New(ish) Beekeeper Column
Off the Wahl Beekeeping
Adding Bees To Your Hive
Richard Wahl
A Bit about Varroa Mites
According to the dictionary, the archaic definition of “bane” is: “something, typically poison, that causes death.” Although Varroa mites are not poisonous, if left untreated they can cause the death of an infested hive. A more current definition of the word bane is “a cause of great distress or annoyance.” I do not think there is a better way to sum up our mite infestation pandemic. The word “pandemic” refers to a disease, and research has shown that mites do pass a variety of viruses which can cause diseases in bees. For a long time it was believed that mites were living off the hemolymph (bee blood) of the bee. More recently, entomology scientists found that the mites are actually living off the body fats of bees and/or of the pupae inside capped cells.
When attaching to bees or pupae, the mites are much like leeches on a fish, each living off the host’s body resources. Mites can pass a number of viruses to the bees, including one of the more obvious ones called deformed wing virus (DWV). If severe, the bee hatches from a cell and wings are so shriveled that the bee cannot contribute to the hive. DWV is often confused with K-wing virus, which is another disease passed on by tracheal mites. Tracheal mites are microscopic and live inside the bee’s tracheal tubes, as opposed to the varroa mites which attach to the outside of bees or pupae.
Therefore from the late 80’s, when the varroa mite first appeared in the U.S., it became necessary for the beekeeper to pay close attention to mite loads in a hive and to seek out treatments for any significant infestations.
When I first began my bee management experience thirteen years ago, I knew nothing about mites, or for that matter much of anything about honey bee husbandry. At that time there was still a lot of publicity about the honey bee decline and the phenomena of Colony Collapse Disorder (CCD) that had recently hit honey bee populations. Some individuals speculated that the varroa mite played a major role in CCD. Although I am not aware that particular supposition became proven fact, it certainly was a probable contributor. So erring on the side of caution, I used a few Check-Mite strips on my first year hive, not yet knowing how to test for mites, but noticing some deformed wings on one or two bees, a sure sign of the presence of mites. Check-Mite was effective against both hive beetles and varroa mites at the time, but seems to have lost its effectiveness against mites possibly due to over use. It took seven or eight years before I saw any hive beetles, probably due to the fact that my hives sit on a cement pad and hive beetle larva mature in soil around or near hives.
As mites in general increased their tolerance for these treatments, better treatments evolved and through the years I have used Mite-Away Quick Strips, Mite-Away II, Formic-Pro, oxalic acid dribbles as well as green drone comb and brood breaks to try to keep mites at low levels. I have found the best technique is to rotate through different types of treatments so the mites do not build up a tolerance to any one particular type of application. The goal is to keep mite infestations low. Even with treatments to minimize the mites, viruses and diseases the mites have passed to the bees can linger for months, much like a bad cold that does not go away in a human that if left untreated could turn into pneumonia. With each of these types of treatments the specific manufacturer’s instructions should be followed very carefully. Handled or applied in an inappropriate manner they could be toxic to your bees or to the beekeeper that is using them. So let’s look at some of the pluses and minuses of mite control treatments that I am familiar with, and have worked for my beekeeping efforts, starting with brood breaks.
Brood Breaks
A brood break occurs when a queen is not laying eggs for a period of three weeks. This can be the result of removing or caging the queen for three weeks, or a new virgin queen that is waiting to hatch out (16 days), along with the time it takes her to go on mating flights, usually estimated to be eight to 12 days. During this time mites have no capped cells to reproduce in and resort to attaching to adult bees. Worker bees tend to do more grooming during a brood break and therefore will knock more mites off their sisters. A chemical treatment during a brood break will also enhance the destruction or slow-down of the mite population. The downside is that the queen is not producing more bees and the bees are not able to raise more bees to support gathering of pollen or nectar for the hive, which in turn slows any honey production.
Drone Comb Foundation
Most bee supply companies sell one piece green plastic drone foundation frames. Since drones are slightly larger than worker bees, the drone starter cells are slightly larger than standard worker bee foundation. Where a standard sheet of worker bee foundation contains just over 3,600 cells on a side, a drone frame contains just fewer than 2,400 starter cells. Once the bees are filling standard foundation with comb cells, a green drone frame can be added next to a brood frame to encourage the bees to draw out drone comb. The trick here is to remove any capped drone cells before they hatch out prior to their 24 day maturity date. Mites seem to favor drone cells since they stay capped until day 24, as opposed to worker cells that will hatch out in 21 days. The extra three days give mites a bit longer to reproduce and mature in the cell prior to hatch out. The suggested norm is to remove the drone frames at 21 days, scrape off the drone cells and replace with a new drone frame.
Another way is to simply freeze the drone frame for 24 hours, killing the mites in the cells, and then replace the frame and let the bees clean out the dead drone pupae and mites, making room for the queen to lay new drone eggs. This method preserves most of the wax cell structure which would require much energy for the bees to reconstruct. The caution here is to not let the drone frame remain past the hatch out time or you will be adding to the mite population. Another technique is to place a medium frame between two deep brood frames. The added space below the medium frame will usually be drawn out as drone comb by the bees much as the bees often do along the bottoms of regular brood chamber frames. Prior to the 24 day drone hatch out, the capped drone cells can be scraped off the bottom of the medium frame, destroyed or fed to the birds or chickens if you have them. This is the least expensive method of mite control but requires a continual calendar watch and three week cycle of frame removal if eggs are being laid in the drone frame cells or on the bottoms of shorter frames placed between brood frames in supers.
