356 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



where the manure had been standing for any considerable length of 

 time it is quite certain that some of the ammonia passes off into the 

 air. With all of the manure examined there was mixed more or less 

 urine. No manure which had been standing for more than a day was 

 tested as it was known that flies do not lay their eggs in such if fresh 

 manure is present. The juice was extracted from a quantity of gar- 

 bage to test relatively its acidity. The complexity of garbage indi- 

 cates that a number of acids are usually present, these probably vary- 

 ing with the substances which are placed in the garbage can. No 

 effort was made to determine the acids which were present in any can 

 as this undoubtedly would vary with each can. It suffices to say 

 that there were enough acids present to neutralize an equal amount of 

 ammonia of a strength of .653 of a per cent. This per cent was found 

 to vary with the staleness or freshness of the material in the can. 

 In no case was acid found to be absent from garbage if it had stood for 

 some time and was rotten. 



After having found the relative amounts of alkali in manure and 

 acid in garbage a number of experiments were conducted to determine 

 if possible the maximum amounts of either of these substances which 

 the house-fly might be able to breed in. A quantity of manure was 

 brought into the laboratory and leached out with distilled water. 

 When thoroughly washed the remaining solid material was pressed 

 until all of the water possible was removed. A portion of this material 

 was placed in each of six bottles. Enough ammonia was added to 

 moisten well but not saturate the material. The ammonia varied in 

 strength in the case of each bottle, the actual strengths being as 

 follows: bottle 1, .001 per cent; bottle 2, .05 per cent; bottle 3, .1 per 

 cent; bottle 4, .7 per cent; bottle 5, 1.4 per cent; and bottle 6, 2.1 per 

 cent. A similar series of bottles was arranged with the difference that 

 hydrochloric acid was added to the manure instead of ammonia. The 

 strengths used in the various bottles were: bottle 1, .001 per cent; 

 bottle 2, .025 per cent; bottle 3, .05 per cent; bottle 4, .1 per cent; and 

 bottle 5, .561 per cent. In each bottle of both series was placed a mass 

 of eggs which had been laid by flies kept in confinement with meat. 

 Each bottle was then corked to prevent the escape of its contents. 



After standing for several days in the laboratory the following ob- 

 servations were made: bottles 1, 2, 3 and 4 of the alkaline series con- 

 tained a large number of larvae. In bottle 5 but two larvse had hatched. 

 In bottle 6 but one had appeared. In both these last named bottles 

 numbers of eggs had not hatched. No effort was made to determine 

 w^iether all of the eggs had hatched in the other bottles as the number 

 •of larvse present indicated that a large percentage had. The larvse 

 in this series pupated and metamorphosed into adults in a regular 



