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.

My selection parameters

I have prepared for and selected for varroaresistance for quite some years. Last year I learned how to test a colony for VSH, a simplified method described by John Harbo, easy for everyone to use.

 DWV-bees on the hardboard

Before that I just allowed a mite pressure in the colonies until they showed virus problems. That meant in practice appearance of wingless bees, DWV-bees, either on the comb, but still easier, on a hardboard in front of the entrance. (Bees with very little resistance are though not quick in throwing out of the hive DWV-bees, or other virus-troubled bees.) You have to visit the apiary every 10 days or so, but a quick look will tell you, plus a look in the hive after opening the inner cover to check how the colony develops. No need to check down in broodnest unless you register something seems to be wrong.

Breeder candidates

Those colonies that keep going and develop normally without any symptoms, during which time no treatment has been done, they are of course then candidates for being breeders, especially coming spring.

 First breeder

In autumn 2011 I had three colonies that had been big colonies (not newly started splits during that year) without treatment for the whole season with no signs of varroa or virus. The winter and coming spring would tell which one, if any, or all, would be able to be used as breeder in 2012. That happened to be only one, H157.

Good to remember is that varroa first began to be a problem in 2008 with first bad winter in 2008-09 and 50% losses. Next winters no such losses.

Next years 5 breeders with VSH as most important

In autumn 2012 I had 11 breeder candidates. In spring 2013 I had at least 5 I judged I could breed from, but that year focused most on VSH. I had just learned to know I could.

I learned about VSH testing that spring in 2013 and did VSH-testing on three colonies.


One was a swarm that looked promising and nice. The mother colony was a feral colony in the wall of the dogtraining center, well within the area of my type of bees. The swarm showed 50 % VSH, half of the pupae with mites had mites without offspring. So even if this colony hadn’t been going for a whole season plus another winter without treatment I used it as a breeder in 2013.  I named it S120.


The second I VSH-tested colony had been a very small the year before and not really a production colony then. But it was in an environment with big colonies which needed thymol so I decided to test it and it showed 40 % VSH (4 pupae with mites had no mite offspring of the 10 pupae with mites found).  K25 it was named. But it was quite aggressive. I decided though that varroa resistance in this stage was more valuable.


The third VSH-tested colony was a walk away-split from a colony that hadn’t been treated for two years. It wintered with such a tiny cluster and still developed so promising and had such a good pedigree background I choose to VSH test it. Well, it wasn’t possible to get any VSH value as it hadn’t any mites in the brood. I was so amazed I decided to breed from it. And I named it R137, as I decided it was resistant, instead of H137.  It must have had a good resistance behavior, but resistance is complicated…


The mother of R137, H109, of course also was used as a breeder due to its history, but she was old and layed 50 % drones in worker cells. Couldn’t really make any VSH test I decided. I grafted one time and killed her.


The fifth I used showed itself to be very old as well and fell off the comb and died just after taking her home in a small split. No VSH-test. That colony I had thought had a new queen that had past the test. But this colony with this the old queen, though good, had been treated every second year with 10 grams of thymol (very little actually relatively) during four years. M176.

Some observations

Why do I tell you all these details? To come to the point for my situation, soon, be patient.

Late in season 2013, S120 showed a couple of wingless bees and got 10 grams of thymol. K25 which really hadn’t had a real production season before it was choosen swarmed thee times in July in 2013! I have never experienced that before, ever. R137 has some peculiar traits. It supercedes its queen every year it seems. And some daughters do too. This year a few wingless bees were seen and it got 10 grams of thymol.

I never do regular swarm controls in my colonies. Usually about 5 % of my colonies swarm. This year many daughters from two breeders from last year 2013 swarmed, from S120 and K25. And almost all daughters from these breeders needed thymol. Some of the daughters of K25 were very aggressive. Remember all queens are mated naturally in the apiaries. The apiaries together form an area with only my type of bees.

Breeder candidates for 2015

BUT maybe it was worth it using the breeders that disappointed me. I must have genetic diversity in my stock. I can’t make queens from just one line (H157).

I have one daughter of S120 and one of K25 that are really outstanding in resistance, honeycrop (more than 150 kg (300 pounds)), very good temper and no swarming tendency. H109 has more than one good daughter. M176 as well. And then there are walk away splits with heritage from the first breeder chosen for resistance H157, which are breeder candidates for 2015. Maybe I will use as well the three breeder used this year, or two of them.

