer would be interested in registering product because of its low cost as a generic.

Residue - In the year 2000, after vaporizing OA, honey showed an OA content between 22.8 and 37.7 mg/kg. Natural concentration of OA (determined by Franco Mutinelli et al, lÂ’acido ossalico nella lotta alla varroasi, LÂ’ape) varies from 20 to 400 mg/kg of honey [http://www.mellifera.de/engl2.htm-Accessed 2/05], 0.02 to 2 g/kg [http://www.mellifera.de/Engli2.pdf]. Use of oxalic acid in autumn does not increase concentration of OA in honey the next season114. Can therefore be used in autumn without affecting honey quality11. 

Maximum Residue Level (MRL) - No maximum limit exist for oxalic acid residue in honey. According to European honey standards, honey may have up to 50 milli equivalents of free acids
[www.apis.admin.ch/en/krankheiten/docs/saeuren/mrl_bienenzeitung_e.pdf]. 

Use of oxalic acid as a miticide can leave taste residues in honey. A taste threshold of 400 - 900ppm (depending on honey aroma and taste) has been set by the Swiss, does not exceed worldwide MRL for organic acid in honey of 40 milli equivalent (meq) acid/kg11. 

Resistance - No reports of resistance have been made. It is suggested that Varroa will not develop resistance to organic acids since they are a natural part of the metabolism of all organisms and cannot be rendered harmless through enzymatic effects50. 

Storage -Store in a tightly closed container in a cool, well-ventilated area away from heat, moisture and incompatibilities.

Disposal - Unused chemical should be taken to an approved chemical waste disposal facility.

Source / Cost - Generic OA is commonly used as a wood bleach.
Â• LoweÂ’s, 12 oz wt (1 pint) $4.98 [Jan 04]. 
(2 cups = 1 pint, 16 tbl = 1 cup, 6 half-tsp. = 1 tbl, hence 2x16x6 = 192 half-tsp.
1 oz wt = 28.35 grams, hence 28.35x12 = 340.2 / 192 = 1.77 g per 1/2 teaspoon)


APPLICATION - Oxalic acid is only effective when colonies are broodless, and during broodless periods, control is excellent. Oxalic acid needs to be combined w/ other treatment methods when brood is present [BC, 3/06, p38]. Can be applied by evaporation, dripping (trickling) or spraying
[www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf].

Winter treatment is extremely important because the mites that are destroyed constitute the basis for next yearÂ’s population. These mites have either survived autumn treatment or entered colony by re-invasion [Source???]. During the broodless period, all surviving mites are found on the bees. An efficient treatment during this time can significantly reduce the Varroa Â“kick-offÂ” population for the coming season and further control measures will not be needed until summer of the coming year [www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf - Accessed 1/19/05]. 

1) EVAPORATION method uses OA crystals, which are heated until they melt and boils into a vapor. The fumes penetrate hive and kills Varroa mites. First (???) used in the Soviet Union, where OA vapors are created outside hive and blown into colony [http://www.mellifera.de/engl2.htm-Accessed 2/05]. In-hive evaporation method developed by Mellifera e.V. Vereinigung fÃ¼r wesensgemÃ¤sse Bienenhaltung, uses a small 12v (car battery) device inserted into hive entrance [http://www.mellifera.de/engl2.htm-Accessed 2/3/05]. See Proprietary Products.

