Bumble Bees and Basswood Trees

Tonight i went to a lecture about bees and basswood trees. Basswood are also known as linden trees. I like basswood trees. I also like eating new basswood leaves in the early spring when they are still small and bright green. They are delicious. Anyway people have noticed that bumble bees sometimes die below flowering basswood trees. This was noted in 1908 and continues to this day. Studies haven't been able to figure out why bumble bees die under basswood trees. We have learned why some bee species are declining but this connection with basswood trees remains a mystery.