This past weekend, in the mountains of North Carolina, I counted around 22 bees on yellow lady slippers (I'm sure there were many more, but these were the ones I could count near the country roadside I was walking down). They would go up into the throat of the flower and then come back out. They seem to pass on the orange lady slipper plants which were growing next to the yellow ones. I also noted they buzzed around the yellow golden rod plants too, but didn't go near a deep purple wild flower. At my home in Georgia, I have seen them on the wild clover in my backyard, but not in the numbers that I saw in North Carolina on the lady slippers. I do have a lot of yellow jackets around my yard, I don't know if they are keeping the bees away. I also haven't seen any carpenter bees like I have in the past years, boring holes in my wooden rockers on my porch.
backyard wildflowers are bee magnets
I had bees on my backyard wildflowers all last summer (2008). The most popular flowers included spiderwort, penestemon, bee balm, butterfly milkweed, swamp milkweed, boneset, coreopsis, and blue-stemmed goldenrod. My latest observation was September 28. (I'm in SE Michigan).