460 



Wirth and Stone: Diptera 



Fig. 14:53. Syrphidae. a, TubHera, tracheal trunk of larva; b, He/ophi'/us, tracheal trunk of 

 larva; c, Myiolepta nigra Loew, puparium, and posterior spiracle enlarged; d-f,h,i, Tubifero 

 arvorum (F.): Puparium, d. Larva: e, tip of respiratory tube showing spiracular disc, lateral view; 

 i, lateral view of larva respiratory tube retracted; i, larval habitus. Adult, h. g, Tubifera basfardii 

 (Macq.), larva, lateral view, respiratory tube extended (a,b,g, Johannsen, 1935; c, Greene, 1923; 

 d-f,h,i, Williams, 1939). 



resembling certain mollusks and usually associated 

 with ants (subfamily Microdontinae); (2) aphidophagous 

 type, leechlike, subc^lindrical, segmented maggots 

 with tapered anterior end and short posterior respir- 

 atory tube, mostly predaceous on aphids and other 

 sofVbodied Homoptera (subfamily Syrphinae); (3) short- 



tailed type, cylindrical, grublike larvae with short 

 posterior air tube, often with subapical, lateral para- 

 pods, mostly feeding saprophytically on decomposing 

 plant material; and ,(4) long-tailed type, the "rat- 

 tailed maggots" which resemble the last except for 

 the long, filamentous air tube, and which usually live 



