In the ever-buzzing world of beekeeping, the health of your beloved colony is paramount. Varroa mites are a common concern among beekeepers, and it's crucial to keep these tiny pests in check. In this blog post, I'll take you through my recent hive inspection and the steps I took to test for and treat varroa mites, including the use of Oxalic Acid Vapor (OAV) treatment. Let's dive into the nitty-gritty of beekeeping care.

Testing for Varroa Mites

Queen Gage's Royal Presence

During my recent inspection, I had the pleasure of swiftly spotting Queen Gage. Her majestic presence reaffirmed the status of the Gage hive as "queenright," setting a promising tone for the day.

Honeybee Hive Alcohol Wash Results with varroa mites circled
Gage Hive Alcohol Wash Results (23 mites!) Sep 28, 2023

The Mite Check

One of the most critical aspects of hive health is monitoring varroa mite infestations. To do this, I conducted an alcohol wash, a widely used method for testing mite levels. From a sample of 300 bees, the results were quite alarming. Gage hive had a staggering 23 mites, which equated to 7.67%—well above the 3% threshold for immediate treatment.

Taking Immediate Action

With the mite infestation rate surpassing the treatment threshold, I knew immediate action was imperative. Varroa mites can devastate a hive, weakening bees and potentially leading to colony collapse. I had no time to lose, so I proceeded with treatment.

Treating Hives with Oxalic Acid Vapor (OAV)

Understanding OAV Hive Treatment

Oxalic Acid Vapor (OAV) is a widely recognized method for treating varroa mites. It involves the vaporization of oxalic acid crystals within the hive, effectively eradicating the mites. The treatment targets the mites' phoretic stage, which is when they are attached to adult bees. The vapor cannot infiltrate the capped brood cells to eliminate mites in the cell.

Treatment Frequency

Determining the frequency of OAV treatment is crucial to effectively combat varroa mites. In this case, I treated both of my hives four times, spaced every five days. This scheduling ensures that the treatment covers a complete capped brood cycle of approximately 12 days, interrupting the mites' reproductive cycle.

Placing vaporizer with oxalic acid (OA) into hive entrance
Placing vaporizer with OA into Gracie hive entrance

Honey Supers: A Delicate Balance

A common question among beekeepers is whether you can leave honey supers on when treating with oxalic acid. This issue is nuanced, and it's important to understand the dynamics involved. According to the label instructions of Oxalic Acid (API-Bioxal™), the application of this treatment is not recommended when honey supers are present in the hive. Unless a modified label or a supplementary label is available for the product, beekeepers are advised not to use it when honey supers are in place. The USDA is actively working towards providing such a supplementary label to facilitate the use of this product with honey supers. You can find more information about this on the USDA website.

My Approach

In line with the label instructions for my Oxalic Acid, I opted to remove my honey supers. It's essential to follow the guidelines provided on your specific product label. I added 1/4 tablespoon of oxalic acid for every brood box in the hive and placed it inside the hive. Then I turned on the vaporizer for approximately 5 minutes, ensuring the effective dispersion of the treatment. Following the vaporization, I sealed the hive entrance for 10 minutes, allowing the vapor to permeate throughout the entire hive for maximum effectiveness.


Managing varroa mites is a key responsibility for beekeepers, and timely action is critical to preserving the health of your bee colony. Regular inspections, testing, and appropriate treatment methods like Oxalic Acid Vapor (OAV) are essential tools in the fight against these parasites. Remember, beekeeping is a labor of love, and your dedication to your hives ensures the well-being of these essential pollinators. Stay tuned for more beekeeping insights and experiences in our future blog posts.