# General beekeeping > Bee health >  Oxalic Acid.

## GRIZZLY

Are there still beekeepers about who DON'T believe in dosing their bees with oxalic acid ?.

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## Jon

Loads of them Grizzly!! It ain't natural you see.

I am doing a presentation on Oxalic at my BKA this evening.
I did the same thing last year and when I asked who had ever used Oxalic, only two hands went up out of about 30 present.

We have organised ourselves and tonight will be taking names and colony numbers with a view to distributing the Oxalic to members in the December meeting. We did this last year for the first time and distributed enough to treat about 150 colonies. it will be a more this year, I would guess about 4 litres. It is incredibly simple to prepare and costs about 10p per colony. This will be my 4th season on the Autum Thymol, Winter Oxalic regime.

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## gavin

Oh, there are many.  Some may have thought about it seriously and decided to use other effective methods. Others could be trying to go cold turkey to see what happens.  Yet more have been seduced by talk of tickling them with powdered sugar and other ways of losing your bees - unless you *really* know what you are doing and are watching the Varroa levels keenly.

I'd really like to know what the levels are of effective vs ineffective Varroa control in different parts of the country.  I noted that there was a comment that 'Fife was particularly bad' in one of the submissions to the UK parliament, referring to winter losses and hinting at you-know-what of course.  

Me?  I'll be making up my 75+1000+1000 in a couple of weeks. Hit them while they are vulnerable and get your bees off to a good start for the year ahead.

Beaten to it!  Yes, I'll be dishing out oxalic in December too.

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## Jon

Some colonies drop next to nothing with the Oxalic but I always find one of two which drop a significant number of mites - over 100.
Some people reckon that Oxalic shortens the life of winter bees and it is also reputed to accelerate the demise of nosemic colonies.
Like a lot of things in beekeeping it is a trade off and anything which removes the mites is likely worthwhile in the long run.

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## prakel

> I'd really like to know what the levels are of effective vs ineffective Varroa control in different parts of the country


maybe you could organize a joint project with the biobee membership....

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## gavin

Lol! Maybe we could plot ash dieback while we're at it and see what spurious correlations we can come up with?

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## Jon

Varroa treatment is like the old maxim about advertising spend. 50% of the spend is wasted but it is impossible to work out which 50%.
I am sure some colonies would be fine for a while without treatment - but how can you separate those ones from the other ones which are heading for trouble. Varroa collapse can be sudden.

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## Mellifera Crofter

Hands up.  I'm one of the loads who don't treat with oxalic acid.  I'll do it if I really have to, but I don't really want to.  So far, in my three years of beekeeping, I haven't yet lost a colony due to Varroa.  I know it can change ...
Kitta

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## Neils

> Some colonies drop next to nothing with the Oxalic but I always find one of two which drop a significant number of mites - over 100.
> Some people reckon that Oxalic shortens the life of winter bees and it is also reputed to accelerate the demise of nosemic colonies.
> Like a lot of things in beekeeping it is a trade off and anything which removes the mites is likely worthwhile in the long run.



Starting to see more than a few people minimising Thymol treatments in preference for more reliance on OA on the basis that it's less disruptive and more effective than the Thymol.

we're having another bee safari in late december to go round everyone who's interested's apiaries and do a mass Oxalic Acid application.

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## Jon

Trouble is, if you have a big mite load December is too late for the first treatment.
Your colony could be full of virus by this stage.

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## Neils

Don't disagree with you but equally I can see the reasoning behind it.  Of the few I've spoken to about it so far I admit that I haven't got a full sense of what they're doing at the moment but I didn't get the impression that they were fully reliant on a winter OA treatment and nothing else.

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## Jon

There seem to be quite a number of posts from people who treated with a thymol product for 4 weeks and then found they still had a masive number of mites dropping when apistan or bayvarol was used. there are a couple of posts on the bbka site which mentioned thousands of mites.

