What is "brachyopini"

The Brachyopini (or Chrysogastrini) is a tribe of hoverflies. Unlike many members of this family these flies are generally darker and less colourful though some genera contain species with an attractive metallic lustre e.g. Chrysogaster. Some like Brachyopa are associated with sap runs where their larvae feed on decaying sap. Others are found in boggy areas where their often semiaquatic larvae feed on decaying organic matter.