In this blog I would like to describe a simplified integrated pest management approach, for managing varroa mite, which can be used by the small-scale beekeeper throughout the year.

It is based on the approach recommended by the National Bee Unit, in their leaflet, “Managing Varroa”.  Click here or on the image below, to find and download the document from the National Bee Unit website.

Managing Varroa in Autumn

At this time of year, any honey supers will have been removed and bee numbers within hives will be falling.  I prefer to use a Thymol based treatment, like Apiguard, during the early Autumn.  It is manufactured by Vita Bee Health, who have some useful information and videos on their website.

It costs about £5 per colony and I bought mine from Bee Equipped Ltd, through Amazon.

Why use Apiguard?

• Thymol is a naturally occurring substance.
• Thymol has been shown to have a positive effect on other conditions too, like Chalkbrood and Nosema.
• It is not a pyrethroid.  Varroa mites have been shown to develop a resistance to pyrethroids.  This happens because the small percentage of mites that survive are the ones which have a higher tolerance to the chemicals.  The effect of regular use of the same pyrethroid is that successive mite generations become more and more resistant.  This does not happen to the same extent with hard chemicals, like Oxalic and Formic acids or with Thymol based treatments.
• I find it simpler and safer to use than some of the acid-based treatments.

How do I apply Apiguard to the hive?

A shallow eke is very useful.  They are easy to make from a single 1.8m long piece of 32mm x 18mm planed stripwood, four 40mm screws and four dabs of PVC glue.  I have tried shallower ekes, which were only 18mm in height, rather than 32mm, but found that the workers started to build brace comb between the top of the frames and the crown board.  They don’t appear to do this with the 32mm ekes.

Apiguard comes in a small foil tray, with a foil lid.  Find the corner with the small pull tab and pull the tab until the lid is almost removed, but still attached at the opposite corner.  There is often almost as much gel on the lid as there is in the tray.  Keeping it together helps when clearing up, as well as keeping the batch code info with the tray.

The opened tray is then put directly above the brood frames, under the crown board.  If after 10 days the gel has been removed by the workers, the second application is placed in the hive.  If there is still some of the first application left after 14 days, the second application is put in the hive anyway.  It is expected that the Apiguard treatment is in the hive for four to six weeks in total.  Once the second application has been removed by the workers, the trays and the eke are removed.

Apiguard and Supers

Any risk of tainting honey with Apiguard residue, or the wax that will be used to collect it, should be avoided.  The certain way to achieve this is by using Apiguard once supers have been removed.

The Veterinary Medicines Directorate state in their “Summary of Product Characteristics” sheet for Apiguard, that the following Special Precautions should be taken: –

• Do not treat during honey flow to avoid potential taste tainting.
• The treatment can be performed immediately after the removal of the supers.
• Do not use the product when the maximum daily temperature expected during the treatment is lower than 15°C or when the colony activity is very low or when temperature is above 40°C.
• Combine weak colonies before treatment.
• All colonies of an apiary should be treated simultaneously.

The manufacturers state that it is preferable not use it with honey supers on the hive, any honey collected at this time can be fed back to the bees and any supers left on the hive should be above the treatment.

How does Apiguard work?

It’s not the vapour that does all the work dispersing the thymol throughout the hive, but the workers removing it.  The workers will use their mandibles to take bits of gel to remove it from the hive, will walk in it and get it on their bodies.  Within a few days it will be trailed throughout the hive and mixed with the food shared through trophallaxis.  The whole nest will have traces of thymol, which then comes into contact with the mites.

Managing Varroa in Winter

During the winter, normally between Christmas and New Year’s Day, I prefer to treat colonies with oxalic acid solution, using the trickling method.  Oxalic acid is particularly effective when there is no brood.  This is because any mites will be on the bees rather than in capped cells.  Click here or the image below to see my post “Simple Oxalic Acid trickling method for the management of Varroa“, which explains the process I use.

Managing Varroa in Spring

The first inspection of the season allows a full inspection for pests and diseases to be carried out.  Click here or on the image below to see my post “First Colony Inspection of the Season“.

One of the key aims of this inspection is to classify each colony into one of the three categories: –

• Promote – The healthiest, calmest, strongest colonies
• Maintain – Healthy, reasonably calm, reasonably strong colonies
• Demote – Weaker or defensive

Click here to see my post “Bee Breeding – Why I put Characteristics before Ancestry“, which explains more about this classification of colonies.

Spring management for Varroa will differ depending on each category.

Promote

These colonies are not treated.  They managed to get through the same winter as the rest of the colonies and are thriving.  They may just be lucky or may have hygienic behaviours or developing resistance, either way they are “keepers”.  These colonies will be used to raise queens and drones.  They will not be merged with any other colonies to avoid any cross contamination.

