Thanks for the reply Michael. I thought it was a long shot that there would be a book specifically on it. Google has left me with bleary eyes and lots of unrelated hits as usual.
I started thinking about it this fall when observing my hive. I had put the mouse guard on a little early and had observed some insects that looked somewhat like fruit flies but with longer legs running around on the front of the hive. The bees didn't pay any attention to them but they avoided contact nonetheless. I would see them scurry under the mouse guard apparently taking shelter there. Later I observed some small wasps(similar to yellow jackets but only about 2/3 the size of a worker) on the front of the bottom board. They appeared to be attempting to lift the mouse guard up to get at the flies. They guard bees pretty much ignored them and they never attempted to enter the hive. I got thinking it was too bad there wasn't some way to train the wasps to hunt varroa
. Although maybe they did as I sometimes found the wasps in the observation tray under the SBB. I then forgot to do any research on the topic until I say your post.