Further information on fly morphology can be found via Wikipedia and this Italian Diptera site.
Main parts of a fly
Head of a fly
Parts of the head
Bristles of the head
The thorax
Thorax in top view
Thorax in side view
McAlpine terminology
Wing venation
Complete venation
This wing has all the veins that were thought to be present in a primitive fly. No known fly has such complete venation, although some tipulids (craneflies) come close.
Reduced venation of a "higher fly"
Wing of Calliphora (Calliphoridae) showing the reduced venation typical of "higher" flies.
Legs
Parts of the legs
Orientation of bristles