360 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



When tested it was found to be neutral. The presence of acid in 

 garbage cans where the larvae do not occur seems to indicate that it is 

 the prohibitory factor. Paine (3) found the larvse of the house-fly- 

 abundant in garbage pails but no observations seem to have been made 

 as to the reaction of the contents of the pails which contained them. 

 Observations carried out under the supervision of Forbes (4) in 1908 

 and 1909 have shown that flies may breed in a great variety of sub- 

 stances. In studying over the list from which larvse were recorded 

 in these observations, it is interesting to note the small number of larvse 

 taken from material which often goes to make up garbage. Materials 

 which contained but a single larvse are: rotten cabbage stump, banana 

 peelings, cooked peas, and seepage from garbage pile. Other sub- 

 stances which might form a part of the contents of any garbage can 

 with the number of larvse each contained are: rotten bread and cake, 

 8; rotten watermelon and muskmelon, 14; rotten potato peelings, 12; 

 old garbage, city dump, 15; rotten carrots and cucumbers, 23. 

 Kitchen slop and offal was recorded as producing 193 larvae. Accord- 

 ing to the experiments recorded in Forbes' paper this latter might be 

 prohibitory to house-flies in two ways. It might be wet as the name 

 would indicate that it was, or it might be acid. If it was wet to satura- 

 tion and the larvse were found in it, then the results are the exact 

 opposite to those which I have obtained. It is ciuite possible that 

 flies are able to breed in fresh garbage before it has had time to rot or 

 become contaminated with any that has already rotted. Again, 

 large pieces of any substance may furnish a breeding place for a num- 

 ber of flies. A mixture of the contents of the can when fresh garbage 

 is added would undoubtedly prevent the laying of eggs upon fresh 

 garbage by flies. In all of the cases where garbage was used in these 

 experiments no large pieces of any one substance were taken. The 

 garbage taken was in a rotten condition and was so thoroughly mixed 

 that the substances which made it up could not be identified. 



Manure or garbage sprayed with an acid of a strength of .75 

 of one percent would undoubtedly be unfit as a breeding place for 

 flies. The dilution here suggested is so great that the cost would be 

 very little if "commercial" hydrochloric acid were used. This acid 

 which was used successfully in these experiments, when used in such 

 dilute proportions would very likely not destroy the value of manure 

 as a fertihzer. Undoubtedly any other acid would prove as good a 

 larvicide. Although the spraying of open piles was not attempted 

 owing to the lateness in the summer, it is believed that an acid spray 

 could be used with good chances of success. 



