Beekeeping/Varroa Mite

Varroa Destructor
Kingdom	Animalia
Phylum	Arthropoda
Class	Arachnida
Order	Acari
Family	Parasitidae
Genus	Varroa
Species	V. Destructor

Wikipedia has related information at Varroa destructor

Also known as the Vampire Mite, Varroa Mite, Varroa Destructor and often mislabeled as Varroa Jacobsoni.

The Varroa Mite is a parasitic mite that can cause serious trouble to beekeepers and their bees alike. This tick-like mite, around the sized of a pinhead, does its damage by feeding on the bee’s hemolymph fluid (akin to bee blood). Mites attach themselves to foraging workers in order to spread themselves from one hive to another. This mite can severally weaken a hive through vampire-like action and through the spread of disease and bacteria. An unchecked mite population will almost certainly lead to the premature death of a honeybee colony.

Within the United States, Varroa Mites have the largest impact when compared to other pests within the beekeeping industry. The Varroa Mite is also nearly completely responsible for the decimation and loss of feral honeybee colonies. Some beekeepers have resorted to reverting to small cell beekeeping and many hobbyist are moving towards top bar hives in an effort to fight against this aggressive foe. Others are attempting to use mite resistant races of bee with some success.

Origin

The Varroa mite was discovered in Southeast Asia in 1904, but now unfortunately spread mostly worldwide. More recently Varroa was discovered in 1987 within the US, 2000 in the North Island of New Zealand, 2007 in the South Island of New Zealand.

In June 2022, Varroa was detected in a sentinel hive in the port city of Newcastle an extensive eradication programme in which a kill radius was implemented around all infected hives failed to eradicate the mite as commercial pollination resumed and the mite spread. In September 2023, eradication plans ceased and Australia began a mite management plan.

Anatomy

Varroa is approximately 1.00 to 1.77 mm in length and 1.50 to 1.99 mm. Its body closely resembles that of a tick, it has eight legs and the apparatus to pierce the epidermal layer of both adult and larval bees in order to feed. The mite is red-brown in color and wide and plainly visible to the naked eye when on brood, and can be more difficulty spotted, on some occasions, on the adult bee.

Life Cycle

Varroa Mite on Pupa

Within a hive mites can reproduce on a 10-day cycle. The female mite, after detaching from an adult bee, will enter the cell of an uncapped brood. The mite shows preference for the drone brood, but will select what is available. Once the cell is sealed, the female will begin to lay eggs and then expire. As the young bee develops, so will the mites. As soon as the new bee is able to leave its berthing cell, the mites attach themselves and start the cycle anew. The life cycle of the Varroa mite is dependant on the existence of brood within a colony.

Symptoms

Possible signs that a mite infection is underway may include, but is not limited, to the following

Mites obvious on brood, emerging bees, or foragers
Deformed bees
Discarded larva
Spotty brood pattern
Apparently sudden death of colony
Dead mites found near the entrance of the hive

Detection

If Varroa infestation is suspected, there is often nothing major lost by examining. However, a colony may be doomed if left unchecked. Checking for Varroa should be part of a beekeeper's regular regime. The following methods are some common ways to detect a possible mite infestation.

Ether Roll

The ether roll test is the grandfather of the sugar roll test, though effective it is not always the best method, as tested bees will die as a result.

Using a wide mouthed jar, such as a mason or pickle jar, collect a sample of bees (not the queen) and fill the jar about ¹/₃ full.
Using ether, such as that from a can of carburetor starter fluid, apply a small amount to the bees (approximately a tablespoon worth). The inside of jar should be slightly moist with all bees at the bottom.
Place the lid on the jar and roll bees for about 20-30 seconds.
If done quickly, the jar may be opened and some of the bees may escape alive, though this is doubtful and the ones that do survive will be ready to sting.
Examine the sides and bottom of the ether filled jar. If you count one or more mites, it is advised that you begin some sort of treatment. If you count around a dozen mites, it means you have a significant infestation, and should immediately begin treatment. If you find more mites than you can easily count, your hive is in serious trouble
Dump remaining dead bees and clean the jar before next use.

Notes

If you can do the either roll, there is little reason not to do the sugar roll instead, as it is not lethal to the bees and is takes no more time.
Soapy water or 70 percent isopropyl (rubbing alcohol) can be used with varying success instead of ether.

Drone Culling

Unfortunately, the drone culling method kills drones to determine if there is a mite infestation. Despite this fact, culling drones is a quick and reliable method to check levels.

