Spptbmbbr, 1909.] 



199 



organisms. The method of the experi- 

 ment was to catch the flies from the 

 several sources by means of a sterile fly 

 net, introduce them iuto a sterile bottle, 

 and pour iuto the bottle a known quan- 

 tity of sterilized water, then shake the 

 bottle to wash the bacteria from their 

 bodies, to simulate the number of 

 organisms that would come from a fly 

 in falling into a lot of milk." By count- 

 ing the number of bacteria in a definite 

 small quantity of this water, it was 

 possible to estimate the total number 

 that were present in the infected liquid. 



Dr. Howard then considers the prac- 

 tical means for mitigating the serious 

 danger to humanity. He says :— " Even 

 if the typhoid or house fly weie a 

 creature difficult to destroy, the general 

 failure on the part of communities to 

 make any efforts whatever to reduce 

 its numbers could properly be termed 

 criminal neglect ; but since, as will be 

 shown, it is comparatively an easy 

 matter to do away with the plague of 

 flies, this neglect becomes an evidence of 

 ignorance or of a carelessness in regard 

 to disease-producing filth which to the 

 informed mind constitutes a serious blot 

 on civilized methods of life." 



" Strange as it may seem, an exhaus- 

 tive study of the conditions which 

 produce house flies in numbers has never 

 been made. The life history of the 

 insect in general was, down to 1873, 

 mentioned in only three European works 

 and few exact facts were given. In 1873, 

 Dr. A. S. Packard studied the transfor- 

 mations of the insect and gave descrip- 

 tions of all stages, showing that the 

 growth of a generation from the egg 

 state to the adult occupies from 10 to 

 14 days." 



" In 1895 the writer traced the life 

 history in question, indicating that 120 

 eggs are laid by a single female, and 

 that in Washington, in midsummer, a 

 generation is produced every ten days. 

 Although numerous substances were 

 experimented with, he was able to breed 

 the fly only in horse manure. Later 

 investigations indicated that the fly 

 will breed in human excrement and in 

 other fermenting vegetable and animal 

 material, but that the vast majority of 

 the flies that infest dwelling; houses, 

 both in cities and on farms, come from 

 horse manure." 



" In 1907 careful investigations carried 

 on in the city of Liverpool by Robert 

 Newstead, indicated that the chief 

 breeding places of the house fly in that 

 city should be classified under the 

 following heads :— 



(1) Middensteads (places where dung is 

 stored) containing horse manure only. 



(2) Middensteads containing spent 

 hops. 



(3) Ashpits containing fermenting ma- 

 terials. 



'' He found that the dung heaps of 

 stables containing hoise manure only 

 were the chief breeding places. Where 

 horse and cow manures were mixed the 

 flies bred less numerously, and in barn- 

 yards where fowls were kept and allowed 

 freedom relatively few of the houseflies 

 were found. Only one midden contain- 

 ing warm spent hops was inspected, 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 

 artificial heat had been produced, such 

 places were infested with house fly 

 larvae and pupae, often to the same 

 alarming extent as in stable manure. 

 Such ash pits as these almost invariably 

 contained large quantities of old bed- 

 ding or straw or paper, paper mixed 

 with human excreta, or old rags, manure 

 from rabbit hutches, etc., or a mixture 

 of all these. About 25 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 fermen- 

 tation. The house fly was also found 

 breeding by Mr. Newstead in certain 

 temporary breeding places, such as col- 

 lections of fermenting vegetable refuse, 

 accumulations of manure at the wharves, 

 and in bedding in poultry pens." 



"Still more recent investigations were 

 carried on during 1908 by Professor S. A. 

 Forbes who has reared it in large num- 

 bers from the contents of paunches of 

 slaughtered cattle, from refuse hog 

 hairs, from tallow vats, from carcasses 

 of various animals, miscellaneous gar- 

 bage, and so on." 



"All this means that if we allow the 

 accumulation of filth we will have house 

 flies, and if we do not allow it to accu- 

 mulate we will have no house flies. 

 With the careful collection of garbage 

 in cans and the removal of the contents 

 at more frequent intervals than teu 

 days and with the proper regulation of 

 abattoirs, and more particularly with 

 the proper regulation of stables in 

 which horses are kept, the typhoid fly 

 will become a rare species, It will not 

 be necessary to treat horse manure with 

 chloride of lime or with kerosene or with 

 a solution of Paris green or arsenate of 

 lead, if stable men are required to place 

 the manure daily in a properly covered 

 receptacle, and if it is'carried away once 

 a week." 