A simple, cheap, homemade applicator / dispenser / vaporizer can be created using pipefittings, see http://bwrangler.litarium.com/varroa-blaster/. Uses 1/2 teaspoon of powder.
[Michael Bush - http://www.beesource.com/ubb/Forum2/HTML/001283.html].
Â• Applied once per treatment.
Â• Do NOT use during honey flow. [http://www.mellifera.de/engl2.htm].
Â• Withdrawal Period - ???
Â• Can be used during winter. Mid to late November (about 50OF) [www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf - Accessed 1/19/05].
Tests applied about Nov 25 and about Jan 8 [http://www.mellifera.de/engl2.htm-Accessed 2/05].
Â• Second treatment should be applied about 2 wks after first, IF brood is present (or uncertain) OR if mite load is high [http://www.mellifera.de/engl2.htm-Accessed2/05].
Â• Temperature - Ambient temperature NOT critical [Source???]. Tested between 35.6Â°F (2Â°C) and 60.8Â°F (16Â°C) [http://www.mellifera.de/engl2.htm-Accessed2/3/05].
Â• Seal colony shut for 10 minutes [BC, 3/06, p38]. Close hive entrance during and for 15 minutes after treatment [http://www.mellifera.de/engl2.htm-Accessed2/05].
Â• Can be used to treat nucs [http://www.mellifera.de/engl2.htm-Accessed 2/05].
Â• Labor - 8 minutes per hive [www.apis.admin.ch/en/krankheiten/docs/saeuren/os_anwendersicherheit_e.pdf-Accessed 1/19/05].
Â• Cost per Treatment - $0.03 ($4.98 / 192 half-teaspoon [DLW])

Method #1 - BROODLESS in FALL - Treat 2 times, 2 wks apart [Michael Bush, http://www.beesource.com/ubb/Forum3/HTML/000217.html].

Method #2 - BROOD PRESENT - Treat 4 times, 7 days apart [Axtmann, http://www.beesource.com/ubb/Forum3/HTML/000217.html].
Move all capped brood (w/ bees) into separate super outside original hive and allow (existing) queen to lay on empty comb. All workers will fly back to (existing) queen, only young bees will remain w/ brood. Cut out queen cells started in separate super (capped brood) and treat w/ OA 3 times, 5 to 7 days apart. Treat original hive 1 or 2 times. After 21 days (when all brood has hatched), combine super (w/ young bees and queenless) to original hive (w/ queen) w/ honey super between [Herbert Axtmann, http://www.beesource.com/ubb/Forum3/HTML/000183.html - Accessed 4/23/04].

Effectiveness - 97% w/ VarroxR Vaporizer [http:www.imkerei-technik.de/varrox_verdampfer.htm - Accessed 7/13/04]. 
Single treatment = 95% [http://www.mellifera.de/engl2.htm-Accessed 2/05].
Effectiveness lower (75-100%) in Dadant hives [http://www.mellifera.de/engl2.htm-Accessed 2/05].
Effectiveness about the same for temperatures between 35.6Â°F (2Â°C) and 60.8Â°F (16Â°C) [http://www.mellifera.de/engl2.htm-Accessed 2/3/05].

Monitoring Results - Evaporation method is slower (to kill mites) than other OA methods.
One day after treatment, only 10% of total mites killed are found on hive bottom. After 1 week, 80% are killed. To determine exact number of dead V-mites, count mites for a period of 3 wks. [www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf - Accessed 1/19/05].
Mite drop increases 270% from day 1 to day 8, but increasing only 18% over next 36 days. Oxalic acid kills mites for at least 44 days (6.3 wks) - see http://www.mellifera.de/engl2.htm (Accessed 2/3/05), Figure 2.

Adverse Effects - Conflicting reports to OA effects on bees range from no deleterious effect to impaired queen performance and poor overwintering success [ABJ, 6/04, p479]. Winter treatments can lead to harmful effects on the bees, when dosages are too high. Trials show that a correctly dosed, ONCE-ONLY treatment w/ OA (spray, drip or evaporation???) is well tolerated by the bees. Dead bees at hive entrance or in hive is not pertinent, because bees which die as a result of overdose of OA, are not found in the hive or near by. It is likely that these bees leave the hive and do not return [www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf - Accessed 1/19/05]. Less than 200 dead bees (on hive bottom) were counted over a 5-week period following vapor treatment and double the mount of OA did not cause a higher deadfall. Average winter deadfall of untreated colonies was near 250 during same period [http://www.mellifera.de/engl2.htm-Accessed 2/05].

