> I now think my problem was non-treatment beekeepers in the area and their bees collapsing. 

This has been talked about for years. Dr. Marla Spivak spoke of the herd immunity and vaccinations. The herd is protected by having the highest proportion of vaccinated individuals. This means fewer people to get infected, and less chance of them contacting each other. If there are a lot of infected people, they are a reservoir for disease. If everyone is vaccinated, there is nowhere for the disease to go. 

So, if everyone treats for mites, the overall population is low. If 60% doesn't treat, they are raising mites which spill over on the rest of us, when the hives collapse. On the other hand, thankfully, the treatment free crowd owns the minority of the hives (80% of beekeepers keep just 1–20 colonies).

In her own words, taken from the WAS Journal, November 2015:

> In recent years with the increase in backyard beekeeping in cities, I have noticed that many small-scale beekeepers prefer not to treat their colonies for mites. I wish all of our colonies could survive without having to give them any treatments. I am a strong advocate of reducing treatments in bee colonies when possible. But observing the extreme losses that backyard beekeepers are experiencing, and monitoring the very high mite levels in colonies in cities, I am starting to rethink the strategy of not treating colonies.

> Here is what happens in a city (or in a commercial beekeeping operation) when most colonies are not treated for mites. Colonies with lots of mites start to decline at the end of the season, and colonies that have been treated and have low mite levels remain strong. The strong colonies start robbing out from neighboring colonies (within 1-2 miles!) that are weak. The robbing bees carry home stored honey, and they also carry home mites from the weak colony. Soon, even previously treated and healthy colonies have high mite levels before winter, and then die off, leaving the beekeeper perplexed.

> If sufficient numbers of colonies in an area are treated, more colonies would be stronger going into fall, and robbing bees would not pick up as many mites. In other words, when more colonies are treated, horizontal transmission of mites would be reduced. This concept, of treating sufficient numbers of colonies, is similar to herd immunity in our livestock and human vaccinations. The goal of herd immunity is to bring pathogen (or mite) levels down sufficiently to reduce the spread of the problem and prevent the demise of the population. There are a number of organic and effective mite treatments available on the market. It is time to bring down the mite population in the U.S.

[I am sorry that we have to revisit this issue over and over again. To me, it's like the faith cure; may work for some people. If I try it and I get sick, they tell me: not enough faith; didn't do it right. I placed my bet on health insurance, expensive but worth it.]

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