There were several of these bees on the Golden Rod, some individuals like this one showing a lot of red on the body, others completely dark. Looking into it, I believe these are Common Furrow Bee (Lasioglossum calceatum, #679). The males show variable amounts of red like this, while the females lack red colouration. These are ground nesting solitary bees, which are usually found in small colonies in short turf or other sunny areas of open ground .