I have not heard that bees are harmed by cranberries; I would imagine they are much like blueberries and if the bees prefer something else they will be on the something else and not the cranberries.
My club had an open hive at a cranberry bog last year during cranberry pollination season. The bees were working the in bloom cranberries as expected. A basic tactic is to not place bees for pollination before the crop is experiencing 10-20% bloom - this focuses the bees on the target crop instead of making them look elsewhere for a meal.
As an aside, the weather is generally much better during cranberry pollination season than in our wild blueberry season. Fewer bees are required because of this to achieve good pollination. I talked with one commercial beekeeper last year who was placing (at grower request) as many as 7 hives per acre on wild blueberries to ensure good pollination considering the weather was often not suitable for bee flight during blueberry pollination season.
It is 32F here now and I heard yesterday that two semis of bees have already arrived locally for blueberry pollination. My thought is that we have weeks to go before the blueberry bloom starts - in other words those two semi loads are way early.
A forum community dedicated to beekeeping, bee owners and enthusiasts. Come join the discussion about breeding, honey production, health, behavior, hives, housing, adopting, care, classifieds, and more!