The Dusky Bog Fly (Parhelophilus rex) is a medium-sized, dark-colored, Nearctic flower fly. Adults have a pair of thin gray stripes on the thorax. The hind femur is almost entirely black. The larvae have long breathing tubes which allow them to live in low-oxygen waters thick with decaying organic matter.
Flight season May – July
Flowers: Willow catkins
Similar species: Parhelophilus obsoletus and Helophilus sp.