Chris Slade said:  > I have never understood the concept of prophylactic
treatment for pests such
> as varroa.  How can you by adding chemicals or making manipulations
control
> beasts that aren't there?<
>
> Unforetunately, once arived, Varooa are ALWAYS there  The most effective
treatment (Apistan) only claims 98% or so kill - so if there are 2500 mites
at treatment , there are 50 left - too few tofind easliy in a colony of say
70,000 bees.  These can rebuild the population back to the treatment
threshold over one year - unless suppressed with say thymol, or drone brood
culling , in which case the treatment intervals can be lengthened - but u
need to monotor each hive with a mesh floor to know if it is safe to leave
any particular  colony for longer.

Robin Dartington
>

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