Formic Acid Treatment for Bees

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Among many treatment options, the use of formic acid for bees is one way to battle varroa mite infestations in our hives. The constant battle to control varroa mites in beehives is a struggle for beekeepers. When these pests invade our hives, we are faced with trying to kill an insect on an insect. That’s not easy.

Two strips of formic acid mite treatment strips on a hive.

Formic Pro is one form of formic acid treatment to control varroa mites. I use it in my hives but not during all of the season. Is formic acid the best varroa mite treatment option for your situation? That depends on several factors including your location. 

Formic Acid Kills Mites

Unlike many of the synthetic compounds created for mite control, formic acid is a simple organic acid. This natural component is found in many foods that we eat – even honey.

It is also friendly to insects in most cases. Ants contain formic acid in their bodies. However, this natural acid, can be powerful too. Just the same as when we use vinegar as a weed killer. These materials are natural but strong.

When formic acid evaporates at warm room temperature the vapor becomes a fumigant that kills varroa mites. It is also reported to help with tracheal mite control – another honey bee pest.

As with many natural substances, the strength or concentration is very important. In this case, the trick is to have a formic acid vapor concentration that kills mites without harming the bees or other resources in the colony.

Honey bee with varroa mite before formic acid treatment in hive and mite on bee larvae.

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How to Use Formic Acid in the Hive

In the U.S., the safest way to use formic acid to treat beehives is with a product made by NOD Apiary in Canada. They are sold under the names: Mite Away Quick Strips (MAQS) and Formic Pro.

These special cotton pads contain a formate ester and are placed in the hive. As the pad absorbs water vapor inside the hive, formic acid vapor forms and releases slowly. It is this vapor that kills varroa mites.

Formic Pro is the more recent product but the main difference between it and the earlier available MAQS seems to be that the shelf life is longer. If you buy either product, check the sell by date to ensure you are receiving fresh product.

The treatment pads are very effective at killing mites with a efficacy percent in the high 90’s. Not only do the vapors kill the phoretic mites (those on the adult bees), the vapor also kills mites in the capped bee brood cells (this is a big deal).

Pads are placed in the hive and don’t have to be removed. After the treatment period, they can be discarded or composted if the beekeeper wishes.

This makes the use of formic acid a quick and easy way to control varroa levels in your colonies.

Challenges of Using this Natural Treatment

Unfortunately, there is no perfect varroa mite treatment. At least, not that I have found. Any method has a risk of resulting in some loss. Beekeepers using formic acid need to be aware of these issues.

  • Temperature during treatment phase
  • Some bee and/or brood loss common
  • Possible queen supersedure

Summer Temperatures

Treating for mites in the middle of a hot Summer has always been challenging for us beekeepers living in the South.

The treatment instructions clearly caution against using formic acid for mite control when the daytime temps are above 85°F.

This can be an issue here in the South. That temperature range, and don’t forget to add in high humidity too, lasts from about May until September in my area. Finding a good temperature window is the issue.

However, you can-and I have, used formic acid during the Summer if you get a break in the heat with cooler temps for 3-4 days at the beginning of the treatment window.

If we are lucky enough to get a rainy weather pattern that lowers the daily highs – that is an opportunity.

Does Formic Pro Kill Bees?

The use of Formic Pro or any mite treatment can result in the loss of some bees and/or brood. The truth is that colonies infested with mites are unhealthy compared to those without mite infestations.

Treating a colony for mites causes stress on the bees. However, loosing a small number of bees that may already be weak is an acceptable risk for most beekeepers. Better to lose a few hundred and build back healthy hive numbers. 

It is common to see some brood being removed from the colony or perhaps a few more dead bees during the first days of treatment.

If you have an extremely weak colony with a low population, formic acid would not be the best choice for varroa mite control.

Some bee bearding during the first day or so is normal – but your bees should not completely leave the hive. After a few hours those clustering outside should return to the interior.

Colonies May Supersede Their Queen

Even though I have never experienced this in my hives, research shows that there is a higher percentage of problems – perhaps loss of the queen in some colonies treated with formic acid.

Of course, there are many reasons a colony may decide to make a new queen. With any mite treatment, and formic in particular – be sure to check your queen status a month after treatment.

Will Treatment Affect Honey in the Hive?

No, when used according to manufacturer recommendations, formic acid residues in honey are not raised to any appreciable level. Likewise, the beeswax comb is safe to be eaten – it is not affected with an accumulation of the acid.

2 Treatment Options Using Formic Pro

  • shorter 2 pad treatment
  • longer 1 pad at a time method

As clearly outlined in the instructions from the manufacturer, there are 2 methods of using formic acid pads in the hive. One method (as demonstrated in this article) uses 2 pads per hive at the same time.

The second method is slightly different. One pad is placed on the top bars of the brood box.10 days later, that pad is removed and another added in its place.

The method of using 1 pad at a time is useful for smaller colonies (weaker) or times when the temperature treatment window may be near the limit.

However, using 1 pad at a time will not kill the mites in the capped brood cells as efficiently. Since that is where most of the mites reside, I opt for the stronger option.

The Process

Basic steps of opening formic acid pouches and placing strip in beehive.

Full instructions are at the bottom of this post – but here are the basic steps of using formic acid for bees.

