44 ENTOMOLOGY FOR MEDICAL OFFICERS 



Classification of Diptera. 



According to the generally accepted scheme of Brauer, 

 Diptera are grouped in two suborders which are defined as 

 follows : — 



Suborder i. Orthorrapha (o/o^o? = straight ; /(5a0j; = seam 

 or suture). Larva with a differentiated head, pupa usually 

 obtected. The imago escapes from the pupal envelope by 

 a straight dorsal slit which is usually longitudinal and 

 sometimes transverse, so that it has no frontal lunule and 

 suture. 



Suborder 2. Cydorrapha {kvkXos = a circle ; pa(p^ = suture). 

 Larva without a differentiated head, pupa coarctate. The 

 imago escapes from the puparium through a circular split 

 at the anterior end, the opening being, typically, made by 

 the extrusion of a ptilinum ; a frontal lunule, therefore, is 

 usually present though sometimes it is not very plain. In 

 this suborder the antennae are usually composed of 3 seg- 

 ments, the third of which is often elongate and carries a 

 bristle, or arista, which is generally dorsal, but occasionally 

 terminal. The 3rd longitudinal vein of the wings is not 

 forked, and the number of complete posterior cells does not 

 exceed three. The empodium is never pulvilliform. 



I. Suborder ORTHORRAPHA. 



The suborder Orthorrapha consists of two series of 

 families as follows : — 



Section i. Orthorrapha Nematocera (vtjjua =. a thread ; 

 K-e'/oa? = horn, or antenna). Commonly midge-like flies. The 

 antennae for the most part are elongate filaments composed 

 of numerous similar, or nearly similar, segments. (The 

 number of segments is often 14 or 16 ; it may be less than 

 14, but is never less than 6, or it may be more than 16.) 

 The maxillary palps are, for the most part, elongate and 

 flexible, and commonly consist of 4 or 5 segments, but 

 sometimes of less than 4. The 2nd longitudinal vein is often 

 forked, the 3rd rarely ; a discal cell is present only in two 

 families ( Tipulida and Rhyphidce). 



Section 2. Orthorrapha .5/-«<:/i;/a7-rt(/3/>axw = short ; /ce'/oa? 



