Non-Treatment Sanity Check

Personally, I am becoming alarmed at the degree to which there is a shift in the way beekeepers view the rather drastic step of not treating their bees for varroa infestation. I feel similarly about the rapid rise of a certain new political party, but I can’t discuss that here. Have normal folks lost their minds? I have had long conversations with myself to try to unpick whether I’m being objective or not, which is, in itself, a possible indicator of madness. The time has come for a non-treatment sanity check, which is what I shall now do.

Why would anyone not want to treat their bees if they are sick with a parasite? The way bee farmers see their bees is that they are livestock from which we derive income. For a beef farmer, it’s cattle, and for a bee farmer, it’s bees. Livestock needs to be treated with respect; if we look after it, we will be rewarded. The Code of Conduct for Members of the Bee Farmers’ Association (BFA) says, among other things:

Where bees are offered for sale or for hire under contract, to ensure stocks are free from disease and are of suitable colony strength and condition.

This , I would argue, excludes bees riddled with varroa mites and associated viruses. The BFA and its members are committed (it says so in our 2025 year-book on page 75) to ensuring high standards of welfare of honey bee stocks. The ‘five freedoms’ for animals under human control have been adapted in terms of their relevance to bees. This includes:

Freedom from disease

• Disease prevention and control measures … are adopted to ensure the health of honey bee stocks and to minimise the spread of disease where it occurs.
• Treatment strategies are appropriate for the specific disease/health issue.
  

Freedom from stress

• The condition of colonies is monitored and actions to mitigate signs of stress are taken.
  

In trying to understand the current fad for non-treatment, I came up with some possible justifications.

Look at all the losses in North America – treating doesn’t work

Well, that’s nonsense. Over-reliance on one form of synthetic miticide, probably without adhering to label instructions in numerous instances, has led to some varroa mites becoming resistant to amitraz. Scientists at the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) found high levels of deformed wing virus (DWV) A and B and acute bee paralysis in all recently USDA-sampled bees. A USDA press release¹ on June 2nd, 2025 states:

“These viruses are responsible for recent honey bee colony collapses and losses across the U.S. Since the viruses are known to be spread by parasitic Varroa destructor mites, ARS scientists screened the mites from collapsed colonies and found signs of resistance to amitraz, a critical miticide used widely by beekeepers. This miticide resistance was found in virtually all collected varroa, underscoring the need for new parasitic treatment strategies.”

What we can say is that, in a country where many bee farmers have used nothing but amitraz for twenty years, the mites are winning, causing fatal levels of viruses in honey bees. The USDA research has not yet been peer reviewed, so their early conclusions about amitraz resistance may not fully stack up. We can also speculate that, had those bee farmers not treated at all, many more colonies would have died. Treating does work, but you have to vary them, not rely solely on synthetic chemicals, and follow the instructions on the label. The sad and damaging losses in North America do not prove that treating doesn’t work, but they do illustrate that mites can develop resistance to synthetic treatments. This previously occurred with the pyrethroid tau-fluvalinate² in many places.

In the UK, amitraz remains largely effective, but reduced efficacy is emerging in some places in Europe. Given the experience of beekeepers ‘over the pond’ I shall be mite washing next June to confirm efficacy. Resistance to organic acids like oxalic and formic acids is less likely to develop anytime soon, and they are do not accumulate in wax.

Treating is Bad, Natural Resistance is Good

Varroa treatments get a bad rap, and it is mainly the fault of the synthetic forms because resistance can develop, and they build up in bees wax. It is wrong to lump all treatments together. It’s ironic that many non-treaters who enjoy the taste and health benefits of organic produce do not always look kindly on varroa treatments approved by the Soil Association’s organic standards (organic acids and essential oils, like thymol). The way I see it, if my livestock is infested with varroa beyond a certain threshold, it’s my duty to deal with the issue before it gets out of hand and severely damages or kills my colonies.

Natural resistance to varroa is, of course, ‘good’. However, the way that such resistance is achieved is important. Anyone who says that the road to resistant bees is easy has not been paying attention. If it was, the queens would be on sale everywhere, and nobody would want anything else. Of course, the resistant bees will need to be good honey producers, not unduly defensive, not likely to swarm at the first sign of warm weather in spring, and good at surviving over our admittedly mild winters (some Scottish members will probably disagree on that matter). If the pursuit of one desirable trait – varroa resistance – results in the loss of the others, what was the point?

