374 



Syrphidae. 



The developmental stages were hitherto not known, but I have 

 examined larvæ and pupæ of JV. floralis and geniculata ; they are 

 quite similar, the following description is taken from floralis. The 

 larva is not leech-like; it is somewhat flat, the dorsal side the most 

 arched; the head-end is rounded, the sides of the body almost parallel; 

 behind it tapers into an attenuated tail-shaped part terminating with 





Fig. 136. Fig. 137. Fig. 138. 



N. floralis. 

 Fig. 136. Larva from above. Fig. 137. Larva from below. Fig. 138. Pupa. 



X 10. 



a thin, cylindrical, rode-shaped spiracular process of brown colour 

 with the posterior spiracles on the end, smTounded by very fine, 

 stellately arranged, feathery threads. The head is retracted; the 

 mouth has no hooks but only a pharyngeal skeleton ; above the mouth 

 is a small process bearing two two-jointed papillæ, the antenna-like 

 papillæ, the last joint of which ends with two small points. At the 

 hind margin of the prothoracal segment lie the anterior spiracles as 

 two small, black, approximated hooks, directed upwards. There seem 

 to be in all twelve segments; the body is transversely corrugated 

 above so that each segment shows about three corrugations ; the 

 whole dermis is chagreened from quite small, recurved spinules, 

 among which some slightly larger on the corrugations and especially 

 at the sides; these larger spinules are more or less distinct; they are 



