A Bee Favorite

It was a chilly morning and for the most part the bees have slowed down.  Not on this flower though.  They were still as active as ever on this plant.  I have to wonder what makes these flowers so special.  I also saw another tagged Monarch (in extras).  It was definitely a different butterfly from yesterday.  I couldn't get an unobstructed shot of the tag, but the last digit is clearly a zero, instead of yesterday's three.