Success and failure of any method is in the details. Its in the details of the execution and its in the details of the circumstances.
This may seem off the subject but sometimes we have to back up from a subject to get some perspective, so let me use a real life illustration to make my point.
A friend of mine had the pressure tank on their well rust through. It was leaking badly. She called another friend who took a short lag screw (very coarse threads) and a rubber gasket and screwed it into the hole. Predictably, it did not stop the leak. I looked at it and suggested we could get a fine threaded self-tapping screw for an automobile oil pan and drill the appropriate size hole, put some gasket sealer on the bolt and a rubber gasket on it and try to seal it with that. The man who had tried the lag screw pointed to the screw and said, we already tried that and it didnt work.
Well, we did try my plan and it did work. So my first point is:
THE SOLUTION ONLY WORKS IF IT IS WELL EXECUTED.
I wasnt sure it would work. Why? Not because I didnt think it was a good plan, but because there were circumstances that I could not know, like how large the rusted area in the tank was and whether there would be enough solid metal to hold the threads. These were things that could also cause a good plan; even a well executed one, to fail.
My second point is:
EVEN A WELL EXECUTED PLAN CAN FAIL BECUASE OF OTHER CIRCUMSTANCES.
Back to FGMO. I have conversed with many people who are using FGMO with good success. I have also heard from people posting here who have said they had failures. In order for all of us to learn from these successes and failures we need to determine what methods on what schedule were used by both the successes and the failures.
We also need to determine the other contributing circumstances that could have affected the success or failure. Its obvious to me from the evidence so far, that FGMO is effective to some degree against mites. Some have found it remarkably effective. How effective is controlled by both the details of the implementation and the circumstances.
So far people reporting failure usually just say things like I tried FGMO and it didnt work. This is not constructive. If you could detail the exact kind of oil, the methods of application, the amount applied, the schedule of application this could be useful for all of us.
People also say they tried FGMO and it DID work. Again, it would be useful for all of us if they would specify what application method was used, what their schedule was and if they had other Integrated Pest Management procedures that would contribute to its success and if they had or have some monitoring methods to check for infestation and what the results of that monitoring were.
My observation is that there is still no magic pill, no silver bullet. If you are of a mind to not use poisons in your hive, then the most promising directions to explore right now seem to be FGMO, Small Cell, genetics, drone brood for trapping mites and essential oils.
I have heard of several people using combinations of Screened Bottom boards and FGMO fog and succeeding. I have reports of people using Small Cell and Genetics and succeeding. I have not heard very many people who are using only one thing and succeeding.
If you care about your bees, whatever you use for treating mites, you need to monitor the results. Mite populations can explode in a matter of days and decimate your hives. Maybe we need to work out what is an acceptable level of infestation AT A PARTICULAR TIME OF YEAR. What is the level in the summer that will cause the sudden mite population explosion and failure in the fall? Obviously there are ALWAYS mites and there are ALWAYS more of them in the fall. At what level can we predict we are going to be in trouble in the fall? At what level of infestation can we predict that things are going well?
If we are going to share information, we need enough information to be useful.