[Pboc. Roy. Soc. Victoria, 31 (N.S.), Part I., 1918]. 



Art. IV. — Relationship of Insects to Parasitic Disease/f 



in Stock. 



By GERALD F. JHILL, F.E.S. 



(Walter and Eliza Hall Fellow). 



(With Plates II.-VIII). 



[Read May 9th, 1918]. 



Part I. — The Life History of Habronema muscae, H. microstoma, 



AND H. MEGASTOMA. 



Introduction. 



Although the life history of Ildhronema muscae has been known 

 for some years as a revsult of the investigations made in U.S.A. by 

 Dr. B. H. Ransom, there are no records of any such investigations- 

 in Australia, where variations tend to occur in the case of certain 

 parasites owing chiefly to climatic and associated conditions. 



Of the life histories of Habronema microstoma and H. megastoma 

 nothing appears to be definitely known either in Australia or else- 

 where. 



In the adult stages these species of Habronema are well-known 

 as more or less common stomach parasites of the horse, their occur- 

 rence under ordinary conditions being generally believed to be of 

 little detriment to the health of the host. During recent years, 

 however, more attention has been directed to these parasites in 

 Australia as a result of the discovery here of larval Habronema, or 

 an allied form, as the supposed causative agents of pathological con- 

 ditions of the horse known as '* Habronemic granulomata " and 

 ** Habronemic conjunctivitis." Further, splenic and stomach 

 abscesses of the horse, due to H. megastoma, appear to have become 

 of more frequent occurrence during the past few years, and there 

 is reason to believe that under certain conditions the mortality 

 caused in stock is considerable. These considerations then empha- 

 sised the desirability of testing under local conditions the life 

 history of Habronema muscae, and of acquiring a knowledge of the 

 life histories of other allied species. 



