Varroa mites are the most deadly pest affecting western bees and can kill bee colonies in short periods of time. Monitoring and testing throughout the spring and summer is essential to keeping your hive healthy. If varroa mites are not properly treated throughout the beekeeping season, it can destroy an entire colony.
The parasitic mite attacks honey bees and brood. Varroa mites latch on to a bee and feed off its blood and belly fat. However, mites mainly affect developing brood as they feed and reproduce on larvae and pupae. Over time this causes malformation and weakening of honey bees as well as transmitting viruses.
What are the treatment options?
Here we will look at a few different treatments, but depending on your area some medications may not work as overtime varroa mites can develop resistance to treatments. It's important to follow your provincial apiculturist guidelines to understand the preferred treatments in your area (AB, BC, Honey Council). It is also important that you always follow suppliers treatment directions when applying treatments.
Here we will discuss three treatments: Apivar, Oxalic Acid and Formic Pro.
Apivar strips strips can be used in the spring and fall but only before honey supers are placed on and after honey supers are removed.
Treatment: Strips are placed in the brood chamber for 42 days minimum to a maximum of 56 days. The recommended dose is two strips per brood chamber. Strips must be removed 2 weeks before placing honey supers.
How it works: The bees walk on the strips and transfer the medication to each other in the hive, as they do this, the treatment transfers to the mites and paralyzes and kills varroa. The treatment is safe for bees, but again, not to be used during or within two weeks of the honey flow.
Formic Pro can only be used when temperatures are 10 °C to 29.5 °C. Because of the temperature requirements, this can be difficult to use in the early spring in northern climates.
Treatment: There are two treatment options: Option 1: Place two strips for 14 days. Option Two: Place first strip for 10 days then remove and replace with a second strip for an additional 10 days. Strips are laid across the tops of the brood frames. Safe to use during the honey flow! It is recommended that you wear safety equipment when applying the treatment.
How it works: Formic Pro works by penetrating the brood cap and kills the mites where they reproduce.
Oxalic Acid can be used in late fall to early spring. It cannot be used when brood is present or during the honey flow. While applying this treatment, protective clothing and a respirator is required to prevent contact with the vapours.
Treatment: Oxalic can be applied several ways, but here we will talk about using a vaporizer. The oxalic acid is placed according to instructions into the vaporizer, and once the vaporizer is heated you place it at the hive's entrance.
How it works: Oxalic acid vaporization sends tiny crystals into the air that attach to surfaces in the hive. It is thought that oxalic acid solution is carried through the hive by the bees and enter through the soft pads of the mite's feet and travels to the blood stream killing the mites.
When should you apply treatments?
Treatment recommendations differ in the spring and fall, and are dependant on your testing results. In Alberta, it is usually recommended to monitor varroa populations at least two to three times in the spring and early summer, and again before overwintering. It is also always recommended that you test and monitor your hives for mites before and after you treat. See our blog about testing. Again, check your provincial apiculturist websites for recommendations.
If you do washing test and you have 3 or more mites/100 bees (3%) or 10 mites/24 h/sticky board, you need to do a treatment. See our video on testing here.
Provincial apiculturists encourage beekeepers to create an Integrated Pest Management (IPM) plan that helps beekeepers monitor hives for pests and schedule treatments.
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If you are a beginner beekeeper, knowing if there are enough honey stores can be hard to figure out on your very first overwintered hive check. The simplest way to check if there are enough stores is to gently lift your hive from the bottom board (without disturbing the hive too much). If it is very light and easy to lift, you DO NOT have enough stores.