24 BULLETIN 118, U. S. DEPARTMENT OE AGRICULTURE. 



noninjurious effect on manure, and lack of extramely poisonous prop- 

 erties. Among the unsatisfactory or partially satisfactory substances 

 are included several which when used in large amounts may kill fly 

 larva? but are placed in this class because of the large amount required 

 or because of their extremely poisonous properties. 



Iron sulphate has been used as a larvicide and in considerable 

 amounts is stated to be effective. However, no studies of the effects 

 of iron sulphate on the fertilizing value of manure have been re- 

 ported. Our experiments indicate injury to the manure even from 

 small applications of iron sulphate (see p. 10). Paris green and 

 potassium cyanid are effective as larvicides. but are objectionable on 

 account of their extremely poisonous nature. 



UNSATISFACTORY OB PARTIALLY SATISFACTORY SUBSTANCES. 



Kerosene emulsion. Pyroligneous acid. 



Kainit. Sodium chlorid (table salt). 

 Isthmian Canal Commission larvicide. Copper sulphate. 



Iron sulphate. Lime-sulphur mixture. 



Several proprietary disinfectants. Paris green. 



Potassium cyanid. Sodium fluorid. 



Formaldehyde. Ammoniacal gas liquor. 

 Calcium cyanamid. 



Satisfactory Substances. 

 Borax. Calcined colemanite. 



By far the most effective, economical, and practical of the sub- 

 stances is borax in the commercial form in which it is available 

 throughout the country. 



Borax increases the water-soluble nitrogen, ammonia, and alka- 

 linity of manure and apparently does not permanently injure the 

 bacterial flora. The application of manure treated with borax at the 

 rate of 0.62 pound per 8 bushels (10 cubic feet) to soil does not in- 

 jure the plants thus far tested, although its cumulative effect, if any. 

 has not been determined. 



DIRECTIONS FOR TREATING MANURE WITH BORAX TO KILL FLY EGGS AND 



MAGGOTS. 



Apply 0.62 pound borax or 0.75 pound calcined colemanite to 

 every 10 cubic feet (8 bushels) of manure immediately on its removal 

 from the barn. Apply the borax particularly around the outer edges 

 of the pile with a flour sifter or any fine sieve, and sprinkle 2 or 3 

 gallons of water over the borax-treated manure. 



The reason for applying the borax to the fresh manure immedi- 

 ately after its removal from the stable is that the flies lay-their eggs 

 on the fresh manure, and borax, when it comes in contact with the 

 eggs, prevents their hatching. As the maggots congregate at the 



