CHAPTER IV 

 SECTION 1 



THE ORDER DIPTERA : THE CYCLORRHAPHA 



THE suborder Cyclorrhapha is divided into two primary divisions, the 

 Aschiza and the Schizophora, as pointed out in the previous chapter. 

 In the Aschiza are included those forms in which the frontal lunule is 

 indistinctly seen above the base of the antennae, while the frontal suture 

 is entirely absent ; the third antennal segment is always simple, and has 

 either a terminal or a dorsal arista ; the third vein is never forked, and 

 there are never more than three complete posterior cells. The em- 

 podium is never pulvilliform. 



In the Schizophora the frontal lunule is distinct and the frontal 

 suture always present ; none of the longitudinal veins are forked, and 

 there are never more than three posterior cells present. The antenna 

 is three-jointed and always simple ; the arista is usually plumose and 

 placed dorsally ; most of the species are bristly insects. This group is 

 further divided into the Acalypterae and the Calypterae. In the former 

 the squamae are small, sometimes even rudimentary ; the thorax is with- 

 out a complete suture, and the auxiliary vein is often small or vestigial. 

 In the Calypterae the squamae are well developed ; the thorax has a 

 complete suture, and the auxiliary vein is always well formed throughout 

 its course. 



Altogether there are about thirty families included in the suborder 

 Cyclorrhapha, three of which, the Syrphidae, Pipunculidae and Platype- 

 zidae, are placed in the division Aschiza ; as none of the species contain- 

 ed in these families are of any interest to the worker they will not be 

 referred to again. In the group Acalypterae of the Schizophora there 

 are no blood-sucking forms, but many of the species are of interest 

 on account of the natural parasites they may harbour ; the families con- 

 taining these species are dealt with below. All the blood-sucking 

 Cyclorrhaphic Diptera, and those forms which are of special interest on 

 account of their domestic habits, are confined to the Calypterae. 



