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In a moment of weakness I posted this on the other place yesterday where it has subsequently gathered dust. I'll never learn.

The issue is how a comparison between total mites killed by a late summer treatment compared with the mites killed by a winter OA trickle might suggest the effectiveness or otherwise of the summer treatment. The problem is counting how many mites fall out after treatment does not show how effective that treatment is but a com[parision between two different treatments at different times of the year might be able to give some indication.

There are two enclosed charts.

Varroa Drop Chart shows the number of varroa that fell during thymol treatment which started I think at the very end of August 2005 and then how many fell after an OA treatment on 31 December. The chart might take a little while to understand as the columns are not evenly spread by date, but the tallest column is 17 September. The two on the right are for 1 and 2 Jan. I didn't check after 2 Jan but you can see the rate has already started to drop off.

The chart Varroa Records I got from somewhere else, can't remember where now, but it attempts to show how a relationship between the mite fall after a late summer treatment and a winter treatment can indicate how effective the summer treatment was.

There are two lines drawn on the chart but there could many more added between them. The lines simply show approximate upper and lower boundaries for low and high summer infestations. Medium infestations would lie between these lines. The two lines simply show that for example, in one hive with a high infestation a low summer fall is followed by a high winter drop if the summer treatment was ineffective. Other points on the lines and indeed any other line you might want to draw between them can show how effective your summer treatment was. The point about the lines is you can't tell just from counting a summer fall how effective your treatment was as you don't know how many mites there were in there to begin with. It is only following the winter treatment that you can tell, after counting the mite fall, how effective your summer treatment was.

For example, a summer fall of 300 mites followed by a winter fall of 50 would indicate an effective summer treatment, but if the winter fall was 200 then the summer treatment was not very good.

Taking the data from my Varroa Drop chart, in round numbers about 400 mites were killed in summer and about 100 in the winter, perhaps a few more as I didn't count to the end - it was too cold! However, a total winter drop of about 30% of the summer fall seems OK from the second chart.

There are of course other variables (such as uniting colonies and introducing brood from other hives) but the point of the second chart is taking a single reading on mite fall is not necessarily a reliable way of knowing how good your treatment is. Comparing readings using different treatments at different times of the year can give more information.

It would be useful if anyone who took accurate records of late summer treatment fall this year also did a count after winter OA and let us know the results.

The issue is how a comparison between total mites killed by a late summer treatment compared with the mites killed by a winter OA trickle might suggest the effectiveness or otherwise of the summer treatment. The problem is counting how many mites fall out after treatment does not show how effective that treatment is but a com[parision between two different treatments at different times of the year might be able to give some indication.

There are two enclosed charts.

Varroa Drop Chart shows the number of varroa that fell during thymol treatment which started I think at the very end of August 2005 and then how many fell after an OA treatment on 31 December. The chart might take a little while to understand as the columns are not evenly spread by date, but the tallest column is 17 September. The two on the right are for 1 and 2 Jan. I didn't check after 2 Jan but you can see the rate has already started to drop off.

The chart Varroa Records I got from somewhere else, can't remember where now, but it attempts to show how a relationship between the mite fall after a late summer treatment and a winter treatment can indicate how effective the summer treatment was.

There are two lines drawn on the chart but there could many more added between them. The lines simply show approximate upper and lower boundaries for low and high summer infestations. Medium infestations would lie between these lines. The two lines simply show that for example, in one hive with a high infestation a low summer fall is followed by a high winter drop if the summer treatment was ineffective. Other points on the lines and indeed any other line you might want to draw between them can show how effective your summer treatment was. The point about the lines is you can't tell just from counting a summer fall how effective your treatment was as you don't know how many mites there were in there to begin with. It is only following the winter treatment that you can tell, after counting the mite fall, how effective your summer treatment was.

For example, a summer fall of 300 mites followed by a winter fall of 50 would indicate an effective summer treatment, but if the winter fall was 200 then the summer treatment was not very good.

Taking the data from my Varroa Drop chart, in round numbers about 400 mites were killed in summer and about 100 in the winter, perhaps a few more as I didn't count to the end - it was too cold! However, a total winter drop of about 30% of the summer fall seems OK from the second chart.

There are of course other variables (such as uniting colonies and introducing brood from other hives) but the point of the second chart is taking a single reading on mite fall is not necessarily a reliable way of knowing how good your treatment is. Comparing readings using different treatments at different times of the year can give more information.

It would be useful if anyone who took accurate records of late summer treatment fall this year also did a count after winter OA and let us know the results.

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