Back in an early 2019 ECWBA meeting the club distributed four different varroa mite control methods that had been used by club members and had successfully (in relative terms) controlled mites and limited winter losses. Another year has passed so we surveyed a number of club members who had implemented these recommendations and have tallied up the results.
Beekeepers A, B, and C used the mix of formic and oxalic acid treatments (Method 2 below) and roughly followed the recommended process. Beekeeper A had 88% hive and winter nuc survival. Beekeeper B had 88% hive and nuc survival. Beekeeper C had 85% hive and winter nuc survival.
Beekeepers D and E used the oxalic only treatments (Method 1 below) and roughly followed the recommended process. Beekeeper D had 100% survival of hives. Beekeeper E did not fare as well and had only about 20% survival. Critical to the use of oxalic acid is that it must be applied 3 times one week apart in order to be effective. Beekeeper E had reduced the 3 applications to only 2 and paid the price.
Beekeeper F used the formic acid and Apiguard treatment mix (Method 4 below). Beekeeper F had 64% winter hive survival. Digging in a little it turned out the Apiguard treatment is a 2 part treatment and must be done in warm weather. Due to cold weather the 2nd treatment did not get applied and Beekeeper F apparently paid the price.
No one apparently used Method 3 below.
It must be remembered that in pre-varroa/virus days normal winter survival ranged from 85 to 90%, so some losses can always be expected.
Every beekeeper marches to his own drummer. But it appears the 2019 ECWBA recommendations if followed will yield good winter survival. Shown below is a reprint of those recommendations.
VARROA TREATMENT RECOMMENDATIONS
At ECWBA meetings we frequently are asked “Tell me how to treat for mites”. Here are four recommended courses of action. We have run these four methods through Randy Oliver’s Varroa model and all four should control the mites sufficiently to get your hives through the year. This will prevent winter collapse. While the spring (April) treatments are not absolutely necessary they will lower the mite and virus levels during the spring buildup. Using any of these four methods will prevent a mite level buildup from year to year.
Method 1—Vaporized Oxalic Acid only
This should be the lowest cost method (ignoring the cost of the vaporizer) but is also the most labor intensive. Oxalic acid treatments are also known to be kinder to the queen. NOTE: Applying oxalic acid vapor while honey supers are on is not EPA approved.
-3 oxalic treatments a week apart beginning April 1st
-Repeat beginning June 1st
-Repeat beginning August 1st
-Repeat beginning October 1st
Method 2-Oxalic acid/formic acid mix
Rotating the oxalic and formic treatments hopefully avoids a buildup of tolerance in the mites. Formic acid is hard on queens, especially during extremely hot weather. Try to apply formic acid when the initial four days of the treatment period are cooler. Formic acid treatments are allowed while the honey supers are present. NOTE: Applying oxalic acid while honey supers are on is not approved by the EPA.
-2 oxalic treatments a week apart beginning April 1st
-A ½ strength Formic acid treatment
about June 1st. A full dose could be
used, but increases chances of losing a queen for not a big benefit.
-A full strength formic acid treatment about August 1st to 15th
-A single oxalic treatment about October 15th
Method 3-Oxalic acid/Apiguard mix
Rotating the oxalic and Apiguard treatments hopefully avoids a buildup of tolerance in the mites. Apiguard is not to be applied while your honey super are on. The thymol in Apiguard will be absorbed by the honey; making it inedible. NOTE: Applying oxalic acid while honey supers are on is not approved by the EPA.
-2 oxalic treatments a week apart beginning April 1st
-3 oxalic treatments a week apart beginning June 1st
-3 oxalic treatments a week apart beginning August 1st
-An Apiguard treatment beginning September 15th
Method 4-Formic acid/Apiguard mix
NOTE: Apiguard can not be applied while honey supers are in place. The thymol in Apiguard will contaminate the honey; making it inedible.
-1/2 formic acid about June 15th
-Full dose formic acid about August 15th
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