Api-Bioxal Powder 4g Increase
Api-Bioxal powder now approved for vaporization at 4 grams per box
After satisfying the requirements of the regulators at EPA, the manufacturer of Api-Bioxal powder has been able to increase the legal dose when the powder is applied with a heat vaporizer. Beekeepers are now permitted to vaporize up to four grams per brood box when treating hives for varroa. In addition to the label update a few years ago that allowed beekeepers to treat with oxalic acid while honey supers are in place, it's becoming easier and easier to rely on oxalic acid to fight varroa mites in our hives.
Catching up to the science
In 2021, Professor Cameron Jack and his colleagues at the University of Florida published their research on oxalic acid dosing. They demonstrated that for colonies housed in single-deep hives, mite levels were controlled better when four grams of oxalic acid were vaporized compared to treatments with less oxalic acid. Despite this scientific research being published years ago, it has not been legal to apply these higher doses of oxalic acid vapor to hives until the EPA approved the label update.
The process
How does a change like this take place? After the scientists published their findings about the need for an increased dose, the manufacturer of the product still must submit the paperwork (and pay the fees) to get the EPA to consider the change. The EPA may require various information about the risks and benefits of allowing the label to be changed. All pesticides in the US are regulated by EPA, and the use of these products is always governed by the label printed on the product packaging. The standard, and very true, saying is the label is the law. This means that after EPA approves the label update, and after the various states have their say on the updated language, the new labels must actually be printed and put onto the packages for beekeepers to actually apply the product at a higher dose.
Older packages of Api-Bioxal powder, even though they contain the exact same powder found in the current product batch, cannot be applied at the new rate of 4 grams per brood chamber. Only the product carrying the new label can be applied at this newly approved dose. Betterbee has been shipping Api-Bioxal powder labeled with the higher dose for about a month now.
What does this mean for you and your bees?
It means that you can treat your bees with 4 (or 3, or 2, or 1) grams of oxalic acid per box when you vaporize the product. If your bees raise their brood in two deep brood boxes, the label allows application of 8 grams of oxalic acid per dose. Importantly, many vaporizers cannot easily hold 8 grams of powder. If yours cannot, you will either need to apply the dose in two batches, or else use a lower dose than the allowed maximum. Perhaps, in time, vaporizer manufacturers will catch up to the science and change their designs to accommodate larger doses of oxalic acid powder. Since you will be adding more oxalic acid to your vaporizer, be sure that your respirator mask fits snugly and be mindful of all safety requirements described on the label.
Beekeepers used to using 1 gram per box may be uncomfortable using this higher dose. Though new research is always being conducted to improve our knowledge of oxalic acid, this paper published in 2024 makes clear that colonies can tolerate even higher doses of oxalic acid than are currently allowed. In the study described in the paper, hives were treated with 5, 10, and 20 grams of oxalic acid. Only at the highest dose did they detect higher levels of bee death, and a reduced amount of brood. Even those impacts were relatively minor, and the reduced brood was not statistically significant. The researchers also looked for effects of these doses on queen performance and the quality of sperm stored in the queens bodies, and found no negative effects. The takeaway from this research is that applying oxalic acid powder at the newly approved higher dose, up to 8 grams per hive, should be safe for bees and deadly for varroa mites.Not for dribbling
Importantly, this increased dose is approved for vaporized Api-Bioxal powder only. It does not apply to the oxalic acid dribble mixture that can be prepared at home. If a beekeeper is interested in a higher dose of dribbled oxalic acid, they will enjoy the newly registered product Api-Bioxal RTU, a Ready-To-Use dribble solution with a higher concentration of oxalic acid. This new product will be available in the US in late 2025 and early 2026.
Want to learn more?
The next installment of our Interviews with Experts YouTube series is an interview between Betterbee Director of Research and Education Dr. David Peck, and Professor Cameron Jack from the University of Florida. Watch the whole interview to hear their discussion of this label update, and to learn more about how they contributed to getting the label to agree with the state-of-the-art science. [Embed video or insert link to YouTube video]
