Genus Melanostoma

6 species in North America (Nearctica.com)

ITIS lists only two species. Andrew Young mentions only one.

Medium sized hoverflies, very similar to Platycheirus, especially the subgenus Pachyspira. They differ from Platycheirus by the cylindrical tibia and tarsi 1 (male and female) and the absence of bristles on femur 1 (male). The females have triangular spots on tergite 3 and 4 (except for the black M. dubium), in contrast to the rectangular spots in Platycheirus females, which may be yellow or grey.

Melanostoma species live in herb vegetation, often parts dominated by grasses. They fly in the vegetation and are best found by sweeping through the vegetation. Adults visit flowers and flowering grass spikes.

Larvae feed on aphids.