Breeders used 2014

The autumn of 2013 I had 36 breeder candidates. I could have bred from more, but I choose to breed from three this year 2014, of which two are sisters, daughters of H157. These are H112 and H105. H157 had quite some daughters worthy of breeding from.  The third breeder this year was L242. After using these three, in the middle of July I made the VSH test on them. In all three the infestation rate in the brood was about 5 %. H112 had a VSH value of 80 %. H105 – 67 % and L242 had 33 %. No treatment was needed for this year either for H112 and H105. L242 got 10 gram thymol late in season. L242 came from a quite isolated apiary with small reinvasion and was moved to my home apiary and probably got more reinvasion here. But all three are wintered very strong.

Maybe I will use H112 and H105 in 2015 as well, we’ll see.

Selection parameters

Now to my point. It seems under my conditions it’s better to focus in first hand on one whole season as big colonies during which no treatment should have been needed (including winter and coming spring), to select breeders. BUT then use VSH testing to tell you which one probably are the best among them, and get confirmation of their status. Of course the breeders must be good in other respects, good honeycrop, good temper and low swarming tendency.

VSH is a good tool for selecting for Varroa resistance, especially when there are difficulties  using anything else, but also as a complement when other methods are used.  I’m glad I can make VSH tests, in addition to the DWV-test I use.

MT-colony conclusion

I have shared the performance of this colony which had almost a box of plastic small cell frames and natural positioning of these frames (as the uppermost broodbox). Which also had a tough experience with mice living in the bottom box during winter.

It gave top crop the first crop of winter rape, dandelions and some raspberry. It showed no wingless bees this year early on as it did last year. But it had an old queen. So the colony decided to shift it’s queen and did. Now they showed a few wingless bees. I concluded that was due to the declining amount of open brood to enter for the mites, son inte last brood of the old queen there was enough concentration of mites to develop some wingless bees. But to be consistent with my way of working I gave the colony 9 grams (two pieces) of thymol dish pieces. Next time no wingless bees.

My impression is that the colony is not performing less good with plastic small cell and natural positioning. Thus the conclusion is that plastic small cell frames are not negative for the bees, neither what I call natural positioning. If any of these configurations are positive is difficult to say. An overall smaller mite pressure in the apiary and the area could be the explanation. Due to epigenetic changes that have improved the bees, or/and conventional selection has done its job with the genepool in the apiary/area. Also plastic small cell frames and natural positioning may have contributed. At least plastic small cell may have good influence as there are more cells for each comb, thus faster buildup.

Waxmoth with DWV?


When making splits yesterday I saw what looked like a bigger Wax moth with crippled wings. I moved like one too, trying to run away without flying. And this one couldn’t fly at all. Is it a bigger wax moth? Can wax moth be affected by Deformed Wing Virus? And can it spread the virus to other bees? I guess though not as effective as other bees when they drift into neighboring hives, or rob them.


First increase, the first apiary

A couple of days ago I started for the new season, to check colonies for need of food and for increase of space for bees and brood. I want to give you some glimpses.

I checked four apiaries that afternoon. In the first one I have 7 colonies.

