Peter Edwards wrote:
> See caveat on oxalic acid here:
> http://www.stratford-upon-avon.freeserve.co.uk/Newsletters/April2006.htm
 From the article:

"A 3% w/v solution (70g oxalic : 1kg sugar : 1 litre water) was trickled 
at a dose of 5ml per seam; this is within the usual range of dosage that 
is recommended.  The treatment was then repeated after a 13 day 
interval; this is not usually recommended.

There was considerable brood damage.  12.6% of young brood (< 3 day old) 
and 9.5% of older brood was removed by the bees after the first 
application.  The figures for the second application were a further 
10.6% and 5.6% respectively.  Perhaps more significantly, the open brood 
area was reduced by 17.5% for 2 months after the treatment.  It is also 
known that the effect of applying oxalic solution by spraying will 
affect brood rearing for 4 months and I would expect the application by 
vaporising oxalic crystals (which is becoming increasingly popular) to 
have at least the same effect."

This appears to be twice the strength used normally, two applications 
instead of one, and no limit of 50ml per colony, so is it really a 
legitimate caution? The studies I have seen say that high concentrations 
do cause bee mortality, so this just confirms it.

Bill Truesdell
Bath, Maine

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