Genus Heterostylum
Heterostylum engelhardti
There is not much of an abdominal pattern on this species. Most of the pile is cream-colored, but some have darkened tips. In general, the species has a slow flight, but it is also capable of explosive warp speed. The distinctive buzz may allow it to be located prior to being seen.
Range: COCH, GRAH, PNAL
Occurs: Late July to Mid-September
Heterostylum robustum
The large size and distinctive black and white pattern toward the tip of the abdomen allow this species to be readily identified. It is fairly common during the spring in riparian areas, sometimes in small numbers. The intensity of the abdominal pattern is quite variable, as are the colors of the halteres and legs.
Range: COCH, GRAH, PIMA, PNAL, STCR
Occurs: Mid-April to Early June