varroa mites

Opposing views of mite management: data vs date

I have always believed in data-based bee management: Gather whatever information you can find and then make decisions based on what you learned. For varroa mites, this means taking samples, counting mites, and deciding on a strategy.

Perhaps this is an old-fashioned idea, dating back ten years when some mite counts actually came out low—low enough not to treat. Granted, that seldom happens anymore, but I still believe in knowing where you stand before you start tossing chemicals into your hives.

New beekeeper reluctance

On the other side of the coin, my friend and master beekeeper Janet Wilson has come up with some compelling arguments for schedule-based rather than data-based treatment. She posits that new beekeepers are often so overwhelmed by uncertainty and inexperience that the thought of sampling bees is off-putting in the extreme. Janet writes:

“We have in our club found that most new beekeepers are not comfortable doing regular mite counts. Very often they reach out for help as winter approaches and share that they did not really know how to do one so they just put it off. I think that first year or two you are just getting used to opening that bustling, growing colony of stinging insects and the idea of doing a capture and count is overwhelming. And most refuse to do alcohol washes as they are understandably reluctant to kill any bees at all.”

I concede that her statement is true. I’ve heard of many newish beekeepers being so intimidated by the sampling process that they procrastinate a day or two—and then 60 or 90—until it is way too late. Only when the colony dies, do they realize they should have done something long ago.

A feasible alternative

In light of this predicament, Janet and her club have come up with a protocol to help new beekeepers through this period of initiation and uncertainty. She explains:

“Given [new beekeeper reluctance], and most particularly for those who live in areas of high bee density, we give [new beekeepers] the option of treating by the calendar. Which in our area sort of translates into “when you get them, right after honey harvest, right before winter wrap-up, and midwinter.”

To me, this sounds reasonable. It is a regimen not dictated “by the calendar” but by the event—a more sensible benchmark. The events—especially attaining bees, harvest, and winter wrap-up—will vary depending on your location. That variation, by itself, will customize the schedule for individual beekeepers in different climates and conditions.

Although I still strongly recommend data-based decisions, I can see Janet’s protocol as both viable and doable for beginners. Technically, it should control most of the mites most of the time in most locations. For a new beekeeper who is stuck, intimidated by testing, or unsure about treating, this is likely a good place to start.

Lingering reservations

My worry is that such a schedule could become a habit that forestalls learning how to diagnose mite problems until another day. But when will that day come?

All forms of animal husbandry encompass jobs we don’t like to do. Everything from cleaning the goldfish bowl to picking hooves can be delayed, often to the detriment of the animal. But learning to do all the parts is necessary to learn the craft, regardless of the animal you’re keeping.

By treating mites on a schedule without testing, the beekeeper loses heaps of information. For example, if you don’t count the mites before and after treatment, how do you know the treatment worked? Perhaps you’re living within a pocket of resistance to a drug like Apivar. You might not know that without proper counts. Or perhaps you accidentally used an expired product. You might not realize your mistake without good counts.

When testing helps the inexperienced

I see counting as being especially important for new beekeepers who are inexperienced at using drip protocols or OA vapor or even something like ApiLife-Var that requires reducing all openings to the very minimum. How do you know whether you did it right without testing?

A lack of information can be detrimental in the future as well. If a certain product shows resistance, wouldn’t you like to avoid buying or using it again? If mite counts were excessively high before you treated, might you want to adjust treatment times next year?

An excellent temporary solution

All that said, I think Janet’s idea might be the perfect solution for a beginner. But it should be a temporary solution, used only while the beekeeper is learning the ropes.

In truth, I don’t like testing either, but I loath data darkness even more. Testing has saved my bees more than once, and I keep that in mind when I feel like stalling. Just a few years ago I used a product that is not supposed to engender resistance. The product was fresh. I followed directions. Everything seemed fine until my follow-up counts showed no change in mite load.

What happened? I still don’t know, and I’ve used the same product occasionally since then with good results. But if I hadn’t recounted—and then retreated—I would have lost most of my colonies. In fact, I can’t think of a single time when testing did more harm than good.

A special thanks to Janet for sharing her system. If you would like to read the rest of her information-packed post, you can find it here.

Honey Bee Suite

A healthy honey bee: The value of data vs date in mite management.

