The most common Coelioxys in the East.  

The most common Coelioxys in the East.  

C. sayi is a nest parasite, 

Slipping into the nests of leaf cutters like Megachile mendica and kin and dropping an egg into the wall of their nests.  In the female, like this one, the edge of the clypeus is slightly indented (hard to see).   Now you know.