Treating vs. Not Treating Varroa Mites: The Role and Limitations of VSH Queens in Mite Control

What Happens if I Don’t Treat or Manage Varroa Mites? 

There are three common outcomes when you don’t treat or intervene, in any way, for Varroa. 

1. Your hive does fine since it didn’t have a very high mite population to begin with or you hit the lottery in beekeeping and your hives are resistant enough to mites to survive without treatment. This is very rare, but it can happen. If you don’t test to confirm this, the odds are certainly not in your favor that this will be the outcome. If I had to guess, I would say this would be the case with only a low percentage of hives in the US unless intentional and careful breeding programs are in place. There are always some beekeepers who say they’ve never treated for mites and their hives do fine; however, that is certainly not the norm. Another noteworthy point to mention is that, even if your hive survives with higher mite loads, you are spreading mites to all hives, both feral and managed, within a few-miles radius of your own beehive as some bees drift from hive to hive. This has become known as a mite bomb. 
2. Your hive dies quickly. This is a common outcome. Mites weaken a hive by feeding on fat body tissue and transmitting viruses to both adult and developing bees. They can quickly or slowly kill hives depending on the mite population and how healthy the hive was to begin with. If the population of mites increases rapidly, a hive can go from a deep box or two full of bees to a few frames of bees—or dead—in weeks. 
3. Your hive is greatly weakened and slowly dies over a period of months. This is the most common outcome. As the mite population steadily grows, the bees' immune systems are steadily weakened. They contract viruses and other diseases and eventually die. Your hive may look fine for a while, but when the weather turns cold in the winter, they will quickly dwindle and die. Many beekeepers think the hive is fine since the population was healthy over the summer, but as the bees begin to cluster as the weather cools, it becomes more apparent how weakened they are, resulting in the hive dying after a few cold fronts.

If I Don’t Control Varroa Mites, Will My Bees Become Naturally Resistant to Varroa? 

Unfortunately, no. Not controlling Varroa will spread it to your other hives and often all the hives within a few miles of your own bees. Not controlling Varroa in some manner is irresponsible as a beekeeper and inhumane to the bees. Just like we would never refuse to treat a pet for an infestation of fleas, mites, or ticks, especially if it could lead to their death, we should practice proper animal husbandry and take care of our bees as well. Breeding bees to become consistently resistant to mites has been the lifetime pursuit of many brilliant beekeepers and scientists, and the great news is that they are getting closer every year! I do think in the next five years we will see some great, commercially available options to largely control Varroa using genetics. 

What Are Varroa-Mite Resistant, or VSH, Bees? 

VSH, or Varroa-sensitive hygiene, bees are bred to remove capped pupae infested with Varroa mites from the hive. They are also better at grooming themselves and removing mites. While it may sound like you can buy these bees and not treat them for mites, that is unfortunately not the case yet. Many breeders claim their bees are resistant, but only a few are. But this is a rapidly evolving situation, and genetics are improving every year. I’m very optimistic that, in the next several years, we’ll see bees that require only one or two mild, safe treatments per year to control Varroa. However, right now, simply buying a commercially available queen and relying on genetics is generally not enough to control Varroa mites. They can, however, be one of many tools used in unison to help control the mites. 

If I Buy Mite-Resistant Bees, Do I Still Have to Treat? 

The majority of the time, yes—as mentioned before, you will still need to use some form of treatment. Bees bred to manage mites are perhaps, on average, 20–30% better at controlling mites. That number does increase each year! And there are local, specialized queen breeders who sell in small quantities and are having even better success. But, for widely available queens, it generally isn’t enough to not control Varroa mites and expect a hive to survive. My general advice to new beekeepers is to focus on learning beekeeping, treat for mites, then experiment once you are more experienced. It’s ideal to try a variety of breeds of queens over time and see what works best for you. There are many other very important factors when choosing queens, like honey production, gentleness, resistance to foulbroods, and so on. 

If I Don’t See Varroa Mites in My Hive, Should I Still Treat? 

This is a really common question. I hear from beekeepers all the time who say they don’t see mites in their hives, so they believe they don’t have an issue. We often see enlarged pictures of mites perched prominently on the backs of bees. However, it is quite rare to see mites on bees’ backs. They prefer to slide between the plates of a bee under her abdomen, making them very hard to see. Plus, the greatest damage mites do is to the capped brood, which you cannot see. The only way to properly determine your mite levels is to test for mites, then treat if needed.

For detailed information on how to test and treat, read, “Varroa Mites in Beekeeping: Effective Testing and Treatment Methods for Success.”