PREVENTIVE MEASURES 201 



Dr. H. W. V^iley, the Chief Chemist of the U. S. 

 Department of Agriculture, was asked for an opinion 

 regarding the effect upon the manurial value of manure 

 treated by the substances experimented with under Pro- 

 fessor Forbes's direction. He replied, 'The materials 

 which you mention would affect the agricultural value 

 of manure in three ways : Alkalies would drive off am- 

 monia, and if in not too large quantities, would hasten 

 fermentation. Lime salts and iron sulphate would 

 tend to render the phosphates unavailable. All of these 

 materials mentioned, with the possible exception of 

 salt, would, if used in sufficient quantity, kill the bac- 

 teria of the manure and thus reduce its value, as un- 

 doubtedly the value of stable manure is largely due to 

 the great number of very active bacteria which it con- 

 tains. I cannot inform you in what quantities these 

 various materials would be required to seriously re- 

 duce the bacterial content of manure, but it would seem 

 that, if used in sufficient quantity to kill larvae, they 

 would have a decided effect on the bacterial life of the 



Removal of Manure and Receptacles for Its 

 Temporary Storage 



The average time elapsing between the laying of the 

 eggs and the issuing of the adult flies, as we have seen, 

 is, in midsummer in the climate of Washington, about 

 ten days. In warmer regions, and with plenty of mois- 

 ture, it may be as short as eight days. Therefore it is 

 by all means advisable to have manure accumulations 



