In describing the bristles of the thorax (dorsocentral bristles and acrostichal), a formula is used in which the first number indicates the postsutural ones, and the second number, following a plus (+) or minus (-) sign the presutural. A few bristles are on the legs, but bristles on tibia 2, are of taxonomic significance. Tibiae are without a dorsal preapical bristle. Hind tibiae are without strong bristles in the basal 4/5. The front femora are without a conspicuous spine beneath. The wing venation usually exhibits first and second basal, anal, and discal cells but may lack one or more of the cells. Wings have a discal cell, or are without a discal cell; without a subapical cell. The anal cell is very short and closed. The costa has one break which is at the end of the subcosta. The subcosta is apparent (faint) and joins vein 1 well short of the costa, or terminates before it (vein Sc is complete or incomplete, apically ending in vein R1 (Agromyzinae) or separate from vein R1, but reduced to a fold that may or may not reach the costa (Phytomyzinae)); . Wing vein 4 extends far beyond the end of the first basal cell. Wing vein 6 is present, falling short of the wing margin. Wing venation is shown in the gallery.