Varroa project 2014 –>

This test is accomplished and funded by LP:s biodling bee equipement supplier, Arne Andersson sideline beekeeper and Erik Österlund sideline beekeeper.



The goal for this test is to see if it is possible:

  • to improve mite resistance in apiaries with 5-10 colonies,
  • to understand the impact of ”isolation” of 3-5 km (3-4 miles) to other beekeepers
  • to understand the role of small cell size in the broodnest
  • to see the role of differentiated treatment of varroa mites, that is treatment of only those colonies that exceed a defined varroa level



Avoid silent robbery

The colonies should be managed as similar as possible to a beekeeper that want to increase the number of colonies with an extensive management method. It should interfere as little as possible with the bees activities and avoid disturbing parameters, which could happen when you open the colonies often, like for example starting robbing in nectar droughts. It could be enough with silent robbery, a robbery activity that you don’t notice. That could be enough to destroy a test, in that the varroa populations are evened out

3% strategy

Therefore we decided to maximize the number of hives for the two main groups in this test to 10 hives (5+5). We also decided to make two or three alcohol washes with 1 dl of bees to monitor the varroa level during the season. When the Varroa level was higher than 3% we planned to treat with thymol. If it appeared wingless bees in or in front of a hive treatment was also to be performed.

Use of thymol

We decided to use dish cloth pads drenched with fluid thymol mixed with a minimal amount of rubbing alcohol (to lower the melting point of the thymol crystals) as treatment against mites when decision was made to treat. You can see how they are done and used in this article:

Crop and feeding

If possible a harvest should be taken and sugar solution (or honey) fed at the end of season after harvest to ensure enough food for winter. The goal should be to leave a fair amount of honey for winter, if possible as much as you think your bees have got genetics to make it through the length of your winters.

Nucs and splits

Increase are made by making so called walk away splits that remain in the same apiary as the mother colony. These are allowed make there own queens, or supplied with mature queen cells made from a good colony in the apiary. This should also be the swarm prevention method.

Elgon and Carnica/Carniolan

We choose to use two different types of bees in the project. One type that has been selected for varroa resistance during many years, Elgon, that has been bred with this purpose since 1989. Another type that hasn’t been selected less, but in other traits are good, pure bred Carnica/Carniolan bees.



Increase of the number of colonies

The number of colonies wintered each autumn would be a way to measure the difference in success between the two parts (large and small cell size) of each main group, Elgons and Carniolans. To be counted in the increase would be the colonies that are brought out from the apiaries and the project, a kind of crop. What we measure will thus be the production of new colonies and survival of colonies to the next season, the difference of fitness. If colonies survive to the next season is not only dependent on the varroa and virus levels in the colonies, but also on other circumstances that influence the survival and how a colony thrive, for example other pathogens like nosema and quality of food like pollen throughout the season.

Start and number of years

Instead of starting the project with 5+5 colonies with each type of bees, we have choosen to start from a fewer number of hives and increase the numbers. And we plan to continue the project for at least 3-4 years. We have choosen areas for the test that are low in nectar and pollen sources. That’s also a reason why the number of hives are restricted to five in each part, which makes a total maximum for each type of bees 5+5 colonies, 5 small cell and 5 large cell.



Four Carniolan colonies, all of them being sister queens from a pure bred Carnica/Carniolan stock, were divided in two groups with 30 m between the groups. These groups were placed in a deeply forested area far enough from the Elgon bees. Here it was no farm in the neighborhood, like it is where the Elgon bees are placed. One group was established on Mann Lake’s standard plastic frame, 4.95 mm cell size. The other on Anel plastic frames with 5.5 mm cell size. Frame size medium (448 x 159 m). Hive type well insulated styren plastic boxes.

The Carnica bees 2014-2015

The Carniolan queens we received in 2013 were introduced into Elgon small cell (SC) colonies on 4.9 mm cell size shallow sized frames (448 x 137 mm). The Elgons are adapted to SC during many years and if nurse bees fed and born in SC should be of importance that criterium should then be met for this test. The Carniolans in their homeland could not draw and thus live well on ”SC”. Here they were adapted immediately through this process, but they could not draw wax foundation 4.9 well even though they lived well on 4.9. Probably because they were not genetically adapted to small cells. Mann Lakes 4.9 they could draw well. Probably because of the high plastic cell wall starters which they couldn’t remodel

In 2014 half of the Carniolans got only Mann Lake’s 4.9 (SC), half got Anels 5.5 (large cell, LC). During 2014 they were this way transferred to these two types of frames. Increasing cell size in the LC-group up to 5.5 was no problem either as they were adapted to 5.5 in their genetics before they came here.

All the Carnica/Carniolan colonies were treated with thymol in 2013, but not much, and in September 2014 after they were moved to their test destination. No DWV-bees were observed in 2014.

The LC part of the Carnica bees 2015

In 2015 in June the LC-group (both colonies) showed 6% varroa level and crippled winged bees, one colony quite badly. They both got one treatment with two homemade thymol pads with about 5 gr thymol each. The LC-bees gave no crop. The Varroa level had not increased again very much and was only about 1 %.

The SC part of the Carnica bees 2015

The SC colonies had 0.3% and 1% varroa level respectively. In beginning of June a so called walk away split was made from one of the SC-colonies. The new queen then of course mated to very closely related drones.

The strongest SC-colony gave a small crop.

In September the SC-colonies still had only around 1% Varroa level. None of the colonies got any treatment in the autumn due to the low varroa levels. The SC-colonies thus got no treatment at all in 2015.

The Carnica bees 2016

The LC part of the Carnica bees 2016

The weakest of thee LC colonies didn’t make it through winter. The second one looked fine in May.

The weather was then rainy and chilly for several weeks, and when the beekeeper returned in late May to monitor varroa levels, in the remaining LC-colony he only found some dead brood and a few dead bees on the bottom.

The SC part of the Carnica bees 2016

In spring 2016 the now three SC-colonies were doing fine, two of them though small in size.

In the three SC-colonies the varroa levels were 3-4% in late May and some crippled winged bees appeared. Thymol pads were applied in June. A walk away split was made from the strongest SC-colony. The weather was unfavorable and the other three robbed the split. It thus died.

In September the three SC-colonies looked fine and got no treatment. The bees superceded the three year old queen.

The Carnica bees 2016-2017

The three SC-colonies were moved to an apiary with better resources for nectar and pollen. Some more pure bred Carnica queens were received in 2016. They will be used to biuld up the test apiaries again. Daughters will be bred from these and mated in the apiary with drones from the survivor colonies of the SC bees.

The whole season of 2016 was bad in producing nectar and pollen. The colonies had a hard time growing in size. It was late in the season when complementary feeding in preparation for winter was done that they grew somewhat in strength. That was the reason these bees were moved to a better place for food.

All three colonies actually were weaker than wanted going into winter. Two colonies made it through winter. The third and weakest died. This colony had probably survived if it had been fed honey (or fondant) and pollen during the worst nectar- and pollen drought periods.



