Thymol Treatment for Varroa

Varroa mites were first detected in the United States around 1987. These visible parasitic mites followed by just three years the detection of microscopic mites that live in the trachea, or breathing tubes of the honey bee. The two species of mites decimated honey bee colonies. For a number of years it was common to not see a single honey bee in a stand of clover on a warm spring day when foraging bees should be abundant. Over the next couple of decades, tracheal mites became less of a killer of honey bees, but Varroa mites remained the most deadly pest of bees. Varroa mites puncture the exoskeleton of the honey bees and suck the bees’ blood, called hemolymph. The resulting wound exposes the bees to a number of viruses; several are suspected of being associated with Colony Collapse Disorder. In an attempt the stop the deaths of honey bee colonies, beekeepers relied upon chemical miticides to kill the parasitic mites. This was a most difficult task of attempting to kill a pest on a living insect without harming the insect. Each of the available miticides killed parasitic mites effectively for a while, and then strains of mites resistant to the chemicals replaced the original mites. Other strategies now being preferred include the use of “softer” agents, like organic acids and essential oils.

In the photo, I am inspecting a frame from the center of the brood nest. Here, bees are completing their last brood cycle of the year. In the center of the frame, a few capped cells hold pupae ready to emerge as adults. Around these capped cells are the empty cells of recently emerged bees. Farther out, a band of worker bees tend to uncapped honey. The outside edges of the frame contain honey capped with beeswax, the colony’s stored food for winter. Photographer and beekeeper, Brandon Dill, www.brandondillphotography.com, took this picture of me wearing protective gloves to apply thymol to treat a hive for mites.

--Richard