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New Recommendations for the Oxalic Acid Trickle Treatment

By Jean-Daniel Charriere, Anto Imdorf and Peter Fluri.

Translated from the Schweizerische Bienen Zeitung 123(9),523-524(2000) by A.E.McArthur MIL


An initial recommendation for the concentration of the Oxalic acid 'trickle' treatment solution was published in the October 1999 issue of the Swiss Beekeeping magazine. In the meantime co-ordinated trickle treatment trials have been carried out in Switzerland and many other European countries allowing new recommendations to be issued.

The two factors of bee tolerance and effectiveness of treatment against the mite were especially investigated. On the basis of the latest results the definitive concentrations and application of the trickle solution are as given on in the table on page 524.

Trials with Oxalic Acid

In autumn 1999, trials for the effectiveness of different solution strengths for the Oxalic acid trickle treatment were carried out in 200 colonies in 10 different apiaries in Switzerland. To check the bee tolerance levels, population development between October 1999 and spring 2000 was recorded.

Foreign Trials

Parallel with the trials in Switzerland, many Bee Research Institutes in other European countries were carrying out independent trials along the same lines.

The results were compared and discussed at a Congress at Zollikofen on the 16th to 18th June 2000 The consensus from this meeting was that it was not possible to make a single 'universal' recommendation regarding the application of oxalic acid for the whole of Europe. There are 3 distinct climatic regions which must be considered separately: South-, Central-, and North Europe. The Central European conditions are relevant for Swirtzerland.

Recommendations for the Treatment of Bee Colonies using the Trickle Oxalic acid Method, valid for Central Europe.

Components of the Solution

35g Oxalic acid Dihydrate in 1 litre of sugar solution 1:1

Amounts of Solution Relative to Colony Size

The amounts quoted relate to a 5 - 6 ml quantity of solution per frame space occupied by bees for Swiss Standard or Dadant brood chambers.

Timing of Treatment

During November/ December when no brood is present.


The provisional solution strength for the trickle treatment of 45g per litre of sugar solution 1:1 recommended in the 10/1999 magazine issue pages 564 and 565, can also be used. In this instance the amount of solution per occupied bee space should be reduced. A 4 ml amount instead of a 5 ml is sufficient.   The amount per colony will also be correspondingly less and vary between 20 - 40 ml according to colony strength.

We recommend however, in future the 35 ml oxalic acid dihydrate be used.

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