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The Classroom

The Classroom – August 2021

- August 1, 2021 - Jamie Ellis - (excerpt)

The Classroom - ABJ - Jamie Ellis
Mite controls

Would you please set up a survey question for readers to respond to regarding their experiences using various mite control products? Ease or difficulty of use, pros and cons, etc. Most controls are relatively expensive in my opinion. Deciding which one to use based on the manufacturers’ advertisements can be deceiving. Recently I bought and used one that was promoted as “The natural solution for Varroa mite control,” “Safe and easy to use.” Then, in the package were the warnings like “Causes irreversible eye damage,” “Use goggles, waterproof gloves,” etc. It turned out to be a gooey, difficult product to use. While installing it, I kept thinking that if I were a bee, I would abscond. $38 wasted in my opinion as I will not use it again. I felt like everything that I touched was contaminated.

Mike Carter
Illinois, June


I really appreciate your question! One of the biggest issues, in my opinion, that we have in the industry today is the relative lack of Varroa control products that exhibit high efficacy in a variety of situations. Most have some sort of limitation, usually temperature related. I live in Florida and many of the labeled products are hard to use for much of the year give the ambient temperature often falls outside the temperature range indicated on the label. That significantly restricts what beekeepers are able to use when they battle Varroa. On top of that, the efficacies of the available products can range from 50-95%. Thus, your colonies can still be left with high mite loads after treatment if they started with really high mite loads before treatment.

The good news is that a survey of product efficacy is not needed. The Honey Bee Health Coalition developed a remarkable guide to controlling Varroa. You can conduct a Google search for “Honey Bee Health Coalition Varroa” and your first option will be the website where the guide and accompanying videos are available for free. The document itself is entitled “Tools for Varroa Management.” Beginning on page 16 of the current version of the guide, every treatment option (chemical and non-chemical) is listed along with its efficacy based on research from various laboratories and reported correlations with lower winter losses according to the Bee Informed Partnership. Thus, the information is packaged nicely in one great document. (For purposes of full disclosure: I am not a member of the Honey Bee Technical Council, neither have I received funds from them. Consequently, I am reporting here what I actually believe to be true. The resource is fantastic.)

One last comment: It is important to know your Varroa infestation rates before AND after you treat. That way, you can determine if the treatment actually worked. Information on how to determine infestation rates is available in the guide and as a video at the same website.


Failing mite treatments

I just finished reading a question in The [May] Classroom from Tina Sebestyen regarding the effectiveness of mite treatments. I would like to share what happened when I treated mites last fall (2020). I have been using Apivar strips successfully for the last few years. I have two hives and have been keeping bees 16 years. Last fall, I tested for mites. One hive had a very high mite count and the other had only two mites. I treated both hives with Apivar. After the 42 days, I tested both hives for mites and the hive with two mites had zero mites but the other with the high count was still over the threshold. I treated that hive a second time with Apivar but did not retreat the zero-count hive.

Long story short, the low mite hive died in January. I took the hive apart to autopsy and determined it died from mites. There were the classic signs of infestation. There were few bees in the hive and the queen was dead, alone holding on to the top of a center frame. Very sad. The few dead bees left had deformed wing virus. There was a nearly full super of honey in the hive. I kept a watch on the other hive which had the large number of mites and thought I would lose it as well. They survived in a small cluster, but they made it. Checking with a sticky board for three days in February, showed no mites. I saw the hive increase and in April I added a medium super. I will be adding another super at the end of this month (May). My question is why did the hive with low mite count die and the other survive?

I too thought it might be the Apivar product. The package had a manufacture date of 2017 but no expiration date. I called the company. The person I talked to said Apivar should not be used two years after the manufacture date. They do not put a “use by date” on their packages. My package was 2+ years out of date and had lost potency. I feel the double dose worked on the heavily infested hive but one dose was not enough for the other hive.

Pat Wackford
Oregon, May


You are asking a difficult question to answer. It is hard to know with certainty. Sometimes, biology can be quite messy with no clear answers. It is very possible that the one hive died to Varroa as you note, even though it was the one with the low infestation rate the entire time (not to mention the fact that you treated it as well). It is also possible that they starved even though they had honey in the hive. Sometimes, cold snaps can cause bees to cluster quickly, pulling away from the food that is all around them. If it remains cold for a period of time, the bees are unable to break that cluster and access the food resources that are even a few inches from the cluster. It could also be due to Nosema, viral loads, etc. It is just really hard to know. Again, though, let us say that it was Varroa-induced. Colonies can be stressed in other ways, ways that would change how they can withstand Varroa stress. In this case, a lower Varroa population can become problematic, when it otherwise would not be in times of abundance or low stress. To put it another way: Sometimes colonies may be able to withstand 5 mites/100 bees while at others only be able to withstand 2 mites/100 bees. The consensus, as you note, is 3 mites/100 bees. Heading into winter, though, you may not even want that level.

