24 



MISC. PUBLICATION 631, U. S. DEPT. OF AGRICULTURE 



ton) (fig. 6, B) is often visible through the translucent anterior end 

 of the maggot, or at least can be seen by mounting or clearing. Since 

 this structure, evidently of integumental origin, is sloughed off with 



mh v asp 



aos^M 



Figure 6. — Diagrammatic drawing of the mature larva of a mnscoid fly : A, Lat- 

 eral view; B, cephalopharyngeal skeleton ; C, posterior view; D, a posterior 

 spiracle. For explanation of abbreviations, see pages 23-25. 



each molt, it can often be recovered from shed larval skins or from the 

 inside of the empty puparium. Two main parts are used considerably 

 in taxonomic studies. The mouth hooks (mh), sometimes called the 

 labial sclerite, are typically two clawlike or hooklike structures, often 



