Agapostemon is a genus of Halictid bees (Sweat Bees). The members of this genus are just gorgeous, and I’ve mentioned them before; for example, they nest in communal aggregations. And I’ve featured photographs of them before (here for example). But, anyway, you can never have too much of a good thing, can you?
This is Agapostemon virescens on Carduus nutans (and she’s pretty enough that I will dedicate an entire post to her):