You also mention in your question that it may be related to the age of the Apivar strips you used. This, too, could be the case, given treatments lose potency/efficacy over time. I always recommend you check your Varroa populations before and after treatment just to confirm that the treatment worked. If it did not work, the treatment may be expired or simply not efficacious under the circumstances used. You would need to use something else if a particular treatment fails.

Drones and Africanized honey bees

 I have been studying why raising European honey bee (EHB) colonies in Florida helps the Africanized honey bee (AHB) problem. I learned about drone congregation areas (DCAs) and some of the work on DCA EHB/AHB drone populations done by your group. Thinking about how I can manage my hives in a manner that will support AHB control, it would seem that promoting EHB drone production would help. There would seem to be a conflict with the Varroa control technique of maintaining drone comb and freezing it before the drones emerge. Are there any techniques that would promote EHB drone production, maybe some way to move the pre-emergent drone comb to an isolated colony for specialized treatment/development or other drone production methods?

David Camps


A former Master/PhD student of mine (Dr. Ashley Mortensen) conducted the work you referenced regarding EHBs/AHBs and DCAs. This work was part of her master’s thesis. You can find her report on this research here: > research > publications by year > 2016 > Mortensen, A.N., Ellis, J.D. 2016. Managed European-derived honey bee, Apis mellifera sspp, colonies reduce African-matriline honey bee, m. scutellata, drones at regional mating congregations. PLoS ONE 11(8): e0161331.

What queen breeders do is add a frame of drone foundation to certain colonies so that counts of EHB drones are high in the area. As you note, this can lead to greater Varroa loads given Varroa’s preference for drone brood. That said, I would argue that Varroa control in these colonies would follow the same pattern it would in ordinary colonies. I would monitor Varroa infestation rates monthly during production season (March – October in FL as an example) and treat when you hit 3 mites/100 bees (reference the “Mite controls” question above for a great document on Varroa control available for free online). In the case of colonies producing a lot of drone brood, you may hit the threshold more often and need to treat more regularly. Given this, I do not think I would do anything else out of the ordinary.

 European foulbrood

Regarding European foulbrood (EFB): It has been stated by a few that you can get this in the damp spring, and it eventually takes care of itself without treatment. I am not sure that is factual. I am writing you to check the validity of this thinking.

Stan Gore
Texas, June


The conventional wisdom is that colonies will pull out of an EFB infection during a major nectar flow or via some focused attention (requeening, feeding, etc.). It all really depends on how bad it is. Most cases of EFB I see are manageable and bees usually pull out of it. However, some are bad enough that intervention is warranted. This can include treating with an antibiotic (for those comfortable doing that) and requeening/feeding. The requeening part is done because the stock of bees is clearly susceptible to EFB. Thus, requeening might help introduce a more hygienic stock into the hive, one that can address EFB better. Feeding will simulate a nectar flow, during which many bee maladies seem to fix themselves. My team and I put together a thorough document on this topic. You can find it here:

Q  More About European Foulbrood

After finding EFB in four colonies and getting confirmation from a bee lab, I am trying to decide how to proceed. After much research, there is conflicting info on treating vs. just destroying all the comb, honey and pollen and starting again. I watched your two-part video on EFB and AFB; it helped but I read that the bacteria in EFB dies off after two months. Can I set aside and safely store all brood/pollen/honey frames and reuse after two months? If I treat with terramycin or tylosin, will the bacteria just keep coming back year after year? I am trying to decide if I should treat or just burn and start from scratch. Any help would be gratefully appreciated!!



Thanks for the questions. Given it is European rather than American foulbrood (AFB), you have a few options.

1) You can wait and see if the bees pull out of it (which they often do when a strong nectar flow comes and as the colony grows in strength).

2) You can requeen and feed the colonies. Sometimes, both of these help bees pull out of it.

3) You can treat with a labeled antibiotic. Given EFB does not form long-lived spores, treating with an antibiotic should cure the colony of the disease. I think it could be a good idea to treat all the colonies in this apiary. If you do this, you have an … .