The Dangers of Varroa Mites for Beekeepers

The Dangers of Varroa Mites for Beekeepers

As beekeepers, we need to understand the dangers of Varroa mites and how they can affect our hives. Unfortunately, these parasitic creatures have become increasingly resistant to treatments over time, making them a formidable foe in our efforts to protect our colonies. In this blog post, we'll discuss the specifics of this particular pest problem and offer practical steps that beekeepers can take to minimize any potential damage caused by these mites. With that being said - let's dive into the details!

Macro shot of Varroa destructor (varroa mites) on honeybee host
Source: Agricultural Research Service, the research agency of the United States Department of Agriculture.

What are Varroa Mites, and what do they do to bees?

The varroa mite is a small arachnid parasite that infests honeybee colonies, leading to colony collapse and the eventual death of the hive. This pest has been known to cause significant losses in beekeeping operations throughout the United States and other parts of the world.

Varroa mites are external parasites that feed on hemolymph, or bee blood, from adult and immature bees. Mites can also transmit viruses between host bees, weakening the bee population. Adult mites measure about 1mm in length and are reddish-brown. They have eight legs and two compound eyes. The female mites reproduce by laying eggs inside sealed brood cells within the colony (capped brood). When larvae emerge from these cells, they become infected with varroa mites as immature nymphs hatch from the eggs and attach to the newly formed bees.

Varroa mite infestations occur when too many colonies of honeybees become infected with this pest. As varroa populations increase, weakened bees struggle for survival against disease, malnutrition, predation, weather events, and other problems common to honeybee colonies. Beekeepers may notice symptoms such as deformed wings or an increase in dead bees around their hives before they realize they have a problem with a varroa mite infestation. If left untreated, colonies will eventually succumb to this invasive species, which can mean severe losses in honey production.

How can beekeepers protect their hives from Varroa Mites?

Fortunately, there are effective treatments available for controlling varroa mite infestations. Various methods, from natural treatments that are plant-derived to chemical pesticide treatments inside or outside the hive entrance, so that bees coming into contact with them will receive effective doses of pesticide when entering or leaving their hive. Other nonchemical treatments include mating disruption products that interfere with male reproductive behavior or sprinkling the bees with powdered sugar to encourage them to "shake it off."

Are there any steps that can be taken to eradicate Varroa Mites from a hive once they have been detected?

To prevent a significant outbreak, beekeepers must routinely monitor their colonies for signs of varroa infestations and promptly address situations where detected. It is also wise for beekeepers to practice good Integrated Pest Management (IPM) techniques such as rotating out old frames of comb every other year, which can help reduce buildups of Varroa populations within colonies over time while giving honeybees a better chance at survival against this parasitic pest species. We found that installing screened bottom boards into the hive so that mites dropping off dying bees fall through mesh screens instead of re-entering hives where they can reinfest new host bees has also been helpful.

What is the future of beekeeping in light of the increasing threat posed by Varroa Mites?

Unfortunately, there is no one-size-fits-all solution to controlling varroa infestations; instead, careful monitoring and implementation of specific control strategies are needed if they are to be successfully managed. Beekeepers must stay informed on the latest research findings to develop an effective action plan.

One method of controlling varroa mite populations is using chemical treatments such as miticides or formic acid pads. However, these costly treatments may harm beneficial organisms other than varroa mites. Therefore, more sustainable alternatives, such as integrated pest management (IPM) systems, have been developed in recent years. IPM systems combine various techniques, such as selective breeding for resistance, physical removal of infested combs, and proper sanitation practices to minimize varroa populations while protecting beneficial insects like bees from harm caused by harsh chemicals or other forms of treatment.

Other advancements in beekeeping technology, such as better hive designs, have also proven helpful in controlling varroa infestations. Hive designs with improved ventilation reduce humidity levels inside the hive, which makes it less attractive for varroa reproduction and survival; this includes those made with plastic materials rather than traditional wood frames, which tend to retain moisture. Furthermore, new advancements in artificial intelligence have enabled researchers to create automated monitoring systems that help identify varroa infestations before they get out of hand so that preventive measures can be taken early on before it’s too late; some scientific studies even suggest that this kind of technology could even help keep colonies healthier overall!