Keeping our honey bees free of varroa mites is a full-time job. Image by David Hablützel on Pixaby.

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  • Rusty,

    If we could find, or even create, a virus that killed or sterilized or deformed the V.Mite, do you think it would be a good thing to treat hives with? This of course assumes that it only attacks the mites.

    • Adam,

      Your assumption—that the virus only kills mites—is the tricky part. Many times in the past, releases of biological control agents have gone awry when the agent suddenly jumped to another organism. To be fair, others have worked exceptionally well. Releasing sterilized males of different species has worked for some organisms, by drastically reducing the number of offspring. Would that work with varroa? I don’t know. How would we ever round up enough males to make a difference? Still, I think it will be some kind of biological agent that eventually takes down the varroa mite. Or at least that’s what I hope.

  • You are supposed to take the bee sample from the brood nest. However, in the fall brood nests often have shrunk considerably or have almost disappeared.

    My “sampling” is one OA vapour treatment. Call it a test treatment. If I find mites I’ll continue in 5 to 8 days intervals for three treatments. If mite count is insignificant I am done. The impact on the bees is low, I understand. Also, you don’t have to open the hive disturbing the bees when it may be cool or windy.

    I am not aware that mites can develop resistance to OA. Does OA not attack the mites’ nerve system?

    Anything wrong with this approach?


    • Dieter,

      My understanding is that the high acidity harms the varroa and they take it up through their feet. Newer information may be out there, so please correct me if I am wrong.

      Although many people claim that mites cannot possibly evolve to resist the acidic environment, I don’t believe that. Thermophilic archaea and bacteria live in the hot springs of Yellowstone which was thought to be impossible. Organisms live at the bottom of the sea under crushing pressure which people thought was impossible, and Trump was elected president, another impossibility!

      I think it is unlikely, but possible, that varroa can develop OA resistance. After all, the bees can resist that much acidity with no problem. If the varroa could become as resistant to it as the bees are, it would no longer work. At that point, an increase in the acidity or dosage would end up killing both.

  • Rusty – reluctance in doing counts is understandable. It is hard for new people to stuff 300 bees in a jar and douse them with alcohol. An issue I had was is 300 bees N=300, or is 300 bees N=1 with N=1 being a single sample out of 10,000 to 40,000 bees. Rather like getting one blood test at a clinic and thinking is has blood sugars nailed. Key to any sampling is being satisfied a sample is truly representative. If not the sample may be misleading. Scheduling at least ensures new beekeepers treat.

  • Some of us choose not to treat and have some success with this method. This strategy is definitely not for everyone and likely not the best first choice of a new beekeeper. Even though monitoring for mites may provide me no ‘actionable’ information for my own bees it does provide me with some insight into the interaction between varroa and honeybees. For folks like myself with numbers (in the hundreds) it does allow me to be more casual about monitoring and of course to question some of the more prevalent presumption concerning the varroa mite problem. As I suggest to the new beekeeper if I lose a few thru varroa it only reduces my work load but it they lose 1 or 2 quite often this represents a total failure.

    As far as new beekeepers go and for those bees I maintain at the Texas A&M lab the protocol I encourage and operate under is to 1) monitor for mites, 2) treat when necessary (ie exceeding some seasonal threshold) and then 3) monitor again. As far as I know all the treatments have been known too fail. As much as anything else it is good to know when a particular treatment does fail so the beekeeper can consider other options.

    My primary message here is… if treating by schedule is an excuse for not testing/monitoring then it is only a matter of time before this protocol will fail.

    Gene in Central Texas…

  • Here is a data-based counter argument against treating based on information from mite tests, rather than by the schedule: does it improve colony survival as reported by the Bee Informed Partnership dataset? Go to and you can select by year, state(s) and by type of Varroa Monitoring Technique. Note that in 2018-2019, for backyard beekeepers (default is “sideline”, I don’t know why), losses are at 40% for both those who did monitor (any method), and those who did not. Also note that those who only used the alcohol wash did lose fewer – 33% instead of 44% lost. I have a theory about why this is… I think we are not yet optimally reading the alcohol wash results. We aren’t interpreting what they mean for the colony in a way that is accurate. I mean, we are trying to find out the _true_ state of the colony, right? Are there few enough mites to relax, or so many that things will snowball? Trouble is (in my area anyways), the brood rearing in spring/early summer is so intense that mite numbers are just magnified beyond control. A mite count of 1/300 in an alcohol wash in May, June or July – in my experience, it can be a dead colony by December. It can have counts of 15 or higher by September. And some of that is mites that were NOT born in the hive making their way in. That’s the unspoken danger that monitoring is useless against, and that makes calendar treating a viable solution.

