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The Varroa Destructor

Treating for Varroa Mites…

If you to stay in beekeeping for any length of time then, you will come across the most invasive pests of the honeybee colony- the dreaded Varroa destructor. This pesky insect is often the downfall of many hives, even when the beekeeper performs proper Integrated Pest Management (IPM), because there seems to be no cure for the Varroa as of yet.. During the past and critical first year of beekeeping, I had little trouble with these pests. However, 2018 is a different story because the hives are thriving and thousands of foragers are out and about every day the weather permits and they are here. Varroa mites can invade any hive and August is the time to check and start treating for these little red pests. They are more numerous than any “tick on a dog, but when the beekeeper has 50,000 and more honeybees in a single “double-deep” box hive it is understandable. The problem is they are akin to fleas, ticks, and mosquitos as they cannot be eliminated, just managed to the best of beekeeper’s ability and finances.

2018 Varroa Stats

Compare these 2018 statistics to those from the 2019 season above. This season contained Carnolian and Italian honeybees. Note: September 1, 2018 had the highest consecration of varroa, at 2.67% for hive H2L and this is still below the 3% threshold that determines if treatment is necessary.

Subsequently, all the hives received an ApiVar treatment from September 1 to October 15 and each hive showed enormous amounts of varroa. Some counts were as high a 216 varroa in a single “sticky board” hive inspection conducted 3 days after treatments began. Regardless of these treatments, by March 2019, all five hives had died.

Thus, logic indicates that under normal circumstances hives H5ZT-C and H6ZT-I should have survived the 2018 season, because they showed the lowest infestation of varroa. The common denominator in the death of all hives seems to point towards a bad lot of ApiVar for it is the only common link between all the hives. It’s difficult to proven without the lot number and old strips to examine, however, the following article below helps to clarify that diseases like AFB or EFB had no part in the demise of the apiary either.

Do not be fooled by thinking that your honeybees are not going to get infested with the deadly parasite called the “Varroa Destructor.” Even beekeepers who monitor and treat for this unwanted pest have the unpleasant experience of finding “dead-outs” in the apiary. Two weeks after this Api-Var treatment was completed I had less than five mites showing up on the “sticky boards” of any hive. Unfortunately, the Varroa had already infected a majority of the bees in each hive and by January 2019 four of the five hives died. These Varroa depleted the body fats of the bees and they never fully recovered because, their immune system was compromised and these hives froze to death during December 18, 2018 and January 2, 2019.

Varroa destructor on thumbnail.I have learned this truth from my honeybees, “The stronger the queen is genetically, the better chances the hive will survive a cold harsh winter.” My research and documentation indicates that a genetically strong queen produces more bees who in turn produce more honey, and who are able to “resist,” not eliminate the Varroa destructor. The remaining hive has a 21-month old queen from 2017, who has out-performed all the other hives in bee numbers and honey production. Knowing this fact, I am not a beekeeper who “executes” the queen every year- as son beekeepers do-, and just to get a new queen.

As long as the queen is producing positive results in the areas of mite resistance, bee numbers, and honey production she stays in the hive. I believe that queens should be replaced only when: 1) she produces few bees, 2) she produces bees with a bad temperament, or 3) the bees she produces are unable to resist the Varroa destructor.

Understanding the root cause of dead-outs…

Varroa destructor

It is no secret to the beekeeper that regardless how hard you try to  manage and protect your honeybees that are going to be “varroa mites” in the hive. Treating all the hives in early spring with oxalic acid and in the late summer with ApiVar helped, however it did not “cure” the problem. Personally, I expected to lose twenty to thirty percent of the apiary but, I never expected that all the hives would die in the same manner and over night. After checking my apiary inspection data in the HiveSmartHQ app, I discovered some interesting facts revealed over seventy-five inspections during the 2018 -19 season:

After the apiary died I sent two hive samples to the USDA Testing Facility in Beltsville, Maryland for a “free” analysis of any disease which may have contributed to Colony Collapse Disorder (CCD) and final dead-outs. The reports indicated no American or European foul-brood diseases and that the colonies died from affects of the varroa destructor. Hence, the hives died from one or more of the various disease which the varroa destructor carries. This points towards the reality that once a majority of the honeybees within the hive are infested with whatever disease the varroa are carrying, the hive is essentially doomed for death.

2019 Varroa Stats

The results below are from various inspections conducted between April and October of the 2019 season. Each sample testing is from a “sugar shake” test and the results are recorded in the HiveSmartHQ app on my iPad. For information, the threshold for Varroa is to maintain less than 3% infestation. More information on this destructor of honeybees is listed on page 8 of the following file- https://honeybeehealthcoalition.org/wp-content/uploads/2015/08/HBHC-Guide_Varroa-Interactive-PDF.pdf. In the chart below, the highest concentration of these destructors existed on September 23rd  at 6.67% and this is well above the average acceptable limit. Thus, treatment was required. Note: Hive ZT7 [T] in the chart is Italian honeybees and hive H10i is a split from ZT7 [T]. Thus, four hives are Saskatraz and two are Italian honeybees.

Varroa mite on bee larvae

Varroa destructor

Current Varroa Destructor statistics for 2019 season (3% is the threshold for treatment)

The simple sugar shake way to test for varroa mites.