THE FLIES THAT CAUSE MYIASIS IN MAX 

 The Genus SYLVICOLA Harris 



145 



Commonly used synonyms are Rhyphus^ Phryne, and Amsopus. 



This genus may readily be distinguished from the others which have 

 a complete discal cell and a three-branched media by the numerous 



Figure ST. — Sylvicola fi n< stralis, larva : A, Head, ventral view ; B, mature larva, 

 side view: C, view of last body segment; D, posterior spiracle. (After Keilin 

 and Tate (68, p. £6).) 



macrotrichia or hairs on the wing membrane ; the macrotrichia, though 

 microscopic, are as large as the hairs on the veins, and are not to be 

 confused with the smaller microtrichla normally present on the dip- 

 terous wing. In addition, the hind tibia bears a comb of short spinules 



on its posterodorsal surface. 



Larva. — The larva (fig. 87) has a free and complete head capsule, 

 three simple thoracic segments, and eight abdominal segments which 

 are divided transversely to form anterior intercalary rings. The 

 anterior spiracles are distinct: the posterior spiracles are crescent- 

 shaped, and the spiracular area is surrounded by five short but distinct 

 processes; the anus is ventral and is surrounded by a shieldlike thick- 

 ening called the perianal shield. 



7.-, I'll:: 4- — 10 



