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Mites are one of the greatest honey bee health threats. They affect honey production and the ability of bees to carry out pollination activities. Essential oils for honey bee mite control save beekeepers from the economic losses they stand to incur. Varroa mites, especially the Varroa destructor species, are responsible for the loss of honey bee colonies globally. They are believed to transmit bacterial and fungal parasites to honey bees. The total number of such colonies lost runs into the millions. A second type of mite affecting bees and honey bee colonies are tracheal mites. These too can be controlled through the use of essential oils for honey bee mite control.
While the destruction of Varroa mites is more widely covered in beekeeping, tracheal mites have received a lesser share of the spotlight. These honey bee mites affect the queen bee, worker bees and drones. They infect the tracheae of honey bees. They reproduce therein and draw nutrition from the bees’ haemolymph. Tracheae mites are well controlled by infusing essential oils for honey bee mite control into the bee feeder. A sugar or syrup mixture that contains a small amount of essential oils is fed to the bees when a colony is suspected or found out to be infested by tracheal mites.
About Essential Oils
Essential oils are produced by plants and stored within the plant for mostly defensive purposes. They offer protection against insects and sometimes animals by repelling them away or being injurious (poisonous) to the animals and insects when they ingest the plants. Extraction of essential oils is mainly by distillation and pressing. Some essential oils that may be used in honey bee mite control have the function of attracting potential pollinators.
Beehives that are infested with mites and left without treatment do not last more than 2 years. The use of essential oils in mite control also curbs spread of mites to other colonies in an apiary. Essential oils are an alternative to acaricides such as Apistan or Apivar. They are cheaper, environmentally friendly and pose fewer risks to the health of bees and honey consumers. Additionally, mites have not developed resistance to essential oils for honey bee mite control – unlike acaricides and other chemical treatments. Terpenes are the major component of essential oils.
Factors Affecting the Effectiveness of Essential Oils
A number of factors affect the effectiveness of essential oils for honey bee mite control. They are mainly climatic factors generally around the relative humidity and ambient temperatures. These affect the evaporation rate of essential oils and consequently exposure of mites in the beehive. Adequate exposure is crucial for effectiveness of essential oils for honey bee mite control.
To go around the limitations of exposure to essential oils for honey bee mite control, a number of delivery systems are deployed. They allow for continuous release of the essential oils at a constant dose. These delivery systems for essential oils for honey bee mite control can operate for extended periods. Environmental conditions do not affect the performance of most commercial essential oils for honey bee mite control delivery systems. In addition to having a working essential oil for honey bee mite control and a consistent delivery system, it is important for beekeepers to apply treatments at appropriate times.
Treating Varroa Mites with Essential Oils
The use of essential oils in controlling honey bee mite infestations is not natural to bees. The essential oils that you use must be acquired from a reliable source. This applies to other products you may add to essential oils. Additionally, the equipment you use to release essential oils in your beehives must also be got from trusted sources. The essential oils that you use should be food grade. The most common essential oils used in mite control are:
1. Lemongrass Oil
Lemongrass oil is very versatile oil with many uses for beekeepers. It has both anti-fungal and antiviral properties and often comes in a spray bottle. Lemongrass stimulates bees to eat food and is used to attract bees to hives. It also contains Citral and Geranic acid that are believed to kill honey bee mites. Lemongrass should be used sparingly in weak colonies since it may attract robber bees to your beehive.
2. Thymol Oil
This is an essential oil that comes from thyme plants. It is common in use against mites in beehives. Thyme oil is found in a number of commercial products for mite control. It acts by blocking the mite’s pores. It also confuses mites and leads to their falling to the bottom of the hive. Used together with a screened bottom board, thyme oil will cause mites to fall to the ground and not be able to get back into your beehive. Thyme oil has anti-fungal properties too, and can prevent chalkbrood as well. The use of Thymol oil should be approached with caution. This is because Thymol oil is injurious to bees at high concentrations.