  • Colony 1: It wintered on three 12 frame shallow boxes. All colonies always have a lot of food for winter (most important so they have enough food for brood in spring and early summer). This colony for a couple of years have needed in my eyes too much thymol due to wingless bees. So I decided to split it and give the two parts a mature queencell. When I split a bad colony I keep the split (which is made including the queen, the two upper brood boxes) in the same apiary moving it to another place. It will this lose its field bees and it will be easy to find the queen and take her away. The split is colony 6 in this apiary. 2012 colony 1 needed 20 grams of thymol (to be compared with the at least 50 grams needed for unselected bees for varroa resistance). 2013 it needed still 15 grams in spite of the new queen, broodless period and a very big split taken. And the need came later in season so I wondered how to interpret this need. The virus probably was hanging around and making life miserable for the bees. The colony shrank in size in autumn, but kept the three boxes though quite some combs in the upper box were exchanged with insulation/dummy combs. I was a little worried for it. But now it made me happy. They are healthy with capped brood and increasing strenght of bees. They got the upper third box filled with combs, three of them foundation and one food. The queen is a daughter of the interesting queen H137, which had zero varroa infestation in the brood last year.
  • Colony 2: It was a walkaway split last year from a colony about 4 km (2,5 miles) from this apiary. The third upper box taken without the queen. Thus it normally gets enough brood and food in that box, but without the queen. I shake all bees in that box down below and put the queen excluder on box two. I put the third back, for a quarter of to half an hour, and then take it on a new closed bottom (with the cover) and move it to another apiary. Also the way I takes it, it gets almost too strong, so I put another empty box with some food and drawn combs underneath it at the new place. The split made a new queen and grew enough, but barely enough, to be wintered on three boxes. It needed no thymol last year as a split. The third box was now filled up with combs of which three were foundation and one food. They looked very nice. Now the mother colony though didn’t look as fine this spring. I saw no wingless bees in that one, but it had had problems during winter and I had to take away the bottom box. It has been weaker and weaker all winter. Still it is not too weak and it had capped brood. I will give the mother colony 5 grams of thymol soon enough. This daughter colony no 2 in this apiary I will keep my eyes on for eventual need of thymol.
  • Colony 3: This colony needed thymol early in the season and it didn’t grow well, so I took the queen away and gave it a mature queen cell in the middle of the summer. The colony grew well and wintered about the same size as the two mentioned. It was given combs the same way, but I was almost giving it a fourth box, the first above the queen excluder, but I concluded it can be done at the next visit. The mother queen to the queen is H109, which also is the mother to H137. H109 was old last year and began laying 50 % drones early in the season so I said good bye to her.
  • Colony 4: This apiary was not a very good one last year. This colony 4 was the only one that gave a good crop in this apiary. Some years are like that. But instead this one gave me a crop for at least two, 130 kg with 23 kg left for winter (280 pounds + 50 pounds). And I used no thymol last year and none the year before, which was the walkaway split year. The mother colony (to this colony) 4 km away didn’t need any thymol either last year. But I hesitate using it for breeding as this apiary is one of the apiaries at the edge of the area with Elgon bees. Thus the queen may have been mated to non-Elgon drones. Should I care? And the colony uses a little too much food during winter. Temper is not the best, but quite okey. The queen is related to H109 and H137 but not close. It was full of bees on three boxes and got a super above the excluder with some foundation and three combes of food as it had very little food left.
  • Colony 5: This is a walkaway split from a colony 4 km away. The mother colony actually is a walkaway split from Colony 4 above, though not mated in the other colony but in this apiary. And now another generation and mating in this same apiary. Could it be part of the explanation why this colony did not winter well and is very weak and showing wingless bees already now. The mother colony 4 km away didn’t need any thymol last year and has wintered well. I plan to combine this weak colony with another very weak colony from another apiary close by and give it 2-3 grams of thymol as soon as possible.
  • Colony 6: This is the split from colony 1 in this apiary made last year. It needed just a little thymol, but much less than the part left as colony 1. It has a queen that is a daughter of S120, the swarm from the wall of the dog training center that had VSH-index of 50 % last year. It looks very nice. Got increase combs as colony 1, 2 and 3 to fill up the upper box no 3.
  • Colony 7: This is a walkaway split from the apaiary 4 km away. The mother line is Kefuss, but that is now many generations back. But still some characteristics of this influence can be seen. Very little food used during winter, late spring build up, but quick when it has started, good honey crop in combination with Elgon. The temper is not the best. They want to swarm more. It is a little behind the others (1, 2, 3 and 6 to compare with) in development, but is coming fine. No thymol was used last year. And the mother colony didn’t need any either. Though the mother colony (in the other apiary 4 km away) defecated a little on the front of the hive.

First cleansing flight after winter


Autumn was warm, with bees flying in november. That’s rare. Winter was mild, only 2-3 weeks with steady freezing temperatures day and night in January. That’s rare too. Spring has come slow with temperatures just above freezing. Sun is rising more and more above horizon. Those days we’ve had sun, which havn’t been many. Now it’s warming in the middle of the day.

Sunday March 9 the great day came, when the bees flew out in their big bathroom after confined to their bedroom for many months. I wasn’t careful where I parked the car, in the open about 100 meters from the hives. The bees happily spotted the shining roof and shouted: Toilet! And dropped what they had had collected during winter.

Last year I used treatment against Varroa on much fewer part of my hives than previous years, 50%. That’s because no more had given me the sign for treatment, wingless bees.

