FLIES AS TRANSMITTERS OF WORM PARASITES. 
/ 
Flies as Transmitters of Certain Worm 
Parasites of Horses. 
By T. HARVEY JOHNSTON, M.A., D.Sc., Professor of Biology, University, Brisbane. 
It is well known that flies play a very important part in public health 
matters, as they can so readily act as passive carriers of various bacteria 
which cause human disease. It has recently been proved that house 
flies act as intermediate hosts for several of the species of tapeworms 
which infest poultry. 
As long ago as 1861, it was pointed out by Carter that in Bombay, 
India, house flies were commonly infested with a tiny nematode parasite, 
which was found in the proboscis. He named it Filaria musce. Tt was 
not until 1911 that its life history was known, Dr. H. B. Ransom, 
of the United States Bureau of Animal Industry, proving that the 
worm was a larval stage of one of three species of. Habronema para- 
sitizing the stomach of horses. In 1912, the author recorded the oceur- 
rence of this worm in certain flies in Australia, viz., the house fly 
(Musca domestica), the stable fly (Stomoxys calcitrans), and the 
common “cattle fly” or “bush fly” (Musca vetustissima, incorrectly 
called M. corvina). That reported from the stable fly is now known to be 
the larval stage of a related parasite of the horse, viz., Habronema 
microstoma. 
In 1916, Dr. Bull, of Adelaide, drew attention to the presence of 
Habronema larve in granulomatous sores in hhorses in Victoria and 
South Australia. He believed that “swamp cancer” of equines in the 
Northern Territory was also due primarily to infection by these tiny 
worms. ; 
In 1918, Drs. Lewis and Seddon mentioned the common occurrence 
in Victorian horses of an inflammatory condition of the eyes, caused 
by larval Habronema worms. At the end of that year, Mr. G. F. Hill 
published a very important paper, in which he described the life 
history of all three species which infest the horse, H. muscw and°H. 
megastoma (the latter causing worm tumours in the stomach), utilizing 
the common house fly (Musca domestica) as their intermediate host, 
while H. microstoma passed through its larval stages in the stable fly 
(Stomoxys calcitrans). Last year Dr. Bull confirmed Hill’s observa- 
tions, and extended our knowledge of the granulomatous condition of 
horses caused by such larvee. : 
Late in 1918 work was begun at Eidsvold, Burnett River, by Miss 
M. J. Bancroft and the author, with a view to determining whether 
all or any of the three parasites could complete their larval cycle in 
- various Queensland flies, more especially those which are commonly 
associated with horses and cattle. The results have been published in 
a paper entitled “The Life History of Habronema in relation to 
Musca domestica and Native Flies in Queensland” (Proc. Royal Society, 
Queensland, 1920). : 
The larve of various flies which breed in horse manure were allowed 
to feed in samples of this material contaminated with the eggs or larve 
of two or more of the species of Habronema, the adults which emerged 
€.9946.—5 369 