Maintain

These colonies are not treated either.  They are healthy though, did OK through the winter and are building up OK.  They may get merged to produce stronger colonies.

Demote

The healthy but defensive colonies are not treated either ! They will be merged, requeened and/or used to provide bees and stores for Apideas/nuc, with new queens.  They are not unhealthy, just a bit grumpy!

This leaves the “weak” colonies.

How do I manage Weak Colonies?

The first thing to do is to try to quarantine these colonies from the others and avoid transferring bees or frames, through manipulations, drifting or robbing.

I apply the following logic to managing these colonies: –

• You can’t make a weak colony into a strong one by treating it!
• If you can tell what the problem is, there is probably a lot more of it than you can see, and the colony probably has other issues too.
• If you can not tell if there is a problem, it’s still weak, assume something is causing it.
• Pests and diseases build up in the brood comb, so treating the bees alone will not solve the problem
• Never waste resources from a good colony on a weak colony, keep the strong ones strong.
• Don’t let weak colonies steal your time in the apiary, look after strong colonies first.

So, my approach for weak colonies is to give them a chance to build up on fresh comb, by doing either a bailey comb change or a shook swarm, depending on the severity of the problem.

Bailey Comb Change

Used for less severe cases of varroa, nosema or chalkbrood.  The colony could also be re-queened with better stock, if spare queens are available.  A thymol-based product could also be used, but you don’t want a colony that only survives because of constant treatment and attention.

Shook Swarm

This is a more drastic approach because the brood will be destroyed, along with the pathogen or pest.  Oxalic acid trickling would also be effective to deal with any mites which have escaped on the backs of bees, but you also need to decide if the colony is worth saving or if the apiary is better off without it.

The picture above, on the left shows the start of a shook swarm.  (There should a queen excluder between that floor and brood body!)  The one on the right shows a hive going through a bailey comb change.

Managing Varroa in Summer

The summer months are about dealing with swarming, ensuring space for brood and stores and allowing the colonies to forage as much as the weather allows.  All colonies are checked for signs of varroa during routine weekly inspections.

No apiary wide treatment is planned during the summer.  An underlying aim of the summer period is to add space to the brood nest with fresh comb.  This can be in the form of drawn sterilised comb or foundation, in additional brood bodies.  The plan is to be able to ensure that by the end of the season the brood nest is established on this new comb.  The old comb can be taken away when the colony shrinks in size in the autumn.

How do I use Drone Brood to manage Varroa in summer?

By placing a super frame on the outer edge of each brood body, colonies will tend to draw out the lower part of this frame with drone comb.  Because of the longer development time of the drones in their capped cells, the varroa mites prefer drone cells over worker cells.  This comb can be routinely removed from the “demote” category of colonies.  This prevents poorer quality drones emerging, as well as removing many of the varroa mites.  In the better colonies, this comb can be used for testing for the presence of mites.  Again, removing this comb, if required, will remove a significant proportion of mites.

If a large colony is found to have a major varroa infestation during the summer, the same logic would apply on dealing with weak colonies in spring.  The colony would probably also have deformed wing virus or other problems too, which are also best fixed with a move to new comb.  This would give the colony a chance to re-establish on fresh comb before winter.

Keeping Records

It is a legal requirement to keep records of any medications used on honey bees.  The national bee unit website outlines the information you are required to record.  They also provide a form which you can use to record hives, dates, batch codes and best before dates.  Click here to see the National Bee Unit “Veterinary Medicines for Bees” webpage“.

I record this information in my journal and take a photo with my camera of the lot code info on the pack.

Summary

In this blog I have tried to describe a simplified integrated pest management approach, for dealing with varroa mite, which can be used by the small-scale beekeeper, throughout the year.  It is based on the approach recommended by the National Bee Unit, in their leaflet, “Managing Varroa“.

• Autumn – A Thymol-based treatment, like Apiguard, is put onto all colonies in the apiary, at the same time, after the surplus of honey is taken from the hives.
• Winter – Oxalic acid trickling is done, using a product like Api-Bioxal, on all colonies in the apiary, between Christmas and New Year’s Day.
• Spring – Colonies are assessed and the healthiest, calmest, strongest colonies, are promoted and not treated. Weak colonies are quarantined and moved to fresh comb.
• Summer – Drone comb removal is used to check and reduce varroa levels.

This approach tries to encourage hygienic behaviour and resistance towards varroa mite, but also recognises that beekeepers have some husbandry responsibilities to help their bees cope, in the short term, with the onslaught of issues they face.

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This blog describes a simplified method of applying oxalic acid, using the trickling method, which can be used as part of an integrated approach to the management of varroa.

Why do I prefer trickling to vapourisation?

Pure oxalic acid is horrible stuff.  If you inhale it, ingest it, or even absorb it through the skin, serious internal injuries can result.  Including the creation of salts which can crystalise in your kidneys or brain!

