MYIASIS 229 



These flies, one of the commonest of which is Gastrophilus equi, 

 the horse-bot, attach their eggs to the hairs. The larvze hatch 

 and crawl on the skin, producing some itching, and cause the 

 animal to lick the place. The larvae are in this way introduced 

 into the stomach, and attach themselves to the mucous membrane 

 by means of their buccal hooks. They seem to subsist mainly 

 on the inflammatory products resulting from the small wounds. 

 When mature the larvae become detached and are passed out of 

 the body with the faeces, and pupate in the ground. 



Up to the present, insufficient attention has been paid to the 

 subject of intestinal myiasis, few of the cases which occur being 

 recorded, and little trouble being tajcen to identify the larvae. 



CHAPTER XXIII 



THE DISEASES OF FLIES 



Flies seem to be totally unaffected by the bacteria, which 

 produce disease in man, with the possible exception of the 

 plague bacillus i^B. pestis). The observations of Yersin (1894), 

 Nuttall (1897) and Matignon (1898, p. 237) all seem to indicate 

 that flies infected with this organism do not live as long as 

 healthy flies. 



Einpiisa Disease. 



Under ordinary conditions adult flies {Mtisca and Fannia), 

 so far as is at present known, appear to be subject to only one 

 serious disease, that caused by the fungus, Einpiisa vmscce Cohn. 

 The majority of flies which die in the late summer and autumn 

 succumb to this disease. They are found attached to walls and 

 ceilings, rigid but in life-like attitudes. On closer inspection it 

 is often found that the abdomen is considerably swollen and 

 " white masses of sporogenous fungal hyphae may be seen pro- 

 jecting for a short distance from the body of the fly, between 

 the segments, giving the abdomen a transversely striped black 

 and white appearance." 