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## Neils

I think the weather has definitely played its part this year.in reducing the effectiveness of thymol treatments. I've also seen a lot more claims of queens going off lay when being treated this year and wonder whether there's something in that it it's a consequence of the generally poor year and forage as much as the thymol.

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## GRIZZLY

Like you Jon I'm going to obtain hive numbers from our membership at this months meetng. I'm doing a small presentation for the less well informed membership at our December meeting - with a "mock" demonstration for our beginners to show them how simple the technique realy is. We purchased O.A in bulk and will distribute ie amongst our members. Do you find it is better to make up the solution rather than distribute the powder ?. Personally I favour the liquid but am open to suggestion.

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## Jon

Hi John
I mix up the solution on the morning of the meeting and the members bring in containers to take the stuff home.
A half litre coke bottle is a decent size for most.
You need something to measure out the liquid.
Last year we had about 3 or 4 litres to distribute and it will likely be more this year.
I got 120 colonies on the list last night and others are sending in colony numbers by e-mail.
I would guess we will be mixing for over 200 colonies.
I think pre mixing is important as someone is likely to mix the stuff up wrongly if left to their own devices.

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## GRIZZLY

Thanks Jon,will have to suggest that members save their wee bottles for next month. WE've bought one of Thornes auto-dispense gadgets which fits into a bulk supply-(modified 4 pint plastic milk bottle).This dispenses 5 ml per pull of the trigger - much easier to use than a syringe and much more accurate per seam of bees. I plan to pass this around local members and bottle up some for more remote people.

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## gavin

> Trouble is, if you have a big mite load December is too late for the first treatment.
> Your colony could be full of virus by this stage.


What that man said.  First time I've used that phrase, not sure if I like it or not!

Make sure that people know this is a treatment for healthy bees in the spring and summer to come.  If the colony had a mite problem in September this isn't a way to escape the inevitable weak or dead colony in the spring, that needed action in August preferably.

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## gavin

> Thanks Jon,will have to suggest that members save their wee bottles for next month.


Do you mean small bottles or wee bottles?!  These wee bottles hold up to 60ml and some of them even have volume graduation marks on the label, great for doling out the oxalic solution!

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## GRIZZLY

> Do you mean small bottles or wee bottles?!  These wee bottles hold up to 60ml and some of them even have volume graduation marks on the label, great for doling out the oxalic solution!


Those sort of bottles are made for the wrong acid - could be an alternative treatment perhaps ?.

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## Jon

> What that man said.


I noticed that phrase a few times recently or you can do it as _'What he said_'
I presume it comes from an American sitcom.
Young Mr Nellie has his finger on the zeitgeist so we need an explanation.




> Others could be trying to go cold turkey to see what happens.


Speaking of which...
There is a thread here and some good pics of mites and mite drop when treatment is late.

My overwintering colonies never have big enough clusters to get the full monthy of 50ml Oxalic. On average they take 30-35 ml and the nucs about 20-25ml.
This year I suspect the clusters will be smaller than usual as queens stopped laying very early.
When measuring out the Oxalic I would give a 10 hive beekeeper about 400ml which they can then measure accurately via syringe on a hive by hive basis according to the number of seams.
When I am treating an apiary I bring along a flask of hot water. I stand the plastic bottle with the Oxalic in a flora tub and fill it up with hot water to keep the Oxalic at about 25-30c.
Treatment usually takes place on a day where the temperature is near zero and the bees are in a cluster so you don't want to be tipping 40ml of freezing cold liquid into the cluster.

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## sbamember

Never put poisons in a recogisable food or drink container.

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## Jon

True enough, you need to be careful. We have sheets of labels and every plastic bottle or container gets a warning label.

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## Easy beesy

> Trouble is, if you have a big mite load December is too late for the first treatment.
> Your colony could be full of virus by this stage.


Hi Jon

Which virus were you referring to please?

Only treatment I use is OxA in winter and on swarms and artificial swarms (avoiding queen).

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## Ruary

Hi, there are numerous viruses which are vecyored by Varroa destructor; ABPV; CWV; DWV; KBV; SBPV.

