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: (1) 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 
