Our general area had heavy bee losses last winter--no good explanation. Beekeepers who did mite counts & treatments still went into winter with hives that were not as strong or as healthy looking as in prior years. The extended cool, overcast weather lasting into April did not allow boosting weak hives with brood from stronger ones. I went from 30 hives to 12, and with about 5 nucs I am trying to over winter, I am up to around 22. This is plenty for me. With 30, I was pressed for time and for equipment. One of our more experienced and diligent sideliners had 85% losses. I suspect some general, fairly wide spread health issues in our areas. If you read beekeeper reports in the historic ABJ issues, there are instances of unexplained heavy losses within fairly narrow geographic areas in a given winter.
Not really on topic for a sugar brick post, so I'll bring it back on topic by offering the opinion that I don't think my losses last winter were because of sugar bricks.