Api-Bioxal Oxalic Acid 350g

Api-Bioxal is EPA-registered oxalic acid dihydrate (97% OA, 3% inert) for varroa mite control in honey bee colonies. It can be applied three ways: vaporization using an oxalic acid vaporizer, as a dribble dissolved in 1:1 sugar syrup (5ml per occupied frame seam, max 50ml per colony), or as a spray on package bees.

Oxalic acid kills phoretic mites — those riding on adult bees — but does not penetrate capped brood cells. This is why it works best during periods of low or no brood, when the majority of mites are exposed on adult bees. A single treatment during a broodless period can eliminate the vast majority of the mite population.

When brood is present, the EPA label allows multiple vaporization treatments spaced several days apart to catch mites as they emerge with new bees. However, efficacy is significantly lower with brood present compared to treating during broodless conditions. Many beekeepers time their primary oxalic acid treatment for late fall or winter when brood rearing naturally slows — but broodless periods vary by year and region, so inspect before treating rather than relying on calendar dates.

Can be used with honey supers in place. Proper PPE is required: respirator, chemical-resistant gloves, and eye protection. Follow the current Api-Bioxal label for dosage rates — the 350g container treats a large number of hives depending on application method. Always read the label before use.