Varroa Mite Treatment: 10 Best Treatments for A Safe Hive

Varroa mites are a parasitic mites originally from Asia. They are small, 8-legged arthropods that are reddish and visible to the naked eye when mature. The mature mites mainly target adult bees by burrowing in between the exoskeleton plates and biting to feed on the bee's blood. Adult bees are strong enough to resist the mite, but the brood, especially the drones, are the real target of the varroa mite as the mite reproduces in the brood. The longer development time of the drone brood gives the varroa mite longer to breed.

The answer is yes; mites are a normal part of the beehive ecology. Beehives commonly have several types of mites, and most of them are harmless or are easy to manage. Bees are also resilient, and, over time, will adapt to mites and develop their resistances as a species. Beekeepers also adapt and learn ways of controlling harmful mite infestations. We can see this bee and beekeeper adaptation with tracheal mites in the past.

However, not all mites are as easy for the beehive ecologies to adapt to, and some, such as the varroa mite, can cause devastating effects during the learning process. The Varroa mite is an implant to the United States, and bees local to the US do not yet have a resistance to them. Varroa mite infestations are teaching beekeepers and bees alike to develop innovative varroa mite treatment options. Knowing which mites to treat and which to ignore is an essential skill that all new beekeepers must learn.

Varroa mites are the number one cause of the bee colony death. Most colonies will survive the first year with a massive mite infestation, but without varroa mite treatment, they will fall in the second year. Most colonies can manage low levels of mites, but over time, the numbers of mites grown until they overwhelm the balance of the hive. Even colonies which survive the experience of a heavy varroa mite infestation will be negatively affected.

Adverse effects for hives with varroa mite infestation are many. The overall health of the bee colony declines. Worker bees do not live as long. Colonies have a higher prevalence of viral outbreaks. An infestation will reduce bee strength and hive. At the worst levels of infestation, you will see effects such as deformities in wings, poor drone reproduction, and shorter drone life.

The hives we manage are artificial replications of the natural hives, and we can assume we need to do some management. All hives have varroa mites, and if they reproduce to a large enough number, you will see them. However, if you see the varroa mites, it may be too late for varroa mite treatment. Treating for mites is not done to eliminate mites but to maintain them at manageable levels.

That "manageable level" is very individual. It depends on your style of beekeeping and whether you want to spend more time in prevention or treatment. We recommend preventing overgrowth of varroa mites by carefully monitoring and treating before the mites are a problem. Anything under 5%, for example, which is defined as five mites seen in a colony of 100 bees, warrants watching and deciding which varroa mite treatment to use in the future, but you may hold off on treatment. Once you reach the 5% mark, it is time to treat.

There are several methods for testing the numbers of varroa mites. You will not count every bee and every mite in your colony. In fact, many of the most damaging mites are the younger ones which are invisibly causing damage to the brood. The most common methods for counting is the sticky mat method, the alcohol shake method, and the sugar shake method. We recommend you look these up and decide which is best for you, but any will provide a reasonably accurate estimate. When getting an estimate, remember that spring and early summer are when mite numbers will be highest.

All varroa mite treatments carry some risk to you, your bees, your honey, or your wax, which is why carefully choosing which varroa mite treatment to use is essential. Only you can decide which type of treatment is best for your hive. There are essentially three methods; mechanical, synthetic chemical, and natural methods.

Mechanical approaches are varied. Screened bottoms on your hive allow the mites to fall through but only affect a small number of the adults. Drone frames create an area where reproducing mites will target. These frames can then be removed, frozen, and replaced, killing the mites before they hatch. But if you do not pull them fast enough, you will end up with more mites than you would normally. You may also manually remove drones. Temperature regulation, such as heating hives, can help reduce mite reproduction but requires careful monitoring.

Synthetic chemicals, which you should rotate, kill mites but some mites have developed a resistance to synthetics and synthetics can infiltrate the honey and wax. Acids work great for killing mites and even work on mites developing in the brood. However, they sometimes result in the queen abandoning the hive, mainly if used at the wrong temperatures. Natural methods such as essential oils or hop guards may work well but can be messy and will affect the beekeeper, so prevent skin contact. Natural fumigants are available but are temperature sensitive and require frequent application.

Hopefully, as a new or experienced beekeeper, you are keeping a hive journal where you track the status of your hive, what works, and what doesn't. Keep a separate notebook or section for each hive so you know which is doing well and which hives require more of your attention. Each time you estimate the percentage of varroa mites, note the number. Each time you treat, indicate the method. Over time you will be able to track what works and what doesn't by observing trends in the numbers.