Six Elgon colonies of two different mother lines divided in two groups with 3 colonies each were set up. These groups were placed in a deeply forested area with a small farm in the neighbourhood. The two groups were placed about 700 meters from each other. One group got Mann Lake’s standard plastic frame with small cells (SC), 4.95 mm cell size. The other got Anel plastic frames with Large cells (LC), 5.5 mm.

Two sister groups were used. One sister group consisted of 4 queens, 2 SC and 2 LC. The other sister group had two queens, 1 SC and 1 LC. Frame size is medium, (448 x 159 mm). Hive type with well insulated styren plastic boxes.

The Elgon bees 2014-2015

The Elgon groups were established with new queens in 2014 and transfered successfully to Mann Lake’s 4.9 and with big difficulties to Anels 5.5.

The queens in the LC colonies were very hesitant to lay in their large cells. One queen totally refused.The broodnest of that queen consisted of only two shallow SC-frames. The resulting colony was of course small going into winter in 2014, but it wintered together with the other two LC colonies in their test apiary.

Most of the colonies, SC and LC, were treated in 2014 with thymol but mostly only in May. So this Elgon test groups of 3+3 were not managed in regard to the Varroa mites, similar to the Carnica groups. In the Carnica colonies the varroa populations were evened out between them, by treating them with home made thymol pads in September 2014.

The Elgon test colonies were taken from different apiaries and the varroa level in the colonies were not known when they were brought to the test site in late August. Earlier in 2014 the colonies who had wingless bees were treated with thymol, in May that was.

The LC part of the Elgon bees 2014-2015

In spring 2015 the Elgon LC group continued to create problems as the bees protested against using LC combs for brood by supersedure their queens, probably in an adaption process.

In April before grafting time and any drones were flying one LC-colony was queenless. The new virgin queen had of course failed to mate and was gone. I combined the queenless colony with the mini colony (the one with the queen that had refused to lay but in the two shallows). This queen still refused to lay in any other comb than the two shallows, so I tried to fool them by giving them a couple of 5.3 mm cell sized plastic frames on each side of the SC combs. That worked. When the 5.3 were filled on each side of the 4.9 they started on the 5.5 next to the 5.3.

It seems it is the workers that prepare the cells for laying, not the queens that are deciding in which cells to lay. (This experience is also in line with what is written in old books from beginning of 1900, that when broodnest have 5.1 you could use 5.6 in honey supers without excluder as the queen didn’t lay in the 5.6.)

In late April 2015 the third (now the second as the other two were combined) LC-colony had a virgin. They were also trying to supersedure their queen. No drones available yet. So she failed. The colony got a queen cell in second half of May. That queen got laying. This colony had 5% varroa level in August and got thymol.

The first colony (former first and second combined) got a small piece of thymol (actually both parts that were combined got half a piece each) early in spring to help against eventual patoghen problems as they had different kind of problems (weak but queenright and queenless). This colony showed only 0.3% Varroa level in August and got no treatment.

The SC part of the Elgon bees 2014-2015

In 2015 the three Elgon SC colonies developed well. Splits were made from two of them. One failed, but finally got a laying queen very late in season. It ended up weak. It was lost during coming winter, the only loss of the Elgons. The smallest of the overwintered colonies had a queen that was laying badly. It was killed and replaced by a ripe queencell.

Four of the now five colonies showed crippled winged bees in July and had Varroa levels between 2-7%. Even the 2% colony showed a few DWV-bees telling me the virus levels in the colonies were quite high. One 3% had no DWV, the weak one mentioned above and it was the only one that didn’t get treatment.

Because the varroa populations in the colonies weren’t allowed to grow strongly (still there were enough viruses in 2015 after years of somewhat higher varroa and virus pressure in the Elgon apiaries of Erik Österlund), the virus amounts in the colonies decreased and also there was no silent robbery. And the varroa populations were evened out at a low level. Thus the situation now was much more comparable with the varroalevels in the Carnica colonies in autumn 2014

The Elgon bees had better nectar flows than the Carnica in 2015 and the Elgon colonies gave a good crop from the Heather in 2015. The average crop was about the same for both SC and LC colonies. In August none of the SC Elgons had above 3% varroa level. They had 0%-3%, and got no more thymol. No colony swarmed in any of the test apiaries.

The Elgon bees 2016

In spring 2016 one of the Elgons, the very weak one in the SC-group died (as mentioned above). Both LC colonies survived.

The LC part of the Elgon bees 2016

In the LC-group splits were made from both colonies. Weather was bad and one failed to produce a laying queen. It got a new ripe queen cell. The parts with the ”old” queens (from the year before) both superseded their queens, in line with experiences in 2015. This year they waited until beginning of summer when there were drones around. Maybe the bees had adapted somewhat to LC now.

The season of 2016 was very bad so no crop was secured from the LC-group. In spring the varroa levels were 0.3% in all four colonies (they became four after splitting in late May). In early September it was 0% – 8.6% – 0.9% – 4%. The two with highest levels were treated with thymol. The other two not. We can see that two colonies had very low levels of Varroa mites. This indicates a good genetic set up for Varroa resistance, also to be able to work with large cells apparently. The queens in the colonies with low Varroa level are sisters, mated in the test apiary. They are daughters to one of the colonies in the apiary, one in a split. The other as a result of supersedure in the mother colony producing this split.

The SC part of the Elgon bees 2016

The four remaining colonies in the SC-group gave a split each. Season was bad and two of the splits failed. A small crop was secured from the strongest of the colonies.

The two colonies with two year old queens supersedured these later in season. The 6 colonies all had 0.3% varroa levels in spring. In August the varroa levels were between 0-1.7%. As we had decided not to keep more than five colonies in each of the four parts of the test, colony no 6 of the SC-ones (the one with 1.7%) was removed from the test area. It wastreated with a small amount of formic acid to get an idea of the mite load and also test the shaker method. It fell 10 mites in a couple of days. The other 5 colonies remaining at the test site didn’t get any treatment.

The Elgon bees in the beginning of 2017

All four colonies in the LC group wintered well, in spite of that two of them were almost too weak, those that had had the highest Varroa levels and been treated.

One of the five SC colonies defecated a lot on the outside of the hive, though not much inside. They did not have a large amount of honey left for winter the previous autumn. And it was of good wintering quality. The winter before all colonies had had a large amount of difficult winter honey, from heather. The colony that died was the strongest and smallest Varroa level. It measured 0% on 400 bees. The was a good amount of food left in the hive after it had died. The colony had an old queen, and just a few meters there had been quite some traffic during late winter from a tree harvester. The other colonies looked fine, with almost no defecation.

Harvest and Varroa level 2015 and 2016 in SC and LC parts of the Carnica bees. The sites for Carnica and Elgon bees are not comparable as the Carnica site was didn’t have the same amount of food sources. Click on the picture to get it bigger and of better quality.


Harvest and Varroa level 2015 and 2016 in the SC and LC parts of the Elgon bees.



