Diptera of the sub-order Orthorrhapha occur in the Lias and Cyclorrhapha in the Kimmeridgian.
In ordinary language the name is used for any species of Siphonaptera (otherwise known as Aphaniptera), which, though formerly regarded as a suborder of Diptera, are now considered to be a separate order of insects.
DIPTERA (Sis, double, 7rTEpa, wings), a term (first employed in its modern sense by Linnaeus, Fauna Suecica, 1st ed., 1746, p. 306) used in zoological classification for one of the Orders into which the Hexapoda, or Insecta, are divided.
The relation of the Diptera (two-winged flies, or flies proper) to the other Orders is dealt with underHexapoda.
The chief characteristic of the Diptera is expressed in the name of the Order, since, with the exception of certain aberrant and apterous forms, flies possess but a single pair of membranous wings, which are attached to the meso-thorax.