Opetiidae

Small, slender bodied flies, wing length 2.0-4.8 mm. Entirely dark colored in both sexes (except for the red eyes) including halteres, legs and all bristles. The male eyes are holoptic, the female strongly dichoptic. The antenna is erect with a terminal two segmented arista. The wing venation is very characteristic with vein M1+2 with a long narrow fork and crossvein dm-cu absent; cell cup is very small but tapered apically. There is a broad anal lobe in the male but the wings are narrower without an anal lobe in the female. The legs are slender without the modifications to tarsi found in Platypezidae. There are only six pregenital segments in both sexes. The male genitalia are small and reflexed under the abdomen; the female has the segments beyond the sixth fused into a strongly sclerotized ovipositor but sclerotized spermathecae are absent. (Chandler 1998)