66 LIFE HISTORY OF HABRONEMA. 



The percentage of naturally infected house flies found 

 at Eidsvold Avas thus 7.6. Hill (1^18, 18) examined 182- 

 flies caught in Melbourne staVjles and found 14 infected; 

 i.e., also 7.6 per cent., H. muscce being the only sjDecies 

 found by him. Both H. mztscce and H. megastoma were 

 represented in our material. Carter (1861) reported that 

 a third of the house flieS examined b}^ him in Bombay 

 were infected with H. muscce. Generali (1886) found 

 about 12.6 per cent, infected in Modena, Itah', during the 

 summer of 1884. Piana (1897) stated that in certain 

 Italian localities the presence of the larva was rarely 

 observed, but that in other districts 20 to 30 per cent, of 

 the flies were parasitised by Habronema. Leidj* (1874) 

 discovered that about 20 per cent, of the house flies in 

 Philadelphia harboured the nematode. Ransom kept 

 statistical record of 137 flies, finding 39, i.e., 28 per cent, 

 infected, his material coming from three widely separated 

 localities in the U.S.A. 



As it is now knoAvn that Musca clomestica can harbour 

 H. megastoma as well as H. muscce, it is quite probable 

 that both species were represented in the material examined 

 by the European and i^merican observers. Hill (p. 58) 

 iailed to find H. megastoma in any one of the 182 adult 

 M. clomestica -collected in stables between May and. 

 November. 1917. 



Bred flies — 31. domesfica (Eidsvold experiments). 



E:cperiment I.- — Horse manure was collected on two 

 occasions during November, 1918, from the stable referred 

 to above. Thirty-nine of the flies which l)red out from 

 this material were examined, 32 being found to be parasitised 

 h\ Habronema, the degree of infection ranging from one 

 to 40 Avorms. No record was kept regarding the number 

 of each species present. 



Experiment II. — In Jime, 1919, flies Avere bred from 

 dung of horse " 8.'" Sixteen were examined, all of which 

 proved to harbour Hqi^bronema, the number counted ranging 

 from two to 41 worms, the average being 16. Both species 

 of Habronema were present, but H. muscce predominated. 



