Welcome to our new blog – Ask our Beekeeper – Where we will post Q&A from monthly meetings or received via “Contact Us”

Oxalic Acid Dribble Method – January 20, 2020

This month in our Q&A session the discussions included candy board feeding and the use of Oxalic Acid to reduce varroa mites within the colony during the broodless times in winter.  Oxalic acid is only effective on the phoretic mites (those mites attached to adult worker bees).  When the hive is broodless, varroa can only survive by hitchhiking on the adult bees (in a phoretic stage).  For a queen right colony, this will generally occur around the winter solstice.  There are two ways currently prescribed for administering an oxalic acid treatment, either the dribble method or through vaporization.    Because the dribble method is simpler, requires nominal equipment and is safer for the beekeeper, anyone can apply this method to their hives.  For most hobbyist beekeeper a liter of solution is sufficient.  A liter of solution can treat up to 20 hives.  To mix the solution take 35 grams of oxalic acid (weigh on a gram scale) and apply to a mixture of 600ml of water to 600 grams of sugar.  Distilled water is recommended as “hard” water (water with high levels of calcium) will react with the oxalic acid.  Once the solution is mixed up it has a short shelf life, any leftover solution should be disposed of.  Fill a 60 mL syringe to 50mL and apply 5 mL (tsp) per a seam of bees.  A seam is the space between the frames. It is recommended not to use more than 50 mL per hive.   Take your time to ensure the solution goes down between the seams and is not spilled on the top bar, as the spilled solution on the top bar will have no effect on the mites.   The syringe can be purchased at most feed stores.  Visit this link to take you to the label and use guidelines for oxalic acid.  https://www.regulations.gov/document?D=EPA-HQ-OPP-2015-0043-0018.

This method can also be used on package bees once they have been hived.  For best results on applying to new packages or broodless hives during temperatures above 50 degrees (outside of winter) is to feed the bees 1:1 sugar solution prior to treating with the Oxalic Acid solution.

Please continue to increase your knowledge and stay up on the best method of application due to the continued evolution of varroa management as more research is completed.