Apivar Treatment
Another treatment that has worked well for me just after the first Spring full hive inspection is the use of Apivar strips. This treatment requires the strips to remain in the hive for 42 days for best efficacy. This is to be followed by 14 more days after strip removal before honey supers are placed on the hive. This total of 56 days with no honey supers will most likely only occur in the early Spring or late Fall unless the intent is to not collect honey for a season. Do not use Apivar while honey supers are on the hive. The recommended practice is to only use Apivar once during the year for adequate mite mitigation. Additionally, temperature has no effect on this treatment although bees are less active in cooler temps and therefore less likely to spread the molecules of amitraz (the active ingredient) around the hive. Even though this is a more recently developed treatment, I have already read one Canadian article that stated some mites are beginning to build a tolerance for this treatment due to extended or overuse as conditional approval of the Apivar treatment came to Canada in 2012, whereas common availability and use in the U.S. has only appeared in the past few years. Another good time to apply Apivar is after a swarm catch since it will possibly take a swarm several months to build comb and expand brood before honey supers are considered for addition to a hived swarm.
Formic Pro Treatment
Formic acid is a naturally occurring substance in nature found in the stings of ants and many small stinging insects. Mites have a lower tolerance for formic acid than the bees and as such the use of formic acid products have been developed to control mite populations. Several different treatments have evolved over time that have formic acid as their active ingredient. Mite-Away Quick Strips, Mite-Away II and Formic Pro all fall in this category. I have used each of these during different years of my beekeeping experience. Each have their specific manufacturer instructions which should be followed very carefully. I will concentrate on the Formic Pro treatment parameters. This treatment is stated in sales catalogs as being “safe to use during the honey flow,” while other research shows it to be safe with honey supers on the hive. But just as a note of caution, I like to wait a week or two after removing Formic pads before removing and processing my honey supers. However, Formic Pro has daytime temperature restrictions of between 50°F to 84°F (10°C to 29°C). Two strips are placed over the brood frames for 14 days or one strip for 10 days, followed by a second single strip for an additional 10 days. Another plus for Formic Pro is that it has a 24 month shelf life as opposed to the Mite-Aways which have a one year shelf life in storage. I once used two year old Mite-Away strips just to get rid of them and they did not seem to have much effect on the mites in that hive, which validated the shelf life claims. The formic acid vapors are stated to be able to penetrate and kill mites in capped cells.
Oxalic Acid Dribble
The use of oxalic acid as a vapor or dribble is another natural substance that has been developed for use in the treatment of mites. Very low quantities of oxalic acid are found in many plants, including leafy greens, vegetables, fruits, cocoa, nuts and seeds. I have not used the vapor method since I have had good luck with the dribble method. The dribble method requires less expensive equipment and I believe works well for the hobby beekeeper, although a bit more time consuming per hive. Larger commercial operations would more likely prefer the vapor method. The dribble method amounts to dissolving oxalic crystals in water and dispersing five ml per frame seam directly onto bees between the frames using 50 ml max per a 10 frame deep. Although temperature is not a factor, application is not recommended if the following nighttime temperatures will fall below 45°F (7.2°C) in order to give bees time to clean each other off. This cleaning action is where the bees remove mites from each other. Since the dribble does not penetrate capped cells, it is best to do this when there is very little capped brood in the hive. This has been my favored late Fall treatment and seems to be very effective just prior to the Winter slowdown when there are very few pupae in capped cells. My last treatment of 2021 occurred on Nov 8. The risk here is that if waiting too long there might not be another day/night above 40°F (4.5°C) and the opportunity is missed. It is not recommended to do more than one dribble in very early Spring or late Fall as the dribble is very hard on any newly hatched brood. If using the vapor method, it is recommended that three treatments be given at five day intervals in order to catch all the mites leaving newly hatched brood cells, since drones stay in capped cells for 14 days. Oxalic acid treatments should not be used with honey supers on. Much more detail on set up and execution of the oxalic dribble method will be a more appropriate topic for a Fall edition.
Summary
There are many different mite applications, each with their own time, temperature, brood condition and honey super directions. Manufacturer’s directions should be followed carefully so as to not damage your bees or contaminate your honey or injure yourself. A very good site that lists comparison information on when to use, length of treatment, temperature restrictions, whether or not it can be used during honey flows and other general info in an easy to read format can be found at: https://www.beekeepingfornewbies.com/comparing-varroa-mite-treatments/. The comparison listing is near the bottom of the internet entry along with other mite related data percentages of non-chemical methods that are often employed by beekeepers. Although this site does not claim to be scientific, it compiles a lot of data from surveys that seem to convey the reality of the beekeeping industries’ fight against the mite pandemic. There are many more sites available at present than were available when I started my management of bees thirteen years ago. As with anything taken from the internet, use your own critical judgement as to its accuracy and use multiple resources to verify the realities you seek. Any of the aforementioned treatments are what I found worked for me. Your results may vary based on your conditions, experience or state of your hives. The best advice I feel I can give is to vary your treatment types so mites do not build up a tolerance to any one method. And if you can develop a strain of bees that do not require treatment of any type, as was the case many years ago, please let me in on the secret.
Richard Wahl
*(some product pictures taken from the internet)
