CONVICT LABOR FOR ROAD WORK. 105 



It has been found that a single fly may carry more than 6,000,000 

 germs on the outside of its body and as many as 28,000,000 in its 

 intestmal canal. What it means, therefore, to have a fly fall into 

 milk or other Uquid food is seen readily. 



The suppression of flies at convict camps can be successfully ac- 

 comphshed only by doing away with their breeding places. Screens, 

 flytraps, sticky fly paper, and poisons all are useful in waging war 

 against them but are not, in themselves, sufficient. The fundamental 

 rule which should be enforced rigidly is that of absolute cleanliness of 

 the camp and its surroundings. Human excreta, garbage, and other 

 wastes must be protected from flies by methods described under para- 

 graphs dealing with those subjects, and such breeding places as 

 stables, chicken yards, and hogpens should be removed as far as 

 possible from the main structures. As flies seldom travel more than 

 500 yards from their breeding places, it follows that if the mess and 

 living quarters be separated from such places by at least that dis- 

 tance immunity from flies will be practically assured. But it is usu- 

 ally impracticable to locate the stable at such a remote distance, and, 

 since piles of manure are favorite breeding places, special measures 

 must be adopted for their disposal or treatment. The most practical 

 of such measures are outlined as follows : 



(1) The manure may be placed in covered barrels each morning 

 for removal by farmers at least twice a week, and the polluted 

 ground about corrals may be sprinkled with kerosene; (2) the 

 manure may be burned in an incinerator; (3) the borax treatment: 

 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 with a flour sifter or any fine sieve, par- 

 ticularly around the outer edges of the pile, and sprinkle 2 or 3 gallons 

 of water over the borax-treated manure.^ With regard to the effect 

 of this treatment upon the value of the manure as a fertilizer, it is 

 recommended that not more than 15 tons of the borax-treated 

 manure be apphed to an acre, as its effect has not been studied in 

 connection with all crops. With borax at from 5 to 6 cents per 

 pound the cost of the treatment will be about 1 cent per horse per 

 day, and if calcined colemanite be purchased in large quantities 

 the cost should be considerably less; (4) the hellebore treatment: 

 Apply to every 10 cubic feet (8 bushels) of manure a mixture of one- 

 half pound of powdered hellebore in 10 gallons of water. As in the 

 case of the borax treatment, special attention should be given to 

 the outer edges of the pile. This treatment is somewhat more expen- 

 sive than the borax treatment, the estimated cost per horse per day 



' Bullfftln No. lis, U. S. Oopartment of Agriculture: "Experiments in tlie Destruction of Fly I^arvac 

 In Horse Manure." Bulletin No. 245, " Further Experiments in the Destruction of Fly Larvae in Horse 

 Manure." , 



