What is "mixogaster"

Mixogaster is a genus of hoverflies native to North America and South America, with 19 known species. Mixogaster is distinct by lacking an appendix on vein R4+5, having a reduced and bare metasternum, an unarmed scutellum, and usually an appendix on vein M extending in cell R4+5. The larvae feed as scavengers in the nests of ants.