3. Eucalyptol, Menthol and Wintergreen Oil
These essential oils are useful as additions in treatments for Varroa and tracheal mites in beehives. They can be used in preparations to aid other more effective and directly acting essential oils for honey bee mite control. Wintergreen is very good for use with grease patties. When eaten by bees, it acts against tracheal mites with great effectiveness.
4. Spearmint Oil
This essential oil is often used together with lemongrass to improve hive health. It works well against Varroa mites by blocking mite pores and disorienting them. A blend of lemon grass and spearmint has been found to help honey bees resistant to the pathogens that may be transmitted by mites. Unfortunately, this action by the two essential oils has not been exhaustively studied.
5. Peppermint Oil
Peppermint in beehives is a strong masking scent. It does not mimic any honeybee pheromones.
6. Tea Tree Oil
Tea Tree oil is used in grease patties in controlling mites. It can be used in place of Wintergreen without any loss in effectiveness.
Below we will discuss using wintergreen and tea tree oil for Varroa mite treatment in more detail.
Wintergreen Oil Varroa Mite Treatment
Wintergreen essential oil is an effective miticide. It is used in treatment of both Varroa mites and thoracic beetles in honeybee colonies. Beekeepers using wintergreen oil Varroa treatment often use grease patties. The oil is also useful in reducing small hive beetle populations in a beehive. Wintergreen oil may be used in a mixture with other essential oils. It can also be interchanged with tea tree oil in Varroa mite treatment.
Wintergreen oil can be applied in a variety of methods, so each beekeeper chooses the best method based on the labor available, equipment they have and the degree of infestation. It is advisable to use a screened bottom board with wintergreen oil Varroa treatment. If you do not usually use screened bottom boards, consider having one in place for the period of treatment. Once treatment is over, you can switch back to a solid bottom board.
In addition to controlling Varroa and thoracic mites, wintergreen oil helps you maintain a healthy hive. It has antifungal properties which keeps the beehive clear of molds.
Using Wintergreen Oil with Bees
The use of grease patties laced with some sugar and wintergreen oil is very effective against thoracic mites. Bees eat the patty containing oil resulting in thoracic mites coming into direct contact with wintergreen oil. It kills the mites rapidly and leaves your honeybee colony free of thoracic mites. The ration of wintergreen oil to sugar in the patty should be 1:1.
Varroa mite control with wintergreen oil is through indirect delivery of the oil to mites. Bees eat grease patties containing wintergreen essential oil. The essential oil then enters the bees’ hemolymph (analogous to blood in humans and other animals). Mites attached to bees then suck on the hemolymph which has some amounts of wintergreen oil.
In Varroa mites, wintergreen oil taken in via ingestion interferes negatively with reproduction. It gradually lowers the population of Varroa mites in the beehive. When used properly, wintergreen oil in grease patties clears your hive of Varroa mites.
Vaporization is one of the other wintergreen oil application methods you can use. Beekeepers that have a vaporizer can use it to treat beehives with wintergreen oil. Vaporizers give even spread of the oil in the beehive. It is fast and very effective. Varroa mites come into contact with the oil that cools on inner beehive surfaces and die.
You can also apply wintergreen oil in a beehive by dripping it onto honeybees. It triggers honeybees to groom themselves, and sometimes each other. This causes removal of mites attached to their bodies. The smell of wintergreen oil on the bodies of bees and beehive also repels mites.
Factors Affecting the Effectiveness of Wintergreen Oil Varroa Treatment
The amount of wintergreen oil that you use in a treatment or single application is important. If you use too little, the oil will have little effect on Varroa mites. A few will die off but a mite population will be left in the beehive. This population will reproduce and continue the infestation.
Luckily, Varroa mites cannot develop effective resistance to essential oils. Beekeepers using inadequate amounts of essential oils such as wintergreen per application in a treatment regime for Varroa mites risk causing the rise of resistance to the treatment.
The proper amount of wintergreen oil to use in a grease patty is at a ratio on 1:1. For dripping, prepare the solution to contain 7% of the oil.
