MSU Extension Pollinators & Pollination

This article is designed to accompany the Honey Bee Health Coalition’s Varroa Management Guide’s information on varroa management products.

For a list of all current varroa mite treatments and their labels, see the United States Environmental Protection Agency (EPA)-registered Pesticide Products Approved for Use Against Varroa Mites in Bee Hives. EPA registrations and pesticide labels can change over time. Follow the label that is on your pesticide product.

EPA issued an Advisory on the Applicability of Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and Federal Food, Drug and Cosmetic Act (FFDCA) for Substances used to Control Varroa Mites in Beehives. The advisory intends to clarify which pesticide products and active ingredients are registered to control varroa mites and how the EPA views use of unregistered products.

Language is from the Honey Bee Health Coalition Varroa Management Guide, from the current label, and from each product manufacturer’s website; wording is identical or paraphrased. Always read and follow the full label when applying a product.

Recent varroa mite treatment products

Amiflex

Name: Amiflex (Véto-pharma)

Active Ingredient: Amitraz (formamidine acaracide/insecticide)

Formulation: A premixed gel applied with a dosing gun to a wooden strip designed for a quick knockdown of mites. The dosing gun measures out 3 milliliters of the product with each pull of the trigger.

Route of Exposure: Contact

Treatment Time / Use Frequency: Each application is two 3-milliliters doses per brood box.

• Low infestation: Apply once. Remove any remaining product at 7 days.
• High infestation: Apply twice:
  • Apply the first treatment.
  • 7 days after the first treatment, remove any remaining product and then apply the second treatment.
  • 7 days after the second treatment, remove any remaining product.

Time of Year:

• Population increase: Must remove product before adding supers.
• Population decrease: Apply following peak population once honey supers are removed.

Registrant-reported Effectiveness:

• Colonies with brood: A single treatment removes 56% of varroa on average. Two treatments removes an average of 81-83%.
• Colonies without brood: A single treatment removes 98-100% of varroa.

Conditions for Use: Apply 2 doses of 3 milliliters per brood box onto provided wooden strips. Place wooden strips in the center of the brood area or in the center of the bee cluster, leaving a minimum of one frame free of gel between two frames with gel. Scrape frames clear of all wax and propolis that could prevent the bees from coming into contact with the gel.

• Colony size: Do not use on sparsely populated and inactive colonies.
• Temperature: No temperature restriction.

Restrictions:

• Honey supers: Do not apply when honey supers are present. Remove any remaining product before adding supers.
• Do not use more than 4 times per year; rotate with other products including different active ingredients.
• Do not use during the honey flow.
• Do not apply Amiflex more than two times in a row before one honey flow.
• Apply when bees are actively foraging (i.e., do not apply in winter if bees do not forage then).

Advantages: Effective unless there is mite resistance.

Disadvantages: Residues may be detected in beeswax & honey. Some indications of mites developing resistance where amitraz has been used for several seasons.

Personal Protective Equipment: Applicators and other handlers must wear:

• Coveralls worn over long-sleeved shirt and long pants
• Socks and chemical-resistant footwear
• Waterproof or chemical-resistant gloves made of barrier laminate, butyl rubber, nitrile rubber, neoprene rubber, polyvinyl chloride (PVC), or vitron ≥ 14 millimeters
• Protective eyewear such as goggles, face shield, or safety glasses.

Considerations: Not available in every state. Currently, an applicator must have Restricted Use Pesticide certification to purchase and apply it. Check current restrictions before obtaining a permit.

EPA Pesticide Label: US EPA, Pesticide Product Label, AMIFLEX, 06/21/2024

EZ-OX

Name: EZ-OX (Mike’s Bees, LLC)

Active Ingredient: Oxalic acid dihydrate

Formulation: Product comes in powder or 1 gram tablets (tablets for sublimation only). Three options to apply: sugar syrup drip with syringe or drenching applicator, vaporization (fumigation or sublimation), and a mist application for caged (package) bees (spray with sugar syrup to engorge bees before applying).

Route of Exposure: Contact

Treatment Time / Use Frequency: Treatment most effective on broodless bees. Use no more than once on dormant (winter) bees but repeated uses during season considered less harmful to adult bees.

Time of Year:

• Early population increase and late population decrease: Use when brood rearing is reduced. May be used when honey supers are on colony provided specified on label.
• Dormant phase: Best used when brood not present.

Reported Effectiveness: 82 to 99% when brood not present (reported efficacy of oxalic acid products from the Honey Bee Health Coalition Varroa Management Guide, 8th Edition)

Conditions for Use:

• Sugar solution method (dribble): Mix 2 grams of EZ-OX oxalic acid powder into ¼ cup of 1:1 sugar syrup. With syringe trickle 5 milliliters of this solution directly onto the bees in each occupied bee space in each brood box; maximum 50 milliliters per colony of oxalic acid in sugar syrup.
• Vaporizer method: of 2 grams of EZ-OX (2 1-gram tablets, or 2 grams powder) per deep hive body (higher than Api-Bioxal). Follow label and vaporizer directions.

