10 THE HOUSE FLY— DISEASE CARRIER 



parasitology in the School of Tropical Medicine of the 

 University of Liverpool in 1907. Mr. Newstead is of 

 the opinion that the chief breeding places of the house 

 fly in Liverpool should be classified under the follow- 

 ing heads: (i) Middensteads (places where dung is 

 stored) containing horse manure only; (2) Midden- 

 steads containing spent hops; (3) Ash pits containing 

 fermenting materials. He found, as has been the ex- 

 perience of observers in this country and India, that 

 the dung heaps of stables containing horse manure 

 only were the chief breeding places. Where horse and 

 cow manures were mixed the flies bred less numer- 

 ously, and in barnyards where fowls were kept and al- 

 lowed freedom comparatively few flies were found. 

 Only one midden containing warm spent hops was in- 

 spected, and this was found to be as badly infested as 

 any of the stable middens. A great deal of time was 

 given to the inspection of ash pits, and it was found 

 that wherever fermentation had taken place and arti- 

 ficial heat had been thus produced such places were 

 infested with house fly larvse and pupae, often to the 

 same extent as in stable manure. Such ash pits as 

 these almost invariably contained large quantities of 

 old bedding or straw and paper, paper mixed with hu- 

 man excrement, or old rags, manure from rabbit 

 hutches, etc., or a mixture of all of these. About 

 twenty-five per cent, of the ash pits examined were 

 thus infested, and house flies were found breeding in 

 smaller numbers in ash pits in which no heat had been 

 engendered by fermentation. The typhoid fly was also 