Vapourisation uses the vapour of pure oxalic acid.  The solution used for trickling is approximately 4% oxalic acid in a sugar syrup solution.  This solution is much less toxic to the beekeeper.

Research has shown that vapourisation is more effective than trickling, at killing varroa.  (click here to see the Sussex university web page on varroa control).  Vapourisation achieved 97% versus Trickling at 93%.  In addition, the bees appear to do better with vapourisation.  Colonies were reported to have 20% more bees four months after treatment.

Despite this knowledge there are three key reasons why I prefer the trickling method: –

• It significantly reduces my risk of exposure to pure oxalic acid crystals, dust or vapour.
• It is simple and quick to do by one person looking after 20 hives.
• The equipment is very portable, readily available and inexpensive.

Making up the oxalic acid trickling solution is a 2-step process

Api-Bioxal is an approved oxalic acid based treatments for varroa.  It comes in a 35g sachet.  The instructions for making up the syrup are on the back of the packet.  Here is my method for following them.

Step 1 – make up the sugar syrup solution

Making up the syrup solution

1. Put an empty, clean milk carton on a set of digital scales
2. Zero the scales
3. Add 308g of water into the carton (instructions say 308ml but it’s the same thing for pure water at 20 degree C, at sea level!)
4. Zero the scales
5. Add 308g of sugar to the water in the carton

You will now have 500 ml of 50:50 sugar syrup solution.  Actually, it’s more of a mixture than a solution at the moment, so put the cap on and shake it until the sugar dissolves in the water and allow it to stand.  The syrup is stable without the oxalic acid crystals, so you can make up the syrup either on the same day you plan to use it, or well in advance.

Make sure you take a note of the lot code and expiry date of the Api-Bioxal for your records.  You can find out more about the legal requirement to keep records of treatments on the national bee unit website by clicking here.

You are now ready to go off to the apiary, with your unopened 35g sachet of Api-Bioxal, your milk carton with 500ml of 50:50 Sugar solution and a clean 60ml syringe.  Don’t forget your gloves and mask.

Step 2 – adding the Api-Bioxal to the syrup

The Api-bioxal is best added to the sugar syrup immediately before it is used, at the apiary.  The instructions on the packet show that the shelf life of the solution, once the crystals are added to the syrup, is only 24 hours.   This can be done by snipping off the corner of the sachet and pouring it directly into the sugar syrup solution in the carton.

This is the only time that you have the possibility of coming into contact with the pure oxalic acid crystals, so use gloves and a mask and be careful.  Make sure to cut just enough off the corner to allow the powder to pour into the carton without any of it escaping down the side or being blown away in the breeze.  Safely dispose of the empty sachet, with the little piece you cut off.

With the cap screwed back onto the carton give it a shake to dissolve the oxalic acid in the syrup.

Planning for Oxalic Acid Trickling

When my hives were fed in the autumn and set up for winter, (click here to see my blog on winter hive preparation), the aim was to have enough stores in the brood bodies to see the colonies all the way through the winter.  Fondant is only added late in winter if the stores in the brood bodies are running low.  Trickling becomes much more difficult if a block of fondant was stuck directly on top of the frames at the start of the winter!

Oxalic Acid Trickling Method

Lay the carton on its side, with the neck elevated, so that the solution does not flow out.  The 60ml syringe is just the right size to go through the neck of the carton.  You are now ready to do some trickling!

The instructions for using Api-Biaxol are clear.  5ml of solution should be applied per seam of bees and that a maximum of 50ml of solution should be used for each colony.

With a little practice it becomes easy to judge the rate to apply the solution with the syringe.  It is more of a controlled dribble than a squirt!

I don’t feel obliged to use all the 5ml per seam or 50ml per colony.  If there are only 6 seams of bees, I’ll only trickle these seams and if two of them are only half the width of the frames I’ll only use half the amount in those seams.

My breeding strategy has given me near native bees, which form small clusters and are efficient with stores over winter, so I don’t want to punish them by drenching them with solution.

Summary

This blog describes a simplified method of applying oxalic acid, using the trickling method, which can be used as part of an integrated approach to the management of varroa.

Despite the research showing that trickling is 4% less effective, there are three key reasons I prefer it: –

• It significantly reduces my risk of exposure to pure oxalic acid crystals, dust or vapour.
• It is simple and quick to do by one person looking after 20 hives.
• The equipment is very portable, readily available and inexpensive.

Pure Oxalic Acid is a very toxic substance and needs to be handled with care.

Api-Biaxol is an approved treatment for varroa and it is a legal requirement to keep records of its use.  Api-Biaxol is easy to get online.

If you have found this interesting please subscribe to my blog and/or share on Facebook.

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