528 FLY MAGGOTS AND MYIASIS 



what is eaten, esjiecially in regard to sueh foods as raw vegetables 

 and partly decayed fruits. 



Myiasis of Urinary Passages. — Ah'iasis of the urinary pas- 

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

 rence. The flies imi:)licated are usually the lesser housefly, Fannia 

 canicidaris, and the closely allied latrine fly, F. scalaris, which 

 have already been described in connection with intestinal myiasis. 

 In most cases Infection occurs from eggs laid near the external 

 0{XMiing of the urethra, the larvae working their way up into this 

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

 oxygen. Contamination is favored by sleeping Avithout covei-s 

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

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

 project themselves with a flicking motion to a distance of from 

 12 to 20 inches. 



