THE FLIES THAT CAUSE .MYIASIS IX MAX 



4.', 



produce specific myiasis (represented in the European fauna by 

 Wohlfahrtia magnified alone) : and (4) species that breed in various 

 media, including decaying flesh and excrement and sometimes refuse 

 of plant origin. Any of these four classes may contain myiasis-pro- 

 ducing forms, although, of course, only the third class contains specific 

 myiasis producers. Any species that occurs in human excrement may 

 conceivably be involved in intestinal myiasis, provided it can survive 

 the anaerobic conditions that exist in the human digestive tract, the 

 peristalsis, and the action of the digestive juices. As to the necroph- 

 agous species, the transition from decaying flesh to neglected 



Figure 15. — Sarcophaga crassipalpis. Details of mature larva : A. Cephalo- 

 pbaryngeal skeleton; B. posterior spiracle: C, anterior spiracle. (After Smith 



(W).) 



wounds or diseased body openings, and from there to healthy tissue, 

 is not a difficult one. since it has been bridged many times by species 

 of this and other genera of muscoid flies. According to Castellani 

 and Chalmers I 26, p. 830), Sarcophaga larvae are not uncommon in 

 sores and ulcers in tropical regions. 



Only scant etiological data concerning these flies have been pub- 

 lished. Indeed, our knowledge of their biology in general is ex- 

 tremely inadequate. It is important to keep records carefully and 

 get accurate determinations. If the literature on human and animal 

 myiasis caused by species of this genus were not cluttered up with 

 so many inaccuracies and conjectures, it would be possible to make 

 much more positive statements on the subject. 



Taxonomy and use of the keys.— Superficially many species of 

 Sarcophaga look very much alike. Chaetotaxy is of some importance 

 in determining the species, but the best identification murks are cer- 



