182 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



by Mr. Banks to an important paper by D. Keilin, which was 

 of such very great and widespread interest that he presented 

 a free translation, as follows: 



ON THE PARASITISM OF THE LARV^ OF POLLENIA RUDIS 

 FAB. IN ALLOLOBOPHORA CHLOROTICA SAVIGNY. 



BY D. KEILIN. 1 



Pollenia rndis Fab. is a very common fly in our regions, 

 but down to the present time we have been ignorant of the 

 conditions under which it lives and under which its larva 

 develops. 



I have been able to prove that this larva lives as a parasite 

 in the general body cavity of Allolobophora chlorotica Savigny . 



My first observations were made at the beginning of Novem- 

 ber, from material collected in the garden of the Laboratory 

 of Evolution. At this time the larva lodged in the general 

 cavity of the genital segments or in the interior of the seminal 

 vesicles of the worm, is transparent, and hardly a millimeter 

 long. 



The larva bathes in the liquid of the general cavity of the 

 host; it stays there all through the winter, and during that 

 period grows very slowly. Its spiracles are probably closed. 



A single individual of Allolobophora chlorotica can support 

 from one to four larvae. 



Very often by the side of the living larva are to be found 

 the debris of a destroyed larvae, either the skin and the 

 mouthpieces or simply the mouthpieces alone, and surrounded 

 by amcebocytes. 



The ensemble is constituted of brownish masses, which in- 

 dicate a reaction of the host against the parasite. It is easy to 

 follow all the stages of this trouble. The living larva is first 

 surrounded by leucocytes, which form several layers and 

 render the larva completely motionless. If this gang of 

 amoebocytes is pulled away, the larva, formerly motionless, 

 commences to move and to travel. Other larvae have sur- 

 vived the beginning of a kind of digestion by the leucocytes. 

 These are always spotted with yellow granulations. One 

 finds the brown masses with the debris of larvae either in the 

 seminal vesicles or in the general cavity of the genital seg- 

 ments or in the general cavity of the terminal segment. 

 From November until the middle of April there is no appre- 



1 Translated from an article in Comptes Rendus de la Societe de Bi- 

 ologie de France, vol. 67, pp. 101-103, by L. O. H. 



