ASCHIZA 



209 



The Aschiza are of little importance in connection with 

 disease, though rat-tailed larvae of one of the families 

 Syrphida. are sometimes passed in the stool. When 

 these have been identified the larvae are those of Eristalis 

 tenax. The syrphids vary greatly in appearance ; they 

 can always be recognized by the supporting incomplete 

 vein running close to the fourth longitudinal (fig. 85). 



One member of another family Phoridce also causes 

 intestinal myiasis. 



This group consists of small, dark, hunchbacked flies 

 with a very simple wing venation (fig. 86). The adults 



FIG. 85. Wing venation in 

 Syrp hides. 



FIG. 86. Wing venation in Phoridce. 



FIG. 87. Wing venation in 

 Ant 'homy 'idee. 



FIG. 



5. Wing venation in 

 Muscidce. 



are capable of living and reproducing in the human in- 

 testines, so that larvae of various ages and adult flies may 

 be passed for months. 



Sepsidce are represented in man by Piophila casei. The 

 larvae " cheese mites," or " skippers," are sometimes passed 

 in the stools, and are still alive. 



The Schizophora are of more importance. The family 

 includes some biting flies that are carriers of protozoa, 

 such as Glossina, Stomoxys, which have been already 

 considered. The non - biting flies are important as 



