DESTRUCTION OF FLY LARViE IIsT HORSE MANURE, 1915. 19 



January 1, 1916, tlie wholesale price was 16 to 17 cents per pound, 

 but it should be obtained in large amounts under ordinary conditions 

 at 11 to 12 cents per pound. The cost of treating manure with 

 solutions of powdered hellebore, when it sells for 17 cents per pound, 

 is therefore 1 cent per bushel. 



Solutions of aniline and emulsions of nitrobenzene with fish-oil 

 soap, reported in Department Bulletin 245 (2), also proved to be 

 effective larvicides, and did not injure the manure, as far as could 

 be determined by chemical and bacteriological examination. 



The indications are that calcium cyanamid, acid phosphate, and 

 kainit mixtures can be used as effective larvicides, if one-half pound 

 of calcium cyanamid is present in the mixture per bushel of the 

 manure treated. The cost of applying a mixture of one-half pound 

 calcium cyanamid and one-half pound acid phosphate per bushel 

 of manure is 1.8 cents per bushel, but this is materially lessened by 

 the increased fertilizing value of the treated manure. 



Among the other substances which have been found effective in 

 reasonable amounts, but can not be recommended because of their 

 extremely toxic action, are potassium cyanid, Paris green, arsenic 

 dip, and pyridine. 