While there is no single silver bullet solution to preventing Varroa Mite infestations, proactive management strategies combined with technological advances will play an integral role in protecting our honeybee populations against this deadly parasite from now on into the future!

Prevention and treatment options abound, but deciding the best for your hives merits some research.

The following suggestions include both natural and chemical treatments:

  • In a local beekeeping class, I learned to apply a light dusting of powdered sugar on hives to prevent mite infestation. When you apply powdered sugar to bees, they will “shake it off,” and the mite goes with it. This technique may negatively impact egg production, and this probably isn’t the best technique.
  • Among chemical alternatives is Thymol, a thyme derivative. We grow Thyme around our hives and in other parts of the farm where the bees feed on lavender. Miteaway quick strips contain Thymol for use in the summer months as long as temperatures are below 84 degrees F.
  • Apiguard is a more concentrated pesticide for use during the winter months. Since Thymol is a thyme derivative, I decided to also try planting a "fence" of thyme around my hives. Thyme blooms heavily in the summer, and the bees love it, so it was worth a shot!

Integrated pest management (IPM) is the practice of controlling honey bee pests with the minimal use of chemicals.

  • Detecting Varroa Mites through Drone Comb. Bee suppliers sell a special “drone” foundation that has larger hexagons imprinted on the sheet. The bees will only build drone comb on these sheets. That’s useful because Varroa mites prefer drone brood over worker brood.
  • By placing a frame of drone comb in each of your hives, you can “capture” and remove many mites. Once the drone cells are capped, remove the frame and place it overnight in your freezer. This will kill the drone brood and also the mites that have invaded the cells.
  • Then, uncap the cells and place the frame (with the dead drone brood and dead mites back in the hive. The bees will clean it out (removing the dead drone brood and mites). The cells will get filled again, and you repeat the process.

Treating Varroa mites

I am a slow learner. I was always really against using any sort of chemical treatments in the hives until I decided to learn more about what each treatment does for the bees and their health. Mites are the issue. So, they need to be eradicated.

In a conversation with the man that I buy my bees from in early July this year, he said to me, "Get your mite-away strips on before mid-August" I said, "I usually do that around the end of October". He replied, "If you wait until the end of October, then I will see you again in April for new bees".

A light went off.

I ordered the mite-away strips and we treated the bees in August, We now do this treatment in June after the first honey harvest. Mite-away Quick Strips are made with Formic Acid. Formic acid is a compound that is naturally found in the hive and is the bi-product of insect bites and stings. It's proven to be effective against varroa mites. This product should not be used in temperatures over 85 degrees and the treatment stays in the hive for only 5 days.

We were lucky this August; it's usually very hot here in the south, we had 5 days that were about 82 degrees and the process seemed to work. We saw lots and lots of dead varroa mites after the treatment. Please don't ask me to count. I can't even keep pace with our inventory. The thought of sitting in the bee yard and counting tiny black dots on a whiteboard late in the day is not going to happen.

The next step in treating the bees involves vaporizing oxalic acid.

Oxalic acid is an organic compound in leafy greens. The way it works is to treat every 5-7 days or as our schedules permit for three cycles. Here is what I've learned about treating varroa mites with a vaporizer and oxalic acid: I lost almost every single hive two years in a row using this technique. I will not do this again. I think it's harmful to both humans and bees. Fumigating bees is not for me. I like using the formic acid pads and the miteaway pads and by adding the screened bottom board, so far so good.

I updated this blog in late January 2023

Last season we had 90 days in a row over 90 degrees and I am of the belief that heat helps with varroa. I understand that there has been a great deal of research into adding heat to hives for varroa management. More on this as I learn more.

Here are other resources to learn more:

Image source: Agricultural Research Service, the research agency of the United States Department of Agriculture.