2) DRIP (trickle) treatment w/ a solution of sugar and 5% oxalic acid has been found to be highly effective in colonies without brood [ABJ, 8/05, p672]. This method is simple, quick, cheap and very effective in broodless colonies [Source?]. Trickling requires double brood chamber colonies to be cracked apart in cold weather [BC, 3/06, p38].
Â• Do NOT use during honey flow. Do not apply OA when honey supers are on hives, or during nectar flows if honey is to be extracted for human use [http://www.biosecurity.govt.nz/pests...es/control.htm Â– p97, Accessed 8/1/05]. Apply any time as needed [Source???]
Â• Withdrawal Period - ??? 
Â• Can be used during winter. Outside temperature is not important, although the solution can chill the bees at low temperatures (below 32F) [http://www.biosecurity.govt.nz/pests...es/control.htm Â– p98, Accessed 8/1/05].
Â• Labor - 1 minute per colony [ABJ, 6/04, p476]. Trickling requires the least amount of time and is easiest to apply [www.apis.admin.ch/en/krankheiten/docs/saeuren/osbienenvertraeglichkeit2003_e.pdf - Accessed 1/19/05].

Mode of Action - When consumed (solution [DLW,12/05]) by bees, probably acts as a protoplasmic poison by acidifying host beeÂ’s hemolymph [ABJ, 6/04, p479]. 
Â• Because OA works through contact, ambient temperature is not critical. Mode of action appears to be low pH of OA solution116.

Prepare Solution Â– Several OA formulations have been tested in Europe. Variable concentrations of OA (1.8-4.5%) are produced by dissolving OA in sucrose solutions (0-60%). Volume used varies depending on bee colony size and strength (30-50 ml/colony) [ABJ, 6/05, p475].

Crystal form of OA only contains 71.4% OA. It is important to use this factor when preparing solutions. To determine the percentage (weight/volume) of OA in a syrup solution, divide the actual amount of OA (weight of OA x 0.714) by total volume of sugar solution. [http://www.biosecurity.govt.nz/pests...es/control.htm Â– p97, Accessed 8/1/05]. (Example: 75 g of OA x 0.714 = 53.55 / 1.67 = 32.06 or 3.2% [DLW, 12/05])
Â• Mix 1 liter of water w/ 1 kg of sugar. Add 75 g of oxalic acid dehydrate. Mix thoroughly. Makes about 1.67 liters [http://www.biosecurity.govt.nz/pests...es/control.htm Â– p97, Accessed 8/1/05]. (Produces a 3.2% solution [DLW, 12/05)
Â• Add 44.8 g (1.6 oz) oxalic acid dehydrate (99% purity; 71.4% oxalic acid) to 1 liter (ca. 1 qt) of a 50% sucrose solution (w/v) [ABJ, 6/05, p476]. (Produces a 4.5% solution [DLW, 12/05])

Amount to Use
Â• Use 5 ml of sugar syrup mixture per frame of bees (100% bee coverage [DLW,12/05) [http://www.biosecurity.govt.nz/pests...es/control.htm Â– p97, Accessed 8/1/05].
Â• 5 ml (0.15 oz) of a 3.2% oxalic acid solution per frame [ABJ, 6/05, p476].

Method #1 Â– 
Trickle oxalic acid solution directly onto bees between frames using a large syringe at a rate of 0.15 oz. (5 ml) of solution per frame. In 2-story colony, trickle only between frames of top hive body [ABJ, 6/04, p476].

Method #2 - Dissolve 35g of oxalic acid dehydrate in 1 liter 1:1 sugar syrup. Use 30ml for small colony, 40ml for medium colony, 50ml for a large colony (or 5 to 6 ml for each occupied super). Drip lukewarm solution directly onto bees between frames. Treat broodless colonies in Nov - Dec when ambient temperature is above 32oF. Use freshly prepared solution or solutions that have been stored for max. 6 months at max. of 59oF.[http:www.beedata.com/files/drip-oxalic-bogdanov.PDF, Bee Tidings, Jan 03, and http://www.stratford-upon-avon.frees...reatment.htm].

