got burrows down into the ground or out into the outer drier 



portions of the manure to go into its resting or pupa stage, 



before it hatches out as an adult fly. Fly maggots in 



manure may be destroyed by the use of borax or hellebore. 



Adult flies may be trapped or poisoned. The traps most 



commonly used consist of a wire cone in a • «« T * 



box or cage largely of wire, with bait under _/ _ . 



., . % 6 J . ' , ~ Fly Poisons 



the large lower opening of the cone. On 



leaving their food the flies go upward toward the light, 

 through the small opening, and into the cage, in which they 

 perish. For fly poisons the U. S. Public Health Service 

 recommends formaldehyde or sodium salicylate. For house- 

 hold use these solutions may be prepared by the addition of 

 three teaspoonfuls of either the 40 per cent, solution of 

 formaldehyde found on the market or the powdered sodium 

 salicylate to a pint of water. Nearly fill a glass tumbler 

 with the solution, place over this a piece of blotting paper 

 cut to a circular form and somewhat larger in diameter than 

 the tumbler, and over this invert a saucer. Invert the 

 whole device and insert a match or toothpick under the 

 edge of the tumbler, to allow access of air. The blotting 

 paper will remain in the proper moist condition until the 

 entire contents of the tumbler have been used and the 

 strength of the formaldehyde solution will be maintained. 

 A little sugar sprinkled upon the paper will increase the 

 attractiveness of the poison for the flies. 



The conquest of mosquito-borne disease is one of the most 

 brilliant triumphs of sanitation. The fact Th r 

 that yellow fever, the curse of tropical f y 

 America, was transmitted by the bite of _, 

 the Mdes mosquito was demonstrated by 

 Major Walter Reed and three other surgeons of the U. S. 

 Army in 1901, by experiments on themselves and other 

 volunteers, Jesse W. Lazear, one of the intrepid investi- 

 gators, giving his life for the cause. As a result of this dis- 

 covery the pestilence which had caused 750 deaths a year in 



33 



