What Is a Varroa Mite?
Varroa destructor, or the Varroa mite, is an arachnid that parasitizes honey bees such as Apis cerana and Apis mellifera.
Varroa mites are members of the family Varroidae, which belongs to the genus Varroa. Varroidae are part of the order Mesostigmata, which belongs to the class Arachnida.[1]
Varroa mites get their genus name from Marcus Terentius Varro, a Roman beekeeper. Varroa mites species name, destructor, comes from the destruction they cause in honey bee colonies.
Varroa mites only reproduce within honey bee colonies. They crawl onto the bodies of bees and consume their fat and haemolymph. It is possible for Varroa mites to transmit five or more bee viruses at the same time.
Varroa mites have the greatest economic impact on the beekeeping industry of all parasites. Both for economic reasons and to protect pollinators, it is essential to control Varroa mite infestations. [2]
What Do Varroa Mites Do to a Colony?
Varroa mites can wreak havoc on a honeybee colony. In spite of the fact that most bees that are infested with Varroa mites live to adulthood, the effects of Varroa mites often disable them, making them unable to carry out their duties to maintain the colony.
Varroa mites decrease bees’ growth by feeding on their haemolymph. Consequently, bees infected with Varroa mites tend to be smaller and lighter than healthy bees. In addition, worker bees infested with Varroa mites live shorter lives than healthy worker bees.
Additionally, bees infested with Varroa mites may have difficulty navigating, meaning that they get lost in the world and cannot locate their way back to the colony. A lack of worker bees is dangerous for bees, since they rely on them to survive. [3]
As another means of destroying honey bee colonies, Varroa mites transmit viruses, such as the deformed wing virus, which causes the bees’ wings to become shriveled up or too small to fly.
How to Identify a Varroa Mite Infestation
When it comes to identifying Varroa mite infestations, it is best to test all of the beekeeper’s colonies on a regular basis. An infestation of Varroa mites can be identified by some general signs.
Beekeepers may observe shriveled or shrunken wings when their bees have been infested with Varroa mites. These bees have a deformed wing virus, transmitted by Varroa mites.
The loss of worker populations is another indicator of the presence of Varroa mites, as the bees die or become lost due to difficulty navigating back to the hive following a Varroa infestation.
Moreover, worker bees and drones that appear smaller than usual may be indicative of an infestation of Varroa mites.
Regular testing is the best method for identifying Varroa mite infestations. For the identification of Varroa mite infestations, several methods of testing are available.
While some methods of testing work best when brood cells are full during the spring and summer, others are best utilized during the fall when there is no brood.
Alcohol Washing
The use of alcohol washing is an effective method for testing adult honey bees for the presence of Varroa mites. As this method does not test the brood for infestation, it is best used when there is little brood in the hive.
Unfortunately, alcohol washing kills bees in the process, resulting in the loss of approximately 300 bees during the process.
An alcohol wash can be performed by filling a jar approximately halfway with rubbing alcohol. The bees should be smoked to calm them, and then half a cup of bees should be placed in the jar. The jar should then be shaken for twenty seconds in order to remove all mites from the body of the bees.
After removing the lid from the jar, the contents should be poured into a bucket of water, using a sieve to catch the bees. Bees will remain in the bucket of water while the mites pass through the sieve, allowing the beekeeper to count them once they land in the bucket.
Sugar Shaking
It is also possible to test adult bees for Varroa mites using sugar shaking, which has the advantage of not killing any bees in the process. Sugar shaking requires only confectioner’s sugar, a jar, and half a cup of calmed bees.
For sugar shaking, beekeepers can simply combine bees and a tablespoon of sugar in a jar. To allow the sugar and mites to be shaken out of the jar once the process is complete, the lid of the jar must have 3-5 millimeter holes.
In order to catch the sugar and mites, the bees and sugar are shaken for at least five minutes in the jar and then transferred to a container of water.
The mites can be seen floating on the surface of the water after the sugar has dissolved in the container of water.
Drone Uncapping
Drone uncapping is an excellent method of testing for Varroa mite infestation when there are large numbers of capped brood cells present in the colony. It is advisable to uncap drones near the end of the summer when the queen is producing unfertilized eggs that will develop into drones.
Drone capping has the disadvantage of killing all uncapped drone broods. There are, however, usually more drones produced than the colony needs, so it should not result in severe damage to the colony.
Drone uncapping typically involves removing three brood frames from the hive and uncapping the brood cells with a capping scratcher. During this process, the undeveloped bees are pulled out of their brood cells, which can be observed on the surface of the larvae and pupae and counted.