And 36 colonies were potential breeders in autumn, the bees in those colonies hadn’t been treated last year or the year before. All of these have wintered very well so far. The year before (2102) I wintered 11 potential breeders. I used 5 of them for breeding last year (2013). 2011 I wintered 3 potential breeders. 2012 I used 1. Regardless of how many pass the test for breeding this year, I will probably not breed from more than about 5. The others I will at least take a walk away split from.

Two colonies have died so far, out of 170+. That’s 1%. I can’t remember when I had such a good overwintering before. But probably some more colonies will die.

Vårrensning9mars2 These two colonies are both afterswarms (with virgin queens)  in July last year, from the same colony. A colony that have never been treated against Varroa. It have VSH-index 40%, but somewhat grumpy in temper and gave a small crop. Both colonies were of course small going into winter, but have been sitting still with a tight cluster until March 9. They have eaten very little food until now.


Only real treatment tell real mite population

Marco Moretti made a valid comment to the sugar shaker post. It doesn’t surprise me that Antonio Nanetti found checking mite populations besides a real treatment is unreliable. It is many factors making the results uncertain. Why beekeepers want to do this anyway is to get an idea when it’s time to treat against the mite.

If you do an oxalic dribble, or trickling, you make a real treatment. And that’s okey with me, if you choose to do that. Before making a real treatment the most reliable mite test is said to be alcohol washing like with the bee shaker described in this blog. The sugar shaker might do well for others. According to findings in USA described by Dennis van Engelsdorp those beekeepers that checked mite populations with alcohol wash, thus keeping track of the mite population had the lowest winter losses, of those beekeepers treating regularely.

John Harbo and his collegues at Baton Rouge lab found in the early 1990:s when they took help of a statistican to find out that checking mite population increase during a period of time was not a good way of testing mite resistance. That’s why they finally ended up checking  infertility of the mites, which finally became the VSH method. (Information from Harbo)

That’s also one of the resons I don’t count mites. I check for virus problems in the hive before treating. The easiest virus and the one most common when mites are becoming many is Deformed Wing Virus (DWV). Maybe that’s too late normally to save the colony. I don’t know. But fortunately I don’t have ”normal” bees. Also a reason for me not counting mites, but looking for DWV, is that I want my bee stock to develop strong varroa (and virus) resistance.


Struggle for resistant bees

STr Apiary smal

Yes, do struggle for resistant bees. Don’t just talk about it! Or say an easy no, it’s impossible, or an easy yes: ”Just do like I tell you.”  Tell me your success story. I tell you mine, well a part of it here.

1989 I went to Kenya and got breeding material from Apis mellifera monticola, the mountain bee. Yes, that was a good longshot. I don’t regret it. In 2000 I visted Lusby’s in Arizona and got hooked on smaller more natural cellsize. I don’t regret that either, even if I’m not sure how much it helps against varroa mites. It’s more natural and bees don’t perform worse with it, in any way. Natural selection benefits survival and it has selected for small cell size in brood area at least. There are obvious benefits like rapid spring build up.

I thought I had regressed my bees down to 4.9 mm cell size when varroa hit hard in 2008. The mites arrived a couple of years before to my area. But it turned out when I analyzed the dead colonies following that many had too many badly drawn combs.

STr Wrong comb Quite some combs looked like this, but they are gone now.

My plan A was that I wouldn’t need any treatment against the mite as I had African genetics in my bees and they were small cell. But a gut feeling told me to have a plan B if something should go terribly wrong. And it did

I didn’t want to use acids as my conclusion was, wrong or correct, that formic is to hard at the bees and dangerous for me. Oxalic put me also in danger as I can’t smell oxalic fumes, but formic it’s no problem smelling. Inner organs and skin you know. I want to keep them going. Nerve poisons like Fluvalinate and organic phosphates like Coumaphos, cancerogenic like Amitraz and it’s breakdowns. My gut said no. The only thing left was Thymol. Yes it kills a lot of microbes as well. But it’s a spice and you find somewhat in basswood honey.

My conclusion was that it’s better with some living colonies than all dead. You can select the best among the living. It’s no use among the dead. Was it possible to use less and less Thymol? The bees were so overhelmed with DWV (Deformed Wing Virus) and mites that no one would have been left of my 250 colonies in 2008. Well, maybe 10 % when autumn 2009 came,…. When spring came 2009 I had lost 50 %. I got a feeling the mites were filled with viruses when coming to the area. I lost several tens of thousands of dollars in left out income in struggle for more resistant bees. But I didn’t want to get caught in the chemical trap.