Source Virology and the Honey Bee edited by Michel Aubert et al ISBN 978-1-904846-77-2


(sorry for the abreviations early morning and not fully awake)

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## Easy beesy

S'ok. I understand the abbreviations.
 Supposing there were no varroa, wouldn't the viruses be spread through the colony anyway?  Are viruses normally spread by trophillaxis?  If so they would still be affected, only more slowly?

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## Neils

I believe that dwv, for example, is now regarded as generally always being present within a colony to some degree. Varroa appears to host and pass on one of the more virulent strains of it.

I don't know enough about bee to bee transmission of viruses but I think you'd have to suppose that even without varroa you'd have some incidences of DWV but certainly those displaying outward symptoms of it tend to be ejected from the hive and from observation seem to spend more time "hiding" in cells than actively participating in hive activities which I'd suppose would minimise transmission in that regard.

I think the main point about reliance on a winter treatment of OA is that while you'd get a good knockdown of mites, during the autumn "production" of the bees that will be needed to carry the colony through spring there is likely to be a high number of mites and no drone brood which can weaken the workers and increase the spread of viruses at a time of year when you really want good strong bees emerging.

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## Jon

> I believe that dwv, for example, is now regarded as generally always being present within a colony to some degree. Varroa appears to host and pass on one of the more virulent strains of it.


There was a paper published earlier this year about the arrival of varroa in Hawaii by Martin et al.
Before the arrival of varroa, there is some DWV present in the bee population in several variants.
After the arrival of varroa DWV is found in 100% of bee colonies and it is the variant which causes maximum damage to the bee population. Gavin posted a link to an article about this on the home page of this site.

I have a few slides posted on the Belfast beekeepers' site which show how the population dynamic of varroa mites changes with time in a colony.
Slide 11 shows why a colony which looks fine all summer can collapse suddenly at the end of August when an increasing mite population combined with a decreasing brood area leads to 80% of the brood being affected by the mites.

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## Easy beesy

Nellie, Jon 

Point taken but its served me well for the past years with never more than 10% losses.  I might just be lucky but I'm gonna stick with it for now.

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## Jon

Well it is better than not treating at all!
I think in the long run you would need to be careful.
All it takes is one year where the mite numbers increase more quickly and you could lose the lot.
I know experienced beekeepers locally who have been almost wiped out by taking a less than rigorous attitude re. varroa control such as treating every other year or treating using quack remedies. Camomile tea is one which sticks in the mind.

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## Easy beesy

How long is long run?  Never had any dealings with quack remedies either. Last 10 years been working ok for me. As I said maybe luck.

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## Jon

We did our Oxalic distribution at our monthly meeting tonight.
Over 6 litres of 3.2% solution distributed at a cost of £1 per 3 colonies.

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## Jon

I treated 11 colonies at our association apiary site with Oxalic this afternoon, mostly nucs which had on averaqe about 3 seams of bees which should be enough to get them through the winter.
There were a couple of decent colonies with 6 or 7 well filled seams of bees.

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## fatshark

> When I am treating an apiary I bring along a flask of hot water. I stand the plastic bottle with the Oxalic in a flora tub and fill it up with hot water to keep the Oxalic at about 25-30c.
> Treatment usually takes place on a day where the temperature is near zero and the bees are in a cluster so you don't want to be tipping 40ml of freezing cold liquid into the cluster.


I was shopping for a few bottles of WaggleDance in Morrisons this evening and noticed they had cheap vacuum flasks. Rather than doing what Jon suggests - which is exactly what I've done in previous years, together with the inevitable spills - I'm going to pre-warm the OA and keep it in the flask as I go round the apiaries. The flask has a convenient pouring spout (so easy to top up the Trickle bottle) and is bright red ... with large lettering OA ONLY!!! on it to avoid any confusion later in the year  :Stick Out Tongue:  !

