SUB- ORDERS OF THE DIPTERA. 39 



9. The Suborders of the Diptera. 



The majority of authors have adopted Braiier's division of the 

 order into Ortiiorrhapha and CYOLORRnAPnA, separated mainly 

 according to the method in which the perfect insect escapes from 

 the pupa-case. These suborders may be thus characterized :— - 



Suborder ORTHOERHAPHA. 



Diptera in whicli the pupa-case is " mummy-like," more or less 

 indicating the outlines of the imago, as in the common crane-fly 

 or " daddy-long-legs '" {Tipula). 



The fly emerges from the dried larval skin forming the pui)a- 

 case tlirough the T-shaped opening which is formed by a. 

 length-wise split on the back, near the head-end, and by a cross- 

 wise split at the front end of this ; or (rarely) through a cross-wise 

 split between the 8tli and 9th abdominal segments. Adults- 

 without a frontal lunule. 



Larva with a " jaw-capsule " (Kieferkapsel) or more or less 

 distinct head. Pupa free, or enclosed in the larval skin. 



Suborder CYCLORRHAPHA. 



Diptera in whicli the pupa-case is oval or egg-shaped, with a 

 comparatively smooth surface, bearing no resemblance whatever to 

 the perfect insect. For example the common house-fly {Musca} 

 and blow-flj^ (Calliphora). 



The fly emerges from the puparium through a circular orifice 

 made by the insect pushing off the head-end.* Adults possessing 

 a frontal lunule. 



" The frontal lunule is a small crescent-shaped piece im- 

 mediately above the antennae, which is characteristic of the 

 second suborder, the Ctclorrhapha. In most of the members of 

 this suborder there is a suture separating the lunule from that 

 part of the head above it, the 'frontal suture'; and frequently 

 this suture extends down on each side to near the mouth. But 

 as the suture is wanting in several families of the Cyclorrhapha 

 it is often difficult to determine whether the lunule is present or 

 not." t (Comstock, 1895.) 



The larva is without anv distinct head. 



* It effects this bj' means of the ptilinum, a small bladder-like organ situated 

 immediately above the base of the antennre, the inflation of which by the 

 imago springs off the upper piece or cap of the puparium. It is of course> 

 only present iu the Cyclorrhapha, siiice the Orthokriiapiia escape from the 

 pupa-case in another manner. 



t Thtse families are the SYUPinD.fi, Pipunculid.e and Platypezid.e. 



