What oxalic acid is legal to use on bees?

Only EPA-registered products may be used in a hive in the US: EZ-OX (EPA Reg. No. 101743-2) and Api-Bioxal (EPA Reg. No. 73291-2). Hardware-store wood bleach is an unregistered pesticide and is illegal to use in a hive.

Why does Lorob Bees recommend EZ-OX?

EZ-OX is 97% oxalic acid dihydrate with no sugar carrier, so it burns clean in a vaporizer, it is labeled for use with honey supers on, it is made in Ohio by Mike's Bees, and it costs roughly a dime per 2-gram treatment.

Is Api-Bioxal the same as EZ-OX?

Both are EPA-registered oxalic acid dihydrate. Api-Bioxal's formulation includes glucose and silica excipients that beekeepers widely report leaving a caramelized residue in vaporizer chambers; EZ-OX does not.

Which Oxalic Acid to Use for Bees: EZ-OX vs Api-Bioxal vs Wood Bleach

Which Oxalic Acid Should You Use to Treat Bees? EZ-OX vs Api-Bioxal vs Wood Bleach

Oxalic acid is oxalic acid, chemically. Legally and practically, it is not. In the United States only an EPA-registered oxalic acid product may be used in a beehive, and among the registered products there are real differences in what's in the bag and how it behaves in a vaporizer. Here is what we use, what we sell, and why.

The short version

Use an EPA-registered product. We recommend EZ-OX: 97% oxalic acid dihydrate, no additives, EPA Reg. No. 101743-2, made by Mike's Bees, a veteran-owned company in Cambridge, Ohio, labeled for use with honey supers on, about $25 for 200 two-gram doses. It runs clean in every InstantVap oxalic acid vaporizer. Hardware-store "wood bleach" is illegal in a hive, full stop.

Why "EPA-Registered" Is the Whole Question

Oxalic acid used to kill varroa mites is a pesticide under federal law (FIFRA). It is legal to apply in a hive only if the product is EPA-registered for that use and you follow its label. The USDA bee lab's own FAQ says it plainly: wood bleach, chemical-supply oxalic acid and oxalic-acid-rich plants are "not registered products," and using them is a label violation subject to enforcement. In February 2024 the EPA went further and issued an advisory reminding beekeepers that using unregistered oxalic acid, amitraz, formic acid or thymol in hives violates FIFRA and can make the honey legally adulterated.

Beyond the law, registration is what earned oxalic acid its 2021 tolerance exemption and, later, label approval for use with honey supers on. That approval applies to the registered products. Wood bleach never got it.

The Registered Products, Compared

	EZ-OX	Api-Bioxal	Hardware-store oxalic acid / wood bleach
Legal in a US hive?	Yes: EPA Reg. No. 101743-2	Yes: EPA Reg. No. 73291-2	No. Unregistered pesticide use under FIFRA
Maker	Mike's Bees LLC, Cambridge, Ohio; veteran-owned, made in the USA	Chemicals Laif (Italy); marketed in the US by Véto-pharma	Various; industrial grade, not labeled for bees
What's in it	97.0% oxalic acid dihydrate, no added inerts to speak of	97.0% oxalic acid dihydrate on the US label; the EU formulation adds glucose and colloidal silica	Unknown purity, unknown contaminants, no label
Vaporizer residue	Burns clean; no sticky buildup in the chamber	Widely reported to leave a caramelized, charred residue that needs scraping, attributed to the sugar excipient	Varies; contaminants can leave deposits
Honey supers on	Allowed on label	Allowed on current label	Not applicable; illegal regardless
Label vaporizer dose	2–4 g per deep hive body	4 g per brood chamber	—
Forms	Powder (400 g, 2 lb, 5 lb); 1 g tablets (50–1,000 count)	Powder (35 g, 175 g, 350 g)	Powder
Cost per 2 g dose (powder)	About $0.12 (400 g at $24.95); about $0.10 in the 5 lb bucket	About $0.31 (350 g at about $55)	Cheap, and not worth a FIFRA violation or contaminated honey
Where sold	Lorob Bees and US bee suppliers	Most US bee suppliers	Hardware stores

Why We Recommend EZ-OX

We carried Api-Bioxal for years, and it works. We switched our own yards and our recommendation to EZ-OX for three practical reasons.

