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.
But the characteristic nature of the avifauna is more clearly brought out when we learn that of the 2000 species just mentioned only about 1070 belong to the higher suborder of Oscines, that means to say, nearly one-half belong to the lower suborder Clamatores.
The Pupipara are also termed Eproboscidea (although they actually possess a well-developed and functional proboscis), and by some dipterists the Eproboscidea are regarded as a suborder .and contrasted as such with the rest of the Diptera, which are styled the suborder Proboscidea.
In reality, however, the families designated Eproboscidea (Hippoboscidae, Braulidae, Nycteribiidae and .Streblidae), are not entitled to be considered as constituting either a suborder, or even a main division of the Cyclorrhapha; they are simply Cyclorrhapha much modified owing to parasitism, and in view of the closely similiar mode of reproduction in the tsetseflies the special designation Pupipara should be abandoned.
With many writers it is customary to treat the fleas as a suborder of Diptera, under the title Aphaniptera or Siphonaptera.