Doing The Right Thing

I am sure that most people want to do the right thing as far as beekeeping is concerned. They love their bees. The mantra, repeated over and over, to follow the path to treatment-free nirvana, seems to be working. When I was at the National Bee Unit (NBU) recently, I heard that 20%³ or more of UK beekeepers do not treat their bees, and the numbers keep rising. I suspect that these same people are happy to treat their dogs for worms or ticks. The suffering of bees is not so easy to detect as the scratching or whining of the family pet. If the beef farmer did not treat his or her cattle, they would soon be in trouble for animal cruelty, and the reputational damage would hurt their sales. And yet, not treating bees is hailed as a great virtue in some quarters. I will concede that some non-treaters are using biotechnical methods rather than chemicals, which is very different to leaving the bees alone.

Breeding Resistance Is Hard

I’m all for optimism and positivity, but it must be tempered with some harsh realities. When I refer to ‘breeding’ of resistant honey bees, I am ignoring instrumental insemination (II). With II, progress can be made more quickly. With open mating, unless you happen to have an isolated mating station that you can saturate with drones from varroa-resistant queens, there will be a long and testing road ahead.

Steve Riley is the author of The Honey Bee Solution to Varroa and a frequent speaker on the subject. Riley’s central message is that bees themselves can provide the solution, if only we learn how to spot and propagate the right colonies. Riley’s argument can be boiled down into three pillars:

• Resistant colonies fight mites themselves through a behaviour called uncapping and recapping, plus chewing out mite-infested brood. Look for “hockey sticks” (pupal fragments) on your insert board.

• Selection in practice is simple: keep insert boards in year-round, watch for pupal debris and patterns of bald brood, and propagate from colonies that stay on top of their mites without treatment.

• Spread resistance locally by requeening with queens from those colonies, mated as locally as possible, ideally in a club context with several beekeepers pooling effort.

It’s a message of optimism: you don’t need hundreds of colonies, just sharp eyes and local collaboration. However, the science shows recapping is an indicator, not a mechanism by which mite reproduction is reduced⁴. One study said, ”Our results suggest that recapping activity does not indicate resistance towards varroa, but rather that worker recapping activity increases in colonies with a higher level of infestation.”⁵ However, recapping often correlates with reduced mite reproduction in mite-resistant populations (though not always). Over-reliance on pupal fragments or bald brood as a proxy is also potentially misleading.

The Monitoring Problem

To have any hope of successfully producing varroa resistant stock, monitoring the level of varroa infestation regularly (monthly) is essential. That is a considerable amount of work for a bee farmer with hundreds or thousands of colonies. One might argue that the payoff, eventually, would be that you will one day not have to buy varroa treatments, but I’m not convinced.

Apart from the sheer scale of the task of monitoring every colony every month, there is the issue of choosing a reliable monitoring method. Several field trials show that, when properly executed (right sample size, vigorous agitation, sufficiently strong alcohol), an alcohol wash can recover up to 95% of phoretic mites from sampled bees. It is widely regarded among beekeepers as the most accurate method⁶ for estimating mite infestation. However, results drop if technique or materials are suboptimal. At different times in the season, many more bees can be in the sealed brood rather than on the bees, but calculations to estimate total infestation take account of this.

Trials indicate that natural mite drop (the sticky board) correlates only weakly with actual colony mite load⁷. It’s just not very good at the job, so anyone using it to monitor mites as part of a breeding programme is already disadvantaged. What’s more, the presence of pupal fragments on the board does not necessarily correlate to varroa resistance. Other types of hygienic behaviour also cause these fragments.

The only bee farmers that I am aware of that regularly carry out alcohol washes on all of their 1,000+ colonies are Golden West Bees, in California. That is run by Randy Oliver’s sons, Eric and Ian. They have developed a machine which, along with a smoothly operating systematic approach, means that it only takes a minute to get a mite reading from a colony. It still adds up to plenty of minutes, baking under the relentless sun, but they are breeding resistant bees at scale. Randy has documented his journey on his website, scientificbeekeeping.com.

In Europe, several breeding groups (e.g. Arista Bee Research, Swiss Bee Research Centre) run systematic alcohol washes on hundreds of colonies annually.

Polyandry Dilutes Your Efforts

A queen mates with 10–20 drones at drone congregation areas (DCAs). Unless most of those drones carry resistance traits, the queen’s offspring will be a genetic lottery⁸. In open mating landscapes, one beekeeper with a few ‘good’ colonies can’t shift the needle. Even at a large scale, such as Randy Oliver’s work, it takes years to build up the numbers of drones from resistant queens.