Select a frame (or comb) with a large patch of capped drone brood. Gently remove adult bees from the frame and locate it to an easy to work area.
Using a capping scratcher to remove the cappings from the selected brood cells. The drone brood within unfortunately must be impaled during this step.
Mites will be plainly visible on the pupae as they are removed from their cells. Two to three mites on single pupae indicate a serious problem. Two to three mites per 50 pupae indicate a low to moderate infestation.
Remove the culled brood, especially if heavily infected, or allow the bees to clean up after returning the frame to its original hive.

Notes

Caped drone brood can be differentiate from capped worker brood as it has larger cells with slightly domed shaped capping.
When returning the frame be sure to return it to its original hive, unless you are absolutely sure it does not carry any disease or mites.
The sugar roll method for detection is a little more time consuming, but no bees must die for it to succeed.

Sugar Roll

The sugar roll method, also called the sugar shake method, is a technique that can be used to fairly reliably determine if bees have a Varroa infestation. In contrast to the ether roll and drone culling, when done properly there is no harm done to the bees in the sample.

Using a wide mouthed jar such as a mason or pickle jar, cut a large hole in the lid and affix a rigid mesh from which bees can’t escape. Size 8 hardware cloth serves this purpose well.
With the jar open, add 2 to 3 tablespoons of confectioners sugar to the bottom of the jar.
Scoop the jar about one cup of bees (or 100 to 200 bees), being sure that you have not captured the queen. Quickly seal the jar with the lid you made.
Covering the lid so as not to loose the sugar, give the jar several vigorous shakes, the more the better (to a point). This will surely aggravate the bees, but should not cause them any serious harm.
Shake the sugar (and mites) out of the jar onto a piece of white paper or something with a similar white background. Set the jar of bees aside in the shade to calm down.
If you count one or more mites, it is advised that you begin some sort of treatment. If you count around a dozen mites, it means you have a significant infestation, and should immediately begin treatment. If you find more mites than you can easily count, your hive is in serious trouble.
Allow your recently jarred and jarred bees ten to fifteen minutes rest before returning them to the hive. This is mainly for the sake of the beekeeper, as the shaken bees may be ready to sting. Although some of your bees are now covered in sugar and appear to bee little ghosts, don’t worry. Their sisters are more than up to enjoying the task of cleaning the sugar off of them.

Notes

Some keepers choose to use a modified sugar roll technique on entire packages of bees, but be sure not to do so to the queen, to avoid risk of injury. This technique is most useful when there is no brood, so it may similarly be stretched to include recently captured swarms. When brood is present, the treatment must be repeated several times at ten day intervals.
Although it is not often recommended to use powdered sugar in conjunction with bees due to anti caking agents that may be present, it should not be a problem with this technique to the little exposure actually obtained.

Screened Bottom Board

Simply installing a screened bottom board allows you to keep mite levels in check with out having to actively monitor.

Notes

It is advisable to apply a sticky board, tacky adhesive, or a thin layer of Vaseline to the catch tray of the bottom board, so that live mites cannot return to the hive.
As with any passive technique, results are not instantaneous and therefore the results may not be dependable or the results may arrive at too late to be useful.

Observation of Bees

If you are easily able to observe mites on foraging bees, the colony is in trouble. Begin to remedy the situation as soon as possible.

Methods of Control

There exist many methods of controlling levels of Varroa mites, each with varying success. Unfortunately most methods are for control only, there may always be a level of mites once a colony has been infected. Only extremely drastic measure, such as culling the hive, can assure a zero mite population.

Any controls using any sort of chemical device should not be used for up to 30 days prior to a honey flow that will be used for collection of honey for human consumption, unless otherwise noted.

Chemical Treatments

Apistan

Apistan is a readily available plastic strip that is treated with a form of miticide. Users should follow the instructions present on the packaging.

Notes

Understand the instructions fully before applying
Do not apply when honey supers on the hive
Most commonly, 1 strip per 5 frames should be used, do not over medicate
Do not use strips for longer than the time stated on the packaging, this will and has caused mite resistance to the poison.
Wear protective gloves when applying and removing strips
Once used, do not reuse strips
Treatment timing is extremely important for success, do not use more than once in the fall and once in the spring.
Do not use in conjunction with CheckMite+

CheckMite+

CheckMite+ is similar to the product Apistan in the fact that it is miticide on a plastic strip. CheckMite+ however uses a different miticide that that which is present on Apistan strips. CheckMite+ should only be used if you Varroa mite infestation has proven to be resistant to Apistan. Users should follow the instructions present on the packaging.

