Using oxalic acid for varroa mite control

  • 25 May 2023 6:46 AM
    Reply # 13206467 on 3250081
    Anonymous wrote:

    With the new approval, what is your method for usage?

  • 30 Jun 2015 11:46 AM
    Reply # 3414602 on 3250081

    "The down side is that oxalic dribble in syrup is absorbed through the bees’ chitin exoskeleton and also ingested to some extent—both routes may cause some degree of temporary or permanent tissue damage. Some brood may be killed (Gregorc 2006) and brood development may be retarded for a couple of months (Hatjina 2005; Higes 1999). Some adult bee mortality may also take place, with foragers being more susceptible than nurse bees, with more mortality in cooler weather (Martín- Hernández 2004)."; Randy Oliver's article "The Learning Curve - Part 3: The Natural Miticides".

    Randy offers good advice and recommendations based on his research and methods for using Oxalic Acid Dihydrate as a treatment against Varroa. The only legal and accepted wording on this product, at this time, is the EPA No. 91266 dated 03/10/2015.

  • 30 Jun 2015 7:22 AM
    Reply # 3410254 on 3250081
    Allen Engle (Administrator)

    You said the Oxalic acid works on the exoskeletons of both the mites and the bees.  Any idea what it does?  Etch or thin (insect dehydrates) or inhibits formation? 

  • 29 Jun 2015 10:01 AM
    Reply # 3408702 on 3250081

    The method of application can be dependent on the time of year the beekeeper opts to apply the treatment. We in central Oregon would probably not open our hives in December for the dribble application but would instead use the vapor (fumigation) method.

    Always know the amount of brood within your colony before making application of this Varroa treatment. Also, exact formula measurement is important by the beekeeper or the colony could pay the consequence.

    Your formula conversion is correct. 

  • 29 Jun 2015 6:11 AM
    Reply # 3408408 on 3250081
    Allen Engle (Administrator)

    Thanks for the link.  I've been looking for an official description/authorization.  The way I read it the strength of the solution is 35 grams per liter.  Only 50 ml of this solution per hive is recommended, which would be 1.75 g per hive. (35g / 1000ml/liter  * 50 ml).

    I wonder about the effectiveness between the two application methods (drizzle vs vapor)

    Also, this authorization is only for Varroa and not for tracheal mites.  Interesting. 

  • 28 Jun 2015 6:05 PM
    Reply # 3408078 on 3250081 

    This link will take you to a readable copy of the official Oxalic Acid Dihydrate precautionary statements and directions for use. Brushy Mountain Beekeeping Supply is the only authorized supplier of this Varroa treatment for the USA beekeepers. 

    An oxalic acid application for Varroa mite control works on the exoskeleton of the mite and as well as the honey bee. For this reason alone, it is important that no more than 35 g of Oxalic Acid  Dihydrate (with distilled water) be used per colony. 

    As a side note, Ruhl Bee Supply was just bought by Brushy Mountain. The Ruhl store will be relocated to Wilsonville. Watch for the Grand Opening of...

  • 12 Mar 2015 7:58 AM
    Message # 3250081
    Deleted user

    With the new approval, what is your method for usage?


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