6 BULLETIN 245, U. S. DEPARTMENT OF AGRICULTURE. 



CHLORID OF LIME. 



Chlorid of lime has been used extensively as a disinfectant and has 

 been tested by Dr. Howard, who found that 1 pound applied to 8 

 quarts of manure killed practically all the larvae, but one-fourth of a 

 pound to 8 quarts was not sufficient (Howard, 1911). In our experi- 

 ments with smaller amounts, namely three-fourths of a pound, 1| 

 pounds, and 3 pounds to 8 bushels and the addition of 10 gallons of 

 water, negative results were obtained. The well-known action of 

 chlorid of lime in driving off the ammonia from manure, the probable 

 toxic effect on bacteria, and the irritating action of the liberated 

 chlorin, as well as the high cost of the substance in quantities suffi- 

 cient to kill fly larvae, precludes its use for this purpose. 



EPSOM SALTS. 



Epsom salts was applied in three cage experiments, using respect- 

 ively 1, 2, and 4 pounds to 10 gallons of water. In no case was any 

 larvicidal effect noticed. No chemical or bacteriological examina- 

 tions were made. 



LIME-SULPHUR. 



Lime-sulphur was used again this year in dilutions of 1 to 10, 1 to 20, 

 and 1 to 30. No larvicidal effect was seen, and since it failed to kill 

 the maggots, no chemical or bacteriological analyses were made. 



SULPHURIC ACID. 



Sulphuric acid was used in 1, 2, and 3 per cent solutions. Two 

 cage experiments with each concentration were carried out. Prac- 

 tically no larvicidal effects were shown in any of the experiments. 

 Sufficient alkaline substances and organic material were present in the 

 manure to combine with the acid in the 1 per cent and 2 per cent 

 solutions, consequently no injurious action on the bacteria resulted. 

 No counts were made where the 3 per cent solutions were applied. 

 When the 3 per cent applications were made the alkaline reaction 

 of the manure was markedly reduced and the percentage of ammonia, 

 in terms of the total nitrogen, was increased from three to four times 

 that of the control. The 1 per cent and 2 per cent solutions had no 

 apparent action on the manure as determined by the chemical 

 results. 



ORGANIC SUBSTANCES. 



As the application to the soil of manure containing inorganic 

 substances is likely to produce harmful effects on plants, due to 

 a slight excess of the toxic element in the soil, it seemed desirable 

 to investigate the larvicidal action of various organic substances, 

 both volatile and nonvolatile. The volatile substances would produce 