Effectiveness - 89-97%117. >90% [ABJ, 6/04, p475]. An efficacy of 95% after 3 treatments using a 5% solution (w/o brood). With brood, 39.2% after 3 treatments [ABJ, 8/05, p672]. A European study seeking to optimize mite mortality rates and reduce adverse effects from oxalic acid in sugar syrup treatment showed 92.2% efficiency using 3.2% oxalic acid in 60% sugar syrup. 4.2% oxalic acid produced slightly better efficiency, but more adverse colony effects. 2.9ml of syrup / comb was more effective (92% mite kill) than 2.5ml / comb (80%)116.

Adverse Effects - Conflicting reports to OA effects on bees range from no deleterious effect to impaired queen performance and poor overwintering success [ABJ, 6/04, p479]. Trials suggest that some hives show adverse effects from DRIP treatment29.

Storage of prepared 1:1 sugar/water/OA solution - Sucrose solution used for trickling changes its color (to brown) after prolonged storage at room temperature as hydroxymethylfurfural (HMF) content increases. This is the substance used to detect a loss of quality in overheated honey. Sucrose solution w/ a high HMF content is toxic to bees. Use freshly prepared solution or solution can be stored a maximum of 6 months at a temperature of 59OF (15OC). Storage at or below 39OF (4OC) is ideal.
[http://www.apis.admin.ch/en/krankhei...agerung_e.pdf].

Treatment Cost -

3) SPRAY treatment is better tolerated by the bees. Use 3 - 4ml (3% concentration) per frame side. Mix 30g dehydrated OA in 1 liter of water [http://www.apis.admin.ch/en/krankhei...agerung_e.pdf].
Â• Do NOT use during honey flow. 
Â• Two autumn treatments are generally required.
Â• Labor for spray application has been estimated at 14 minutes per beehive50.

Effectiveness - 82-99%69; 114; 47.

Adverse Effect - Conflicting reports to OA effects on bees range from no deleterious effect to impaired queen performance and poor overwintering success [ABJ, 6/04, p479]. Long term (4) SPRAY applications of 3% oxalic acid in autumn and spring showed significantly negative effects on brood development and queen survival62, although other studies did not show such effects114; 19.

Treatment Cost -

4) PAPER TOWEL method called OsInAl (OxalSaure In Alcohol). OsInAl can be used in fall, even when colonies are breeding. You can leave the OsInAl tissue in the hive during the winter. OsInAl is NOT suitable to treat strongly infested colonies in summer. It is useful to treat splits with OsInAl. The bees must have contact with the tissue. OsInAl is not immediately effective like OA trickling. The effect lasts over several months. 

Formula for 40 tissues: 200g oxalic acid, 1 liter 70-90% alcohol, 50g citric acid. You can use thin tissue (cheap towels for cleaning) made of PE-fibers or other artificial material in size of 20x25cm (about 8x10Â”). Dissolve the oxalic and the citric acid in the alcohol. Put the batch of towels in a plastic container and spill the solution over the towels. The alcohol is used to resolve the oxalic acid. The alcohol evaporates within 2-3 days and the OA is evenly spread in the towels. Pay close attention, alcohol kills the bees! Do not use the towels soaking wet! Citric acid (hygroscopic) is needed to (keep) towels wet in the hive. OsInAl works much better, when the towel is wet. Kills 60-90% of the mites. 
[Bumble Bee, http://www.beesource.com/cgi-bin/ubb...316;p=2#000032 - Accessed 2/21/05].


PROPRIETARY PRODUCTS 

OXAMITER STRIPS - (Ingredients: Different natural acids including oxalic acid and scented oil) A long-term treatment that should begin in spring or after harvest. Use 1 strip per 9 frames. Hang strips between brood frames or place across top bars. Strips should remain in hive for a period of 5 weeks, and should be replaced if removed (chewed up) by bees. At end of treatment period (5 wk), remove remnants and store securely in original package, closing bag w/ tape and place in a dark, dry location until next use.

Monitor after Treatment - Repeat if mite drop exceeds 20 or more mites at end of 5 weeks [http://www.members.shaw.ca/orioleln/new_oxamite.htm].