There are many different suppliers of essential oils. Each of these suppliers has their unique concentration of the oils they sell. When buying your wintergreen oil for Varroa treatment, the concentration of the oil is a significant factor. Oils that have been diluted will require you to use more per treatment. It is best that beekeepers buying wintergreen oil for Varroa treatment get the highest concentration they can get.
The purity of essential oils is also important in their use as miticides. Pure wintergreen oil is best for use in Varroa treatment. Additives that may be found in diluted and mixed oils may be injurious to bees. Additionally, the added impurities may be residual in honey or bees wax and affect the quality of your beehive products.
3. Degree of Infestation
The number of Varroa mites present in a beehive greatly affects the effectiveness of wintergreen oil Varroa treatment. Early detection of Varroa mite infestations is thus important. Beekeepers should have regular beehive inspections so that they find Varroa mite infestations in their early stages. A heavy infestation of Varroa mites requires more treatments over a period of time. It does not need you to apply more of wintergreen oil. With light infestations, a few treatments spread out over a few weeks are enough to clear mites from your beehives.
Tea Tree Oil for Varroa Mite Treatment
Tea tree oil can be used alone or in a blend with other essential oils for maximum effects. There are different ways of applying tea tree oil in a beehive for Varroa mite treatment. You may spray the bees with the oil, use a vaporizer, drip the oil into the beehive, feed it to bees in a grease patty or use the oil in an oil trap.
Vaporization and dripping are the most effective methods of applying tea tree oil for bees in Varroa mite treatment. When applying tea tree oil for Varroa mite control, you may mix it with some thyme oil or oregano oil in equal proportions.
How to Spray Bees with Tea Tree Essential Oil
Spraying is one of the methods of applying tea tree oil into a beehive. To spray bees, prepare a solution of tea tree oil, water and some sugar. A hand sprayer can be used to give a fine mist. The aim is not to overly wet the bees.
The mixture of tea tree oil and sugar triggers grooming behavior in bees. The sugar makes some of the mixture to be ingested by bees. It helps against any thoracic mites that bees may have. Additionally, it delivers tea tree oil via the bee’s hemolymph in a delayed release path that is effective against mites that emerge after your initial application of the tea tree oil.
By spraying the bees and hive with tea tree oil, you make mites crawling in the hive come into contact with the tea tree oil. They then get affected by the oil and cannot climb onto bees.
Dripping Tea Tree Oil for Varroa Mite Treatment
Prepare your mixture of tea tree oil and put it in a plastic bottle. Cork the bottle and make a small hole in the bottle. Drip the oil onto bees in the beehive by pressing the bottle to make a fine jet of the oil mixture.
When using this method of tea tree oil application, take care not to flood the beehive. Dripping essential oil into the beehive is fast. A few jets of the essential oil per beehive box are enough to treat against Varroa mites.
Using Tea Tree oil in Patties
Sugar patties are great for feeding bees. You may add some tea tree oil in patties that you prepare yourself. The bees feed on the patty and come into contact with the oil on their bodies as well. Honeybees moving around the beehive spread the oil which then comes into contact with Varroa mites.
Other Varroa mites get the tea tree essential oil via the bees’ hemolymph. They get affected and die. Tea tree oil in the bees’ hemolymph causes a negative effect on mite reproductive capabilities. It is a slow way to control Varroa mites but effective all the same.
Vaporization of Tea Tree Oil
Vaporizers are beekeeping equipment that runs on electricity. They heat up and vaporize essential oils into the beehive. Essential oil for use in a vaporizer does not require mixing with anything. To apply tea tree oil using a vaporizer, put a few drops in the vaporizer and connect it to your power source. The oil is vaporized and spreads evenly into the beehive. It then cools and attaches to beehive surfaces.