The losses in the Elgon groups have been quite normal, on the lower side. It has in percentage been higher in the Carnica groups, especially among the LC bees. The higher amount of losses can be explained by the low availability of pollen and nectar, especially during 2016. That’s why the test site for the Carnica bees has been moved. One conclusion is that during times with small amounts of available pollen and nectar a solution could be to feed the colonies fondant/honey and pollen to develop healthier and stronger colonies better adapted to survive winter.

The strategy of 3 %

The strategy to measure the Varroa level a couple of times during the season and use Varroa treatment (dish cloth pads, about 50 x 58 x 1.5 mm [2”x2”x1/16”], drenched in thymol) when/if the Varroa level is higher than 3 % (only treatmnent in these colonies, not in those below 3 %) has minimized reinfestation, maybe altogether. You thus get a true picture of the Varroa level in the colonies and thus a better selection of the most resistant colonies and the most susceptible ones. You could for example have expected that the different cell size groups had affected each other so that eventual difference in the varroa levels had evened out, especially among the Carnica bees as the two groups there were only 30 m apart.

Little need for Varroa treatment

Relatively little of Varroa treatment has been used, probably partly explained by the absence of reinfestation, no silent robbing. Most treatment has been used in the LC colonies of both the Elgon (2016 when reinfestation had been removed) and Carnica (2015, in 2016 there was no LC left) colonies.

The strategy of 3 % seems to have eliminated the need of Varroa treatment in the SC part of the Elgon bees due to elimination of reinfestation and enough good development of the varroa resistance with the Elgon bees.

This strategy has also lessened the need for varroa treatment to every second year with the SC part of the Carnica colonies and the need for treatment then has been small. Thymol in this context has been effective.

Cell size and fitness

In the LC part of the Carnica bees the need for treatment has been bigger probably because of a quicker development of the Varroa population. It seems fitness has been lower here probably partly due to the bad pollen and nectar availability. But fitness may also be lower because of other reasons. The Carnica LC colony that died in May did not die due to high varroa level. Lack of protein and/or other pathogens (like nosema) can be the cause. The Carnica test site is moved to a place with better food sources.

One can object to this conclusion of lower fitness for LC bees because the number of colonies are low.

On the other hand were all original queens in the Carnica group sisters and all colonies in SC and LC groups (Elgon and Carnica) are behaving consistent in this respect. And any difference in fitness between the two cell size groups among the Carnica bees should have been to the advantage of the LC colonies because the SC colonies had become inbred. Usually follows a lower immune system with inbreeding. Possible impact of this small distance would have been small(-er) difference in the varroa levels between the two groups due to evening out of the varroa populations. The 3% strategy, measuring varroa levels and treatment when it was above 3%, lowered the varroa populations enough to eliminate (totally or enough) the silent robbery.

In 2016 the only colonies that needed treatment were in the LC colonies of the Elgon bees. It should though be noted that with a stock of bees that have been selected for Varroa resistance it is possible to find colonies that are resistant also on large cells. Two colonies (with sisters queens) had very low levels of Varroa mites.

The honey crops, the bee strength of the colonies indicates, and the resulting number of colonies in the SC and LC parts of the stocks of bees indicates that it is no disadvantage to use small cells in the broodnest, rather the contrary.

 Summary of production of new bee colonies, increase in the number of wintered bee colonies. These figures could be seen as a measure of the vitality of the different cell size groups. There is a difference to the benefit of SC bees both in the E group (Elgon bees) and the C group (Carnica bees). Click on the pictures to get them bigger and of better quality.


Suggestion on a breeding program for increasing Varroa resistance in a bee population. The background for these suggestion is the results of this project, so far.


Reworked website with new info

Hello dear beekeepers!

I’ve been reworking my old website. not my blogs. The English part became ready enough to be published and I launched it on


There are quite some new material there. In the article “Resistance breeding” some of the experiences from 2016, very positive and quite important experiences. On that topic there will be more info later on.

This website is so called responsive, which most are these days. It means that it automatically adapt to different screen sizes, down to that of a cell phone. It’s made with and easy working and free app called Rocket Cake.

Reinvasion is worst

Last year 2015 was a bad year for the bees in more than one respect. Long cold spring and bad summer. But late summer was good as was the autumn. The bees could recover and prepare for next year.

Fresh pollen was low in spring 2015 . The immune system wasn’t at its best. And the bees couldn’t fly as much as they needed. Where nosema was present it could infect new bees instead of disappear with sick bees as those couldn’t make it back to the hive.

I treated more hives and used more Thymol last year than I had done earlier years. Early in the season I saw what was coming and decided to try some new strategies to get forward on the path to better Varroa resistance and finally get rid of chemicals.

Leif Hjalmarsson

Very often I have reminded myself of the experiences from an apiary of Leif Hjalmarsson in the southern part of Sweden. He got 5 Elgon queens from me already in 1997 and established an apiary at least 2 miles from other bees. The bees to which he introduced the queens had been treated with Apistan for about 5 years and were very low in number of mites. The bees had probably been adapted somewhat to the presence of the mite. Leif used large cell size, 5.4 mm. He never had to use any miticide on those bees until he died early this year. I do miss him! He was dear friend and a good beekeeper.

Already when we started to combine the Monticola bee with our Swedish bees there could be seen resistance traits. Therefore I had hoped that Varroa mites would be no problems when they arrived in my apiaries. This would not be the case. Even though I had as well regressed my bees to small cell size, 4.9 mm.

I have been wondering since 2008 when the mite started to create problems, why they were a problem for my bees with me, but not for “my” bees with Leif? Last year I decided I had to let the fact that Leif Hjalmarsson established this apiary of his more than 2 miles from other bees affect how I designed my bee management. I want of course to get better resistance with my bees in my apiaries.

A lot of focus had to be put on avoiding reinvasion, bees picking up mites from colonies with high infestation level of mites, within my own apiaries and others within about 1.5 miles.

Better selection 2015

But the difficult circumstances for the bees last year also meant that selection pressure was stronger and it was easier to choose a good breeder, if there was any. And there were good breeders, especially colony S241 which I have mentioned in an earlier blog post, but also C243. I introduced many new queens in my colonies last year, especially from S241. I had only found one mite in S241 in the brood when I tried to found out the VSH degree. And that mite had no offspring.

1. Project 1, 3 miles from other bees in a forested area started in autumn 2014. I had not treated the colonies in this project in that autumn when the project apiary was established. During 2015 I treated a couple of colonies when they showed crippled winged bees. The varroa level was not alarmingly high, so virus effects came early in infestation. Evidently reinvasion from the colonies with DWV didn’t occur very much to the other colonies in the project apiary, as in autumn 2015 varroa level was low in all colonies. Varroa level was also very low this spring 2016, and so it is now late in summer 2016.

Bee shaker1 The Bee Shaker is a valuable tool in getting a quick and easy figure of the Varroa level in the bee colonies in an apiary. Type in the search box: Bee Shaker – at the top of this blog, and you will find more info about it.

