The expert group of Finnish Assosiation of Beekeepers informed 2002 that varroa is not problem in Finland. That is answer of beekeepers, who has varroa in their hives.
There are many good means to keep the level of mites low enough. Allmost in every hive there are mites now in Finland.
Mite arrived over Russian range 30 years ago. It took 20 years to mite to go over whole Finland.
Mite came from Asia and they still keep bees there.
In this forum we talk about varroa alot like an final disaster. But as I understand, readers are not interested about methods, which really work. What are they searching? - A miracle?- WHY?
Also in Finland some beekeepers try to bring up the bee, which destroy the mite without chemicals. And every where I guess , in Poland, in Russia, In Slovacia, in Germany and so on - What we have now? If you have some hives, do not believe too much - sorry.
Those methods we use now in Finland are from Eastern Europe. They are cheap and good. They have not money to get " a miragle solutions". Still they keep bees in Asia and in East.