Re-infestation Masks Genetics

Regular monitoring will show up some colonies that have a very high mite load – so called mite-bombs, or robber-lures⁹. These need to be dealt with (treated or culled) to prevent the spread of mites to other colonies. Even a genuinely resistant colony can see mite numbers spike if neighbouring colonies collapse. Robbing and drifting spread mites around. This makes it challenging to know whether a colony is failing because its genetics are poor or because it was swamped by outside mites.

Measurement Noise

Traits like varroa sensitive hygiene (VSH) or reduced mite reproduction (RMR) have variable heritability⁸ and are strongly influenced by environment. That means you need large numbers and standardised testing to make real progress.

Few Resistant Lines Available

Despite decades of work, Europe still has very few commercially available resistant lines, and those that exist require controlled mating to maintain. Projects like SMARTBEES and COLOSS stress the importance of scale and coordinated breeding, rather than lone efforts. It is worth noting that Buckfast and VSH projects (e.g. in France, Netherlands, Norway) have generated lines with measurable resistance — they remain niche but not absent.

Complex Genetics

The genetics of resistance are complex. The genes that determine varroa resistant behaviour are spread all over the genome (polygenic). Multiple studies show moderate heritability with strong environmental influence — you don’t get a simple Mendelian ‘resistant gene’ like eye colour in humans. The combination of genetics plus environment gives us another challenge; perhaps a colony that is resistant in one area will be less so in another.

Rose Tinted Spectacles

When I hear people speak in favour of non-treatment, they often don’t disclose their losses. Furthermore, many will say something like, “I don’t monitor varroa nowadays – I know they are resistant, so why bother?” When they do inevitably lose colonies, you can bet that the reason given will never be related to varroa. It will be something like isolation starvation. Of course, high varroa combined with high levels of DWV shortens the lives of bees, meaning that they cannot maintain a large cluster over winter, and so they die from isolation starvation.

I hear other classic statements like, “Sure, I have high mite loads, but many of them will be infertile, so it’s okay.” Or my favourite, “I’m not really concerned about how much honey I make – that’s not why I keep bees.”

I’m A Treater

For the sake of transparency, I am not exactly proud to admit that my losses over the 2024/25 winter were 16%. Higher than I would like, but perfectly manageable, particularly as I over-winter quite a few nucleus colonies which can quickly fill the gaps. My target is 10% or less, which I achieved the previous winter. I am very confident that if I stopped treating my bees, over half of them would be dead within two years.

My treatment regime recently is as follows:

• Amitraz strips in all colonies in early March, off by mid-April
• Formic acid in August on production colonies after the honey is off
• Oxalic acid on production colonies in early December
• Nucleus colonies get Thymol in the autumn, not formic acid

When using Formic Pro, we cover the tops of the pads with the foil wrapper, which reduces the initial ‘flash’ of product released. This results in queen losses from using formic acid being below 10% (often below 5%). We use Langstroth boxes, which are obviously larger than Nationals. I think that when queens are superceded after formic acid, it was probably going to happen anyway.

That’s right, folks; I’m doing three treatments per year on production colonies. It was alcohol washes over several summers that led to me adding the spring amitraz treatment. Unfortunately, when I do my winter oxalic acid treatment, some colonies have sealed brood, and that can cause mite problems the following summer. The amitraz mops up the mites which survived the oxalic acid, and sets the colonies up well for the summer ahead. This may seem like overkill to some, but for now, it works for me and I think the cost of treatments is justified.

If the amitraz stops working at some point, I will be hoping that another treatment will have been approved for use by then. I would prefer to use something else, but thymol can stop the queen laying for a time, which is not what I want in spring. Oxalic acid dissolved in glycerol and soaked into absorbent pads¹⁰ has shown promising results as a summer ‘supers on’ treatment, but it is not allowed in the UK. Another possibility is shook-swarms, plenty of syrup to help them recover, and oxalic acid before the first brood is sealed. Lots of work, and quite drastic, so I’m not sure about that one. Good for reducing disease, but probably also good for reducing the honey crop! There are also variations of a technique in which a second brood box is added towards the end of the Spring flow. A split is made later on, with one half having the sealed brood and the other just the open brood, which can be treated with oxalic acid.

Sanity Check Completed

For those who buy queens, I’m sure that they would happily buy ‘varroa resistant queens’ if they ever become widely available, and that could eliminate, or severely reduce, the number of treatments needed. This would be fantastic. After many years of some people trying, we don’t have access to thousands of queens that can head colonies that will never need treating. Maybe one day. But even then, monitoring mite loads will be required to spot problems early.