2. Project 2 started late summer 2015 as I treated all colonies in an apiary 1.5 miles from other bees of mine with an effective pesticide/miticide in August that year (I hated to do use it), to mimic somewhat how the apiary of Hjalmarsson was established. The varroa level now in August 2016 was surprisingly low, almost not detectable. It was in this apiary I had planned to reduce Varroa level by removing all capped brood frames twice with a week in between, in those colonies showing higher Varroa level than 3%. The highest level now in August was 0.3%.

Bee shaker2 The Bee Shaker will help you to decide if any colonies has to be removed (or any other action taken) from your apiary in which you are developing the Varroa resistance in your bees. It’s a simple and quick method, but you kill 300 bees. That is though nothing compared to numerous bees dying if you do nothing. Viruses and mites killing thousands of bees besides the normal die offs from worn out bees in their daily work, where tens of thousands of bees are dying.

3. Those colonies I decided last year I would shift queens in this year, I treated with thymol in April/May this spring even if they showed no signs of Varroa or virus symptoms. With this I think I secured that those colonies wouldn’t produce mites that could reinvade the other colonies in the apiary. These kind of apiaries are the most numerous of mine. I have not checked the varroa level in all colonies spring and late summer in these apiaries.

Up til now in late August 2016 I have found this odd colony in just a few apiaries, showing one wingless bee. I have tested those colonies with the bee shaker for the Varroa level and only found a few colonies with a Varroa level higher than 3 %.

In one apiary I had this colony with a decreasing varroa level during the season. Three weeks after the early August measurement with just above 1 % Varroa level, I made a new measurement. Now it showed 5 %! Too many mites for the colony to have produced it during these three weeks. Less than a mile away there is another beekeeper, with Elgon bees, but not selected for Varroa resistance for some years. No wingless bees. The colony had probably picked up the many mites from one of his colonies. I didn’t treat, but gave it a sticky board on the bottom to check the natural downfall. And a new Varroa level check will be done in a month. Hopefully this colony will be able to reduce the Varroa level. We’ll see.

An apiary at the edge

Let’s look at one apiary at the edge of “my” Elgon area. With that I mean that drones from other beekeepers’ bees can influence the matings of virgin queens. Also the risk of reinvasion is of course higher. Last year was of course not only difficult for my bees but also for the bees of other beekeepers. In this apiary I treated two colonies quite a lot last year, and also this spring and shifted their queens. The other colonies in this apiary has not been treated this year. But they were all treated last year with Thymol. Now in August I saw a bee that looked like it had the beginning of wings being crippled in one of those colonies. So I tested the Varroa level, 4 mites in 350 bees = 1.1 % Varroa level. It got no treatment of course. Very pleasing result.

A couple of small apiaries

I have a couple of small apiaries in which I checked all colonies with the Bee shaker in spring this year, 0 or a couple of mites in 300 bees. No colonies treated this spring as I didn’t plan to shift any queens this year. I had shifted some last year. I checked these apiaries now in August.

In one of the small apiaries with two colonies and a split I found 4 mites in one of the big colonies and 32 (!) in 300 bees in the other. This was too many in the later colony for it to be able to produce them by itself. No crippled winged bees. Also a sign of that those mites were picked up from somewhere else. This colony had a history of needing Thymol every year, so I chose to treat with Thymol and am planning to finally shift the queen next year. 500 meter away is double the amount of hives of another beekeeper (with Elgon bees which were not from my selection in recent years). He had had problems with one of his colonies.

The situation in the other small apiary will be described later in a blogg post of its own.

Avoid reinvasion when bees adapt

The conclusion is that it’s very important to avoid reinvasion of mites when your bees are developing their ability to control the Varroa mites. They need mites to do that, but no or few extra mites from other colnies that makes it more difficult for them to survive.

On the other hand can the explanation for the better varroa resistance with my bees, as it seems, partly be explained by the fact that I shifted quite some queens last year to S241-daughters. Bess from their colonies will drift somewhat into other colonies, as bees from all colonies do. In this case these drifted bees may well help controlling the Varroa level and possibly also teaching the original bees of the colony to fight mites better.

Genetics is of course important when bees adapt, changes in the composition of the DNA. Selection by culling the worst and multiplying the best. But bees adapt too quickly for the genetic changes to explain in all. Epigentic changes is of uttermost importance here, changes how the existing DNA is expressed, how it’s used. It’s impossible to explain the resistance developing in S. America and S. Africa in about 5 years in any other way. As epigenetic changes occur when environmental changes act upon the chemical environment closest to the bees. The precense of the Varroa causes chemical changes in the bees, in the brood cells, etc. These epigenetical changes are inherited to next generations until new environmental changes cause other epigenetical changes. We understand that chemical help against Varroa will hinder the bees’ own control mechanisms to develop fully. There will be a balance act of avoiding all kinds of miticides as much as possible without letting the bee colonies die. Avoiding reinvasion will be very important then helping the bees developing their control mechanisms fully.

As was pointed out in a previous blog post, my bees are held on small cells, which may contribute to the very low overall mite level. The mite level in Leif Hjalmarsson’s apiary he didn’t treat for many years was at least in the beginning when we measured substantially higher. He used large cells.

I’m convinced that when the bees have learnt how to control mites effectively they can handle reinavsion of mites as well, maybe also in larger numbers. I would call that VISH (Varroa Intruder Sensitive Hygiene.:)) I suspect this can take some years. Then they probably sometimes need some reinvasion to keep their skill at a high level.


Last year I saw more wingless bees than I had expected and I used more thymol than I had expected. I realized that I could partially thank the bad weather fort thias. The bees had got too little of pollen. Their immune system was not at its peak.
It was not easy to find suitable breeder queens, ie, who showed great varroa resistance. I found a colony that had not needed varroa treatment for a few years and it had not had any wingless bees. VSH test could not be done as I found only one mite in more than 100 pupae. And this mite had no offspring. So if you would allow it to determine the VSH-level, this would be 100% VSH. However, the so-called statistical significance was non-existent because of the low number of mites (just one single one). Well, the low number of mites were decisive. S241 was last year’s most important breeder colony.
This summer, I have not seen much of mites and almost no wingless bees so far. Some odd mites in 4 colonies, of more than 140 hives. Well, those who got the most thymol last year, got Thymol in May this year and then got its Queen replaced. So that’s one explanation, about 15 colonies. A colony that was a split from one of those 15, which raised a queen of their own was the first. Due to it’s history it got Thymol as soon as I saw the wingless bee. The queen will be shifted.

A problem hive had got a daughter of S241 last year. A Beeshaker test though showed 0% varroa level. Viruses still a problem in spite of no mites? 

The other day I saw a wingless bee on the hard board in front of the entrance of a colony that had got a lot of Thymol last year. It did not get Thymol in May as it was shifting its queen in May, I found a dead virgin on the hard board and drew that conclusion. I decided to make a test with the Bee shaker due to the wingless bee. I did it yesterday, July 20, 19 mites out of minimum 300 bees , 6.3% varroa level. The hive got Thymol.