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## Neils

Good idea fatshark

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## fatshark

I agree, though I say so myself. The WaggleDance honey beer was a stroke of genius  :Big Grin:

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## gavin

Definitely a stroke of genius.

As for warming the oxalic, does it really matter?  I keep a couple of wee plastic bottles of the stuff in a trouser pocket to keep the worst of the chill off it, but never go to any bother to make it warm.  The cluster is going to be fairly cool anyway, and the volume is small so it will quickly convert to cluster temp without chilling a lot of bees.  I'd have thought.

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## Jon

And would you drink your red wine chilled just because it will be up to body temperature by the time it hits your stomach!!

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## gavin

Just think of the oxalic acid as a nice glass of Chardonnay and you'll be fine.

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## Jimbo

Did 4 colonies the other day with OA. Looked better than I thought. The weakest had 3 seams of bees and the others 5 to 6 seams so should make it through the winter without loses but then I do live in the West!

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## gavin

> Did 4 colonies the other day with OA. Looked better than I thought. The weakest had 3 seams of bees and the others 5 to 6 seams so should make it through the winter without loses but then I do live in the West!


I did mine today.  All eight alive and some surprisingly prosperous given the predictions of heavy losses from some folk I respect.  Three had 10-11 seams of bees, a remarkable strength for my apiary anyway.  Here's a tenner:



Also another strong at 8.5 seams, and only one of the eight currently looks vulnerable as it is on just two frames.  That one had a near-death experience with Varroa before I took charge of it late in the summer, swapping it for a healthy nuc returned to the beginner with the Varroa problem.

That's the oxalic treatment finished for me.

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## Jon

I still have about 18 to treat and I hope to do them at the weekend.
10-11 frames is really strong. I think my strongest are on about 7 frames.
Mine overwinter with small clusters most years, probably 5-6 is average and this year a wee bit smaller.
You can get a 2 frame colony through the winter with a bit of TLC but you won't get any spring produced honey from it.
what temperature was it today? the clusters open up quite a bit when it is mild.

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## gavin

It was about 4C and there was a breeze picking up.  A grey day.  Some of the colonies were really quiet and one had the cluster well down the frames.  Some, like the one shown, were busier with active bees on the top but I don't think that the cluster was particularly dispersed.  

Some were light but doling out the fondant wasn't so easy as I broke my knife!  Even tried sawing the blocks (it was the only likely implement in the back of the car) but I gave that up and I'll finish the job another day.  The one in the picture was hungry so I reassembled it with the spare super off, the crownboard straight on the cluster, a full (12.5kg) block of fondant still in its (open) bag over the feed hole, empty brood box around it, the spare super parked back on top, and a sheet of 50mm Kingspan under the roof.

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## Bridget

Gavin very interesting picture.  No chance of opening up like that here - far too cold and windy.  I was trying to remember what mine looked like last year when I did an OA and I don't remember them clustered on top of the frames. More down between the frames. 
Checked my leftovers OA from last year and it seems its out of date.  Would OA go out of date or just a sales ploy from Thornes?


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## Jon

You need to make it up as fresh as possible. The sugar in it make it go off quite quickly.
it definitely does not last year to year although the dihydrate powder you get from Thorne lasts indefinitely.
It only takes 10 minutes to make up a fresh batch.

As Gavin commentated, that lot were low on stores and that brings them up to the top as they start at the bottom and work up.

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## gavin

> You need to make it up as fresh as possible. The sugar in it make it go off quite quickly.
> it definitely does not last year to year although the dihydrate powder you get from Thorne lasts indefinitely.
> It only takes 10 minutes to make up a fresh batch.
> 
> As Gavin commentated, that lot were low on stores and that brings them up to the top as they start at the bottom and work up.


Yes Bridget, bees at the top is not a good sign and that box was light.  Not so light now, it has 12.5kg of fondant on top!  The converse is, of course, that if they are down between the frames they still have stores over their heads, and that is good.  I had only one like that.  It looks like the colonies I had at the heather have raised a lot of late brood, squandering much of the heather honey they stashed away down below but raising a lot of young bees in the process.  They all have many lines of brown dust on the floor insert showing where brood was being raised.

