The letter to the ABJ was fairly non-specific, but what I understand him to be referring to is the phenomenon of continually selecting for survivor mites from worker brood. Assumming all drone brood mites are killed, Then each generation of mites would, presumably, be better able to reproduce in worker brood, as all survivors have the traits that enable this behavior. Since not all mites can reproduce in worker brood, there is a strong chance that the traits needed to do so are recessive (otherwise, the majority of mites could do so). Keeping a large number of drone-produced mites on hand would presumably suppress the traits needed to reproduce in small cells. If you somehow managed to breed a mite that easily reproduced in worker cells, then this mite would, presumably, be better able to adapt to breeding in 4.9 foundation. That assumption of perfect kill of drone produced mites is quite a large one, however. You could end up with a small population of weak mites (stunted due to forced reproduction in worker cells), although not likely. This might let you drop chemical treatment. However, you would have to keep removing the drone brood on a regular basis, including any drone brood laid on non-bait comb. It is equally possible that you could completely eliminate varroa from your hives after a faily short time period, if you had 100% SMR bees -- forcing all reproduction to be done in drone cells, which you are removing. If you could remain isolated after that (note, there is NO chance of that in this part of the US), you could then cease treating, so long as you never imported any new bees and swarms never reached your area. Personally, it seems that the use of drone comb continously in the brood area is just asking for trouble. You are increasing the percentage of drone brood in the hive, which dramatically increases the number of mites able to reproduce at any one time. Only if you pull that comb every few days, never missing due to weather, illness, work schedule or a vacation will you kill those mites -- which might not otherwise have even been in the hive at all. You still get mite reproduction in drone cells mixed in with other frames of brood. Occasional use, as a means of diagnosing infection rates, is another matter entirely. K. Oland -----Original Message----- From: Bob & Liz the theory of creating a mite which only prefers worker brood to be small as all research points to varroa loves drone brood and worker brood is a second choice.