Figure 1. Bombyliidae wing - The wing venation of Bombyliidae is distinctive, with veins R2+3 and R4 bending forwards to meet the costa almost at right angles to it.
Figure 2. Calypter - Lower calypter of a sarcophid fly.
Figure 3a. Mesoscutal sulcus - Transverse sulcus of mesoscutum complete - calypterate families.
Figure 3b. Transverse sulcus of mesoscutum broadly interrupted.
Figure 4. The haltere is a modified hindwing of Diptera. It is a balancing organ used to maintain stability during flight.
Figure 5. The vena spuria is vein-like thickening. It occurs in the family Syrphidae.
Figure 6. Ptilinal suture - a fissure crossing above the antenna and down the sides like an inverted 'U'.
(Head removed from body.)
From Wikipedia ......
The defining feature of the Schizophora is the presence of a special structure that is used to help the emerging adult fly break free of the puparium; this structure is an inflatable membranous sac called the ptilinum that protrudes from the face, above the antennae. The inflation of the ptilinum (using fluid hemolymph rather than air) creates pressure along the line of weakness in the puparium, which then bursts open along the seam to allow the adult to escape. Once the adult emerges, the fluid is withdrawn, the ptilinum collapses, and the membrane retracts entirely back inside the head. The large, inverted "U"-shaped suture in the face through which it came, however, is still quite visible, and it is this ptilinal suture or frontal suture from which the name "Schizophora" ("split-bearers") is derived. The term was first used by Eduard Becher.
Figure 8. Wing vein CuA+1A not reaching wing margin.
Figure 9. Veins CuA and 1A joining near the wing margin.
Orthorrhapha and Cyclorrhapha - Aschiza.
Figure 10. Holoptic eyes - where the eyes are continuous across the top of the head.
Figure 11. Plumose antenna or feathery antenna. In this case of a male mosquito.
Figure 12. Scutellum and subscutellum of Tachinidae. The prominent subscutellum is typical of Tachinidae.
Figure 13. Labellum