1DWV 19 mites, 6.3% Varroa level – Thymol.

Today I came to an apiary with a daughter of the 241 (introduced in 2015) which have had no need for Varroa treatment in a couple of years, neither 2014 nor 2015. This colony was now a strong colony that given a good crop. With still some time to go for eventual more honey to come.

241d No need for treatment for a couple of years (2014 and 2015) plus probably this year. Actually lower Varroa level now compared with spring ( at least not bigger).

In May, I tested interesting candidates for being breeders with the Bee shaker. This 241-daughter was among those of course. The Varroa level was 2%. I didn’t give it Thymol as this was not more than 3%. I had several colonies, including several 241-daughters, that got only a few grams of thymol in spring 2015, which showed no mites at all (zero) out of more than 300 bees. The two best with different heritage (one was a 241-daughter) I used as breeders this year.

1% 4 mites, 1,3% Varroa level now.

2% -colony I tested today July 21 regarding the Varroa level, 4 mites out of a little more than 300 bees. 1.3% infestation level. At least not higher Varroa level after 2.5 months. A strong hive that has given a good crop. The Varroa level would have been much higher if the bees could not get rid of mites themselves. This colony has thus been able to get rid of mites by themselves. What a great feeling!
Now this does probably not only depend on the queen. It was introduced to a colony that had not needed any treatment for at least a year. The worker bees might have learned the new queen’s bees some tricks how to deal with mites. It would not surprise me if there is a combination of reasons for the mite fighting ability of this colony.

The Bee Shaker – where to take the sample

It has been discussed where to take the bees when making the test for infestation level of Varroa mites with the Bee Shaker. From a brood frame or just near the brood. The first week of May, I did a test with the Bee Shaker of a number of bee colonies. After that I inserted sticky boards to collect the natural downfall. This happened to coincide so that two colonies tested with the Bee Shaker also got sticky boards. The sample of bees for the Bee Shaker were taken from the middle of a the super just above the queen excluder.

Skakburksprovtagning A good compromise place to take the beesample from to the Bee Shaker is in the middle of the first super above the queen excluder. You don’t have to look for the queen. Not close to the entrance where the number of mites are fewer than average. And not far awav from the brood, when there are many honey supers. The number seems to vary more there.

Those colonies tested were choosen as I had found them to be potential breeders. The two colonies mentioned both had one (1) mite in the Bee Shaker out of about 350 bees, ie about 0.3% infestation level. Three weeks of natural downfall thereafter gave 7 mites from one and 8 from the other. The sticky boards covered almost the entire bottom. Let’s say I missed seeing two mites. If so it was thus about 0.5 mites per day.

Multiplying this figure with 120 I have heard gives a figure for the total number of mites in the colony. 0.5 x 120 = 60 mites in total then. The number of bees in the colonies were at least 30 000. But let’s say it was 30 000. Then 60/30000 would maybe give an infestation rate = 0.2%. But now I’ve seen reports that one should multiply by 30 (20-40). Then it will be completely different figures (in “favor” of the Bee Shaker). Collecting natural downfall should be done during the normal brood period, not in the very beginning or the very end of the brood season. In the case of the natural downfall of varroa mites, mites will also come from mites emerging from brood cells that have hatched during these three weeks. The natural downfall should therefore have given more mites compared with the Bee Shaker if these methods should have given corresponding figures. Therefore, the conclusion should be that the Bee Shaker revealed a greater proportion of the total number of mites in the hives than the natural downfall did.

The Bee Shaker could therefore be trusted to be an enough reliable tool to show infestation levels of Varroa mites, when samples are taken close to the brood, but not from brood frames.

Wingless bees and varroa level

Before varroan came there could be seen occasional bees with undeveloped/deformed wings in spring. Maybe it was the influence of DWV, Deformed Wing Virus. But it may also have been chilled brood. During the final phase of the pupa development to finished bee the wings are formed. Cold nights and too much of brood could maybe have caused undeveloped wings.

Today, one can probably assume that when you see a wingless bee, it’s DWV responsible. Varroa mites are paving the way for many viruses into pupae and adult bees that had not previously bothered bees. Moreover, these viruses multiply in mites. So today mites spread viruses more efficiently than when the mite had just arrived in Europe. Why that is so is another interesting discussion that probably involves the use of miticides.


The Bee Shaker

The Bee Shaker is a great way to keep track of the level of mites in the bee colony, especially in spring and late summer, so the amount of virus can be kept reasonably low by allowing people to fight the mite if it exceeds a certain degree of infestation. (If that is the strategy chosen.) A good benchmark that many use today is 3%, three mites on one hundred bees (9 mites in 300 bees/1 deciliter of bees).

It also means that to develop a bee stock towards better varroa resistance, you don’t treat against the mite, especially below a mite level of 3%, whenever in the season it is measured.

But if there are wingless bees in the bee colony? It’s usually a sign of DWV and thus too many mites. Here is the Bee Shaker again a good tool, to find out if there really is a high degree of infestation of mites when you see a wingless bee. If you decide to treat against mites if the level is high you might do it to prevent the spread of mites to other colonies nearby.


A colony with a wingless bee

Last year’s breeder queens seem to have produced many queens that have given colonies that control the mites quite well. One of these daughter queens was introduced to a colony that had problems with mites. Perhaps the biggest problem was virus.

This colony was quite weak in this spring and developed slowly, compared to the other colonies in the apiary. I concluded that I would have to check the brood nest to find out the cause. Maybe the colony was shifting their queen?

On a later visit to the apiary about June 20, I saw one, only one, wingless live bee on the hard board in front of the entrance. I then looked in the brood nest, but saw no more wingless bees on the brood frames. But the brood frames had a so called shot gun pattern with a lot of “holes” where you would have expected capped brood as the other cells on the comb contained capped brood. Many pupae seemed to have been removed by the bees. Most likely not due to inbreeding as the queen had mated in the apiary and the number Elgon colonies in the neighborhood was quite high. No trace of any brood disease could be seen so I concluded that a likely cause could be cleaning out of varroa-infested brood. Or could the bees detect virus in the pupae and remove it, without there being a mite in the cell, and remove the pupae?

Could that be the reason why the colony developed so slowly – that the bees were throwing out mites? How had they managed? The wingless bee could indicate that they had not done so well and that the amount of mites was big. Now it was time for a Bee Shaker test to find out the level of Varroa infestation. (Here you can read more about The Bee Shaker, its uses and possibilities:

Here you can see a video clip when doing this test (sorry I’m talking my mother tounge Swedish):

The sample showed zero (0) mites! Then it’s no use to treat, There were far too few mites in the colony. Why had there been a wingless bee recently before the test?

VarroaVirus The brood frames looked less spotty and the colony stronger.

July 8 I was visiting the apiary again. Once again I saw a wingless bee on the hardboard. But now I knew the Varroa level was low. Still no use treating. I looked in the brood nest. The colony was a little stronger still and the brood frames had fewer “holes”. The bees look healthy. They were recovering.

