Ghislain

> Two rules here, Allen:
> - only one application of oxalic acid in a bee's lifetime
> - no application when brood in the hive

This what worries me most about oxalic - how many times does the queen get 
dosed in her lifetime.  I am breeding for A.m.m. where queens can live up to 
five years before superseding.

I understand that in some countries (Denmark?) it is normal practice to 
re-queen after oxalic treatment.

I have also read in a paper somewhere - sorry, I can not find the 
reference - that brood rearing may be depressed for up to four months after 
OA treatment.  That would suggest that treatment should be made as early in 
the autumn as possible in order to minimise its impact on brood rearing in 
the following spring.

This is from Apidologie 30
Negative long-term effects on bee colonies treated with oxalic acid against 
Varroa jacobsoni Oud.
Mariano Haiges Aránzazu Mbeana Miguel Sauárez Jesús Llorente
"Although no effects of the treatment were seen in the colonies during the 
application period [6, 9], the long-term study of the colonies clearly shows 
a negative effect of the acid, at least when brood was present. The most 
important finding in this study was that the increase in the number of brood 
cells was significantly higher in the control hives than in the treated 
colonies. The loss of a queen and two colonies cannot be related to 
mismanagement by the apiarists, as all colonies were inspected after 
treatments and all queens were present. This long-term negative effect of 
oxalic acid on bee colonies has not been reported before. Although the 
efficacy of oxalic acid is very high in autumn when there is little brood, 
the detected negative long-term sideeffects on colony development require 
more thorough studies to determine the reliability of its use."

I am sticking with thymol.

Best wishes

Peter
52.194546, -1.673618 

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