1. Wear all protective wear suggested by manufacturer. When you open the outer package, you will see two foil pouches inside. These hold your 2 treatment pads.

2. Have all needed materials handy – including thicker gloves (rubber beekeeping gloves). You will need to cut open the foil pouches (scissors). Hold pouches well away from your face – the scent is intense.

3. The pads holding formic acid are made of a paper-like substance. Separate them into 2 pads – if they are connected by the short ends (sometimes they are), cut them apart.

4. You will place one or two pads on the center of the brood box (on top of frames). This show the placement for the one pad option. Close up the hive and follow the rest of the instructions noted below.)

Follow Up

Always read the instructions provided by the manufacturer – things change!

Formic acid is a very effective treatment option for beekeepers living in regions where temperatures allow. Be sure to check your queen status a month after treatment (which you should always do anyway).

Also, check your varroa levels a few weeks after any treatment. You can not assume it worked – too many variables.

Though I use Oxalic Acid Vaporization as my primary mite control method, there are times when other products are effective. I generally use formic acid in my hives in the Fall when the temperatures moderate.


Using formic acid for varroa mite control can be part of a good plan for hive management. However, no treatment can save a hive that is dead on its feet.

You can’t wait too late or too much damage will be done. Monitor colony conditions and make sure to you know when to time mite treatments to get good end results.

Hopefully this quick and easy formic acid treatment will get you on the road to healthier bees.

Two formic pro mite treatment strips on a hive.

Formic Pro Acid Treatment for Bees

Charlotte Anderson @ Carolina Honeybees, LLC
Blessed with a period of cool temperatures, the beehives are ready for a treatment using Formic Acid Pro. Colonies are active and foraging with daytime temperatures in the 70’s.
4.34 from 3 votes

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Read my Disclosure.


  • Chemical resistant Gloves
  • safety glasses
  • extra empty honey super (box)


  • Formic Pro Mite Treatment
  • Grid board (to close screen bottom boards)
  • extra empty honey super box
  • Bucket of water close by (in case of accidents)


  • Read the Directions on the Formic Acid Package
    I know, I know. Sometimes we like to rush ahead and not read all the precautions on packages.
    But, you should follow the manufacturers directions for safety purposes and to get the best use out of the product.
    Each sealed plastic package contains 4 strips of Formic Pro. The standard treatment option is using 2 per hive. Therefore, a package is enough to treat 2 beehives.
    Package strip of formic pro for mites image.
  • Prepare safety gear – determine choice of layout
    After putting on the safety gear – as outlined on that package label you just read 🙂 , open the package. Inside you will find 2 sealed foil packages and an instruction pamphlet.
    Each sealed foil package contains 2 treatment strips. The enclosed instructions give you some options on how to lay the pads on your hives. Consult this because your needs may be different than mine!
    Sealed packages of formic acid inside envelope image.
  • Cut open treatment pouch
    Use scissors to cut open one of the foil treatment pouches. Stand way back, maybe hold your breath a bit – this stuff smells nasty. What does formic acid pads smell like?
    Some folks say it smells like vinegar – I say it just smells strong. The scent will dissipate in a minute.
    Your 2 pads may be joined a bit at one end, just separate them. But, don't unwrap the pads – they go into the hive just as they are.
    Formic pro pads in opened pouch image.
  • Prepare beehive for formic mite treatment
    After reading the instruction pamphlet that came in your Formic Pro, you can decide how to place the pads in your hive.
    In my situation, I am using 2 strips per hive – placed on the top bars of the bottom deep or hive body. (We are currently having a cool weather pattern).
    Light your smoker, puff a little white smoke at the hive entrance and under the top lid. Give it a minute to work.
    Disassemble the hive until you get down to the brood box. If you have a bit of burr comb on the top bars – scrape it off.
    Top bars in brood box of treatment hive image.
  • Place formic pro strips in hive
    Place the treatment strips of Formic Pro directly on the top bars of the lowest brood box. The instructions give you several options for placement. Use the one that best fits your hive situation.
    If the bees are in the way, gently smoke them down first. When they smell the formic pad – they will move out of the way!
    2 formic acid pro pads varroa mite treatment on hive image.
  • Reassemble Hive Components
    Restack the other boxes on your hive as they were. You do not need to use a shim (or spacer) between the boxes.
    A small gap may be noticeable at first but once everything is back together this should mesh together. As long as no bees can enter – you are okay.
    Small gap between beehive boxes with formic acid pro treatment in place image.
  • Add extra super box
    The manufacturer recommends adding an extra honey super to your hive. This gives the bees room to expand during the formic acid treatment and yet stay within the hive.
    As I had already added an empty honey super to my hives (for space), this was already done.
    Extra honey super on hive during mite treatment image.
  • Close Screen bottom – open front entrance
    To facilitate the movement of the formic acid vapor through the hive, there are 2 remaining tasks you must complete.
    If you are using screened bottom boards on your hives, use the grid board to close them during the 10 day treatment.
    And most importantly, open your hive entrance to the full width. Bees normally ventilate the hive through the front opening – a full open entrance is important when using formic acid for bees.
    Open front hive entrance during formic acid treatment image.


*Always read the manufacturers directions and closely follow their recommendations for safety and effective use.
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