What Is the Best Varroa Mite Treatment?
In order to ensure that the Varroa mites do not develop resistance to any particular treatment method, a variety of treatment methods is the best method of treating bees for infestation with Varroa mites.
Therefore, there is no perfect treatment for Varroa mites, but rather several effective treatments that can be rotated.
Chemicals
There are various chemicals and miticides used to control Varroa mite populations. The chemicals and miticides are available in foil packs or strips that can be placed in the hive to control Varroa mites.
Apiguard is an excellent option for those looking for a natural chemical because it is derived from the thyme plant. In addition to being easy to use, Apiguard poses no danger to bees or humans when compared to other chemicals[6].
Comb Trapping
Comb trapping is another method of controlling Varroa mites without the use of harsh chemicals.
Drone combs are placed in the hive, which have larger hexagonal shapes imprinted on them. Due to the larger size of the cells, the bees will build a comb on this frame and lay only drone brood in it.
Varroa mites prefer to reproduce in drone brood, so they are most often found in this particular brood frame.
If this frame is removed and frozen, then the Varroa mites that are present will be killed. The drone brood in the comb will be destroyed by this method, but most colonies produce more drones than are necessary.
Sugar Dusting
Another natural way to control Varroa mites is sugar dusting. Essentially, the bees and capped brood cells are dusted with sugar, which causes the Varroa mites to drop off of the bees. Sugar dusting does not kill bees.
It is recommended that beekeepers smoke the beehive before performing sugar dusting in order to calm the bees. As well, it is essential not to dust open brood cells with sugar, and to only apply sugar to capped brood cells.
Types of Varroa Mite Treatments
| Active Ingredient | Dosage | Method of Application | |
|---|---|---|---|
| Apistan Strips | Fluvalinate | One strip for every five frames.[4] | Hang one strip of Apistan per five frames of hive. |
| Apiguard | Thymol | Two foil packs two weeks apart. | Place one foil pack in the hive, and place another one two weeks later. |
| Mite Away Quick Strips | Formic Acid | One strip in the brood box for ten days.[5] | Place a strip near the top of the brood box for ten days. |
| Comb Trapping | None | N/A | Place special drone brood boards into the hive. These have extra large hexagonal bases which the honey bees will build their drone brood cells on top of. The Varroa mites will mostly reproduce within these drone brood cells, which can then be removed and frozen to kill the Varroa mites. This can be repeated as many times as necessary to reduce Varroa mite populations. |
| Sugar Dusting | None | A few tablespoons of confectioner’s sugar | Dust the adult bees and closed brood cells with confectioner’s sugar, which will force the Varroa mites to fall off of them. |
What Is the Best Time to Treat Varroa Mites?
Varroa mite infestations should be treated at least twice a year, early in the spring and just before the fall.
The purpose of varroa mite treatments in spring is to prevent mite populations from growing at a time when the bee colony is still establishing itself.
In the fall, treatment for varroa mites focuses on reducing mite populations before the reduced colony overwinters.
Can Varroa Mite Treatment Be Used During Honey Flow?
There are some Varroa mite treatments that cannot be used during honey flow. There are some Varroa mite treatments that contain toxins that are capable of contaminating honey and beeswax in the hive, making them inedible to humans.
How Many Times A Year Should Beekeepers Carry Out Varroa Mite Treatments?
Varroa mite treatments should be performed by beekeepers at least twice a year, in the spring and in the late summer.
In the event of a severe infestation, it may be necessary to perform Varroa mite treatments even more frequently. It is important to keep in mind that even more natural methods of mite control can cause stress within a hive, so it is also important not to treat it too frequently.
How to Prevent Varroa Mites
Knowing that Varroa mites are present, as well as how many mites are present, is the first step in preventing them. The best way to achieve this is to regularly test the brood and adult bees for mites. In this case, regular treatment for Varroa mites can be carried out.
The most effective way to prevent Varroa mites is to choose bees that have been bred with a resistance to the mites.
The bees are selectively bred to increase resistance to Varroa mites, and purchasing such bees will reduce the Varroa mite population in your colony.
It is almost impossible to completely eradicate Varroa mites from a colony. Bees should be protected by reducing the number of Varroa mites to a level where they do not pose a threat.
Sources
[1] Wikipedia [2] Beeaware [3] Dummies [4] Beekeeping for Newbies [5] Perfect Bee [6] psu.edu
