DESTKUCTIOIvr OF FLY LARV^ IN HOESE MAISTUEE, 1915. H 



nitrogenous constituents, in the two treated samples, was markedly- 

 higher than m the two controls, and the alkalinity also was increased. 

 These changes were due to the presence of nitrogen and lime in 

 the calcium cyan amid. 



Calcium Cyan amid and Acid Phosphate. 



Varying amounts of calcium cyanamid and acid phosphate were 

 used in preparing mixtures in order to determine the most effective 

 combiuation. The results of 5 cage experiments at Bethesda, Md., 

 are recorded (Table 3, Nos. 1 and 2). From three-fourths pound 

 to 2 pounds of cyanamid and from 2 to 6 pounds of acid phosphate 

 were used in the various mixtures tested. The larvicidal results, 

 from 90 to 99 per cent, with mixtures contaming 1 pound or more of 

 the cyanamid were very satisfactory. It is evident from the results 

 in the table that three-fourths of a pound of cyanamid is not sufficient. 

 Some additional cage experiments and one series of tests in boxes are 

 recorded in Table 5. In the cage experiments mixtures of 1 pound 

 of cyanamid with 1^ pounds of acid phosphate, and 1 pound of 

 cyanamid with 8 pounds of acid phosphate were tested in duplicate. 

 The results agree with those in Table 3, showing that 1 pound of 

 cyanamid in cage experiments was a fairly effective application. 



Bacteriological and chemical analyses of samples of manure from 

 the cages are given in Table 5, Nos. 1 and 2. The bacteria were 

 reduced in both series by the treatment, alkalinity was slightly re- 

 duced, and the water-soluble and ammonia nitrogen results showed a 

 tendency to increase. The ammonia results in No. 2, where the 8 

 pounds of acid phosphate were used, were markedly higher than the 

 controls. 



The results of the experiments in boxes are given in Table 5, 

 No. 3. They show an apparent larvicidal action averaging 89 per 

 cent. It is probable that the surface exposure of the manm'e in the 

 boxes is the important feature in determining the effectiveness of this 

 treatment, although these three experiments do not bring this out as 

 fully as might be expected. Box A had a surface exposure of 5 square 

 feet, box B of 8 square feet, box C of 7 square feet, and box D of 7^- 

 square feet. 



The bacteria counts averaged 75 per cent as high as for the control 

 sample, 3D. The alkalinity of the water extracts of the manure 

 showed no definite change in any case. The water-soluble nitrogen 

 was increased in two samples, and reduced in the third; the ammonia 

 nitrogen was decidedly increased in the treated samples, while the 

 amid nitrogen was increased only in sample 30. 



The results of several open-pile experimen ts are shown in Table 

 4, Nos. 5 to 15, inclusive. The mixtures employed contained from 

 one-third of a pound to 1^ pounds of calcium cyanamid, and from 