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## Mellifera Crofter

> ...  They all have many lines of brown dust on the floor insert showing where brood was being raised.


Is the difference between brood gnawing their way out of cells and bees uncapping honey cells the colour of the debris on the floor insert, Gavin?
Kitta

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## greengumbo

> Is the difference between brood gnawing their way out of cells and bees uncapping honey cells the colour of the debris on the floor insert, Gavin?
> Kitta



I'd be interested in this as well. Still not got my eye in with regards to colour but there are two obvious browny dust lines on my varroa board that I just assumed were uncapping debris.

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## Jon

You can sometimes see where bees have started to uncap stores as there will be a heap of debris on the tray at a point some distance away from the cluster. They uncap stores and move them nearer to where they want them but can obviously only do this in warmer spells of weather. Cappings debris from emerging brood tends to be darker than the debris from stores being uncapped. If bees have decided to ditch pupae due to lack of food or chilling you will often see segments of bee legs on the tray. This is most noticeable during Thymol treatment in autumn where the odd colony decides to uncap a lot of brood.

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## gavin

There are often lines of slightly fibrous-looking mid-brown debris under the middle of the brood nest.  I'd always assumed that this was the remains of the cocoon spun by a pupating bee, chewed off the cap of the cell and cleared out inside the cell too.  The debris around this can be of different colours but is usually whitish and sometimes with sugar crystals mixed in.  Wax and solidified stores I thought.  Immediately around the brown line area there is often more pollen than elsewhere - but probably not at this time of year.

I'll take a picture next time I see a good example, unless anyone wants to beat me to it.

In winter it is reassuring to see as it means that the colony was raising brood late in the autumn and so the queen is in reasonable shape.

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## Bridget

This has been one of the most illuminating threads.  I had no idea they would uncap stores and move them


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## Jon

I have a not very good photo of a varroa tray where you can just about see where stores have been uncapped. Sometimes it is quite obvious but I don't always have the camera with me.
It is pretty obvious where the cluster is and you can just about see where stores have been uncapped.
This is from a couple of years ago in March.

varroa-tray1.jpg varroa tray2.jpg

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## gavin

In these shots it seems that the material isn't falling down vertically between straight combs, or has been subsequently mixed, as the lines are not clear.  However - mostly brown fibrous stuff in the middle; pollen around this and also mixed in; paler stuff with sugar crystals further out.

The pollen would normally be around and over the brood nest so some falls in the same place as brood debris.

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## Mellifera Crofter

Thanks, Jon and Gavin.  I don't think any of mine has brood at the moment, and very little uncapping was going on when I last looked (but the boards are mostly out).

Yes, the lines aren't visible - or do I imagine seeing that your frames are arranged warm-way, Jon?
Kitta

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## Jon

All mine are warm way.
That was a poor illustration I posted but it was the only one I could find amongst my photos.
I am off to do the last of my colonies with oxalic this afternoon and I have the camera so maybe I will come across a better example.

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## gavin

Here is the one that was shown as the 'tenner' the other day.  The floor debris will have accumulated since mid to late September so it is showing where there was brood then.  The bees were occupying slightly more seam area two days ago than the brood area.  There is a little liquid, perhaps oxalic acid, and the brown stuff looks damp.



Another strong one but only occupying part of the seams.



... and one across much of the length of the seam.  I estimated that the 3-month mite fall (including the last two days after oxalic) was about 200.  If the full number is 500 (guessing) then the oxalic acid treatment should leave about 10 mites (at 98% effectiveness).  However I lost swarms last summer into the castle walls so there could easily be surges in numbers whenever those colonies collapse.  



Close-up of that one (with my crappy phone camera, Jon may do better):



PS  Cold way!  (Is that the annual warm way - cold way argument over then?!)