Virus apparently remain in the colony for a while after mites are eradicated – by the beekeeper or the bees.

Keeping track of the infestation level

In the search for breeders for this season I tested a number of hives for the infestation level of Varroa mites in the beginning of May. Those choosen had not been treated for mites either not at all last season, or very little with thymol in the spring last year after showing an odd wingless bee. This was before the time of the Beeshaker with me. Better hade been to use the Beeshaker before using thymol to really know the infestation level.

I used the Beeshaker (more info about it and how to use it: There were colonies with 0 mites from somewhat more than 300 bees. The best of those I use as breeders this year.

I also gave a number of colonies a thin tray with a coarse mesh that bees couldn’t pass hrough. High enough from the bottom of the tray so the bees couldn’t clean the tray. It covered almost the entire bottom. The purpose was to collect natural downfall of mites over a period of time.

I send some queens abroad and the Board of agriculture wants to be sure I have no tropilaelaps mites and no small hive beetles. (Both of those two pests have not been found in Sweden, tropilaelaps not even in Europe, the small hive beetle only in Italy.) Three weeks before the veterinary and the bee inspector came to visit for checking my bees I inserted these thin trays. Of course the inspector and vet also checked for American foul brood.

Varroagaller Varroa trays for checking natural downfall of mites. The one to the left without mesh cover.

Two of those hives I had checked with the Beeshaker got a tray. Three weeks later one of them had 7 mites on the tray. The other had 8. The bee shaker had given 1 mite each for these two hives.

1 mite per 300 bees is 0.3% infestation level on the bees (not counting the mites in the brood, those are usually at least the double amount).

Let’s say I missed 2-3 mites of the natural downfall. That would then be 10 mites in let’s say 20 days for easy math. That gives 0.5 mite per day. It’s been said that natural downfall per day during the brood season multiplied by 120 gives about the total number of mites in the colony. That would make 60 mites in total in those two colonies. The number of bees in those colonies were more than 30,000 each. But let’s say it was 30,000. If we divide 60 by 30,000 we get an infestation level of 0.2%. This level is though including the mites that had been in the brood during these 20 days, so the figure is not directly comparable with the 0.3% to confirm that the two methods give about the same result. The estimation of multiplying with 120 and other uncertainties makes comparison and/or the methods not exact anyway.

Does this comparison give an indication that these methods are good enough for checking the varroa infestation? Both methods have been used by others to decide when to treat or as a selection help for varroa resistance.

When the infestation level is so low as given above, it’s not possible to check the VSH trait either, as you will find too few pupae with mites. You can ask yourself if it’s at all necessary to test for mites anymore. I agree. But all my hives are not as good as these and reinfestation occurs. So I think I have to keep track in some way. Not in first place I think to find the best ones, but to find the ones with most varroa so I can protect the others from reinfestation.

The perfect resistant colony is of course such a one that is not very much affected by reinfestation, not letting in bees with mites on them for example. I will test colonies in August as well and I will check the hard boards in front of the hives for crippled wing bees or grey young bees crawling around as indications for viruses following to high varroa infestation.

Varroa resistant worker bees

Magnus was a beekeeper in his youth in western Sweden. He quit in 1996 but started again in 2013 with his wife Ulrika. Then they bought from an older beekeepers a pavilion with seven bee colonies, most of which were splits, new colonies.

Varberg1 It was a big pavilion on wheels that they bought.

It was not crowded with bees where this beekeeper lived from whom they bought the bees. Maybe a couple of miles (3 km) to other bees than his. He treated with oxalic acid against Varroa once a year. Nothing more was used for keeping the Varroa population down. And he bought a Buckfast queen now and then to help the genetic variation.

Varberg2 The hives in the pavilion are long hives with 30 combs 12″x12″ (30 x 30 cm).

The pavilion was moved to Magnus and Ulrika in September. They saw wingless bees from three colonies. Two of these were splits from the third. Of the other four were at least two splits from one of the rest, No. 9. The fourth, No. 10, appeared to be related to No. 9, because of the behavior and appearance. Maybe No. 9 was a split from No. 10 in 2012. The argument for this is that in 2014 the queen just fell of the combs in No 10 and died. Perhaps the queen was the oldest of the two.

Magnus and Ulrika has their bees quite isolated too (about 3 km) in relation to other bees. In October 2013 they treated all seven colonies with oxalic acid. From the three with wingless bees fell very many mites due to the treatment. From the other four just about 10 mites from each. These four were also the only one to survive the winter.


Low level start in 2014

In August 2014 they treated all colonies with thymol. Now they were ten. Magnus and Ulrika wanted to bring all colonies into a low level situation concerning mites as a start for the coming years. The next year they planned to check the infestation level of mites with the bee shaker bootle and treat only those with an infestation level of at least 3% in August.

They probably did too many splits, as some were a bit weak in autumn. No. 10 was still there, but with a new Buckfast queen from a queen breeder. No split had a daughter of No. 9 or No. 10 as its queen. Only No. 9 had its original queen.

No colony had been purchased and brought into their area from “outside”. All new colonies were splits from the first four who survived the first winter with Magnus and Ulrika.

The mites that fell after thymol treatment were about as many as the previous year after the oxalic acid treatment, that is very few.

Seven survived the winter. Three splits were obviously too small and did not make it.


Bee shaker 2015

In autumn 2015, they wintered 13 colonies. They controlled the infestation rate in August with the help of the bee shaker (, ie alcohol sample of 300 bees. Only the “old” colonies were tested. Magnus and Ulrika did not want to weaken the splits made in 2015. Two of these were a bit weak in the autumn due to queen problems. If an “old” colony had more than 3% infestation rate (9 mites from 300 bees) also the splits made from it would be treated was the strategy.

Those which had higher infestation rate than 3% in August were treated with thymol. There were three colonies that had just over 3%. Only those three which no splits had been taken from. Some of the other “old” colonies had only one mite from 300 bees, i.e. 0.3% infestation level. All the others except the three were not treated.

Ten colonies survived to 2016. Two of the three dead were the weak due queen problems in the autumn. The third died of local starvation. There were some empty frames between food combs and the bee cluster.

No colony during the last two winters have died because of large levels of Varroa. Varroa is evidently not a problem. Varroa levels have always been low in these colonies that originated from bees from the No. 9 and No. 10, also in 2013.


The colonies from the No. 9 and No. 10th

What naturally would come to mind is that we have found a tiny varroa resistant local bee stock genetically, if the queens are all descended from the No. 9 and No. 10. But that is not the case! Several of the daughter colonies had received queen pupae from a queen breeder. Some had been laying queens from the same breeder. He doesn’t select for varroa resistance and use effective miticides. Still, even colonies with these queens have very small levels of varroa. But the worker bees that these queens were introduced into came directly or “indirectly” from No. 9 or No. 10. Some splits from No. 9 were made in 2015. The other “mother colonies” were splits made in 2014 from No. 9, though with queens from a Buckfast queen breeder. These colonies are not ffsprings genetically, “only” “social offsprings” through the worker bees. The colony No. 10, is the social offspring of the original No. 10. Eight colonies are social offsprings of No. 9. No. 9 have the original queen. Only No. 9 have a “true” varroa resistant genetic set up.


