June, '14] HUNTER: HOUSE-FLY DISCUSS'IOX ' 289 



of the heap has by this time become less attractive to the flies owing 

 to exposure and the fact that larvae have already worked over it. 



Reference was made earlier in the paper, in discussing the relative 

 merits of counts of larvae or of flies emerging as standards of compari- 

 son in judging insecticide values, to the diflEiculty of obtaining a fair 

 sample of a manure heap. This fact is emphasized by the foregoing 

 observations. Further, calculations have been made of the number 

 of flies which might be produced from larvae in a manure pile of a 

 given size based upon estimates of the number of larvae occurring in a 

 pound of manure. Such estimates are obviously far from accurate, 

 and while it m^ay be a good policy to impress the lay mind with poten- 

 tial dangers of a heap of stable refuse, we should not do so at the 

 expense of veracity. I am ashamed to admit that our knowledge of 

 the breeding habits of the house-fly in manure piled under various 

 conditions is by no means as complete as it should be and it is very 

 desirable that other workers should make observations on such habits 

 as the conclusions may prove of no little value in aiding the agri- 

 culturalist in the problem of the control of breeding places. If the 

 conclusions in regard to the peripheral breeding habits of the fly in 

 well-piled manure are correct, the advantage of storing in concrete 

 and wooden chambers receives material support. 



Me. L. O. Howard: Experiments have been carried on in Wash- 

 ington and New Orleans of a similar character to those given by 

 Doctor Hewitt and I would like to ask Mr. W. D. Hunter if he will 

 explain what has been done in this direction. 



Mr. W. D. Hunter: This year Doctor Howard inaugurated a 

 series of house-fly experiments in Washington, almost parallel with 

 Doctor Hewitt's. They grew out of the idea that Doctor Howard had 

 had for several years that the whole subject of the treatment of the 

 breeding places of the house-fly had not been sufficiently investigated. 

 The same idea Doctor Hewitt has mentioned occurred to Doctor 

 Howard, that is, the necessity for basing experiments upon considera- 

 tion of the effect of applications on the manure. At that juncture 

 Doctor Howard called upon the Bureau of Chemistry, and cooperative 

 experiments were begun, the Bureau of Entomology looking after the 

 entomological part of the work, and the Bureau of Chemistry to deter- 

 mine the effect of the different applications upon the chemical com- 

 position of the manure, and a bacteriologist was brought in at the 

 same time to determine the activity of the bacteria of the manure. 

 Without knowing, as far as I am aware, of the plans that Doctor Hewitt 



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