528 FLY MAGGOTS AND MYIASIS 



what is eaten, especially in regard to such foods as raw vegetables 

 and partly decayed fruits. 



Myiasis of Urinary Passages. — Myiasis of the urinary pas- 

 sages, both urethra and bladder, is a rare but occasional occur- 

 rence. The flies impUcated are usually the lesser housefly, Fannia 

 canicularis, and the closely aUied latrine fly, F. scalaris, which 

 have already been described in connection with intestinal mjdasis. 

 In most cases infection occurs from eggs laid near the external 

 opening of the urethra, the larvae working their way up into this 

 tube and even into the bladder; apparently they need very httle 

 oxygen. Contamination is favored by sleeping without covers 

 in hot weather, so that flies have free access to the anal and 

 genital region. The larvae, when escaping, are said to be able to 

 project themselves with a flicking motion to a distance of from 

 12 to 20 inches. 



