A scientific article came out recently with evidence that bees like thistles! (Of course we already knew this…)
Here’s a link to the article, which came out recently in the journal Diversity and Distributions. http://onlinelibrary.wiley.com/doi/10.1111/ddi.12397/full
The main point of the article is that these noxious invasive thistles provide important floral resources for bees precisely because they are so impossible to kill. They survive where other plants die, under extreme disturbances of mowing and pesticide usage.
The point is not to plant thistles in your backyard (they’re really hard to control!), but that, given that they are already there and we’re not successful at eradicating them, we should take into account their beneficial aspects as well.
Namely, that bees like thistles (especially bumblebees and small carpenter bees)(Russo et al 2015).