THE POLY POD LARVA 



59 



It has also been described by Eastham (1929) in the Proctotrypid 

 Phcenoserphus viator which parasitises larvae of the beetle 

 Pterostichus niger. In the Figitidae the polypod stage follows 

 the protopod or eucoiliform stage, but in Ibalia and Phceiioserphus 



Fig. 34. Figites anthomyiarum. Above, protopod larva x 140 ; 

 below, polypod larva x 90. ^A'^., Anus ; C.E., endo-skeleton 

 of head ; O.P., oral papillae ; R.A., rudimentary appendages ; 

 S.O., sensory organ. (After James (reduced).) 



the protopod stage is presumably passed within the egg, since the 

 first observed instar is polypodeiform. During the polypod stage 

 these parasitic forms live immersed in the blood of their hosts, 

 and, as is the rule in such cases, respiration is cutaneous. In 

 consequence of this adaptation the typical peripneustic condition 

 is not acquired until a later instar. The number of pairs of 



