Platycheirus scamboides
Platycheirus scamboides (Curran 1927), the yellowspine sedgesitter, is a rare species of syrphid fly observed in northeastern North America. Hoverflies can remain nearly motionless in flight. The adults are also known as flower flies for they are commonly found on flowers, from which they get both energy-giving nectar and protein-rich pollen. Larvae are aphid predators. References

Diptera of North America
Hoverflies of North America
Syrphinae