This is actually Boneset (Eupatorium perfoliatum), which I perhaps incorrectly identified earlier in the week as Ironweed. I find pictures of this same flower with both labels on the internet, though they are members of totally different families. I am suspecting the Ironweed name has gotten applied to both plants, because of the similarity in the flowers and growth habits. Boneset is a large showy plant I see growing mostly in dryer areas near water…and a magnet for insects of all types. This specimen is at Factory to Pasture Pond in Kennebunk, where there is a good sized, though isolated, stand of it. I have been watching it daily to see when the bugs would start coming.

I was actually photographing this Monarch on the same plant, when the bee flew in. Twofer!

Canon SX40HS. Program with iContrast and –1/3EV exposure compensation.  1240mm equivalent field of view. f5.8 @ 1/200th and 1/400th @ ISO 160 and 400. Processed in Lightroom for intensity, clarity, and sharpness.