Mites crawling in the hive come into contact with the oil and die. Using a vaporizer requires you to seal all holes in the hive through which the tea tree oil vapor may escape. Make sure that there is no comb lying at the bottom of the hive when using a vaporizer. It may ignite due to the heat from the vaporizer and cause a fire in the beehive.
Preparing Tea Tree Oil for use in Varroa Mite Control
Preparing your tea tree oil mixture depends on the method of application you will be using. Proper mixing is important to ensure you apply enough of the tea tree oil per beehive.
- For spraying and dripping, prepare a 7% mix of tea tree oil in water. You may add 7-8 spoonfuls of sugar for every 1 liter of water you use. A drop or two of thyme oil can be added to the mixture with no loss of effectiveness.
- When applying tea tree oil for Varroa mite treatment via sugar patties, add 3-4 drops of the oil to every 500 grams of sugar patty you make.
- In the vaporization of tea tree oil, vaporize 3-4 drops of the oil for every beehive box you have in your stack.
Pros and Cons of using Essential Oils for Honey Bee Mite Control
- Essential oils for honey bee mite control offer beekeepers that are mindful about their footprint on the environment to practice beekeeping without resorting to chemicals.
- Essential oils when used in controlling honey bee mites reduce populations of honey bee mites or help the beekeeper completely rid their beehives of mites.
- There are various ways of applying essential oils into your beehive. Beekeepers have choice of the method they use. The chosen method should the one which is suitable and affordable to the beekeeper.
- Equipment used with essential oils in beehive mite infestation control is safe, easy to find in stores and can be purchased online. The equipment often has warranties as is common with most beekeeping supplies from reputable sellers and manufacturers.
- There are many different types of essential oils available for purchase. Beekeepers have enough in their hands when it comes to choices of essential oils for honey bee mite control. Small amounts of essential oils are required per application.
- Blends of two or more essential oils may give you better efficiency in controlling mites. They also help beekeepers achieve other desired behavioral effects in the beehive where they use them. Small amounts of essential oils are required per application.
- Beekeepers without adequate information may not easily arrive at the best essential oils for honey bee mite control to use. Different essential oils have varying effectiveness against mites of different types in honey bee colonies.
- Honey bees may be affected by essential oils for honey bee mite control. Each essential oil has varying effects based on its nature and concentration. Some oils when introduced into a beehive may alter bee behavior, place your colonies at different risks, or in worst case scenarios turn lethal to your bees.
- Essential oils for honey bee mite control works best with screened bottom boards. This may not be a preferred option for beekeepers who want their beehives to have solid bottom boards.
- The use of essential oils for honey bee mite control requires a period of time to lapse before beekeepers can safely harvest honey for human consumption.
- Essential oils are not cheap to purchase in the market. They are difficult to obtain form plants and thus dig deep into beekeepers’ pockets.
Essential Oil Therapy to Control Varroa Mites
Essential oil therapy to control mites in beehives and apiaries can work in two ways. First is direct contact with mites, and the second is through the bees’ hemolymph. Delivery of essential oils for honey bee mite control through bee hemolymph requires the bees to feed on some of the essential oil. Mites sucking on the hemolymph of such a bee show effects in a day or two.
Direct contact is more effective in killing off mites in a beehive. A bee that comes into contact with your essential oil preparation may transfer the oil to mites within the beehive. In most cases, a mite that comes into contact with the essential oil dies off in a few minutes. After direct contact with essential oils, mites find it difficult to climb onto the back of bees. Those that manage to reach the back of bees get poor attachment.
Bees that feed on an essential oil preparation may transfer the oil to fellow bees and larvae. The female Varroa mite that feeds on larvae or sucks the hemolymph of bees that has an effective essential oil dies soon after. Where mites do not die after indirect contact with essential oils, their reproduction is affected. This may lead to more time being taken to control an infestation, but it is nevertheless effective. Feeding on essential oils for honey bee mite control is very effective against tracheal mites. Contact between the mite and the oil affect the mites and they die off.
