The Diapriidae

 gaster simple in the sense that it is clearly differentiated into a dorsum and a sternum, showing 4 ring segments distal to the larger tergite.  eyes hairy)

 gaster remarkably modified, showing no clearly differentiated dorsum and sternum; no dorsal ring segments visible as such, the apical segments more or less completely telescoped within the large tergite; ovipositor very short, its sheath showing as a short stub. (The apical gastral segments can be extruded to resemble a scorpion’s tail; flagellum thin and thread-like Related to Cinetus but the marginalis is at most about half as long as the radial cell