M 



LIFE HISTORY OF HABBONEMA. 



disseminator, but, though its habits are somewhat similar, 

 its range is restricted to the more northerly parts o! 

 Australia. In Queensland, as far south as the Burnett 

 River, it appears to be the commoner species. Though 

 met with occasionally in the Brisbane district, the common 

 outdoor Muscid fly there is M. vetustissima. M. domestica 

 is essentially a house fly, i.e., it is in close association with 

 man, houses and stables, and occurs especially indoors. 

 The other two are, as already stated, outdoor species. 



In discussing " swamp cancer " of horses in the 

 Northern Territory, which Bull (1916 ; 1919) regards as 

 3, form of habronemiasis in opposition to the view held by 

 liewis (1914) and Seddon (1918), Bull mentioned the 

 possibility of the condition being due to any one of the 

 three species of Habronema (Bull, 1919, p. 120). He went 

 on to say that evidence was not in favour of either 

 H. muscce or H. megastoma being the cause since they 

 passed through their larval stages in M. domestica, a fly 

 which was not usually found far afield. He believed 

 {p. 121) that H. microstoma was much more likely to be 

 the cause since its intermediate host, Stomoxys calcitrans, 

 possessed a wider range. He thought it possible that 

 swamp cancer might be due to other species of Habronema 

 carried by some other Muscid, e.g., M. vetustissima, but that 

 if this be responsible then one would expect to find lesions 

 dn the conjunctiva. 



Perhaps the discovery that the two widely distribuied 

 " bush flies " can carry infection may assist in elucidating 

 the problem of swamp cancer. Both of these flies (as do 

 -also M. terrce-regince and 31. hilli) frequent injured surfaces, 

 and will visit the puncture made by a blood- sucking fly. 

 In the serum, worm larvae could le deposited from an 

 infected fly and thus a granuloma Le initiated while frequent 

 reinfection would load to extensi^ e tissue alterations. 



Bull (1919, p. 131) mentioned that the microscoj^ic 

 picture of " swamp cancer " which is present in 75 per cent, 

 of horses in the Solomon Islands was very like that 

 described as occurring in habronemic granulomata in 

 Australia, larvae, apparently of different ages, being seen 

 in the tissues. We might state that one of the flies with 



