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.)