    Why isn’t monitoring helping colonies survive better?

  • Oh, but this is not an easy situation!

    We’re trying to compare treating when a treatment may not be required (and I don’t believe that any of the treatments are harmless) vs beginner inability to locate the queen ahead of doing a destructive test, and reluctance at doing the test anyway. It is a steep learning curve.

    There are plenty of ways for people to “save the bees” without keeping bees. I conclude new beekeepers understand what they are getting into. My students all get Randy Oliver’s “Queens for Pennies.”

  • Hi beekeepers, This treatment method is very disturbing to me. I have had many kinds of animals and plants under my care, and the idea of giving medications, applying chemicals, or even …. hold it, this is so wrong in so many ways I can’t believe someone would even suggest this. I don’t like saying these things, but I’m only giving my honest opinion. If you choose not to acquire at least a minimum understanding of your endeavor, then be responsible enough to try something else. There is no shame in admitting that something is just a little too much for me.

  • I agree with Janet’s system for beginners. They are overwhelmed as it is with their new bees, learning how to do this and that. The real problem is that people are permitted to have bees, chickens, bunnies, etc., without any knowledge of what to do to keep them alive. Only AFTER they get the animals do they try to learn about them, if at all. Kind of backwards. I know people who have been beekeepers for 5 to 20 years and still have the knowledge base of a first year beekeeper. It’s too sad. They just replace bees yearly and put them into the old contaminated hive with no thought of what they are doing. They just don’t care. Some of the hives I see haven’t been switched out since dinosaur days. People tend to protect their ignorance. They are replaceable to most of them. They toss them out like they are plastic bottles.

    I find if you give new beekeepers a schedule they can keep that up. I also make new beekeepers give me a weekly mite count from the white board. This is simple for them to do and doesn’t disturb the hive. It’s effortless, thus they may do it. This way I can get a gist of what’s going on and if the mite count is too high or going up, then I can tell them to remedy the situation by mite washes, etc. As a mentor and a teacher, I keep track of all new beekeepers and make sure they do this or that for their first few years. I stress to them that the mite is their number one enemy. I go to their property and check their bees with them.

    We are finding, though, that hives are being overrun by mites in mid-June. They are crashing by July, so one must keep their schedule flexible. Mite washes at least once a month during the flow can help keep these hives from crashing. Also, the August 15th cut off for mite treatments is not working around my area. If treatments are not done by July 15th, hives will start to crash by September. It seems that the mite takeovers are happening earlier and earlier each season. If you don’t treat before August 15th, forget them making it through the winter.

    When I hear beekeepers around me say they wait until after fall flow to treat, I cringe, as my heart knows the hives are goners. People don’t realize that it only takes a week or two to lose a whole bustling hive. If all the brood is infected when they emerge, there are no bees to replace the worn out bees and thus the hive is gone. The drop is in the thousands.

    I don’t mean to ramble on, but this is a peeve of mine ! You ‘hit’ me where it hurts ! It is a good idea, though, to give new beekeepers a schedule to follow. So much of what they teach in bee classes is too much for a newbee and they teach it way too fast. It overwhelms them and they don’t understand because they have never been in a hive or even seen the inside of a hive. We need new beekeeping mentors that can teach a new updated way for the bees and get rid of all the old outdated stuff that they still follow yet is no good to anyone. Keep up the good work Rusty ! You’re on the “A-list”.

    Thanks for the post Rusty. Maybe people will start to do things a tad differently and take care of the bees a little better. Mentors should take more care in what they teach newbees as well, as most forget they are new and have no knoweldge. They offer them mite treatments and then do not warn them of the dangers that can happen with this or that treatment. I should write a book ! What NOT TO DO in beekeeping. ha ha !

    • Debbie,

      Interesting point about the creeping dates. I used to be successful if I completed fall treatment by Sept 1. Then, I was forced to go earlier and finish by August 15. Now I shoot for an August 1 completion. (This is me, the data women, talking about dates, right?)