It runs clean. Api-Bioxal's formulation includes a sugar (glucose) carrier that beekeepers on both sides of the Atlantic report caramelizing in the vaporizer chamber into a black, charred deposit that has to be scraped out. In a vaporizer that cycles every 10 to 30 seconds, buildup in the chamber changes how the acid heats and how much reaches the hive. EZ-OX is essentially pure oxalic acid dihydrate; the bowl comes out clean, treatment after treatment, which matters for both the dose your bees receive and the life of your vaporizer.

It's made here by a beekeeper. EZ-OX is registered to and produced by Mike's Bees LLC in Cambridge, Ohio, a small veteran-owned company. When we need to ask a question about the label, we call a person who keeps bees.

It costs less. Roughly a dime per treatment in the bucket size. With oxalic acid, the acid is never the expensive part; there's no reason to pay three times as much for a product that gums up the chamber.

Powder or Tablets?

EZ-OX comes as loose powder and as pre-measured 1 g tablets. For the InstantVap we use the powder, because the adjustable plunger already gives you a repeatable 1–4 g dose and powder vaporizes evenly across the chamber. Tablets are convenient for dribble-free field kits and for beekeepers who don't want to handle a scoop, but check that your vaporizer's chamber and plunger are designed for them; some corded units don't handle tablets well.

How Much to Buy

At our recommended 2 g per brood box, a 400 g bag is about 200 single-deep treatments, and a 5 lb bucket is over 1,100. A backyard beekeeper with five double-deep hives running a summer cycle of six rounds plus the fall and late-winter broodless treatments uses roughly 160 g a year; a 400 g bag lasts two seasons if stored sealed and dry. Oxalic acid dihydrate keeps for years in a closed container away from moisture.

The Label Is the Law

Whatever product you use: read its label, wear the PPE it specifies (a NIOSH-approved respirator with acid-gas cartridges for vaporization), stay within its dose and application limits, and don't treat in an enclosed overwintering building. Our guide to using an oxalic acid vaporizer safely walks through all of it.

Tools We Use (and Recommend)

InstantVap Oxalic Acid Vaporizer: the cordless, battery-powered oxalic acid vaporizer we use in our own yards to keep mite loads low, which is the single best defense against every problem on this page. See the Lite, Compact, Original and Turbo. Lorob Bees is the primary US seller, with stateside customer service and a warranty we stand behind.
Mite Monitoring: the Easy-Check mite wash. How to do a wash in five minutes.
Oxalic Acid: EPA-registered EZ-OX.

Happy Beekeeping from the Lorob Bees Team

Written by Rob Pollock

Rob keeps bees in Baltimore, Maryland, and owns Lorob Bees. He built and repaired his own corded oxalic acid vaporizers for years before becoming the primary US seller of the InstantVap, and he still picks up the phone when one needs service. Oxalic acid vaporization is the thing he cares most about in beekeeping, because it's the treatment that keeps hives alive without breeding resistant mites. More about Lorob Bees.

Keep reading: Explore all Lorob Bees beekeeping guides — varroa, oxalic acid vaporization, pests and diseases, all in one place.

Sources

US EPA, EZ-OX pesticide product label, Mike's Bees LLC, EPA Reg. No. 101743-2, amended January 2026
US EPA, Api-Bioxal pesticide product label, EPA Reg. No. 73291-2, June 2025
US EPA, Bee Advisory: pesticides used to control varroa mites in beehives, February 2024
USDA-ARS Bee Research Laboratory, Oxalic Acid FAQs
Federal Register, Oxalic Acid; Exemption from the Requirement of a Tolerance, February 2021
Api-Bioxal Summary of Product Characteristics (EU), excipients: colloidal silica, glucose monohydrate
The Apiarist, Vaporising Api-Bioxal (residue observations)

General beekeeping information, not a substitute for the product label. Always read and follow the label of any product you use in a hive.