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## Jon

Warm way, cold way, the main issue is where you like to stand when working the colonies.
I always stand at the back of the box.
I don't think it makes a button of difference to the bees.

I did 10 colonies and 8 nucs earlier this afternoon.

The 10 colonies had a total of 46 seams so 4.6 average.
That is smaller than last year as the average was 6.7 seams when I did Oxalic on 20 December.
One had only 2 frames and the strongest had 7.

The nucs were very evenly balanced all with 3 seams of bees.
At this stage of the year I would not expect to lose more than one or two of these.

This was a decent sized colony which has eaten a good few kilos of fondant.
Stores are good in this one and you can see capped stores 3 frames in on the frame with the green lug.

winter-cluster-col83.jpg

This was more typical, 4-5 seams but should still be ok.
I usually remove 3 of 4 frames and close down clusters like this with insulated dummy board to reduce the space.

winter-cluster-col95.jpg

This is 1 week of debris on a tray.

winter debris.jpg

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## gavin

From the side for me.

Your floor debris seems to have little sign of the consumption of stores - which fits the season of course.

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## Jon

A couple of years ago I weighed nucs during November and December and was amazed how little they consumed. I think from memory it was only about 300 grammes per week on average.

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## Mellifera Crofter

> ...
> 
> PS  Cold way!  (Is that the annual warm way - cold way argument over then?!)


Oh - I was only checking my perception skills!  Did I, or din't I, spot a faint line on Jon's board - and I did.
K

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## fatshark

Treated all mine with OA today. Windy and overcast, but at least it wasn't raining and the temperature reached 9 degrees. The thermos flask with prewarmed OA worked a treat as did one of those refillable Trickle containers from Thornes. Most of the bees were quiet and well tempered despite being exposed to the wind and a mild drenching in warm sugar solution. 

All looked healthy with between 2/3 seams of bees in wooden nucs, 4/5 seams in 8 frame Paynes poly nucs and a few up to 9/10 seams in cedar hives. Funnily enough the only hives to look short of bees were those on double brood boxes, presumably because they were well buried. Even the Kielers looked OK and got some OA as I'd missed them from Apiguard treatment earlier.

Pleased they all looked strong enough to get through the winter ... main thing to worry about now is DLQ's by springtime  :Frown: 

Happy Christmas everyone  :Smile:

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## Jon

I just checked some trays below colonies which got oxalic 6 days ago and there were far more mites than I expected.
Normally when I apply Oxalic I might find a dozen or so mites but the 4 trays I looked at had up to 200 mites on each.
My best guess is that the cool weather late summer meant that the Apiguard was not as efficient as usual.
This could also explain why I have found that clusters are smaller than usual. More mites and virus produces shorter lived bees.

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## fatshark

Same here Jon. Apiguard mite fall (September) was really low, but I've now had a couple of consecutive days with about 100 mites dropped (National). I'm not sure whether it was inefficient Apiguard or just a period of extended brood rearing going into the autumn. I'm certainly not aware that the temperatures here were particularly low in September.

Another thing to worry about is my honey fudge has failed to set  :Frown:

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## Black Comb

Not boiled it (slowly) for long enough.

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## saskia

The guy from Aberdeen -Alan bowman gave a very good talk on gene knockdown the other day in Edinburgh one of the interesting things he said was that someone had looked at old museum s(?Victorian) samples of honey bees for viruses, and the ones we find we're mostly present but at orders of magnitude lower levels than found in presence of mite. I have often wondered about transmission of viruses in absence of mite- still not sure what it would be.. I had assumed not trophyllaxis -but don't know enough about viruses and how they multiply etc which cells they invade,and how thy effect bees..

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## Jon

Hi saskia
A paper which was published earlier this year by Martin et al looked at the arrival of varroa on some of the Hawaiian islands.
There are different variants of Deformed Wing Virus which occur naturally in bee populations but once the mite arrives, one type of DWV comes to predominate and unfortunately this is the variant of DWV which causes most damage to honeybees. There was a thread started on this earlier in the year.