As for producing queens, it seems to me that the huge effort and large scale required mean it is quite a stretch for most bee farmers, including me, to follow Randy Oliver’s example. It makes sense to monitor varroa levels and to try to raise new queens from a breeder queen who headed a colony with low mites throughout the season. Of course, all the other desirable traits will need to be there too. The degree to which those traits can be passed on to future generations will depend on control of the drones. That is why scale is important – the hobby beekeeper with ten colonies is facing an almost impossible task, but it does depend on the local drones. In some areas, it might actually work, for a while at least.

For those who have the bee-power and who follow a rigorous breeding programme with regular monitoring, I have great respect. If everyone who makes queens tries to include varroa resistance as one of the traits selected for, perhaps, one day, we will all be able to reduce treatments to once a year, or less. I have an II breeder queen for next year, which contains Elgon¹¹ genetics. The daughter queens will be open-mated, so I am not expecting miracles, but I suppose it is evidence that even a sceptic can dip his toe in the water.

References

1. USDA Agricultural Research Service (2025) USDA researchers find viruses from miticide-resistant parasitic mites are cause of recent honey bee colony collapses. United States Department of Agriculture. Available at: https://www.ars.usda.gov/news-events/news/research-news/2025/usda-researchers-find-viruses-from-miticide-resistant-parasitic-mites-are-cause-of-recent-honey-bee-colony-collapses/
2. Elzen, P.J., Eischen, F.A., Baxter, J.R., Elzen, G.W. and Wilson, W.T. (1999) ‘Detection of resistance in US Varroa jacobsoni to the acaricide fluvalinate’, Apidologie, 30(1), pp. 13–17. https://hal.science/hal-00891561/document.
3. Valentine, A. and Martin, S.J. (2023) ‘A survey of UK beekeeper’s Varroa treatment habits’, PLoS ONE, 18(2), e0281130. doi:10.1371/journal.pone.0281130
4. Hawkins, G.P. and Martin, S.J. (2021) ‘Elevated recapping behaviour and reduced Varroa destructor reproduction in natural Varroa resistant Apis mellifera honey bees from the UK’, Apidologie, 52, pp. 647–657. doi:10.1007/s13592-021-00852-y.
5. Morin, M.L. and Giovenazzo, P. (2023) ‘Mite non-reproduction, recapping behaviour, and hygienic behaviour (freeze-kill method) linked to Varroa destructor infestation levels in selected Apis mellifera colonies’, Journal of Veterinary Diagnostic Investigation, 35(6), pp. 655–663. doi:10.1177/10406387231172141.
6. Mississippi State University Extension (2018) Sampling for Varroa mites using an alcohol wash. Mississippi State University Extension Service. Available at: https://extension.msstate.edu/publications/sampling-for-varroa-mites-using-alcohol-wash.
7. Oliver, R. (2018) Re-evaluating Varroa monitoring: Part 1. Scientific Beekeeping. Available at: https://scientificbeekeeping.com/re-evaluating-varroa-monitoring-part-1/.
8. Guichard, M., Dietemann, V., Neuditschko, M., et al. (2020) ‘Advances and perspectives in selecting resistance traits against the parasitic mite Varroa destructor in honey bees’, Genetics Selection Evolution, 52, 71. doi:10.1186/s12711-020-00591-1.
9. Peck, D.T. and Seeley, T.D. (2019) ‘Mite bombs or robber lures? The roles of drifting and robbing in Varroa destructor transmission from collapsing honey bee colonies to their neighbours’, PLoS ONE, 14(6), e0218392. doi:10.1371/journal.pone.0218392.
10. Oliver, R. (2020) Instructions for extended-release oxalic acid. Scientific Beekeeping. Available at: https://scientificbeekeeping.com/instructions-for-extended-release-oxalic-acid/.
11. Elgon Bees (2025) Elgon Bees – Varroa tolerant breeding project. Available at: https://www.elgon.es/.
12. Reams, T. & Rangel, J. (2022).Understanding the Enemy: A Review of the Genetics, Behavior and Chemical Ecology of Varroa destructor, the Parasitic Mite of Apis mellifera. Journal of Insect Science, 22(1), 18, 1–10. https://doi. org/10.1093/jisesa/ieab101
13. Illustration in the style of early 20th-century cartoons. This artwork is original and not associated with, or endorsed by, King Features Syndicate or the Popeye franchise.