Restrictions:

• Honey supers: Approved for use when honey supers are in place.

Advantages: Cleanses adult bees of mites during broodless periods.

Disadvantages: Corrosive. Liquid dribble application may chill adult cluster. Single application not effective in colonies with much brood. Fumigation application is dangerous to applicator health - follow label precautionary directions for handling, including a well-fitting respirator; orientation upwind is recommended; the vapors quickly recrystallize.

Personal Protective Equipment:

Handlers and Applicators who apply product by the solution method must wear:

• Long-sleeved shirt and long pants
• Socks and shoes
• Chemical resistant gloves (barrier laminate, butyl rubber ≥ 14 millimeters, nitrile rubber ≥ 14 millimeters, neoprene rubber ≥ 14 millimeters, natural rubber ≥ 14 millimeters, polyethylene, polyvinyl chloride ≥ 14 millimeters, or Viton ≥ 14 millimeters.)
• Protective eyewear such as goggles
• Wear a minimum of a NIOSH-approved particulate filtering facepiece respirator with any N, R or P filter.

Handlers and Applicators who apply product by the vaporizer method must wear:

• Long-sleeved shirt and long pants
• Socks and shoes
• Chemical resistant gloves (barrier laminate, butyl rubber ≥ 14 millimeters, nitrile rubber ≥ 14 millimeters, neoprene rubber ≥ 14 millimeters, natural rubber ≥ 14 millimeters, polyethylene, polyvinyl chloride ≥ 14 millimeters, or Viton ≥ 14 millimeters.)
• Protective eyewear (goggles or face shield)
• Wear a minimum of a NIOSH-approved elastomeric half mask respirator with acid gas cartridges and combination N, R, or P filters.

Video: Watch the Honey Bee Health Coalition’s Oxalic Acid video

EPA Pesticide Label: US EPA, Pesticide Product Label, EZ-OX Tablets, 12/09/2024

VarroxSan

Name: VarroxSan (Vita Bee Health Limited)

Active Ingredient: Oxalic acid dihydrate

Formulation: Slow-release fiberboard strips

Route of Exposure: Contact

Treatment Time / Use Frequency: Use up to 4 strips per brood chamber per application (1 strip per 2.5 frames of bees). Leave strips in for a 42–56 day treatment period.

Time of Year: Early population increase, population peak, and population decrease

Registrant-reported Effectiveness: 92-98% with an average of 96%.

Conditions for Use:

• Fold each strip in half and hang over 1 frame in the brood area or bee cluster, slightly away from the comb surface. Maintain a distance of 2 frames between strips (i.e., place on frames in positions 2, 4, 6, 8). Reposition any strip not in contact with the bees to be closer to the cluster. Remove after a maximum of 56 days.
• Colony size: No conditions noted.
• Temperature: No restrictions, but more effective when the external temperature is about 15°C (60°F) or above and there is internal bee activity.

Restrictions:

• Honey supers: Approved for use when honey supers are in place, but treatment must be separated by at least one chamber to extract honey for human consumption.

Advantages: Has a knockdown and long-term effect on mite levels.

Disadvantages: Strips can be challenging to insert into the hive without disrupting the bees on the comb and hang properly between frames.

Personal Protective Equipment: Handlers and Applicators who apply product must wear:

• Long-sleeved shirt and long pants
• Socks and shoes
• Chemical resistant gloves (barrier laminate, butyl rubber ≥ 14 millimeters, nitrile rubber ≥ 14 millimeters, neoprene rubber ≥ 14 millimeters, natural rubber ≥ 14 millimeters, polyethylene, polyvinyl chloride ≥ 14 millimeters, or viton ≥ 14 millimeters.)
• Protective eyewear (goggles or face shield)
• Wear a minimum of a NIOSH-approved particulate filtering facepiece respirator with any N, R, or P filter.

Considerations: Not available in every state. Ensure that the strips are in the cluster of bees. Anticipate colony growth in spring and add an additional strip to account for the change in size. Avoid applying in periods of intense nectar flow when possible.

EPA Pesticide Label: US EPA, Pesticide Product Label, VarroxSan, 8/19/2024

Acknowledgements

This article was written collaboratively by the authors as part of the Managed Pollinator Protection Working Group, which is supported by the North Central IPM Center. A version of this article will be posted on multiple university websites.

This work is supported by the USDA National Institute of Food and Agriculture, Crop Protection and Pest Management Program through the North Central IPM Center (2022-70006-38001) and USDA ARS cooperative agreement 58-6066-9-046.

This work is supported by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] from the USDA National Institute of Food and Agriculture.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.