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## gavin

As for the mechanisms maintaining the diverse DWV types at a low level without Varroa to vector them ..... I haven't a clue but there are people on this forum who have talked knowledgeably about such things and maybe they'll be along in a minute.

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## Black Comb

So for colonies with the high mite count post oxalic what and when do you plan to treat with?

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## Jon

If you apply Oxalic in a broodless period it should get rid of the mites quite efficiently - but other than that a shook swarm in spring is one option.
I have used Apiguard in autumn followed by Oxalic in winter for several years now and it has worked for me without any other treatments being necessary.

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## Black Comb

Same here Jon but counts noticeably higher this year.
Shook swarm is favourite for me at the moment.

Anyone tried queen trapping?

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## Calum

Lactic acid at this time of year... 15%, 8ml sprayed per side of a frame full with bees Will use it on my shook swarms next summer to, too reduce the initial varroa infestation levels...

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## Bobs-bees

Carried out Oxalic acid treatment on 3rd January 2013. This after NOT doing any other treatment last year.
Hive contains 7 seams of Bees. I have been feeding Fondant since late November.

4th Jan Day 1.       39 Varroa.
5th Jan Day 2.       140   ..
6th Jan Day 3.       66    ..
7th Jan Day 4.       51    ..
8th Jan Day 5.       38    ..  

I suppose you can double these findings as there will be trapped varroa on the mesh floor, also on the bottom bar ledge of the frames.
Quite pleased about these results so far BUT there is still a high risk of losses as the weather is about to change back to winter mode.
Bob. In not so sunny Rainham. Kent.

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## Mellifera Crofter

I yesterday counted the mite fall from ten hives over eleven days.  It worked out at .036 mites per hive per day - a mite leg per day?  (Four mites altogether in total.)

As I've mentioned earlier, I've not treated with OA so I suppose you'll tell me I should not feel too happy just yet - that they're there and I just don't know about it.

I'm not for or against OA - I'm just a bit reluctant about it.  Acid over the bees in the middle of winter ...

Kitta

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## Jon

Hi Kitta
There is plenty of research to show it does them no harm. It's an acid but only at 3.2% strength. The Acetic acid at 80% used for fumigating frames and bee equipment is dangerous stuff but the Oxalic at that strength is a fairly benign product. It's best warmed to 30c before being applied.

Re. the natural mite drop, the official advice is to treat if necessary when the mite drop is above a certain level.
Personally I find this completely unreliable. Over the summer I sometimes don't see a mite for months then when treatment starts you can have several hundred drop over a day or two. 
If I treated 10 hives I would find a couple with next to no mites dropping and a couple with quite a high mite drop. You just can't tell which is which until you treat.
Mites plus their vectored viruses is still the main problem in beekeeping.

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## Mellifera Crofter

Thanks Jon.  I thought you might say something like that, and I'm sure you're right.  Maybe next winter ...  I did treat them with Apivar in September and will do so again in spring.
Kitta

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## snimmo243

I have some Oxcalic trickle left over, enough for 1 hive if anyone in West Lothian area needs it

Steven

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## EmsE

I applied the OA to my colonies last weekend and was pleasantly surprised at the strength of them. The pre treatment varroa drop was checked for one of the hives (hive 7) which was 3 mites over 7 days. Post treatment results were
Hive 1) 86 mites / 6 days
Hive 2) 49 mites / 6 days 
Hive 6) 5 mites / 6 days 
Hive 7) 158 mites / 6 days (different site to the rest)

It's good to see that the OA has had an impact.

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## Jon

Those are fairly typical results. I see a lot of variation in mine as well. I only monitored 4 of mine out of about 30 and one of them dropped about 250 mites over 10 days. Your hive 3 could have gone without a treatment but there is no way of knowing that beforehand.
They will all benefit from the reduced mite load.
A colony starting the year with 150-200 mites could well be in trouble by June with a mite load over 1000 by that stage.

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## Mellifera Crofter

> ... It's good to see that the OA has had an impact.