      I often wonder what is happening. Are there more mites per unit area in the country? Are the mites more invasive? Are the viruses more damaging? Is it a bit of everything or something we don’t understand? It’s all kind of overwhelming.

  • What an excellent article! Full-disclosure – 2020 will be my 3rd spring as a beekeeper. Started in 2018 with 3 hives and headed into this Winter with 14. I am a “semi-retired” entomologist (PhD in 1980) but I had never worked with bees (long story). My expertise have been in bio-control/natural enemies, crop protection, traits/GMO’s, and the seed industry. The advice/protocol based on the calendar does go against standard IPM practices. However, doing “something”, even if it isn’t the “best” practice is still better than doing nothing and that is a key point in this discussion. I am guessing most rookie beekeepers struggle with even the thought of taking a cup of bees – that they just got – and dumping them into a container of alcohol! I include myself in that group. I would encourage this protocol as a one-time or first year activity for rookies. Encourage them to find a mentor (I have several!) and then enhance their expertise in fighting mites. Take care ALL, Ike

    • Thanks, David. Good observations. Truth be told, I still hate the alcohol thing, but I’ve learned its benefit and figure if I can keep my colonies alive and healthy it is probably worth the sacrifice…but gotta say, it makes me cringe.

  • Thanks for the nice shout out, Rusty! You raise the cautionary tale: this year two of our club members, very meticulous, careful beekeepers realized from post treatment mite counts that their late summer mite treatments had either failed or been overwhelmed. They ended up with massive mite infestations that they would have missed had they not both monitored ambient (the daily rate) of mite drop onto the mite counting sheets (easy to do as they both use Country Rubes bottom boards, a great BB and they do not pay me to say that!) and tested for mites. Upon treatment (OAV) the sheets were black with mites. Turns out both beekeepers had multiple mite bomb colonies nearby. Either via robbing or drift, all those mites ended up in their hives and caused a fall meltdown. We are still waiting to see if multiple OAV treatments will allow the colonies to go through the winter. Because at first we were all unsure whether their late summer mite treatments were ineffective, it made most of us go back to our apiaries and do mite counts to be sure we weren’t in the same boat. One piece that came out of that experience is that we must make area wide swarm control/management a priority in spring. Colonies that cast swarms become late summer mite bombs when they set up in the wild sans the help of a beekeeper.

    • Janet,

      I love that you wrote the original comment and this one as well. It helps people think, see alternatives, and learn from the success and failure of others. Great topic, important points, lots to learn. I’m going to experiment with your newbie schedule myself and check out those bottom boards. Thank you!

  • I agree with data, but why do we have to to kill to learn? I kill to eat, but to kill just to count mites seems like a waste and 18th century technology. Can’t we learn a better way? I’m glad we don’t use the alcohol wash on humans!

    • Robbie,

      The other way to think is that we sacrifice a few hundred in order to save tens of thousands.

      Alternatively, you can count with a sugar roll. It is not as accurate, but it can tell you a lot.

  • Rusty,

    I’m a big fan of data-driven treatments., as I live in an area with a Russian Queen breeder. I regularly find hives with few or no mites during testing, which I do not treat. The data lets me know which hives to treat and which queens to replace, I check every month so I can graph out the results in the fall.

    Another aspect that I expected you to mention is the social nature of beekeeping. Treating hives at the same time in a region reduces the chance of drift and cross-pollinating of mites, especially in high-density urban areas. I think it is a good practice for first-year beekeepers who otherwise might not bother at all.

    Our club provides sampling workshops in April and August to demonstrate how to sample mites for club members. We do both a sugar and an alcohol test to compare the result. The sugar roll (which I like to use) is just as accurate as the alcohol wash if you do it properly (based on BIP protocol, with two rounds of sugar), and our workshops bear this out. It does take more labor and time, which is one drawback.


    • Thanks Erik. You make a good point about synchronizing the treatments. I know of several large bee clubs that encourage their members to treat on a specific weekend in order to slash the number of mites that can move around by drift. It works best in areas without a lot of feral colonies, however, so results may vary.

