Re: Local absence and local extinction, a confounding factor in TF prescriptions
The yellow counties in NY probably are that way because those counties are where Apiary Inspectors worked checking migratory hives. The absence of any color on the other counties can not reliably be taken to mean the absence of varroa mites, but the absence of anyone looking more likely.
I am willing to bet that there are no counties, or even Townships, in NY State where bees are kept where varroa mites can't be found. W/in the Adirondack Park, w/in the Blue Line as we say in NY, almost no bees are kept, so no varroa. But, even w/in the Blue Line, where there are bees there will be varroa mites.
Speaking as one who experienced the spread of varroa mites, from when there were none in some parts of the Sate until there were no places where they could not be found. Seems like that took about 5 years.
The answers are the end. The questions are the journey. Journey on.