Tracheal mites are generally impacted by essential oils for honey bee mite control. Their breeding suffers when they are exposed to grease patties. The use of essential oils for honey bee tracheal mite control is mainly done when there is no honey collection for human consumption scheduled to take place.
Essential Oil Dispersal Methods
Beekeepers have a number of dispersal methods to choose from when using essential oils for honey bee mite control. The varying methods have different levels of efficiency and effectiveness. They utilize different technologies. Some are easy to apply, while others have a high level of complexity.
1. Grease Patties
Grease patties are the easiest way to apply essential oils for honey bee mite control. They are placed between beehive frames on the top sides. Bees coming into close proximity with the grease patties lead to mites that are on bees getting into contact with the grease patty. The initial use of grease patties over time has been to control tracheal mites. In recent years, following an upsurge in the number of beekeepers seeking natural and organic beekeeping, grease patches have found use as a Varroa mite control method too. Grease patties should not be used when honey harvesting is due. They may also lead to infestation of your beehive by small hive beetles.
A simple grease patty recipe is made by mixing one pound of solid vegetable shortening and three pounds of sugar. A small amount of essential oils is then added to add odor that attracts bees to the preparation. A suitable container should be used to hold the patty in your beehive. You may also use an absorbent material that acts as a wick to gradually release the grease patty to bees as they come into contact with it within the hive.
2. Oil Traps
Beekeepers using essential oils for honey bee mite control may use a base with an oil trap. The oil trap is accessed from behind the base and does not disturb your hive. You may winter your hive with the oil trap. The traps in the market fit different sizes of hives including 7-frame and 10-frame beehives. Commercially produced oil traps for use with essential oils for honey bee mite control release a constant amount of the essential oils into the beehive. They are however dependent on bees coming into contact with the oil trap. Using an oil trap removes the possibility of using a screened bottom board, or renders it useless in mite control if it is already present in your beehive.
Evaporators/vaporizers of varying sizes are also used to disperse essential oils for honey bee mite control. Notable evaporators are electric and smoke cannons. Electric vaporizers that are suitable for both beginner and professional beekeepers use DC (direct current). Those running on AC (Alternating Current) are trouble for beekeepers during winter, and who may not easily get mains electricity to their apiary’s outdoor location. They are operated using varying energy sources. The best electric vaporizers work with a variety of batteries and use up little energy to effectively vaporize essential oils for honey bee mite control. Most vaporizers give beekeepers a good period of operation between battery swaps. They give excellent distribution of essential oils.
The smoke cannon is a contraption that employs the same ideas as a beehive smoker. It blows smoke from the leaves or crystals of the plant bearing the essential oil of your choice. This smoke when blown into a hive bears helps you with mite control. Smoking bees may stress them out. This makes the smoke cannon unsuitable as a delivery method for essential oils for honey bee mite control. The amount of essential oils carried into the hive through smoke is also often in question. Heavy duty modern essential oil smoke cannons use water, ethyl, 96% alcohol or purified kerosene as solvents.
Popular electric evaporators for essential oils for honey bee mite control are easy to use and heat up fast. They are portable and compact. Manufacturers of electric evaporators may supply them with spoons or scoops to measure and add essential oils. The temperature of the heating part may reach 2500 C. The vaporizer itself is long, with a heating part on one end of a rod. It has a handle and a power cord may dangle from the handle or on the heating part of vaporizers. The handles of vaporizers are made of wood. The use of wood insulation allows safe handling of the vaporizer by beekeepers. Electric vaporizers running on DC are supplied using safety battery clips. Each battery clip should be attached to the correct battery terminal during use.
How an Essential Oil Evaporator Works
Essential oil evaporation in a beehive is easy to carry out and effective treatment for Varroa mite control. It can however be ineffective if done improperly. Beekeepers who understand how an essential oil evaporator works are better suited to use essential oil to control Varroa mites successfully. There are two types of essential oil evaporators: continuous release and fast release essential oil evaporator.