Notes

Understand the instructions fully before applying
CheckMite+ should only be used if you Varroa mite infestation has proven to be resistant to Apistan
Do not apply when honey supers on the hive
Most commonly, 1 strip per 5 frames should be used, do not over medicate
Do not use strips for longer than the time stated on the packaging, this will and has caused mite resistance to the poison.
Wear protective gloves when applying and removing strips
Once used, do not reuse strips
Treatment timing is extremely important for success, do not use more than once in the fall and once in the spring.
Do not use in conjunction with Apistan

Dusting

A dusting of powdered sugar or wheat flour in conjunction with a screened bottom board or a sticky board can cause mites to fall and be captured. Though this method can be used during honey collection, it should only be used as a last ditch effort. This must be repeated once a week for two to three weeks to make any kind of lasting effect.

Notes

Only dust the adult bees, as open brood may perish due to dusting. However it may be said that Dr Fakhimzadeh of Helsinki university has suggested that sugar DOES NOT has a negative effect on open brood and egg damage only seems to occur when dusting with sugar and Oxy-Tertra-Cycline (OTC) indicating that it is the OTC that is doing the damage. Nevertheless Jim Fischer of WSBA points out that we should avoid open cells ready for laying as the queen will only lay in clean cells
This process must be repeated as it will not affect mites that are sealed in cells with brood or affect mites that are piggybacking on absent foragers

Drone Culling

Similar to the method of detection of the same name, drone culling can be used to reduce the number of mites infesting a hive. This process can be done as hone supers are on the hive.

When starting a colony, use a sheet of drone brood foundation, per hive body.
Occasionally when the brood comb is full simply cull the drones by placing the entire frame in the freezer.
Once frozen comb has defrosted replace it in the hive to allow the bees to clean it and refill the comb.
Repeat as necessary.

Notes

If drone foundation is not available, take about an inch tall piece of normal foundation and simply used this as a starter strip by installing it on the top of a frame. This method allows the bees to create their own comb, though it may not always be successful in creating drone comb.
Instead of freezing, uncapped drone brood can be hung in order to feed local birds, but do not replace the frame in this instance as it will be more than likely destroyed by the appreciative birds.
Instead of freezing drone can be culled by heating, though this often readily becomes a waxy mess is not kept under control.

Breaking Brood Cycle

The act of breaking the brood cycle, by culling the queen, and allowing the bees to raise their own queen will prevent Varroa mites from laying eggs and thereby end their life cycle.

Notes

Instead of culling a healthy and productive queen, she can be used to requeen a separate hive or begin a Nuc.
Instead of using a self produced queen, you can replace with a store bought queen, but you must allow for a natural broodless cycle
This method could be used during a honey flow, but a lack of new workers will cause it to be poor honey season.

Grease Patties

Using grease patties with or with out essential oil will cause a decrease in tracheal mites. They are sometimes used as a varroa mite control method. Though it is preferred to use patties with essential oils, it should not be done during a honey flow. To be effective, grease patties must remain on the hive year round.

Essential Oil Treatment

Using essential oil in a sugar syrup feed as been show to reduce mite levels. Syrup feed should not be supplied when honey supers are on the hive.

Tobacco Smoke

A heavy tobacco smoking in conjunction with a screened bottom board or a sticky board can cause mites to fall and be captured. Though this method can be used during honey collection, it should only be used as a last ditch effort. This must be repeated once a week for two to three weeks to make any kind of lasting effect.

Notes

When smoking, be sure that the smoke is not too hot, use cool smoke only
This process must be repeated as it will not affect mites that are sealed in cells with brood or affect mites that are piggybacking on absent foragers

Formic Acid

Formic acid is very caustic, and toxic to both bees and humans if not used properly. The liquid form of formic acid is somewhat dangerous to use, but is safe if handled carefully. Wearing gloves is essential. Beekeeper supply houses may sell a time-release gel form that is easier to use and less toxic.

notes

Follow directions before using
Take caution in use as it is toxic to bees and beekeeper alike
When used, formic acid will also treat tracheal mites

Food Grade Mineral Oil

Some beekeepers use an electric or propane insect fogger to apply a mist of food grade mineral oil to their bees. This has been shown to induce a grooming behavior in the bees which can reduce mite levels when combined with a screened bottom board.