> Those are fairly typical results.  ...


EmsE and Jon, how, or with what, did you treat your hives in the autumn, and what were the results then?
Kitta

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## Jon

Apiguard on almost all of them except for a few nucs which were treated with Apilifevar which was on offer from Thorne.
I started treating from the middle of August when I got the supers off.
Again, I only monitored a few and the mite drops were not exceptional, maybe a couple of hundred.
I suspect the thymol based treatments were not as effective as usual as it was very cool weather here for most of the treatment time and thymol treatments work best when the temperature is over 15c.

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## nemphlar

I used a thymol autumn treatment on 7 out 9 the other 2 were given FA and from the drop seemed quite effective at the time. The queens in the 2 FA hives continued to lay late into the year and are bigger where the thymol hives stopped. after OA treatment in mid December, with 1 exception the bug drop in the thymol treated hives is low in double figures after 4 weks, while the 2 Fa's and 1 larger thymol hive were in hundreds less than 200 admittedly. Does seem unavoidable that a prolific queen will give perfect conditions for varroa

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## EmsE

I treated all my hives with Apiguard in the autumn. In some of them, the Queens stopped laying about this time too. I didn't check the mite drop as carefully at this time (plan to this year though) but did see a lot of mites fall during the treatment, however I have also been concerned that whilst there was a good fall of mites in the autumn, the Apiguard may not have been as effective as it could have been due to the cool weather at the time. 

The hive that has given me the biggest mite drop so far is one that I didn't think would still be here due to the queen not laying and their refusal to take stores in the autumn. There are now 6 seams of lively bees bees and they are enthusiastically making their way through a slab of fondant. :Smile:

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## Mellifera Crofter

Thanks for the replies.  I did wonder whether the kind of treatment might play a role in the necessity of using OA during winter.  I used Apistan until the autumn of 2011, and then Apivar spring and autumn last year.  I was shocked at the amount of varroa I found in one of my hives last spring on my first inspection - so it would be interesting to see what I'll find this coming spring having changed to Apivar and still not using OA.  Will let you know.
Kitta

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## Adam

> Thanks for the replies.  I did wonder whether the kind of treatment might play a role in the necessity of using OA during winter.  I used Apistan until the autumn of 2011, and then Apivar spring and autumn last year.  I was shocked at the amount of varroa I found in one of my hives last spring on my first inspection - so it would be interesting to see what I'll find this coming spring having changed to Apivar and still not using OA.  Will let you know.
> Kitta


Kitta,
A commercial beekeeper I speak to occasionally uses Apivar and he says that it works very well so he treats once per year. Puts it in in Autumn and removes it in the Spring. He does no other varroa treatment.

I have no problem with oxalic acid over bees, it works well and I have not seen any issues with it.  (I even put acid on my chips but that's dilute acetic of course).

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## Jimbo

I used Apivar for this first time in autumn last year and got a significant large drop in all my hives. I have followed this up with a winter treatment of 3.2% Oxalic acid which is a soft chemical to get the last few varroa that the Apivar did not get. Beekeepers in Denmark have been using Oxalic for years with no adverse affect as long as you keep to the correct concentration.

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## Jon

As Jimbo says, Oxalic acid has been used all over Europe since the 1990s and there is stacks of research looking at the best dosage to use and whether there are any negative consequences for the bees.
It is not a controversial treatment and is one of the least aggressive ways of keeping varroa numbers down.

http://ebookbrowse.com/oxalic-acid-t...-doc-d83040618

http://www.ibra.org.uk/articles/Oxal...idues-in-honey

Randy Oliver has a load of info on his scientific beekeeping site

http://scientificbeekeeping.com/oxal...-1-of-2-parts/

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## Mellifera Crofter

Thanks for the links, Jon, and the reassurance from everybody that I won't harm my bees using OA.  I believe you.  Interesting about that commercial beekeeper, Adam.  I'll see how my bees have coped in spring.
Kitta

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