Naturrum 2016

The first weekend in April 2016, I had a lecture at the Visitor Centre at Getteron at the west coast of Sweden close to the little town Varberg. I talked about breeding bees resistant to varroa. In the afternoon there were some workshops. One on how to check the infestation level of Varroa with the Bee shaker. The other how to make dish cloth pieces with thymol to treat against Varroa.

Varberg3 Magnus and Ulrika pouring alcohol in the Bee shaker. Somewhat more.

Magnus had brought a colony that hadn’t been treated against varroa the previous year. The queen was an introduced egg-laying Buckfast queen from a queen breeder. A queen which was not selected for varroa resistance. We hoped it would be a substantial amount of varroa in the colony so there would be some to count at the bottom of the Bee shaker.

Varberg4 The fourth comb from the rear with a lot of bees on it but no brood, to minimize the risk of including the queen.

Varberg5 The bees were shaken into a corner. With a measuring cup a little more than 1 dl bees were talken and poured into one half of the Bee shaker.

Varberg6 After the bees had been poured into one half of the Bee shaker the lids were screwed on top. Then the alcohol was poured on the bees from the other half. This half was then screwed to the rest. Now the Bee shaker was shaken for one minute. Turned around, still shaken until all the alcohol had went down in the lower part.


Too few mites

In August 2015 it was one mite in 300 bees in that test colony at the workshop. Now April 2 the colony was a strong and healthy colony of bees filling the box that had been the winter room. The bees were very calm and sampling went well. I lifted the fourth comb from the rear, with no brood, but close to the brood. To our “disappointment” it showed only one mite in 300 bees. One can truly say that we were surprised.

Varberg7 When all the alcohol had went down, the Bee shaker was lifted above the head and the mites were counted on the bottom of the Bee shaker.

How could this colony be varroa resistant? And No. 9? And the colonies that were made with bees from No. 9 but with no daughter queen from No. 9. All Magnus’ and Ulrika’s current colonies and their social offsprings have demonstrated surprisingly low amounts of mites all of the years with them. Although their queens are not genetically related to the original resistant colonies. They are though social offspring, as described above what that means.


The explanation

I had in my lecture talked about the experience of Hans-Otto Johnsen and Terje Reinertsen in Norway that can hardly be explained otherwise than that worker bees in resistant colonies teach other bees how to control mites.

Sampling with the Bee shaker on Getteron confirmed what I had lectured in a most interesting way.


Look for resistant bees

Now is the time for beekeepers that have had varroa in their colonies for a few years and have not yet checked the downfall of mites after treating. Check the differences of downfalls between different colonies. Especially you can discover good colonies in apiaries located somewhat isolated and in which there are not so many bee colonies. This lessen the risk for reinvasion of mites in the colonies. It’s good if the apiary have somewhat developed a stock of its own, ie no colonies or packages have been brought into the apiary in recent years and mostly queens have been bred from colonies in the apiary.

I’m sure there are many resistant colonies to be found today, but you must look for them.

You should make splits from the best ones.

The poorest colonies should not be used to make splits from, in any case you should avoid it.

You can buy Bee shakers here:


Resistant genes are important but resistant worker bees are more important

Of course, it requires a certain amount of resistant genes for a colony of bees to be able to develop resistance and be able to teach other worker bees how to control mites. When there are colonies which have developed good resistance it seems less genetic resistance quality is required to be able to be taught ability to control mites than to initially develop and learn this property.


If you find resistant colonies

If you find resistant colonies, even if they are somewhat bad tempered, swarmy, and only give small crops of honey, take care of them like golden nuggets. Move them if you can to an apiary of their own somewhat isolated, a couple of miles (3 km) to the other bees. Make splits from them and give those splits pupae bred from good tempered bees, reluctant to swarm and high producing.. Then continue to do splits following year from the best varroa resistant colonies and let them make their own queens. Doing so also from the original resistant colonies and let them make their own queens. Now there are good drones in respect to other good qualities from the previous year’s new colonies. Continue the following years to replace the poorest queens with those bred from the best in the apiary.

Bee shaker for sale

Varroa Shaker_20160117_003

If you want to know the Varroa level in the bee colony this tool is handy. Twice a season can bee good if you use it for example in selecting your breeders. And which colonies need a new queen (high Varroa level). It’s quick and you get an answer directly in the apiary.

Now a bee supplier in Sweden has the Bee shaker for sale. He calls it Erik’s Varroa shaker. Maybe it’s too expensive to send it to US. But some beekeepers in European countries no too far from Sweden may be interested. If you don’t want to make one yourself.

You can communicate with the producer Bjorn Gagner through e-mail: Price is probably somewhere between SEK 100-200 + shipping (about EUR 15 + shipping).

You can read more about it here:

The shaker is meant for making a an alcohol wash test.

  1. Fill one of the 500 ml jars to 2/3 with for example methylated spirit or rubbing (isopropyl) alcohol.
  2. Take a frame closest to a brood frame, don’t include the queen! She’s most probably walking on a brood frame.
  3. Shake the bees from the frame into a bowl or pan.
  4. Scope with a measuring cup little more than a deciliter (3.5 oz) of bees and pour them into the jar with alcohol (the bees die☹)
  5. Screw the glued lids with the netting and the the two jars together and shake for a minute.
  6. Turn the jars upside down and continue shaking until all alcohol has come down into the former empty jar.
  7. Lift the cans above your head to the sky and count the number of mites on the bottom of the lower jar (which now has the booze).
  8. If it is less than 3 mites in May and 6 in August you will probably do nothing about the mites.
  9. If one decides to treat, you can use several methods. One method is to use thymol. Another to remove all capped brood frames (worker- and drone brood) twice with a week apart. The latter method is perhaps the one to prefer if you breed varroa resistant bees. Because then you interfere the least with the epigenetic adaptation of the bees to fight the mites.



The bee shaker and varroa resistance

Skak botten 2lc One mite from 300 bees.

I understand that sometimes it’s a good idea to get an idea of the infestation level of varroa mites in bee colonies. You can take samples from a couple of colonies in an apiary to get an idea when to treat. But my first concern is breeding varroa resistant bees.

I have never monitored the varroa infestation level in my colonies. I haven’t had time and I haven’t found any reason for it because I thought I had found a good compromise – treating with Thymol when I saw wingless bees on the hardboard in front of the hive entrance, checking every 10 days or so.


Good results up till now

I give a colony one or two pieces of dish wash cloth containing 5 grams of Thymol each when I see wingless bees crawling on the hard board in front of the hive. But this means I don’t treat every colony at the same time (hopefully some not at all in a season). This results in some colonies with higher mite loads not showing wingless bees yet. So these colony (-ies) will through reinvasion increase mite levels again quite quickly in those colonies recently treated.

