12 BULLETIN 118, U. S. DEPARTMENT OF AGRICULTURE. 



number of flies from these two controls is 310. Presuming that the 

 infestation of the manure at the start of the experiment was the 

 same in all cages, it appears from the table that sodium chlorid used 

 at the rate of 2J pounds per gallon killed 55 per cent of the larva?. 

 The 1-pound per gallon application showed a 30 per cent destruction 

 of the maggots. The chemical results of the salt-treated manure are 

 not very different from those of the untreated manure except that 

 there is an apparent increase in the nitrogen and ammonia in the 

 water extract of the treated samples. Only one bacterial examina- 

 tion was made and this showed that the strongest salt solution 

 reduced the number of bacteria somewhat. 



COPPER SULPHATE. 



Xos. 3 and 4 of Series B. Table I. give the results of two cage 

 experiments with copper sulphate. When compared with the con- 

 trols it would seem that the dosage of 1 pound per gallon killed 67 

 per cent of the maggots and the one-fourth pound strength 57 per 

 cent. 



The bactericidal power of copper sulphate is well known. When 

 added at the rate of 1 pound per gallon sufficient copper sulphate 

 remained in solution to kill 87 per cent of the bacteria. Their number 

 was not affected by the smaller quantity of this chemical. 



The chemical analyses show an injurious effect from the heavier 

 application of copper sulphate, which reduced the amount of soluble 

 nitrogen and the alkaline reaction of the water extract. TTith the 

 weaker strength the only apparent effect is a slight reduction of 

 water-soluble nitrogen. Xo open-pile experiments with copper sul- 

 phate were carried out. 



LIME-SULPHUR MIXTURE. 



Lime-sulphur was used in three cage experiments, but in no open 

 piles. There is no evidence that the lime-sulphur possessed any lar- 

 vicidal power, for more flies developed from the cage receiving a 

 1-5 treatment than from the control. The bacteria do not appear to 

 be affected by this treatment. From two other experiments where 

 lime-sulphur was used in strengths of 1-15 and 1-30 fewer flies 

 emerged than in the control, but this was probably due to differences 

 of infestation. 



In addition to the chemicals mentioned, acid phosphate, a proprie- 

 tary fertilizer, and several proprietary disinfectants were tested with 

 negative larvicidal results. 



PARTIALLY EFFECTIVE LARVICIDES. 



In Table II. page 15. some results obtained with potassium cyanide 

 Paris green, and formaldehyde, which were found to possess some 

 larvicidal action, are recorded. Each of these three substances in the 



