gavin

Trickling treats

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gavin
, 30-12-2011 at 02:53 PM (4150 Views)
Yesterday my bees (bar one colony at home) got their mid-winter sweet and sour treat. Previously I've used the 4.5% oxalic acid dihydrate recipe (which some call 3.2% oxalic as that would be the weight/volume strength if people used anhydrous oxalic acid). This really confuses people. There has been a lot of stuff posted in various places recently and not all of it is right.

The standard recipe - as has been posted elsewhere on this site - is:

75g + 1000g sugar + 1000ml water, or fractions thereof. It makes 1670ml. Adding the oxalic to hot water helps get it dissolved, then add the sugar and stir.

An alternative is to make the 1:1 syrup first then add 45g of oxalic acid dihydrate to every litre of syrup.

However there has been some discussion on one of the more sensible internet beekeeping places - the Irish list (thanks Ruary) - so I am trying a more dilute solution this year. As is anyone else getting their solution from me. This comes from the Swiss paper by Charriere and Imdorf which shows that a lower concentration seems to be just as effective and doesn't appear to have the small effect on the strength of the colony which is sometimes seen with the 4.5% recipe. Their recommendation was to use 3.5% oxalic acid dihydrate in 1:1 syrup, so that it what I'm doing this year. 5 ml per seam up to 50 ml per colony.

The recipe for 3.5% (weight/volume) oxalic acid dihydrate in 1:1 syrup is:

58g + 1000g sugar + 1000ml water, or fractions thereof. It should make about 1660ml.

An alternative is to make the 1:1 syrup first then add 58g of oxalic acid dihydrate to every litre of syrup.

Did I use 50ml on any? You bet! Of the four colonies that had been up the glens for the heather, one has a problem - a late attempt at supercedure which might have failed - and the other three are all the strongest colonies I've seen at this time of year. Two on 10 seams, one on 9 but even that one was well across the seams. It looks like all three are going to explode into two brood boxes early in spring. The others had between four and six seams, all respectable cluster sizes for the end of December. All the heather colonies were markedly lighter than when they came home. The one with 9 seams was very light, so perhaps not a sensible stock to breed from. Three of them got a half box of fondant each yesterday and some of the others will be monitored as spring arrives and the stores decline rapidly. 2012 should be a good year. The association apiary probably isn't faring as well - I'll check on them the next suitable day.

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Updated 31-12-2011 at 01:56 PM by gavin

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  1. Jimbo's Avatar
    I use the 75g Oxalic 1000ml H20 and 1000g sugar and have done for a number of years with no ill effect noted. I also distribute this mix to all the members of HDBA with no reported ill effects. It is interesting to see some research on using a weaker mix. I may try this next year as I treated last week 11 colonies of various strengths from the weakest at 2 seams up to 7 seams. The amount I applied varies with approx 5 ml per seam so the total dose will be quite variable per colony. On my visit to Denmark it was stressed not to use too high a concentration of Oxalic and I was suprised to find a big city beekeeping association using from 4% up to 6%, that is when they were not busy gassing themselves and their bees by sublimation. When I am making up the Oxalic I do not use heat I just put it on a mixer until everything is dissolved in case the heat denatures the Oxalic
  2. gavin's Avatar
    Sadly, there are companies in the UK selling a 6% mix which has to be higher than the optimum. I'll let you know what I make of the weaker solution but I don't plan doing detailed counts so it will just be an impression in spring time once they start making drone brood. Wouldn't think that the oxalic solution would denature on heating but I wouldn't heat it (much) after the sugar goes in. You're a good lad making all that oxalic. I give tubes of the stuff with a disposable dropper to a few others locally, but having seen such strong colonies yesterday I'm revising my view of how much you might need for a typical hive.
  3. Calum's Avatar
    here was the result of my treatment, the average was about the same for all colonies on that site, impressive and worrying!
  4. gavin's Avatar
    Ooof! Did you catch them in time I wonder?
  5. Calum's Avatar
    no worries, seen worse. There are plenty of bees in the colony still, question is did I get enough mites?
  6. Jon's Avatar
    How many days drop is that Calum?
    I never like to see that many mites but your colonies of Carnica are probably double the size of mine and can carry more mites.
    One of mine dropped 150 over 4 days but others dropped none at all.
    Not to be outdone by Jimbo, I distributed about 4.5 litres of Oxalic to members of Belfast and District at 3.2%
    I have used Oxalic at this strength for three years and not seen any obvious ill effects.
    I think only myself and two others have used it before but I did a talk on Oxalic back in October and the info was posted to the association website.
    You need to use a bit of common sense as some seams are fuller than others so I vary the amount per seam between 3ml and 5ml
    Even the strongest colonies are supposed to receive no more than 50ml even if they fill double brood.
  7. Calum's Avatar
    hi
    that is the result after 13 days, & Carnica are the most common bee here. The final mite count should be after 3 weeks- so something might still fall. The colony was fairly strong - 5 frames the hive next to it was a bit stronger with 6-7 frames (mite fall pic below). Helping out my beekeeping guru as he is 81 - we saw about the same mite fall / frame in his 24 colonies. So I can say that seems not too abnormal for this area this year, expected losses are at 30% now for bavaria the mild weather is no good at all for the bees.. so far i lost two colonies to varroa from 23, the rest seem fine so far.