True Flies (Diptera)

The Diptera are known as the true flies and are characterised by one set of flying wings with the hind pair developed into halteres (II in 5), accelerometers which provide neural information on the orientation and changes to direction of the fly.  Flies are also characterised by the lack of chewing mouth parts, as they only consume liquid food sometimes by digesting it externally and sucking it up via a modified labelluma and labium (Lb in 9).