But this way I’ve been able to develop more and more resistant bees and still produce a good crop. There have been a number of bees not producing any honey. Winter losses have been reduced from 30 % to 10-15 % (except the first year with varroa trouble when I lost 50 %).

The bees have been better chasing mites and remove infested brood. I’ve got good reports from for example Poland and Germany of low populations of varroa in colonies headed by Elgon queens, compared to other bees. And the VSH trait is becoming better and better. Daughters of my colony with the highest VSH % (80) gave colonies that in Poland dropped 2-5 mites after effective treatment while other colonies dropped more than 1000.


Thymol is useful but hinders total adaptation

I now have been aware that by having this regime I have a constant quite high varroa population in the apiaries as a whole, and thus probably a climbing virus pressure. In a way this is good as selection is done also on virus resistance.

How do I know that? Now when I’ve used the bee shaker somewhat this year I’ve seen that colonies may show wingless bees (DWV-virus) at low mite infestation. Such low infestation you didn’t expect them to do so, sometimes even as low as 2 % infestation (a daughter from a colony with high VSH trait [80%]! This experience and others similar, raise the question if very high VSH comes with higher susceptibility to viruses.). Wingless bees at 2 % infestation is totally different from a report I’ve got from a test further down in Europe. (There they normally treat effectively every year.) In that test where they didn’t treat at all, my bees didn’t show any wingless bees at 35% infestation while other bees had a lot.


How to explain the high infestation level in the test

Now I have to try to explain why my good bees could arrive at 35 % mite infestation. This is interesting and brings up another topic as well. The importance of memories of the worker bees (their knowledge how to chase mites), not only their genetics (and epigenetic history). My queens in this test down in Europe were introduced to bees that had not been selected the same way as mine, and those bees had been treated effectively every year. The bees could probably not chase mites as well as mine.

But of course the genetics from my queens would more and more influence the workers to build up a better behavior when it comes to chasing mites. When the bees have arrived at a good mite chasing mood they learn new bees born in the colony what they have achieved, more than what just come directly with the genetics. In Norway with Terje Reinertsen and Hans-Otto Johnsen experiences are achieved pointing strongly to this.

In an apiary where many colonies are non-resistant as in this European test, you get a mixture of all bees in the apiary through drifting and robbing. This is taking place more and more when the mite populations in the colonies rise. As it did in this test as the colonies were not treated at all.

In a situation when colonies are receiving a lot of mites from neighboring colonies, even the very best kind of mite chasing behavior is maybe not enough to keep mite levels low.

In the test apiary previous to this test, effective treating every year had kept the mite and virus levels low, so the mite population could grow much in the test without showing wingless bees – like in the beginning when the mite first arrives to an area. Then the virus levels are usually very low and there could be 10 000 mites and more in a colony without any signs of viruses (documented case in Sweden in 1987 when the mites were first detected on the island Gotland in the Baltic).

The bees in this test were on 5.5 mm cell size, while my bees are kept on 4.9 mm.


Also Thymol hinders total adaptation

I have talked to some beekeepers whose bees are totally treatment free since many years (Hans-Otto Johnsen in Norway, Richard Reid in Virginia and Myron Kropf in Arkansas). Their bees have now small populations of mites and are showing no wingless bees.

I have come to realize that also Thymol is a chemical that hinders the bees to fully adapt to handling the mites successfully on their own. It is in first place the epigenetic adaptation I have come to think of that is disturbed when alien chemicals (like miticides of all kinds) are present. Epigenetic changes take place when a chemical change occur due to environmental changes, like for example the presence of the mite. (But it should be said also that if you use Thymol regularly spring and late summer in a system not selecting better bees like I do, winter losses can be kept low. I know because beekeeper friends do like this.) Also Thymol like other miticides is lowering the immune system of the bees.

How do I then integrate these insights to go further in becoming totally treatment free?


A new strategy to try

I’m planning a new strategy, at least to start with in one quite isolated apiary. I have to stop using Thymol. First though I think I have to knock down the mites effectively to reduce the virus level. And then get a better control of the number of mites and take action without any chemicals if varroa populations are rising too much in colonies.


The role of the bee shaker

Here the bee shaker will play a role. And I have looked more into how Randy Oliver uses it. It’s much easier to shake a frame of bees into a bowl or pan and then with a measuring cup scope somewhat more than a deciliter (3.5 oz) of bees and pour them into one half of the bee shaker, half filled with alcohol (for example methylated spirit or rubbing[isopropyl] alcohol). Then screw it together and shake for a minute before reading the result. Compared to holding the bee shaker close to a frame side with bees and pour bees into it moving it slowly upwards, the alternative of Randy Oliver is quicker (at least for me). The next step is to test the VSH trait in the best colonies.

Skak yngelrum Start checking from one side in the uppermost box with brood. The queen hopefully will run to the brood if she is outside the brood area (probably not). The comb closest to brood you check so the queen is not there. 

Skak deciliter Shake the bees into a pan or bowl. Scope up somewhat more than a deciliter of bees (3.5 oz)

Skakburk sprit Pour the bees into one of the halfs of the bee shaker, which is half filled with alcohol. Screw the other half tight on top. Shake it for a minute.

Skak botten1lc Turn the shaker upside down and continue shaking until all the alcohol has poured down. Lift it up against the sky and count the mites. This colony had 14 mites on 300 mites and it got two pieces with 5 gram Thymol each. It showed no wingless bees.

What I hated to do

So what I’ve done so far is something I hated to do. In one quite isolated apiary I used an effective chemical miticide (only this time I promised myself) in August 2015. I wanted to use something else than Thymol to give the bees a break from that chemical. And I wanted to knock down the mite population effectively to lower the virus pressure in the apiary. I collected the knocked down mites. (In the rest of the apiaries I plan at the moment to continue as before.) The colonies that had needed most Thymol earlier in the season had the highest downfall of mites. They got probably continuously reinfested from other colonies that happened to not show wingless bees while they anyway had quite high mite loads. The defense system of these quickly reinfested colonies was probably lowered by Thymol, which made this relatively quick reinfestation possible.

One colony that hadn’t needed any Thymol at all (and very little the year before) and still had given me 80 kg (175 lb) of honey with 20 kg (45 lb) left for winter dropped less than 200 mites. And this happened in this very bad season of 2015. This colony is of course a breeder for the coming season.


The new strategy

Next year I will in this new strategy apiary make splits from the best colonies and place them in the same apiary (or if the number is enough there, place in other apiaries). In the least good colonies in this apiary (those with highest infestation level) I will kill the queen and give them a ripe queen cell bred from a good colony in this apiary. I check the number of varroa (infestation level) with the bee shaker twice a season in all colonies in this apiary. Each time it will take about 5 minutes per colony. And I look for eventual wingless bees on the hard board in front of the entrances. Before the number of mites rise too high (whatever that is), or when I see wingless bees, I plan to remove all capped brood (worker and drone brood) once or twice with a week in between. I haven’t decided what to do with those brood frames yet. Any suggestion?