We have heard a lot about colonies collapsing, presumably most of the mites
also die when this happens. This looks like a way of selecting the less
virulent mites for survival. (It selects beekeepers too.)
Perhaps this is why tracheal mites are, in my experience, quite unusual in
England now. We have no registered treatment for tracheal mites and almost
no complaints from beekeepers about this.
Brian Gant
Buckfast, UK