When doing a 24 hour mite drop count (with varroa screen/sticky
> > board), is there any consensus on what count should prompt treatment?
>
> Jim said: Well, there is one, and it has even been tweaked a few times,
but I feel
> that it will do you more harm than good.

Jim illustrated how questionable any single figure guide must be when
colonies vary so much in size.  But there is an even more important factor,
according to Prof Mark Winson of Simon Fraser Uny who visits UK to lecture.
Apparently, varooa are not all that lethal to bees - bees from under weight
larvae catch up after eating pollen, although longevity is affected.  It is
the viruses vectored by varooa that kill. Even worse is a combination of
varooa and tracheal mites - such colonies go down very fast indeed. So some
colonies survive with 8,500 mites - others die with 3,000.  UK gov policy is
based on limiting max population to 2,500 - the excellent (free) Maff
publication 'Varooa - monitoring and forecasting mite populations within
honey bee colonies in Britain, 1998'  contains graphs from which the number
of days before any estimated mite population will expand to 2,500 (latest
date for treament) can quickly be seen.  Tim Arheit has given the web site
adress for the online calculator (which looks more complicated to me).

Winston has presumably published his reseach - a reference to an article
would be helpful if any one knows.  The importance of controlling tracheal
mites alongside varooa suggests that thymol based treatmments such as Api
Var may be very helpful,  alternated with some harder killing substance
(oxalic acid?) .

Robin Dartington

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