Oxalic acid is an organic compound that occurs naturally in many foods. It is naturally found in the hive, but at concentrations to low to affect mites. By using OA as a vapor or dribble, you can raise the concentration to a lethal level for the mites without harming the bees. It is not recommended to use while honey supers are on because it allows the OA vapor to dissipate too much and will not be effective where it is needed, in the brood chamber.
Oxalic Acid has been found to maintain low mite counts on a healthy hive, but it will not reduce the amount of mites in a struggling, high mite load hive. It does not penetrate brood caps so it is best used on new packages, swarms, or broodless colonies.
Vaporizer Method: Use 1g OA per brood chamber (@ 3/4g for a 5F nuc, 1g for an 8/10F brood box 2g for a double deep or 3 mediums). Keep the hive closed up for 10 minutes after treatment. OA vapor has been proven to be very effective and because it is an acid, cannot build a resistance.
Dribble instructions: Dissolve 35 g OA into 1 L of 1:1 syrup, Dribble 5ml of the solution into each occupied area on the bees using a syringe, being careful not to dribble directly onto the queen. Do not use more than 50ml solution per hive. OA dribble has had mixed results of effectiveness. Partly due to user error and because of how it works in the hive.
Two common problems we commonly see. When vaporizing, people neglect to stuff a rag in the front entrance, put their debris tray in bottom or wait a full 10 mins. If the OA does not stay in the hive, it is not effective. With the dribble, we see it applied in cold weather. Moisture and bees do not mix. These are human errors and can be prevented. Keep those bees healthy.
PPE: Be sure to wear nitrile gloves, a quality respirator and safety glasses. Some also recommend long sleeves when using the dribble method.
*We recommend using a Varroa Easy Check for an accurate mite count before and after treating.
*Varroa Mites are a HUGE problem and the #1 natural cause of a colonies mortality. (#1 is actually the beekeeper). Please research Varroa and understand alllllll of the different treatment options and the mite it’s self by clicking The Honeybee Health Coalition non profit site
For the most recent information on the studies of Oxalic Acid being used to kill mites check out Randy Oliver’s site: Scientific Beekeeping