SCIENCE AND INDUSTRY. 
We might mention that, though the horsedung used in our experi- 
ments in Brisbane contained all three species of Habronema, H. micro- 
stoma was found only in Stomoxys, while the other two species did not 
develop in this fly, but parasitized M. musca domestica, M. terrwregine 
and M. hill, which were bred out from material from the same source, 
and sometimes from the same material. It is unlikely that either M. 
vetustissima or M. fergusoni would serve as hosts for H. microstoma, 
though it is quite likely that the buffalo fly (Lyperosia exigua) could do 
so. : 
Escape of Habronema from Flies. 
It was previously thought that the tiny worms escaped from the fly 
and gained access to the horse’s stomach (where further development 
occurs) as a result of accidental swallowing of dead or living infected 
insects during feeding, the worms becoming liberated as a result of 
digestive agencies. It was suggested as a possibility that they might 
escape by rupturing the fly’s proboscis in a manner similar to that 
by which final embryos escape from mosquitoes. 
We have been able to prove that the larve can escape from the 
proboscis of infected flies belonging to several species when the latter 
are feeding on saliva. In other words, laryee can make their exit when 
flies are frequenting mucous surfaces, e.g., mouth, nose, eyes, or even 
sores and wounds. They would readily pass through the mouth, to 
eventually reach the stomach of the horse, there developing to maturity 
after undergoing a series of moults. Should the larve escape to the 
conjunctiva, or into a sore or abrasion, or even the wound made by some 
biting fly, then a habronemic granuloma might be produced, such, for 
example, as those described by Bull, Railliet, and others. In the case 
of Stomoxys, Habronema. microstoma might escape directly into the 
tissues during the puncturing by the fly. Of course, the larve which 
are deposited elsewhere than in the vicinity of the mouth, ultimately 
perish, though before doing so they may set up the inflammatory condi- 
tion which at length results in a granuloma, or perhaps even swamp 
cancer. ~ 
The chief transmitter of equine granuloma is probably not Musca 
domestica, but M. vetustissima and M. ferguson, together -with 
Stomoxys, though the house fly is perhaps mainly responsible for its 
occurrence in stabled animals. M. domestica prefers shade conditions, 
and does not worry horses and stock like the two species of Musca 
just mentioned. The latter are essentially outdoor flies, and occur in 
such incredible numbers in drier areas (especially after rain) as to 
constitute veritable plagues, which worry man and beast alike, invading 
the mouth, eyes, nose, food, &. The most widespread abundant Aus- 
tralian fly appears to be M. vetustissima, but in the northern parts of 
the continent (from about 25° S. northwards), M. fergusoni, a larger 
fly, seems to be the more common. 
The life histories of the four native species of Musca referred to 
in this article have been recently worked out by Miss Bancroft and the 
author, the results having been published in the Proceedings of the 
Royal Society, Queensland, 1919 (M. fergusoni and M. vetustissima), 
pee Memoirs of the Queensland Museum, 1920 (M. terreregine and 
{. hilli). 
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