Formic Pro for Varroa Mite Control | How to Use & When to Treat

Warning: Do not use Formic Pro when temperatures steadily exceed 85°F. See use instructions below for details.

Varroa destructor mites can reproduce rapidly in a honey bee colony. A female mite enters a brood cell with a larva, and once the cell is capped, gives birth to male and female mites, who then mate with each other. All of these mites feed on the vulnerable, developing pupa sharing the cell with them and pass along any diseases and viruses that they may be carrying. As you can imagine, this can lead to exponential growth of varroa in colonies – one mite goes in and up to four come out to repeat the process all over again. Every colony has varroa mites – even if you can’t easily see them on your bees.

The main way a beekeeper can combat varroa mites is by keeping an eye on the number of mites in the hive and treating when the mite count exceeds a certain threshold. Choose from three different methods of counting your mites: mite monitoring boards; sugar roll; or an alcohol wash.

There are many treatment options out there, but a great spring through early fall option is Formic Pro.

What is Formic Pro?

Formic Pro is a polysaccharide gel strip treatment containing formic acid. There are two main benefits to using Formic Pro over other treatments: it is the only treatment that penetrates the cappings of brood cells to kill the mites reproducing within, and it can be used with honey supers on the hive. It has a two-year shelf life when properly stored (out of direct sunlight and in a dry location). Check the expiration date before using and do not use it if the product has expired.

NOD, the manufacturer of Formic Pro, claims an efficacy rate of 83-97% at killing varroa mites in a colony. In line with this stat, a 2019 study showed an 82-89% efficacy rate depending on which treatment method was used.

How do I use Formic Pro?

There are two Formic Pro treatment methods: laying one strip across the frames for 10 days, two consecutive times (for a total of 20 days), or laying two strips across the frames for 14 days. The 20-day treatment is intended to "knock down" mite levels while the 14-day treatment will virtually “knock out” the mite population.

Here are some helpful tips on using Formic Pro:

Formic Pro is designed to be used with standard Langstroth equipment or the equivalent. More information on placement in different hive setups (standard, all mediums, 8 frame) can be found below.
Colonies should consist of at least 10,000 bees (or six deep brood frames). Anything smaller than that should not be treated with Formic Pro.
Only use when temperatures range from 50-85°F (10-29.5°C). The greatest release of formic acid occurs within the first three days of application. If the outdoor temperatures are very warm but you have a 3 to 5 day window of 70-84°F (21-27°C) weather, you could apply the treatment. Keep in mind that there are risks to treating when it’s too hot, including excessive brood, bee, and queen loss.
All colonies in an apiary should be treated at the same time. It’s a well-known fact that bees from hives in close proximity to each other will “drift” between colonies, bringing their mites with them. It’s most efficacious to treat all at once to prevent a mite build-up later on.
Ventilation is key! Open up the hive entrance and remove all entrance reducers, mouse guards, and robbing screens. Entrances must be the full width of the hive. If you are using a screened bottom board, the mite monitoring board should be inserted to retain the vapors within the hive.
Do not feed sugar syrup, pollen supplement, or anything else during treatment.
Wait at least 24 hours after doing a full hive inspection to apply Formic Pro. This also applies to removing supers from the hive. Do not manipulate frames or alter the size of the hive at all when applying the treatment.
Wear PPE (Personal Protective Equipment) during application. Anyone who handles the Formic Pro pads should wear coveralls over a long-sleeved shirt, long pants, socks and shoes, acid resistant gloves (PVC, neoprene, or nitrile), and protective eyewear. Handle the pads downwind of you to avoid breathing in the vapors.
Do not remove the paper wrapping on the strips. This biodegradable wrap was designed to act as a wick to control the release of the formic acid over the 14- or 20-day treatment period.
Do not disturb the hive for a full 7 days after treatment. Do not remove the tray from the screened bottom board, do not feed, do not inspect, just stay away!
Increased bearding activity outside of the hive during treatment is normal. This is the bees’ way of controlling the vapor concentration within the hive.
Allow a minimum of one month between treatments. Do not treat in conjunction with other miticides.

Where do I place Formic Pro strips in my hive?

The Formic Pro strips should be placed in the middle of the brood nest. Regardless of whether you are running double deeps, all mediums, or 8 frame equipment, locate your hive’s brood nest at the time of treatment, and place the pad(s) as close to the middle of it as possible.

Generally, this means placing the pads in the following locations:

Traditional double deep hive configuration: Place between the two bottom deeps.
All-medium hive configuration: Place between the second and third mediums.

NOD tested the use of Formic Pro with polystyrene hives, such as Lyson and BeeMax, and found no indication that contact with formic acid causes any melting or chemical reaction. However, entrances on polystyrene hives may need to be modified to meet label requirements (at least ½ inch height entrance that spans the full width of the hive).

As a rule of thumb, adding an empty super to allow the bees to move away from the vapors may be helpful.

Check out NOD’s Formic Pro application video here.

Have you done your mite counts and discovered that they are higher than they should be? It might be time to apply Formic Pro and attack the issue before it grows into a more lethal problem.

Formic Pro Products

The Betterbee Product Corner is written by Quinn Korzeniecki, Betterbee’s Marketing Manager, and aims to explain the history and how-tos of products that Betterbee sells. If you have any ideas for future product overviews, please email them to newsletter@betterbee.com.