534 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 10 



The flies used in the experiments were caught in fly traps and Hber- 

 ated in a cage 6 x 6 x 21 feet square in which the apparatus was set 

 up on a level table. This cage had the roof and one side solid while 

 the ends and west side were of wire screen. Flies of various species 

 were liberated in the cage but all of the eggs obtained in the course of 

 the investigation were placed in a breeding chamber and the house-fly 

 was the only species obtained from the large number of flies bred. 



The tests were run from about 10.30 in the morning until 4.00 in 

 the afternoon and at the close of the exposure the funnels were removed 

 and the number of eggs in each recorded. The flies distributed them- 

 selves about equally upon the series of funnels and exhibited no notice- 

 able tendency to congregate especially at any of the odors tested. 

 Only in the case of the strongest dosages of ammonia was there a dis- 

 tinct repellent effect after the experiment had been run for several hours. 



In the following tables the results of our experiments are summarized : 



Table 1. — Comparison of Results Obtained with Carbon Dioxide and Air 



The above series of experiments consists of two divisions, as indi- 

 cated, in one of which the conditions in the two sets of apparatus were 

 duplicated, air being forced through the bran in the checks after 

 bubbling through water, while in the other no current of air was pro- 

 vided for the checks to correspond with the gentle current produced 

 by the evolution of carbon dioxide. There was also another difference 

 in the two divisions. In the first the two sets of units were intermingled 

 and set only from 4 to 6 inches apart while in the other the checks 

 were grouped at one end of the series so as to reduce the possibility of 

 their being influenced by the proximity of the funnels evolving car- 

 bon dioxide. It will be noted that the checks intermingled closely 

 with the carbon-dioxide units and emitting air at the rate of from 10 

 to 250 bubbles per minute yielded practically the same average num- 

 ber of eggs as those checks which were isolated and without air cur- 

 rent. 