Source / Cost - $12.50 per 10 strips


OXAVARR - Kill some bees, but not enough to be significant. Available in Uruguay and Chile [BC, 1/05, p21].

COWEN VAPORIZER by Cowen Manufacturing Co. Inc., Parowan, UT. Available 2005 [BC, 10/05, p6].

HEILYSERR VAPORIZER - Heilyser Technology Ltd., 685 Dalkeith Ave. Sidney BC, V8L 5G7
Â• Model JB200 is powered by 12-volt car battery. COST - $65.00
Â• Model JB600 is for use w/ Styrofoam Hives. COST - $49.00
Â• Model JB700 requires a propane torch. COST - $67.00
Â• Model JB700D can treat 2 colonies at same time. COST - $168.00
[http://www.members.shaw.ca/orioleln/Vaporizer.htm].

VARROXR VAPORIZER - German made (Mellifera e.V.), distributed by Andermatt BIOCONTROL AG, Stahlermatten 6, CH-6146 Grossdietwil, Switzerland. World-wide patent pending.
Â• VX100 Vaporiser is powered by 12-volt car battery. COST - About $148.00 (120,00 Euro)
Â• VX101 Extension Cord, 7m. COST - About $47.00 (38,00 Euro)
Â• VX102 Mask (FFP 3 S/L) COST - 
Â• VX200 Oxalic Acid Tablets, 100ea. Available soon in blister packs. 
COST - About $25.00 (20,00 Euro)
[http://www.imkerei-technik.de/varrox_verdampfer.htm - Accessed 7/13/04].
Â• Hive entrance must be minimum of 0.409Â” (14mm) high and 3.169Â” (85mm) wide to introduce the VARROX vaporiser [http://www.mellifera.de/engl2.htm-Accessed 2/3/05].
Â• Uses 2 g OA dehydrate per 3 minute treatment. 
Â• Effectiveness - 97% [http:www.imkerei-technik.de/varrox_verdampfer.htm - Accessed 7/13/04].
96.8% (92-98%) [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
95% for single treatment [http://www.mellifera.de/engl2.htm-Accessed 2/05].

VARREXR EVAPORATOR - Consist of a heatable pan filled w/ oxalic acid dehydrate and connected by cable to a 12 volt car battery. Pan is pushed through hive entrance underneath brood combs. Similar to VarroxR Vaporizer [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Uses 2 g OA per 4 minute treatment [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Effectiveness - 90% (76-96%) [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].

ISENRINGR EVAPORATOR - A bent copper tube sealed at lower end. OC is filled into tube and tapped downward. Tube is inserted through hive entrance underneath brood combs. Lower part of tube containing OC is heated outside hive using a flame
[http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Uses 3 g OA per 3 minute treatment [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Effectiveness 88.6% (38%-96%) [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].

VARROGAZR EVAPORATOR - A vertical copper tube is filled w/ OA and heated w/ a flame, and a horizontal copper tube is inserted into hive. A small 1.5 v battery-powered ventilator is fixed to horizontal tube and blows sublimated OC into hive [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Uses 2.4 g of OA per 3 minute treatment [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Effectiveness - 92% (89-98%) [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].

KRUSOR EVAPORATOR - A special gas burner is connected directly to evaporator and sublimated OA is introduced into hive by means of a plastic tube inserted through entrance [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Uses 2.4 g OA per 3 minute treatment [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].
Â• Effectiveness - 29% (15-42%) Unsatisfactory treatment success is due to sublimated OA re-sublimates within plastic tube due to low temperature. Only a small part of OA reaches colony in form of an aerosol [http://www.apis.admin.ch/en/krankhei...dampfen_e.pdf].

REFERENCE: (Except as noted)
Review of Treatment Options for Control of Varroa in New Zealand. Dated Feb 2001. http://www.maf.govt.nz/biosecurity/p...nt-options.htm Â– Accessed 2/27/04.


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## shinbone (Jul 5, 2011)

Wow! That is a heck of a compilation of info on OA.


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