  • In the UK we use open mesh floors (I think you call them screened floors). To monitor mite levels, we just slide a plastic insert (not even sticky) under the mesh and after leaving it there for 5 days or so, count the mites dropped and divide by the days it was in place to give the daily mite drop. If there are more than two a day then treatment is usually indicated, depending upon the time of year. No disturbance to the colony, no bees killed!

    I sometimes do an icing sugar dust on the top bars and brush it into the seams without disturbing the frames (not the same as your sugar roll); an hour later if more than 10 mites have dropped onto the insert I treat further (eg icing sugar every 5 days, or Apiguard or Oxalic acid vapour depending upon time of year. I think we probably maintain lower levels of mites than I see in American literature. I have just completed my series of Oxalic Vapour treatments as every year I experience a mite bomb from nearby dying neglected or feral colonies towards the end of October (using a board inserted under the mesh floor which is much safer for us and less disturbance to the bees) and many of my colonies are dropping zero mites now. This will keep the mites low well into the summer.

    I don’t know anyone over here who does alcohol washes; so much effort and dead bees. But I do encourage all our new and existing beekeepers to monitor regularly.

    I really enjoy reading your posts Rusty, very thoughtful and thought provoking.

    Amanda, President of Brighton and Lewes Beekeepers, UK

  • One of the problems with doing alcohol washes as a means of monitoring is that once you get over 10 hives or so, you begin to randomly select hives to monitor. This year as I was doing my scheduled OAV treatments, I had 19 hives drop fewer than 50 mites 72 hours post treatment. But 1 hive dropped what I estimated to be well over 1000. This hive had had normal drops just the month before. Doing a wash, I might have missed it. As it was, I treated all my hives once per week until the mite count in the 1 hive came back down as evidenced by the drop dead count.

  • After losing all my hives last year even after doing OAV 3 times in the fall. I did no mite counts and am sure I lost them to mites. I bought survivor bees (Old Sol, Saskatraz, German and Kona) and this year I monitored mite counts. Based on using OAV for over 20 years in Europe, they have seen no resistance so I intend to primarily use OAV but will do an Apiguard treatment in late August based on my mite chart. In my location, my hives went from very low mite counts to peaks of 440 to 560 mites in a 6 week period starting in late September. Each hive peaked at different times and I ended up treating 10 times with OAV. All hives are now under 50 with most under 10. The Kona hives had the lowest mite counts and never got over 50. I plan on one more treatment or until under 5 mites. I’m not going to kill 300 bees in the alcohol wash and I don’t think the powdered sugar is effective. I’ll do 1 OAV to test mite loads as someone mentioned above. I think a schedule is a good idea but I think new beekeepers would benefit from doing treatment AND mite counts. An interesting aside is that based on some recent research, it would be beneficial to put hives further apart. My hives sit right next to each other with a Kona with 6 mites beside a New World Carne with 500 mites.

  • Rusty

    Have you tried the thermal treatments for mites? If this really works the way it sounds it could be a good way for us all to be able to get away from chemicals and just do it regularly.
    From what I have read the idea is to heat the hive to 106F for 2 to 3 hours. Kills the mites (and other pests like SHB) both in the comb and on the bees. Not sure how to really control that temp throughout the hive.

    • Herb,

      I don’t know much about it, although I’ve heard that as the temperature rises, fanning increases at a frantic rate to compensate for the heat and lower it. In short, I think it’s easier said than done, but it’s certainly an interesting idea.

  • Rusty, what do you feel about repetitive OA treatments. I read where people are treating weekly for four or five weeks and yet they say “it doesn’t hurt the bees’. My belief is it might not hurt the bees because they only live for four to six weeks, yet the poor Queen gets all the treatments forced upon her and she lives almost two years ! Plus, with repetitive treatments after fall onto the winter bees, they get multiple treatments. Doesn’t this affect them at all? I would think covering them with acid all the time would have some kind of effect on the colony. I must say that I am not a fan of this kind of treatment, yet it’s the ‘in thing’ to do.. The risks of starting the hive on fire and messing with the bees when they are cold just isn’t my cup of tea. Thoughts?

    • Debbie,

      I think you know I don’t like it either. I do not/will not use OAV for a number of personal reasons, but also because I think that, cumulatively, it will hurt the bees, especially, as you point out, the queen and the winter workers—all of which must live a long time. I think it is so popular because it leaves space between the bees and the beekeeper—they don’t even need to open the hive to use it.

