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Formic Acid Treatment for Bees-How to Use It

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 always easy.  Among many treatment options, the use of formic acid is popular. The product Formic Pro is one popular way to control varroa mites in bee colonies.  Is it the best one for your situation?  Here are the pros and cons of using Formic Pro for treatment of varroa mites.

Honey bee with varroa mite before formic acid treatment in hive image.

Formic Pro for Treatment of Varroa Mites

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. 

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Ants also contain formic acid in their bodies.  However, this natural acid, can be powerful too.  When it evaporates at warm room temperature the vapor becomes a fumigant that kills varroa mites. 

It is also reported to help with tracheal mite control. Both of these pests of honey bee colonies cause the death of many bees.

However, the trick is to have a vapor concentration that kills mites without harming the bees or other resources in the colony.

Formic acid pro pads on beehive control varroa mites image.

How to Use Formic Acid for Bees?

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 they kill the phoretic mites (those on the adult bees), the vapor also kills mites in the capped bee brood cells.

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

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 Interfere with Natural Treatments

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.

That temperature range, and don’t forget to add in high humidity too, lasts from about May until September in my area.  Although, I have not used the organic acids or thymol treatments in recent years, they are very effective and fast.

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.

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 and build back healthy hive members. 

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 a weak colony with a low population, choose a different treatment option for varroa mite control.

Colonies May Supersede Their Queen

Even though I have never experienced this in my hives, research shows that there is a higher percentage of queen replacement 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, honey comb is not affected with an accumulation of the acid.

Installing Formic Pro Acid Treatment in a Beehive

Blessed with a period of cool temperatures, my bees are receiving a treatment using Formic Acid Pro.  Colonies are active and foraging with daytime temperatures in the 70’s.

Materials Needed:

  • Formic Pro Mite Treatment
  • Grid board (to close screen bottom boards)
  • extra empty honey super (box)
  • Chemical resistant Gloves
  • Glasses – Long Sleeves etc
  • Bucket of water close by in case of accidents

Time needed: 30 minutes.

General instructions for using formic acid treatment in beehives

  1. 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.

  2. 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.

  3. 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.

  4. 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 the 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

2 Treatment Options Using Formic Pro Acid for Varroa Mites

As clearly outlined in the instructions, there are 2 methods of using formic acid pads in the hive. One method (as demonstrated here) uses 2 pads per hive.

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 using 1 pad at a time is useful for smaller colonies 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 well. Since that is where most of the mites reside, I opted for the stronger option.

Final Thoughts on Using Formic Pro Acid to Control Varroa Mites

Though I use Oxalic Acid Vaporization as my primary mite control method, there are times when other products are effective. Formic acid is a very effective treatment option for beekeepers living in regions where temperatures allow.

Some bee bearding during the first day or so is normal – but your bees should not completely leave the hive. Be sure to check your queen status a month after treatment. Hopefully this quick and easy formic acid treatment will get you on the road to healthier bees.

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