342 PARASITISM 



receive the tubular larvipositor (or ovipositor). The two structures 

 act in unison, and the introduction of the larvipositor follows upon 

 the action of the piercer in perforating the host. The ventral 

 region of the abdomen is strongly carinate, and bears backwardly 

 directed spines together with a prominent backwardly directed 

 process of the fifth sternum. These structures evidently aid the 

 fly in maintaining a firm grip on the host while the puncture is 

 being made. In Neocelatoria ferox which parasitises the beetle 

 Diabrotica Walton (1914) concludes that the host is gripped, as it 

 were, by the " forceps " formed by the piercer and the sternal 



process while the parasite makes 

 the perforation. In this species 

 the sternal process is borne on 

 the second segment, and is 

 strongly dentate (Fig. 81). 



In Compsilura the instrument 

 is a true larvipositor, and the 

 larvae are present in the uterus 



Fig. SI. Neocelatoria ferox Walt. 'Lett: of the parent prior to 

 abdomen of female. Right : figure , ... -^ , . , i 



showing probable functioning of deposition. In certain other 

 appendages. a, Ovipositor. b, Tachinidse (species of Alophora, 

 Piercer. c, Process of second ^t i • j t^ . \ t» . i 



abdominal segment, d. End view Hyalomyia and Xysta) Pantel 

 of host beetle {Diabrotica). (From concludes that oviposition takes 

 Walton.) , , , 



place by an analogous pro- 

 cedure. The presence of eggs but little advanced in development 

 when in the uterus, the absence of an incubatory pouch, and 

 the existence of a complex piercing ovipositor support his 

 contention. He also places the Conopidae provisionally in this 

 same group. 



In the Agromyzid Cryptochcetum a highly specialised piercing 

 ovipositor is present : it appears to afford a striking example of 

 adaptation to a parasitic mode of life, since the eggs are inserted 

 within the body-cavity of coccids of the sub-family Monophlebinae. 

 The ovipositor has peculiar structural features which seem to 

 preclude its origin as a specialisation of the rasping type of organ 

 found among other Agromyzidae (Thorpe, 1934). 