Thymol for susceptible bees you need minimum two trays with 25 g thymol each (50 g in total). 10-14 days apart. If only treatment normally too little in a year. For some years now 80 % of my bee colonies have been treated. I have used in average10-15 g of thymol a year on my colonies (all included then). A few needed 35-40 g. They have of coursed got new queens.

Str Thymol Small One piece of Thymol with 4-5 grams on a struggling colony in spring.

I now winter about 170 colonies. I have lost 15 % of the colonies the last winters. (But this winter seems to end much better.) 30 % of those that survive have been small, got treated and new queens and gave no honey. The average honeycrop, including the 15 and 30 % mentioned has been about 50 pounds (25 kg). The top colony almost every year reach 400 pounds. The apiaries differ a lot in yielding nectar.

Str Thymol Strong 15 g of Thymol on a strong colony in summer, with supers above the excluder. Few cases.

I treat only (and I do it mostly right away regardless when it is in the season) when I see a couple of deformed winged bees outside or inside the hive. The hives are equipped with a board half a meter in square in front of the entrance for easier seeing what the bees are dragging out of the hive. Mostly the colonies are being treated in spring or in late summer. Those few treated with honey supers on get the honey ventilated in zig-zag stacks of supers in a warm room with a fan going for at least a week before extracting. To vent out thymol smell.

There’s only my stock of bees in quite a big central area where I have my bees. In the outer areas my bees dominate. I keep about 10 colonies in each apiary and they are as close as I can find places for them. 1 mile (1.5 km) between them would be ideal. The queens are mated in the apiaries.

Last year (2013) I used thymol on 50 % of my bees. In average I used 5 g thymol, all colonies included. For breeders I use colonies that havn’t been treated for at least the two previous years. The number of breeder candidates has increased for every year. Last year I started to check the VSH trait. I think this will make it possible to check eventual breeders a year earlier then before.

The VSH tests I did last year on my 5 breeders gave the following results: 1) 50 %, 2) 40 %, 3) not possible as I didn’t find one single mite in the brood, 4) not possible as the four year old queen died of age early (I just was able to make one graft), 5) not possible as the three year old queen produced more than 50 % drone brood.

Str Good Apiary A good apiary. Bee escapes on. Next visit the bee blower rids the boxes from the remaining bees. It will be when yo take 4 boxes like from the colony to the right. (That’s at least 150 pounds of honey).

I don’t count mites

I know it can be beneficial to count mites. But I don’t have the time. But those colonies I check for VSH, they will get figures enough to get the infection rate for mites in brood. (But I just check some.) Sometimes I’ve heard that two thirds of the mites are in the brood. If that’s correct then the infection rate on bees (phoretic mites) is half of that.

Many use the infection rate increase from one time till some time later to get a figure of resistance, saying the colony with lowest increase is more resistant. That might be true, but infection rate is dependent on other factors then mite reproduction success in the colony, such as reinvasion of different causes.

So I use the lazy method checking for signs of virus (DWV), thus also selecting for virus resistance. Then when I see this, I treat, with thymol, just the colony (-ies) showing virus. Over the years the number is decreasing and the amount of thymol is decreasing also, telling me this is a method that works.

Spritb For alcohol wash I recommend taking bees in the broodnest third frame from the back or one side to avoid including the queen in the alcohol and getting away from the entrance.

If you count mites, the most accurate method I think is alcohol wash, of as many bees you can afford (100-300 bees) when the colony has no brood (or as little brood as possible).

Sprit2b Shake the bottle with bees and alcohol strongly for a minute to loosen the mites. Pour them on a double sieve. Flush water on the bees strongly and count the mites in the second sieve. Also count the bees in the first sieve.

But beware where you take the sample. Don’t take it on bees close to the entrance. Mites are fewer there according to findings of Thomas Kober (personal information). So how do you avoid entrance bees if you have all the combs sitting with their edges towards the entrance? The best place maybe is in the broodnest but as far away from the entrance as possible, box two or even three maybe. I havn’t seen a paper on where the best place is. Maybe you have?

This is another reason I don’t count mites, the uncertanity if the density of mites is the same in different places in the hive.