Every week I get the A.R.S. (U.S.D.A.) summary and every once in awhile there is something there for beekeepers. The article that I'm linking here is not particularly informative but it includes further reading links that lead to other links that lead to other links... For some unexplained reason this particular article discusses a study of winter squash pollinators without ever linking to the study itself...huh? These summaries are always very brief and their greatest value, to me, is to point me toward a topic that I may otherwise be unaware of.
http://www.ars.usda.gov/is/pr/2008/081230.htm

George