      I get lots of reports of beekeepers using multiple OA treatments “but the bees died anyway.” The question then becomes, did they die of mites or die of OA poisoning? I don’t think the answer is always clear.

      At first, OA was used once in broodless periods. Now it seems beekeepers apply it every time they walk outside. I don’t see these folks as beekeepers as much as hobby pesticide applicators. Such fun.

      I’m still using messier techniques that require me to actually go into the hive, such as Apiguard, HopGuard, and occasionally oxalic drip. I guess you could call my technique old-fashioned, uninformed, Neanderthal, or whatever. I will get slammed for saying something negative about OA, but whatever.

  • Just a couple observations.

    1) I see mite counts go way up in my hives when I begin treating. This is because my neighbor doesn’t treat. His (organic) bees realize they’re doomed and come to my hives to survive. This happens every year. If I just treated once and walked away, I wouldn’t be killing the mites on all the new bees that have wandered over to my healthy hives. I’ve come to expect my mite loads to increase when I treat.

    2) Mite application by calendar seems a little like saying I’ll take 2 Tylenol on January 1st, maybe an Aleve on February 15th, and a dose of decongestant on the 3rd Tuesday of March. Would that work for a person? Probably not. We wait for the headache or the pollen, then treat and retreat as necessary.

    • Kat,

      I love to laugh, so you made my day: “Mite application by calendar seems a little like saying I’ll take 2 Tylenol on January 1st, maybe an Aleve on February 15th, and a dose of decongestant on the 3rd Tuesday of March.”

  • I would simply say – do both. Treat- spring and fall. cheap. bees are expensive. Monitor- all the time. Look in front of the hive for bees crawling because they are unable to fly due to mite damage to their wings while developing. Inside the hive, keep an eye out for malformed wings as well. it works.

  • Rusty,

    Love your website. Thanks for another great article. This is a question I have struggled with for quite some time and have had more than one pointed discussion with fellow beekeepers on this subject.. I like the approach of data based treatment but Janet’s comments ring true. I work with a lot of newbees and teach beginning classes her comments and this article are helping to rethink the issue of data vs. date. Thanks,

    Bob Hooker

  • Philosophical question – if one of my colonies has mites, should I treat them all?

    I picked up a swarm recently, did an alcohol wash today, and they seem to have quite a few; I’ll be dropping treatment strips in tomorrow. Then I grit my teeth and did a wash on my also recently acquired nucs, et voila! they appear to be totally clean – altho I can’t guarantee that I did it right (one of them was particularly uninterested in providing enough sacrificial lambs and I decided I had enough stings for one day). I hived the swarm a field away from the nucs, but of course, they are roaming the same overall territory. Should I pro-actively treat the nuc colonies too?

    • That’s a tough one. Logically, I think you shouldn’t treat a colony that doesn’t have mites. But from a practical point of view, if you’re going to do one, you should do them all. In other words, I don’t agree with myself.

      As you already know, drift is the real problem. Drones have nearly zero homing instinct, they just go anywhere they think they can get a free meal. And even workers, especially in a managed apiary with multiple hives, don’t do too well. I’ve heard that as many as 30% return to a different hive at the end of a foraging trip. Hives nearest the perimeter pick up the most, meaning they probably go in the first one they come to.

      This isn’t such a problem with wild colonies because they don’t tend to nest close together. It’s also well known that a worker with a load that’s needed—whether it be nectar, water, or pollen—will be welcomed at the door.

      With that much crossover, mites will soon be everywhere.

  • Now that I’ve slept on it, I realize I left a silly question. Of course, treating for mites when there are no mites isn’t useful; treatments are specifically to kill mites, not impart some magical immunity to the bees. However, I’ve never done alcohol washes before so I’m not completely confident of my results, and my “mite-free” colonies now have a close neighbor (~75 yds) that is definitely infested. I didn’t hive the swarm right next to my healthy hives, or I’d be more inclined to go ahead due to expected drift; then again, they’re likely to be rubbing shoulders working all that clover together. Maybe I should plan to test the colonies again in . . . what, 2? 3? weeks? Sigh. Nothing is as easy as it looks with these little creatures.

  • Welcome to the obsession. Before you decide to rely too heavily on the CO2 method, you might want to look at Randy Oliver’s assessment of it on his site.