Continuous release evaporator
A continuous release evaporator releases small amounts of essential oil vapor into the beehive. It holds the essential oil preparation in a container and drips it slowly onto a hot plate or heated element. This type of essential oil evaporator requires a constant source of power. The best continuous release essential oil evaporators are electric.
Fast release evaporator
The fast release essential oil evaporator heats your essential oil preparation quickly and releases the vapor into the beehive. It uses electric power and gets the job done quickly. Popular designs of fast release evaporators use either DC or AC current to heat the evaporator. These evaporators go into the bottom of the hive.
Which Oils are best Distributed with an Evaporator?
Essential oils are volatile and evaporate quickly when used in an evaporator. The oils that are best distributed with an evaporator are thyme and oregano essential oils. The two essential oils come from plants in the mint family and have high efficiency against Varroa mites. Other useful oils in Varroa mite control that you can distribute with an evaporator are eucalyptol, menthol and wintergreen.
How much Essential Oil to use in an Evaporator?
A preparation of thyme and oregano oils is best released using an electric evaporator. You may use continuous release evaporators when your apiary is near an electric power outlet or source. The preparation is made using 15 parts of water, 15 parts of 96% ethanol, 2 parts of mineral oil (food grade), one part food grade gelatin, thyme and oregano oil in equal proportions to make them to 7% of the solution.
Approximately 20 ml of the solution is enough for a single beehive when evaporated in a continuous release evaporator. Place the evaporator above a 3 mm hardware mesh cloth in the uppermost brood box of your beehive.
How to use an Oil Trap
Various oils are used in trapping Varroa mites in beehives. They are used with a screened bottom board that allows mites to fall into the trap. The oil trap is built in a tray shape that goes under the screened bottom board. Oil is applied to the inner surfaces of the trap to kill Varroa mites. You can use oregano, thyme, wintergreen, menthol or eucalyptol essential oils in your Varroa mite oil trap. Mineral oil in dilute preparations may also be used in an essential oil Varroa mite trap.
To use an oil trap successfully to control Varroa mites, you need to have screened bottom boards in your beehives. Apply oil to the inner surface of the trap tray and slide it into place under the screened bottom board. Bees do not come into contact with the trap or oil in it. Mites that get detached from bees fall into the trap and are killed by the essential oil you used in the trap.
For increased effectiveness when using an oil trap to control Varroa mites, consider using some sugar and oil preparation on bees. Spraying the preparation on bees makes them groom themselves. This results in increased Varroa mites being dislodged from bees.
Early detection of Varroa mites is important for successful control. Identifying a Varroa mite infestation requires you to check for the mites clinging to the bees in your beehive on their rear side of the thorax. You may also use the sugar shake, sticky board or alcohol wash methods to identify Varroa mite infestations in your honeybee colony.
A Final Word
Honeybee mites are a major problem in beekeeping. They cause a number of problems to a honeybee colony including deformed wings in bees and shortened honeybee lifespans. Beekeepers use essential oils for honey bee mite control as one of the treatment methods to keep mites in check. Using an evaporator is one of the ways beekeepers apply essential oils in a beehive. You may also use an oil trap to control Varroa mites in a beehive. Honeybee colonies that are overwhelmed by mites collapse or abscond from the hive. There are some species of honeybees that are resistant to Varroa mites or can overcome mite infestations. Furthermore, you can use essential oils for honeybee mite control with no risk of the mites developing resistance to the treatment.
It must be noted that not all essential oils are effective in mite control in beehives. A blend that includes Thymol in the essential oil has been found to be most effective in honey bee mite control. Essential oils for honey bee mite control have a mite mortality rate above 90%, and closer to 100%. The residues of essential oils in honey are low even when they are used on a long-term basis. A single treatment with essential oils is often not adequate to lower mite populations to levels where they do not cause economic injury. Essential oils can be easily applied alongside other treatments and methods in an integrated management strategy for Varroa mite control by beekeepers.
Have you used the essential oils for Varroa mite control in your beehives? Leave a comment below and let us know what you think of it.