Here is a link to the full text of one of my favorite books, "Plants and Beekeeping" by F. N. Howes, a former botanist at the Royal Botanic Gardens at Kew, and a long time beekeeper in the first half of the 1900's. http://archive.org/stream/… If you scroll down a bit there is a section on poisonous and unpalatable honey, describing incidents and floral sources. He notes however that when the honey is ripe and capped over then it is probably safe. My own observations revealed that honeybees aren't too interested in Rhododendrons if there is better forage available, even when Rhododendrons are in abundance. Bees seem to have a preference for flowers in the sun, with some exceptions of course, while Rhododendrons are often grown in the shade (here anyway). I have seen bumblebees on them though. -Travis