Do we know above what temperature threshold Varroa start feeling
uncomfortable and perish ?  Would it be at the point when a 'bee beard'
starts forming ?

Thank you,

Waldemar

>>> As reported a couple of weeks` ago, new research in Canada has
demonstrated
> a downside to screen boards.  Apparently Varroa is much more sensitive to
> high temperatures than are honey bees, and that accounts for the fact that
> Varroa is not a significant problem in tropic climates.  Since screen
boards
> reduce hive temperatures, the Canadian researchers apparently conclude
that
> they actually promote Varroa reproduction!  (This could account for
> Shimanuki's and Pettis's observations that while screen boards initially
> have a significant effect on reducing Varroa populations, by the end of a
> honey season Varroa populations in hives with screen bottoms are equal to
> those in hives with solid bottoms.)